# Shop Heating



## jbolt (Nov 9, 2021)

Wondering what others are using to heat their shops?

My shop came with a fuel-oil heater that sat on the floor in the back and was gravity feed from a 275 gal tank outside. The shop at that time was not insulated or finished inside. I have now insulated and drywalled. Also had an insulated overhead door installed so the temperature swings are fairly mild if kept closed up. 

I left the flue for the oil heater in place thinking I might reuse it. Now as I am finally able to start placing equipment and such I don't want the heater where it is nor do I think I want to deal with fuel-oil. I don't think fuel-oil is commonly used here. Electricity or propane seem to be the norm for those of us out in the sticks.

Shop is 900 sf interior with 12' ceiling.


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## Reddinr (Nov 9, 2021)

I'm also working on a solution.  Right now I'm using a propane-fired room heater like one of the industrial ones you might see in a warehouse.  It heats quickly but it is noisy and it short cycles.  I'm thinking about augmenting with a mini-split.  Maybe use the propane heater for quick heat and then maintain with the mini-split.  I'm staying posted for other ideas.


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## Cadillac (Nov 9, 2021)

Look into infrared heaters they are very efficient. They are what are hanging over The registers at a Home Depot. They heat everything in its path. Another good heater are the tube type radiant heaters. It’s a 4” tube ran along the ceiling area. Can be had in different lengths. Seen them sold in northern tools catalogs Same as the infrared heaters. Electric would be the most expensive


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## woodchucker (Nov 9, 2021)

jbolt said:


> Wondering what others are using to heat their shops?
> 
> My shop came with a fuel-oil heater that sat on the floor in the back and was gravity feed from a 275 gal tank outside. The shop at that time was not insulated or finished inside. I have now insulated and drywalled. Also had an insulated overhead door installed so the temperature swings are fairly mild if kept closed up.
> 
> ...


Oil is very efficient. Much more so then electricity. You can run your heater even if the electricity is out on a small generator.
I guess W coast different from E coast. On the E Coast, oil is predominant in rural areas. Propane too, but w/propane if you want to change companies, you need to change tanks... They rent them to you. Some submerge them underground, and have to dig them up... so changing companies becomes costly. And companies here know that and F with you.  Oil remains a good deal.   Also propane does not give as many btu as oil, or natural gas.


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## jbolt (Nov 9, 2021)

Cadillac said:


> Look into infrared heaters they are very efficient. They are what are hanging over The registers at a Home Depot. They heat everything in its path. Another good heater are the tube type radiant heaters. It’s a 4” tube ran along the ceiling area. Can be had in different lengths. Seen them sold in northern tools catalogs Same as the infrared heaters. Electric would be the most expensive


I have used portable infrared heaters. I would assume you would need something to circulate air for even heating?

I have not seen the tube type radiant heaters. I will have to check it out.

I'm not real keen on electrical units. Cost to operate and eating up some of the electrical load. 

I have been looking at the vented propane ceiling mounted heaters. Simple to install. I believe the code allows for up to two 100 gal propane tanks to be installed next to the building so I wouldn't have to put in a tank away from the building and run pipe underground.


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## jbolt (Nov 9, 2021)

woodchucker said:


> Oil is very efficient. Much more so then electricity. You can run your heater even if the electricity is out on a small generator.
> I guess W coast different from E coast. On the E Coast, oil is predominant in rural areas. Propane too, but w/propane if you want to change companies, you need to change tanks... They rent them to you. Some submerge them underground, and have to dig them up... so changing companies becomes costly. And companies here know that and F with you.  Oil remains a good deal.   Also propane does not give as many btu as oil, or natural gas.


I have the heater, tank and flue but I don't want it on the floor. I don't know enough about them to know if it or some other type of oil burner could be mounted off the floor.


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## matthewsx (Nov 9, 2021)

jbolt said:


> Wondering what others are using to heat their shops?
> 
> My shop came with a fuel-oil heater that sat on the floor in the back and was gravity feed from a 275 gal tank outside. The shop at that time was not insulated or finished inside. I have now insulated and drywalled. Also had an insulated overhead door installed so the temperature swings are fairly mild if kept closed up.
> 
> ...


Heating your shop in Mountain View is very different from my old one in Northern Michigan. 

I was talking with my HVAC guy in Elk Rapids a few weeks back and he strongly recommends heat pump technology (mini-splits). What he told me was using any kind of fuel to heat air or water gives a max of ~97% efficiency, where heat pumps can hit ~300%. 

I had a natural gas IR heater in my 2400 sqft. shop building in Michigan and it worked great, also have a small Mr. Heater in our garage there. 

The HVAC guy who's shop is in the same town is planning on switching over to mini-splits soon so there's that....

It's probably worth checking with a local company but if it was me I'd put in a mini-split since it gives you cooling as well as heating. The one we have in our bedroom is on a 15A 110v circuit and it keeps the place warm when it's way below freezing. It's also on the same sub-panel as our hot tub and it's never been a problem. We didn't see any increase in our electric bill.

John


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## ddickey (Nov 9, 2021)

I use a heat pump until it gets real cold then infloor heated by natural gas. At least that's the plan.


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## rabler (Nov 9, 2021)

I'll second the mini-split, as you get heat and AC, and at least the one I'm using also offers a dehumidifier mode, which I haven't really tested as my shop already had a dehumidifier.  I have a 24x32x12 space that is only lightly insulated and a 15k BTU unit does nicely in this climate.

The efficiency of a heat pump for heating does decrease as outside temp goes down (really, as the difference in temperature between the outside air and the inside air), so when the temperature difference gets more than ballpark 40 or 50 degrees F you may want an alternate heat source.

My new shop will have a wood stove, mini-split, and I'm trenching a natural gas line but don't plan on connecting that for anything right now.


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## woodchucker (Nov 9, 2021)

matthewsx said:


> Heating your shop in Mountain View is very different from my old one in Northern Michigan.
> 
> I was talking with my HVAC guy in Elk Rapids a few weeks back and he strongly recommends heat pump technology (mini-splits). What he told me was using any kind of fuel to heat air or water gives a max of ~97% efficiency, where heat pumps can hit ~300%.
> 
> ...


I didn't know that you could exceed 100% when talking heating or AC.
The colder the environment the less a heat pump works. 

just looked it up, it's impossible for any heating system to reach 100% efficiency.  PERIOD!  He was lying to you.


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## jwmelvin (Nov 9, 2021)

woodchucker said:


> just looked it up, it's impossible for any heating system to reach 100% efficiency. PERIOD! He was lying to you.



That’s the beauty of the Carnot cycle. It moves heat, rather than using an energy source to provide heat directly. So it can move more heat energy than it requires in electric energy. Air conditioners and heat pumps can achieve greater than 100% “efficiency” when you define efficiency as the heat added or removed from the room divided by electricity consumed.


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## jbolt (Nov 9, 2021)

I updated my profile. I'm not in CA anymore. Now in Southern Oregon so a little colder in the winter and a little hotter in the summer.

I only have 60A to the shop so not sure what a heat pump would require. I'm not sure I really need AC in the shop.


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## woodchucker (Nov 9, 2021)

jbolt said:


> I updated my profile. I'm not in CA anymore. Now in Southern Oregon so a little colder in the winter and a little hotter in the summer.
> 
> I only have 60A to the shop so not sure what a heat pump would require. I'm not sure I really need AC in the shop.


Oregon is hotter than CA in the summer? Because of humidity or temp?


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## matthewsx (Nov 9, 2021)

I'm glad someone else on here has the technical info on how this stuff works.

Kevin (K&K Heating) is a trusted friend, I've worked side by side with him and his crew during ice storm emergencies where we had to run generators to keep our customers pipes from freezing. He's not someone who's ever lied to me or anyone I know AFAIK, just doesn't work running a service business in a small town.

Our mini-split in Michigan works fine from -12 to 90 degrees F so far, and it consumes a negligible amount of electricity. It's 21's century technology that doesn't depend on combustion (at least at point of use).

Like I said, consult with someone who does it for a living. Kevin plans on changing his shop over soon, I've watched him grow his business from one van to an entire fleet with a dozen techs, so I think he knows a thing or two....

John


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## rabler (Nov 9, 2021)

woodchucker said:


> just looked it up, it's impossible for any heating system to reach 100% efficiency. PERIOD! He was lying to you.


It is a cheating number. Efficiency (or any %) is really a ratio of two things.  But you can play games with what you are counting.  Electric resistive heat is pretty close to 100% if you count watts of electricity at your power meter vs watts of heat produced.  Only inefficiency is the very slight heat lost in the wires from your meter to the actual heater.

But, if you use a heat pump, you can essentially create more heat in a room than watts of electricity used. The extra "energy" comes from cooling the great outdoors. So the argument really is a heat pump produces 3x as much heat as a resistive heater for the same amount of electricity used. _"Therefore it is 3x as efficient."  _ Since most people care about heat produce per $ of electric bill, it is true on a watts per dollar basis.


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## matthewsx (Nov 9, 2021)

Not gonna get into a debate here, yes I know about the second law of thermodynamics. This man taught me about it.









						A very special day
					

US manned space flight resumes today. Watching it from a laptop on top of my dad's old workbench.  https://www.spacex.com/launches/  John




					www.hobby-machinist.com
				




Pretty sure when you talk about efficiency it's in comparison to something else, (ie. radiant gas heat), so relevant for this conversation.

John


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## rabler (Nov 9, 2021)

jbolt said:


> 60A to the shop so not sure what a heat pump would require


The Pioneer mini-split uses 6.8amps at 240V for their 18,000 BTU unit. I believe that's running amperage not startup, but they are inverter (VFD) based so I would imagine the startup surge is not horrid.


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## woodchucker (Nov 9, 2021)

matthewsx said:


> Not gonna get into a debate here, yes I know about the second law of thermodynamics. This man taught me about it.
> 
> 
> 
> ...


wow, your dad skipped 2 grades. very impressive. Not many men fly across the country in a small plane. Yes many do, but many don't.
that's a tough task navigating and flying at the same time across the country.  Is he still around?


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## woodchucker (Nov 9, 2021)

rabler said:


> The Pioneer mini-split uses 6.8amps at 240V for their 18,000 BTU unit. I believe that's running amperage not startup, but they are inverter (VFD) based so I would imagine the startup surge is not horrid.


I'll be installing a Mr Cool mini split with my son possibly this weekend if it gets here Friday like it's supposed to.  
I guess I am having a hard time understanding how something is more efficient than 100%.. I guess I'm thick..


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## rabler (Nov 9, 2021)

matthewsx said:


> Pretty sure when you talk about efficiency it's in comparison to something else, (ie. radiant gas heat), so relevant for this conversation.
> 
> John


The real question is 'Why do I care how efficient it is?'.    For the same technology, more efficient should mean less cost, but comparing electric heat pumps to combustion heat is apples to oranges, given that it is unlikely your energy sources cost the same.


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## RJSakowski (Nov 9, 2021)

matthewsx said:


> ..............................
> I was talking with my HVAC guy in Elk Rapids a few weeks back and he strongly recommends heat pump technology (mini-splits). What he told me was using any kind of fuel to heat air or water gives a max of ~97% efficiency, where heat pumps can hit ~300%.
> .............................
> 
> ...


The rest of the story re: heat pumps is their maximum efficiency occurs when the temperature difference between the heat source and the heat sink is near zero.  As the temperature difference increases, the efficiency drops rapidly.  A heat pump using a geothermal source is the best bet as ground temperature is fairly constant year around.  At my location, the temperature is around 54ºF so heating a shop to 65º is still fairly efficient.  Properly utilizing ground heat requires some rather sophisticated equipment.  One way that it is done is to use a deep well as the source with a closed loop for the refrigerant.  There are open loop systems as well but there is a risk of contaminating the ground water. Another way would be to use a large buried tank.

Simple electrical resistance heating is 100% efficient.  The problem is that it is relatively expensive and best used in low demand situations like mild climates  or low use areas.  My attic workshop has both a mini split heat pump and baseboard resistance heating.  The workshop is normally isolated from the rest of the house and isn't heated unless in use.  The space has the chimney from our wood furnace running through the center and this will keep the space at around 55 - 60º when unoccupied.   I use the resistance heating to bump the temperature up to  65 or 70º when I want to work up there.  If the outside temperature is above freezing, I will use the heat pump to maintain the working temperature; otherwise. I use the baseboard heating.


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## jwmelvin (Nov 9, 2021)

rabler said:


> The real question is 'Why do I care how efficient it is?'. For the same technology, more efficient should mean less cost, but comparing electric heat pumps to combustion heat is apples to oranges, given that it is unlikely your energy sources cost the same.



That’s a useful position but I think it means only that you’d like to compare heating options by BTU/hr/$. That’s not really so hard to do.


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## RJSakowski (Nov 9, 2021)

jwmelvin said:


> That’s the beauty of the Carnot cycle. It moves heat, rather than using an energy source to provide heat directly. So it can move more heat energy than it requires in electric energy. Air conditioners and heat pumps can achieve greater than 100% “efficiency” when you define efficiency as the heat added or removed from the room divided by electricity consumed.


A heat pump operating in refrigeration mode is always less than 100% efficient.  Operating in heating mode, it is more than 100% efficient although for large temperature differences, the efficiency is not much greater than 100%.  Also, the actual efficiency depends upon design and will always be less than the theoretical efficiency.


rabler said:


> The real question is 'Why do I care how efficient it is?'.    For the same technology, more efficient should mean less cost, but comparing electric heat pumps to combustion heat is apples to oranges, given that it is unlikely your energy sources cost the same.


Well put.  The bottom line is what is the cost in $/Btu.


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## matthewsx (Nov 9, 2021)

woodchucker said:


> wow, your dad skipped 2 grades. very impressive. Not many men fly across the country in a small plane. Yes many do, but many don't.
> that's a tough task navigating and flying at the same time across the country.  Is he still around?


Sadly we lost him in 2018, I do my best to keep his memory alive and live the best life I can with what he taught me.

I do have the two machine tools and workbench in the photo....

John


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## vtcnc (Nov 9, 2021)

Small shop in VT. About 16x24. Installed a 12Kbtu mini-split. Haven't been through a winter yet with it. Ask me in February when it starts to warm up a bit how it works out. For cooling in the summer, it was the best.


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## rabler (Nov 9, 2021)

RJSakowski said:


> . The bottom line is what is the cost in $/Btu.


Maybe.  I’d compare that to time to recoup the installation cost.  (Is $ total cost or just energy cost?).  A simple resistive baseboard heater is cheap.  Heat pumps are costly and have ongoing maintenance.   And unlike a home, heating probably isn’t 24/7

Rather than apples to oranges, maybe we’re comparing technical jargon to marketing jargon


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## woodchucker (Nov 9, 2021)

So got a question, my son went to get paperwork for the permits, and his local town was not helpful... surprise surprise.
He was trying to get an electrical permit for the new sub panel and another for the mini split.  They want him to calculate the whole house.

Do you need a permit usually for a mini split?


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## matthewsx (Nov 9, 2021)

woodchucker said:


> So got a question, my son went to get paperwork for the permits, and his local town was not helpful... surprise surprise.
> He was trying to get an electrical permit for the new sub panel and another for the mini split.  They want him to calculate the whole house.
> 
> Do you need a permit usually for a mini split?


We did not, I ran the electrical for ours.

John


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## rabler (Nov 9, 2021)

woodchucker said:


> So got a question, my son went to get paperwork for the permits, and his local town was not helpful... surprise surprise.
> He was trying to get an electrical permit for the new sub panel and another for the mini split.  They want him to calculate the whole house.
> 
> Do you need a permit usually for a mini split?




Personally, I suspect they do some of these things to steer you toward hiring an electrician over DIY. I suspect they get tired of people wanting the permit office to walk them through the whole design.


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## woodchucker (Nov 9, 2021)

rabler said:


> Personally, I suspect they do some of these things to steer you toward hiring an electrician over DIY. I suspect they get tired of people wanting the permit office to walk them through the whole design.


he is hiring an electrician to put the sub panel in, the guy is reluctant to pull a permit , and he's a licensed electrician. That panel will be off the cut off switch by the meter. His house has an outdoor cut off switch... I have not seen that before seems weird.


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## matthewsx (Nov 9, 2021)

When we upgraded our home from 60 to 200 amps I had them install an outside cutoff. That way I can work on the panel, also have an input for my generator and have a way to isolate from the grid.

John


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## rabler (Nov 9, 2021)

woodchucker said:


> he is hiring an electrician to put the sub panel in, the guy is reluctant to pull a permit , and he's a licensed electrician. That panel will be off the cut off switch by the meter. His house has an outdoor cut off switch... I have not seen that before seems weird.


I believe that is driven by having a place for the fire department to kill power before hosing down the building.


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## jwmelvin (Nov 9, 2021)

RJSakowski said:


> A heat pump operating in refrigeration mode is always less than 100% efficient.



I’m curious why you say that.


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## RJSakowski (Nov 9, 2021)

woodchucker said:


> So got a question, my son went to get paperwork for the permits, and his local town was not helpful... surprise surprise.
> He was trying to get an electrical permit for the new sub panel and another for the mini split.  They want him to calculate the whole house.
> 
> Do you need a permit usually for a mini split?


I went with the MrCool DIY system, chiefly because it didn't require a certified HVAC person.  I didn't need a permit for installing my mini split.  I ran my own electrical and did the complete install myself.


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## woodchucker (Nov 9, 2021)

I would have no problem running the electrical off the sub panel, but not putting in the sub from the cut off. 
He and I will be installing the Mr Cool before the electrical guy.


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## Dabbler (Nov 9, 2021)

I'm in Calgary.  We get to -40 (C or F you pick) most winters, but not for long.  I heat with natural gas with a 50K BTU unit 

BUT

It is far more important to consider your insulation, especially your floor.  Here NatGas was very cheap until a few years ago.  Now I'm adding insulation in my 600 sq ft shop, as it has begun costing as much to heat it to 5C as my house to 23C  (40F and 75F)


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## woodchucker (Nov 9, 2021)

My latest remodel in my bathroom, I used rockwool it is way warmer than your standard insulation. I believe thats due to its density in preventing the wind from getting through it.

It has a few advantages.
The mice don't like it.
It doesn't get wet if you have a leak or flood.
I use pieces when using a torch near a finished cabinet.. it's flame retardant.  I also use it to keep the heat in while heating something.
It's recycled metal slag..

Foam has the disadvantage of if it's installed incorrectly it may not cure. If it doesn't cure, it can be toxic to you.  If it is done right, it's probably the best insulation but it is not as fire retardant. It is a retardent, but not AS powerful a retardent.


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## 7milesup (Nov 10, 2021)

woodchucker said:


> My latest remodel in my bathroom, I used rockwool it is way warmer than your standard insulation. I believe thats due to its density in preventing the wind from getting through it.


I could write a white paper on that comment.  
Closed-cell foam.
Open-cell foam (although the difference is minuscule compared to open-cell foam).
Dense pack cellulose.
Rock wool.
Fiberglass.
Wood shavings.
Nothing.

The above is the general order of insulating value, but it is a lot more complicated than there is space to write here.  If the wind is getting through your walls, you have bigger issues than the type of insulation, but if the wind is actually blowing through your walls, spray foam is your only option.   The "wind" that you (or your contractor) might be talking about is convection.  Each stud bay develops a micro convection current within the wall and the degree to which that convective current develops is dependant upon the delta between the inside and outside temperatures.  This is why fiberglass loses "R" value as the outside temperature drops.  Spray foam prevents this convection within the wall and therefore maintains nearly all of its "R" value as the temp drops.  I could go on....

I heat my shop with wood heat since we own property that is completely wooded.  A year ago I installed an 18k BTU Friederich mini-split.  The air conditioning is awesome and does a wonderful job of cooling my 1300 sq ft shop.  It also does a superb job of heating it, or at least taking the chill out until my wood stove is making heat.  I installed the mini-split myself but had a friend (HVAC pro) come over and charge it up with refrigerant. 
I also have the tubes for in-floor heat installed, but with the rising cost of propane, that option is going to sit there for the foreseeable future.  I have in-floor heat in the lower level of my house and there is nothing better. I also have it in my garage so doing oil changes are almost pleasurable.

Radiant tube heaters are fantastic too, but there is a minimum distance that they can be mounted at.  12-foot ceilings would probably work but check the specs on them.  No air is circulated with radiant because it heats objects, not air.  Actually, heating air and moving it around is quite inefficient.


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## vtcnc (Nov 10, 2021)

jbolt said:


> I updated my profile. I'm not in CA anymore. Now in Southern Oregon so a little colder in the winter and a little hotter in the summer.
> 
> I only have 60A to the shop so not sure what a heat pump would require. I'm not sure I really need AC in the shop.



My 12k unit is on a single pole 20A 120V dedicated circuit.


Sent from my iPhone using Tapatalk


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## vtcnc (Nov 10, 2021)

woodchucker said:


> So got a question, my son went to get paperwork for the permits, and his local town was not helpful... surprise surprise.
> He was trying to get an electrical permit for the new sub panel and another for the mini split. They want him to calculate the whole house.
> 
> Do you need a permit usually for a mini split?



I can’t imagine why you would need one.


Sent from my iPhone using Tapatalk


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## pineyfolks (Nov 10, 2021)

I use a 150000 btu space heater in my pole building when I have to go out in the winter. I also have an infrared heater over my work bench. The space heater is noisy and it raises the temperature so fast everything will start to sweat without the ceiling fans on. I'd prefer to have all infrared heaters in my shop.


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## BGHansen (Nov 10, 2021)

My shop is 32' x 40' with a 10' ceiling.  Walls have 8" of insulation, 12" in the attic.  I went with a Mr. Heater Maxx 125,000 BTU propane unit, rated for ~3300 sq. ft.  I could have gotten away with a 55,000 or 85,000 unit, but went with the 125,000.  I leave the shop at 40 F.  The heater is hooked to a Google Nest thermostat which lets me kick the heat on remotely.  That's not much of an issue with the overkill on the heater; it'll heat the shop from 40 F to 55 F in 10 minutes.  

The heater is in one corner of the shop and blows across the room.  There are 3 ceiling fans on the opposite side that blow air up at their lowest setting.  I initially had the ceiling fans on high but felt the cool breeze when working at the far wall.  My shop has a clock/thermometer about 8' high on the wall opposite the heater.  The thermostat is on an adjacent wall about 4' high.  When the heater kicks on, the air by the thermometer is about 5 F warmer than the thermometer.  Once the heater kicks off it only takes a few minutes for the ceiling air temp to match the thermostat.  I was surprised how little air movement was needed to normalize the temp.

The overhead heater is not annoyingly loud, but loose papers on my workbench go for a ride when the fan kicks on.  A couple of threads with my installation are below.

Bruce










						POTD- PROJECT OF THE DAY: What Did You Make In Your Shop Today?
					

I lived in New England and New York State (A LOT of deer) for many years, and a lot of folks I knew had those deer whistles. I also knew a lot of folks that hit deer, and a lot of them had the whistles - A mixed bag, at best I've had deer run into the SIDE of my vehicles a couple times - I mean...




					www.hobby-machinist.com
				











						POTD- PROJECT OF THE DAY: What Did You Make In Your Shop Today?
					

I lived in New England and New York State (A LOT of deer) for many years, and a lot of folks I knew had those deer whistles. I also knew a lot of folks that hit deer, and a lot of them had the whistles - A mixed bag, at best I've had deer run into the SIDE of my vehicles a couple times - I mean...




					www.hobby-machinist.com


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## jbolt (Nov 10, 2021)

BGHansen said:


> My shop is 32' x 40' with a 10' ceiling.  Walls have 8" of insulation, 12" in the attic.  I went with a Mr. Heater Maxx 125,000 BTU propane unit, rated for ~3300 sq. ft.  I could have gotten away with a 55,000 or 85,000 unit, but went with the 125,000.  I leave the shop at 40 F.  The heater is hooked to a Google Nest thermostat which lets me kick the heat on remotely.  That's not much of an issue with the overkill on the heater; it'll heat the shop from 40 F to 55 F in 10 minutes.
> 
> The heater is in one corner of the shop and blows across the room.  There are 3 ceiling fans on the opposite side that blow air up at their lowest setting.  I initially had the ceiling fans on high but felt the cool breeze when working at the far wall.  My shop has a clock/thermometer about 8' high on the wall opposite the heater.  The thermostat is on an adjacent wall about 4' high.  When the heater kicks on, the air by the thermometer is about 5 F warmer than the thermometer.  Once the heater kicks off it only takes a few minutes for the ceiling air temp to match the thermostat.  I was surprised how little air movement was needed to normalize the temp.
> 
> ...


How much fuel does your heater use?

The mini-splits seem to be highly recommended but have a higher initial install cost. All in I figure a 24Kbtu mini-split would be about $2.2k. A 50Kbtu propane unit is $1k.

AC sounds nice but summers are not excessively hot here. When ever possible I prefer having the shop door open so I'm not sure how much I would use the AC. If I have AC I might be inclined to use it so the would increase the annual operating cost.

So it comes down to cost to operate. When will the higher cost to run fuel overtake the offset in cost to install?


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## rabler (Nov 10, 2021)

My current shop, 30x32x8 has a 80,000 BTU Mr. Heater NG heat, and as others have mentioned it is an overkill.  The new shop, 40x56x12, I'll probably put in another 80000 BTU unit, I just can't see needing the 125000 BTU for this climate.


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## RJSakowski (Nov 10, 2021)

jwmelvin said:


> I’m curious why you say that.


This is a bit confusing and I spent a few hours last night trying to get my head around it   My original conception goes back to my college physics class almost 60 years ago and details are kind of murky.  Late hours, combined with age and a glass of brandy don't help with the recall.

In viewing the equations for the coefficient of performance (COP) , as shown on Wikipedia (ihttps://en.wikipedia.org/wiki/Coefficient_of_performance), it appears for heat energy  extracted by a heat pump in cooling mode, the COP will exceed 1 under most conditions.

However, I am reassured in my recall by this quote in the opening paragraph in the above link: _"Most air conditioners have COP of 2.3 to 3.5. Less work is required to move heat than for conversion into heat, and because of this, heat pumps, air conditioners and refrigeration systems can have a coefficient of performance greater than one. However, this does not mean that they are more than 100% efficient, in other words, no heat engine can have a thermal efficiency of 100% or greater."._

However, from a practical point of view, we are interested how much energy it takes to move a certain amount of heat energy from a cooler temperature to a higher temperature and the COP is a good indicator.


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## jwmelvin (Nov 10, 2021)

Yes for sure the laws of thermodynamics remain intact. When discussing “efficiency” for purposes of heating or cooling, it is a very different question. I appreciate the follow up. 

Since I have a boiler and hydronic heating in some areas of the house, I’m working on a hydronic unit heater for my shop. That said, I remain very tempted by a mini split.


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## Winegrower (Nov 10, 2021)

My shop is about 30x25.   The climate here is rarely freezing in winter, never really needs AC in summer.    I have a 135,000 BTU propane heater that is too big,  a 35,000 BTU that is too small, so I added infrared heaters over the lathe area and the mill area.  That works fine, even at $0.40/KWh if I work out there all day, it’s $4 or $5, and I break more than that in end mills.   So it’s not too expensive, and much more convenient.   If I have visitors I can heat the joint up, if it’s just me I wear an insulated vest.


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## westerner (Nov 10, 2021)

My shop is 24x28x10, R11 fiberglass in the walls, R19 fiberglass in the lid. 5/8 sheetrock, firetaped only. 
We are at 7200 ft. elevation, in an area with some trees, and shelter from direct wind. (usually).
The shop has a 55 gal. drum woodstove, and nothing else for heat other than two 4x4 single pane windows facing southwest. 

Last winter was my first one retired. I spent ALOT of time in the shop, lucky me. Burned about 2.5 cords of pine in the shop alone. 
The house has a propane forced air furnace that I hate, and a state of the art airtight woodstove that I LOVE. That stove likes oak, and burns it efficiently. The drum stove has very little thermal mass, and so does not work well with fuels less combustible than pine. 

Sometimes I wish the shop had a more efficient stove with more mass and heat retention. Sometimes, tho, I really appreciate the fact that the drum stove gets to radiating its heat quickly. It does not take long at all to drive the chill out in the morning.


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## Alcap (Nov 11, 2021)

This will be the third winter at this house and still trying to decide what way to heat the garage . Block 30 x 40’ approx . The only insulation is on the ceiling 9’ . The garage doors are new and insulated . 7 old windows 5x5 that probably came from a factory being torn down . Lots of ways for heat loss , at least now .  The guy had a wood stove sort of in the center but had a long flue pipe almost horizontally to the outside wall . I’m pretty sure that’s a bad idea but it was probably like that for 50+years . Ive tried one of those propane heaters from Tractor Supply https://www.tractorsupply.com/tsc/p...MIoO3n_pGQ9AIVA3xvBB10DAntEAQYBiABEgIaUfD_BwE it does throw some heat and if you put a small box fan will get it towards you but after I went through a gas grill size bottle in a few times out there I shut it off  as much as I can .   Hoping to find some ideas from you ( that’s my son‘s bike I’d be scared to ride it )


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## BGHansen (Nov 11, 2021)

jbolt said:


> How much fuel does your heater use?
> 
> The mini-splits seem to be highly recommended but have a higher initial install cost. All in I figure a 24Kbtu mini-split would be about $2.2k. A 50Kbtu propane unit is $1k.
> 
> ...


I used about 200 gallons of propane last year.  We'd locked in at $1.60/gallon so under $350 to keep it at 40 F 24/7, then 55 F when I spent more than an hour in the shop.  I went with the 125,000 BTU to be able to quickly heat up the shop.  Way overkill, but it'll take it from 40 F to 55 F in 10 minutes.  I have no real data on the 80,000 unit, so guessing it at 20 minutes to heat up the shop.

All of the Maxx units I looked at are 85% efficient.  Sure, my 125,000 is putting more out the stack when it's running, but it doesn't run as often.  The 80,000 and 125,000 both needed 1/2" black pipe for the gas supply and used the same vent stack kit.  I bought mine from Menards during an 11% rebate period.  The heater was $700, vent stack $100, probably around $50 for the 1/2" black pipe (shut off valve, elbows, straight pipe, etc.), ~$20 for the flex-line with a second shut off valve, $30 for the length of 14/2 NMB (including a 15A breaker and box), $10 for the thermostat wire, $20 for some threaded rod to hang it.  It was well under $1000 after the rebate.  I bought a $13 manual thermostat but my wife gifted me a Google Nest thermostat for Christmas at around $150.  At the time, the 80,000 BTU unit was $500, I went with the 50% larger unit for the extra $200.  

In the end, spent $1000 to heat the shop up 15 F in 10 minutes vs. $800 to heat it up in 20 or more.  The fuel used would be the same, plus the installation cost/work.  I figured it'd be the last heater I'd ever buy so went overkill big.  I would GLADLY do it again as the comfort level is PRICELESS!  

My shop in the middle of summer has gotten up to the low 80's inside.  The ceiling fans go from blowing up in the winter to down in the summer.  I don't have a problem with rust as the air movement keeps things from accumulating condensation though I do oil all of the cast iron surfaces.

Bruce


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## 7milesup (Nov 11, 2021)

To note:
An oversized air conditioner is a no-no.  An oversized AC unit will have short cycle times, which does not allow it to properly dehumidify the air and therefore the comfort level will be much lower.
With an oversized heater, much larger temp swings will be experienced, also resulting in lower occupant comfort.  Probably not a big deal in a shop but certainly noticeable in a house.

This is not at all a jab at you Bruce, it was just a best-practices standard that came to my mind while reading through this thread.


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## RJSakowski (Nov 11, 2021)

7milesup said:


> To note:
> An oversized air conditioner is a no-no.  An oversized AC unit will have short cycle times, which does not allow it to properly dehumidify the air and therefore the comfort level will be much lower.
> With an oversized heater, much larger temp swings will be experienced, also resulting in lower occupant comfort.  Probably not a big deal in a shop but certainly noticeable in a house.
> 
> This is not at all a jab at you Bruce, it was just a best-practices standard that came to my mind while reading through this thread.


 I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.

My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off.  As I understand it, the heat pump varies it's output according to demand.  The only time that I hear the compressor kick in is when I make a change in temperature.  The interior fan remains on all the time the unit is powered on but slows to a crawl as well.  The exterior fan will cycle off and on depending upon compressor and condenser cooling demands.  Room temperature remains constant at the set temperature.

Presumably, other state of the art mini splits use similar technology.


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## Winegrower (Nov 11, 2021)

BGHansen said:


> The ceiling fans go from blowing up in the winter to down in the summer.



Here is a very minor controversy.  I recently installed a ceiling fan in the shop, and the manual said to blow up in summer, down in winter.   Which is right?  Is there a correct answer for this, does it depend on shop geometry, etc?


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## BGHansen (Nov 11, 2021)

Winegrower said:


> Here is a very minor controversy.  I recently installed a ceiling fan in the shop, and the manual said to blow up in summer, down in winter.   Which is right?  Is there a correct answer for this, does it depend on shop geometry, etc?


I've always run them just the opposite; down in the summer, up in the winter.  Key thing is keeping the air circulating.  I prefer the up in winter so I'm not feeling a draft.  Here's an answer from Google asking "ceiling fan up or down in winter".

Bruce


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## rabler (Nov 11, 2021)

Yep, ceiling fan direction is a question of wind chill.


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## 7milesup (Nov 11, 2021)

RJSakowski said:


> I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.
> 
> My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off.  As I understand it, the heat pump varies it's output according to demand.  The only time that I hear the compressor kick in is when I make a change in temperature.  The interior fan remains on all the time the unit is powered on but slows to a crawl as well.  The exterior fan will cycle off and on depending upon compressor and condenser cooling demands.  Room temperature remains constant at the set temperature.
> 
> Presumably, other state of the art mini splits use similar technology.


Correct RJ.  I should have been more clear that I was referring to conventional heating and cooling systems. The mini-splits utilize inverter technology so have that wonderful ability to ramp up and down. 
I built a new house in 2019 and the whole house A/C does not have that ability.  My furnace has a two level burner in it that will adapt to some extent for changing conditions, but not like a mini-split will.


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## Winegrower (Nov 11, 2021)

On fan direction:  Well, there you have it, I suppose.   I'll switch it around and see which I like best.  Perhaps it doesn't make a lot of difference, just having a fan stirring things up is most of the solution.


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## rabler (Nov 11, 2021)

RJSakowski said:


> I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.
> 
> My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off.  As I understand it, the heat pump varies it's output according to demand.  The only time that I hear the compressor kick in is when I make a change in temperature.  The interior fan remains on all the time the unit is powered on but slows to a crawl as well.  The exterior fan will cycle off and on depending upon compressor and condenser cooling demands.  Room temperature remains constant at the set temperature.
> 
> Presumably, other state of the art mini splits use similar technology.


It is also interesting to note that at least the Pioneer brand mini-splits can actually put out more BTUs of cooling than their rating.   For example, my 18000 BTU unit can put out between 7592-24806 BTUs of cooling, and some very similar range for heating.  I believe above 18000 BTUs you don't get the rated SEER efficiency.

The remote has a rapid cool-down mode in the extended settings that allow you to make use of the maximum capacity without tapering off as you near the set temperature.  It would be interesting to know the control algorithm, whether it has a PID component, or just a temperature differential algorithm.


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## ddickey (Nov 11, 2021)

I always thought you wanted to pull up in summer because the cool air is lower.


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## DAM 79 (Nov 11, 2021)

A shop that size wouldn’t take that much it all depends on how well insulated it is how many windows doors r-value of insulation and so on a have a old pole barn with tin on the outside 20x40 very little insulation I have a wood stove and also a propane gas furnace with straight AC coil on top ( it was free and only a year old ) I can heat it quickly and cool it quickly I have lots of trees also to shade it all my machines very rarely get any surface rust . It all boils down to what you can afford for install and electric/utility bills wood stoves heat up nicely and are cheap to run propane is nice will deliver heat in the 130-140 degrees out the vents a heat pump will run good down to around 40 degrees give or take them they start to struggle but that’s why the have electric back up heaters in them to help out and also when unit goes into defrost .a ductless or (Mini Split ) they are the next choice again all depends on what you get (Mitsubishi) would be my choice they have the best warranty and never have any problems they will work well down to around 30 degrees or so if you step up to the Hyper Heat Models there good down to -13degree and still keep a high seer rate  but there not cheap !!!!! If it were me I would do a ductless unit and be done and have a wood stove to help out when it gets really cold !!!!! Been in the trade for 28 years  just my two cents


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## RJSakowski (Nov 12, 2021)

A ceiling fan creates an artificial convection flow.  Whatever air gets moved down moves up in other areas of the space.  In that sense, it makes little difference as to whether the fan blows up or down.  It is basically homogenizing the air and eliminating stratification. 

There are extenuating circumstances that could come to play.  If you like the warmer upper air blowing down on you as you sit in your recliner, then set the fan for a downdraft, etc.


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## Dabbler (Nov 12, 2021)

Let me add the while inconvenient to have a breeze, air movement helps to minimize and mitigate surface moisture (rusting).  The only time I turn off my furnace fan is while I'm MIG or TIG welding.


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## Watchwatch (Nov 12, 2021)

How hard is it to install a mini split? 

I got a quote of $6k for a Mitsubishi 18k btu and about laughed the guy out of my shop.

There is an el cheapo mini split in Amazon for $750. We have pretty mild winters here that don’t get much below freezing at night. I just want to keep the shop dry year round, above 50 in the winter, and cool if I want in the summer. Tough to justify an expensive mini split.


Sent from my iPhone using Tapatalk


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## jwmelvin (Nov 12, 2021)

Watchwatch said:


> I got a quote of $6k for a Mitsubishi 18k btu and about laughed the guy out of my shop.



My quote was $6.1k for a Fujitsu 18k BTU/hr. Crazy.


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## Dabbler (Nov 13, 2021)

I did myu own install for a 50K BTU gas heater all in for 500$....


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## 7milesup (Nov 13, 2021)

I installed my own mini split.  I fab'd up my own mount for the compressor to sit on outside but you can buy them for$100 or so.  I gave the hvac guy $200 to come out to hook up the lines at the compressor and verify the charge.   Plus the $1400 for my 18,000 btu Friederich from Skipthewarehouse. $1800 all in including some odds and ends.


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## twraska (Nov 13, 2021)

If you have enough ceiling height I’d go with radiant tube heaters.  They warm the machines then they give off heat to the air. This keeps them dry and prevents rust.  May not be an issue for you but for me in humid SETexas, it’s a big deal.


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## ddickey (Nov 13, 2021)

I installed my mini-split too. Pretty easy but I had to borrow a vacuum pump. Unless you have one with the manifold you'll have to pay someone to do that. Rent some scaffolding for the inside unit. My buddy made a unistrut mount for his mini-split.


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## RJSakowski (Nov 13, 2021)

Many jurisdictions require a licensed HVAC person to do the install.  I have the necessary equipment, vacuum pump, manifold, etc from working on automotive A/C, but chose to go with the MrCool DIY system as it has prefilled lines and compressor and doesn't require an HVAC person to make the final hookup.  My initial location for the compressor was on a rooftop and the idea of hauling all the equipment up and working in  a precarious location didn't appeal to me. My final location was on top of a porch roof with a fairly shallow pitch so the location wasn't nearly as demanding but I'm still glad I went with the DIY system.

I see that MrCool has made some changes to their DIY system, offering different lengths of lines and line extensions.  Previously, the only option was a 25' line, which was the reason I went with the porch roof installation (I needed 35' to reach the ground).  They are also a bit more cagey about installation requirements, probably coming from the legal beagles.  

The most difficult part of the installation was the prep work.  I had to make a plywood backing board to mount the indoor unit as I couldn't tie into two studs.  The coolant lines exited the attic space and into the soffit in an inaccessible location which required the better part of a day of hand labor to make a sufficiently sized passage for the lines.  My compressor hangs from the side of the house rather than sitting on the porch roof.  To mount the compressor made shims to match the taper of the siding boards to provide a flat surface for the mounting brackets.  With all that work done, the actual install was less than two hours start to finish.


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## ddickey (Nov 13, 2021)

Mr. Cools are more expensive than non DIY units if I remember correctly. I have a Daikin but believe the Mitsubishi have the reputation as being the best.
One thing to remember if you do buy a mini-split is make sure you know what is included. Lineset, cover for lineset, brackets for mounting the condenser might or might not be included.


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## Todd727 (Nov 14, 2021)

I have a 2400 sq foot shop building.  I had a commercial 5 ton packaged HVAC unit installed, everything sits outside and the heat is provided by propane.  The entire installation was ~$6000.  It works perfectly.  It was 31 degrees yesterday morning and the insulated shop was a pleasant 65.  I'm not keeping it warmer than that, as I really just need it to be warm enough to prevent condensation.  The AC was outstanding all summer too.









						5 Ton 14 SEER 80,000 BTU Goodman Gas Packaged Unit
					

The Goodman GPG1460080M41 is a gas heat and electric AC packaged unit, ready for any application where it is not convenient to have an indoor furnace or air handler. At 14 SEER and 80% AFUE, the GPG1460080M41 is an inexpensive option with a standard efficiency designed for rooftop and...




					hvacdirect.com


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## jwmay (Nov 14, 2021)

Nothing really exciting for me. I use an electric radiator. It's on all winter, and keeps it warm enough with no noise. I have a preference for quiet heat. Lol


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## woodchucker (Nov 14, 2021)

the Mr. Cool unit went in ok, we ran into a problem with the wall. He's got multiple roof lines, so they left a 2 foot cavity from the outer wall to the inner wall.  That caused us 2 issues, one we overcame, drilling from one wall to the other, but with some careful measuring we lined up pretty well.  He doesn't have much height there, so it's 59" off the floor. But we ran into the fascia board to be straight, so we took the slight off and we are good with that.   Being 24" is exactly the length of the tubing to the connector... so that really is where the main problem was, the bend was to occur at the connector. damn... We didn't get the duct for the tubing and electrical on time... so we are not sure how that will play into things.. whether we will have enough room to softly turn with that connector.    He also decided he didn't want the unit on the concrete because of the snow drifts, so we mounted it up higher on the clap board.   So I didn't get to play with my Hilti.. that thing cuts through concrete like butter... and it's so quiet and soft... It makes any other hammer drill look like crap.

Staying up here another day to do some finish work... ran out of light and we are hoping the outside duct comes tomorrow to install a cover over the tubing.


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## Alcap (Nov 15, 2021)

Has anyone thought or used about electric radiante heat under a wood or laminate area in front of their machines . I have some of thoes rubber mats but if they were warmer my feet sure would be happier!  I installed hydronic radiant floor heat under the dinner room and kitchen . Its enjoyable walking barefoot on it . One thought would be covering a section of the shop where the machines are with a vapor barrier, foam board , heat mat system , not under the machines , then bamboo or other type of floating floor covering . It’s listed as .016” thick .Here’s something from Home Depot but sold other places also different brands . https://www.homedepot.com/p/QuietWa...vers-30-sq-ft-QWARM3X10F240/205350261#overlay. https://images.thdstatic.com/catalog/pdfImages/96/96706e1c-870e-428f-8c24-77d4db7408f8.pdf


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## woodchucker (Nov 15, 2021)

Alcap said:


> Has anyone thought or used about electric radiante heat under a wood or laminate area in front of their machines . I have some of thoes rubber mats but if they were warmer my feet sure would be happier!  I installed hydronic radiant floor heat under the dinner room and kitchen . Its enjoyable walking barefoot on it . One thought would be covering a section of the shop where the machines are with a vapor barrier, foam board , heat mat system , not under the machines , then bamboo or other type of floating floor covering . It’s listed as .016” thick .Here’s something from Home Depot but sold other places also different brands . https://www.homedepot.com/p/QuietWa...vers-30-sq-ft-QWARM3X10F240/205350261#overlay. https://images.thdstatic.com/catalog/pdfImages/96/96706e1c-870e-428f-8c24-77d4db7408f8.pdf


that's neat, for a spot location it looks promising, bigger, and it gets expensive fast. Plus you need to have a laminate floor.


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## RJSakowski (Nov 15, 2021)

At 12 watts/sq.ft., it would be minimal heating.  If installed over concrete, I expect most of the heat would be absorbed by the concrete.  A good insulating backing would help but will raise the  floor height.  If you decide to go that route, I would suggest using a foil faced foam board for backing. https://www.homedepot.com/p/RMAX-Pr...-R-3-2-Foam-Insulation-Board-637902/313501506


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## Alcap (Nov 15, 2021)

That foam board isn’t for floors . The foam board I was thinking of using was a product like this . https://www.homedepot.com/p/Owens-C...Insulation-52DDNGX/315197962#product-overview . Ive used 2” similar under the basement slab on our old house and from the band joists to the footer . It was blue I think it was Dow Corning


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## Alcap (Nov 15, 2021)

This foil type vapor barrier over the foam board instead of plastic underneath  might be better to reflect the heat . https://www.insulationmarketplace.com/product/smart-foil.html


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## Alcap (Nov 16, 2021)

After reading about the laminate flooring all the ones that were at a reasonably price wanted a climate controlled and not even sure it would make a difference doing all that work and $$ I ordered this Cozy mat to see how well . Not knowing how well it would withstand chips a sacrifical or something that will take the higher temperature of this mat 150*f . https://www.cozyproducts.com/collections/all/products/super-foot-warmer


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## jbolt (Nov 19, 2021)

Circling back on this I think my best option in a forced air unit. The radiant tube heaters are interesting but my layout isn't ideal for one. For those of you with with forced air how are you accounting for combustion air? Mr. Heater units use room air. Some of the Modine units have separate outside air intakes. My shop is well insulated and pretty tight.


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