Shop Heating

[pineyfolks]

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.

 

[BGHansen]

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?

That's what we do , and that's what we are . :big grin: @Firstram. I appreciate that. I do believe that you have to be a few fries short of a happy meal to have that many chucks tho.

www.hobby-machinist.com

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

POTD was done yesterday; ironically “spring time” on the first day of summer. My wife has a coworker who bought a KitchenAid mixer that is missing a spring at the mixing head (for securing attachments). He found a replacement spring on line for $35 and was complaining about the cost. We have the...

www.hobby-machinist.com

 

[jbolt]

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?

That's what we do , and that's what we are . :big grin: @Firstram. I appreciate that. I do believe that you have to be a few fries short of a happy meal to have that many chucks tho.

www.hobby-machinist.com

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

POTD was done yesterday; ironically “spring time” on the first day of summer. My wife has a coworker who bought a KitchenAid mixer that is missing a spring at the mixing head (for securing attachments). He found a replacement spring on line for $35 and was complaining about the cost. We have the...

www.hobby-machinist.com

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?

 

[rabler]

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.

 

[RJSakowski]

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.

 

[jwmelvin]

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.

 

[Winegrower]

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.

 

[westerner]

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.

 

[Alcap]

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 )

 

[BGHansen]

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?

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