Shop temperature control

[Batmanacw]

My shop is pretty small. 12 x 20. It is very well insulated. It has stayed right at 70⁰ all summer with me only running the AC while I'm in their for about $0.07 an hour. I'm rarely in there all day so cooling has been crazy cheap this year.

In the Ohio winter I've been keeping it around 40⁰ with an oil filled radiator heater. Then I heat it up when I go in there. That was partly a portable buddy propane heater and another electric heater like the radiant heater I mounted at the end of the shop.

I've decided to eliminate combustion in the shop to avoid the moisture that comes with it.

If I run my oil radiant heater at 600 watts non stop for 30 days it will cost me $59. That would put me at 50's to 60's depending on the outside temperature. It cost me around $0.20 to run a second electric heater at 1500 watts for an hour to kick the temperature up to around 60⁰ where I like to work. The secondary heater would probably only add a dollar or two a month because of the short duration of use.

What I don't know is how much efficiency is gained by maintaining the warmth in the walls, floor, and machines. If I maintain 50⁰ I wonder if my oil heater will run non stop or catch up and shut off occasionally.


No....I'm not installing a mini split in my tiny shop. My window unit is costing my less than $10 a month.

I'm more interested in how things will go by keeping it warmer all the time. Less temperature swings would be nice. I live in the frozen tundra.

 

[Martin W]

I think we all go thru this who live in the Northern Hemisphere. We all want a nice warm shop and tools that won't rust, but in reality, it costs a lot of money.
I would say if you're out there every day. then set it higher. If you are out there once or twice a week then turn it lower.
I have a wood stove and a 230 volt electric heater. The wood stove is lots of work but inexpensive to run so that is mostly what I use. It has its problems also. It's either 80 in the shop or 60, depending on my ambition.
If you install a wood stove in your shop. Make sure it is at least 18-20" off the floor for any flammable vapors. Especially if you park tractors or vehicles nearby. (some municipalities or insurance companies have different specs.)
Martin

 

[Batmanacw]

I think we all go thru this who live in the Northern Hemisphere. We all want a nice warm shop and tools that won't rust, but in reality, it costs a lot of money.
I would say if you're out there every day. then set it higher. If you are out there once or twice a week then turn it lower.
I have a wood stove and a 230 volt electric heater. The wood stove is lots of work but inexpensive to run so that is mostly what I use. It has its problems also. It's either 80 in the shop or 60, depending on my ambition.
If you install a wood stove in your shop. Make sure it is at least 18-20" off the floor for any flammable vapors. Especially if you park tractors or vehicles nearby. (some municipalities or insurance companies have different specs.)
Martin

Once I get a bigger lathe there won't be room for a wood stove and I don't like sweating while I work. I'd rather work at 50⁰ than 80⁰. Lol

 

[Tuba Dave]

I work in my shop at least 10 hours/day. I keep the heat running all winter at about 63 degrees and use the AC in the summer when it gets to 80. Humidity plays a big part in the latter decision.

I have a 24x40 concrete slab with a stick frame building (passive heated 12x40 second floor). I have a through the wall heat pump (like in hotel rooms), and my entire shop uses less than $25 per month of electricity (heating, machines, lights, little fridge, hot water heater, everything).

Especially in winter, thermal inertia is your friend. Somewhere there is probably a way to calculate BTU's used to maintain vs change (raise or lower) temperature. If I am going to sit for more than 2-3 minutes in my car (I get a lot of bridge lane closures where I live), I'll turn off the engine. I think buildings are probably less efficient at maintaining temperature than car engines are at fuel economy.

BTW, the heat pump controls humidity extremely well, and I don't have to worry about fuel, fumes or sparks.

I hope this helps. All information is helpful in one way or another!

PS in order to keep the heater from running 100% of the time in the winter, I have a ceiling fan that helps distribute the heat and a thermostat that is about 6 feet away from the heat pump. My old one did not have a remote sensor (it was on the intake vent) and I felt that it would run continuously as it was just sucking in cold air from the floor. Mixing the air in the shop will help prevent constant running of a heater

 

[Batmanacw]

Last year I tried to keep the shop around 40⁰. The killawatt said it cost about $20 a month.

When I get home from traveling during the week I can set the oil radiator to cut off around 60⁰. It will either hit 60⁰ or run continuously. Then, when I'm in the shop, I can add heat if required to get to 60⁰ if 600 watts doesn't cut it. That keeps my heater from running continuously.

Not a bad compromise.

 

[BGHansen]

Mine takes up 32' of a 40' x 56' barn (shop is 32 x 40) with a 10' ceiling. I have 6" batts in the walls and 14" of fiberglass batts in the ceiling.

Like you, I leave the shop at 40F in the winter unless I'm headed out to work. Mine has a 125,000 BTU Mr. Heater MAXX hanging in a corner; way overkill for the shop size as a 55,000 BTU unit would have worked. It's hooked to a Google Nest thermostat which I can turn on from the house. If I'm out there for an hour, I'll bump it up to 50F; more than an hour it's at 55F. I went way over on the heater capacity for a quicker warmup from 40F; the 125,000 BTU unit heats the 40'x32' to 55F in about 15 minutes. The 55,000 BTU unit would take an hour; I didn't want to wait that long.

I don't do anything for the summer except keep the doors closed when it's hot out. It got into the mid-90's yesterday, high in the shop got to 81F. I have a high-mounted wall clock (my wife got tired of walking out to the shop to come in for dinner, hence the large wall clock) with a thermometer. The shop has 3 ceiling fans that run 24/7/365 on the opposite side of the heater. In the summer, they blow down, in the winter, they blow up. I don't have a problem with rust as the air is constantly moving with the fans and I keep the machines covered with way oil and/or LPS 1.

I used to leave the fans on high and noticed that when the heater kicked on, the ceiling air was at about 2F higher than the thermostat during the initial heat-up; air was moving really well. Problem was, if I was working near a wall by the fans, I felt the cool breeze on the neck. With the fans set to their lowest speed, the ceiling air will get to 6F higher than the thermostat and levels out to about 2F after 10 minutes. I don't notice them in low speed in the winter.

We use about 150 gallons of propane a year at the barn; $2.60/gallon on our latest buy so about $400 a year to heat the shop. Very acceptable for the comfort. In my youth, I was the cubmaster for our son's boy scout troop and recall having to open the 16' barn door in the winter (for light) to do some cuts on the table saw; the fluorescent lights didn't work below 20F!

Bruce


The big box stores sell electric and propane/natural gas overhead heaters


This is my 125,000 BTU unit up in a corner; bottom is at about 7 1/2'

 

[rabler]

I'd suggest looking for a way to heat other than resistive heating, which includes oil-filled electric and electric radiant. Generally it is the most expensive options to operate. Big advantage of electric is that it is cheap up front to buy and no or minimal install, but you pay for it in the long run.

 

[Batmanacw]

I'd suggest looking for a way to heat other than resistive heating, which includes oil-filled electric and electric radiant. Generally it is the most expensive options to operate. Big advantage of electric is that it is cheap up front to buy and no or minimal install, but you pay for it in the long run.

Worst case I'm looking at $300 a year to heat my shop with zero moisture issues. Probably not that much. Most suggestions I've received involve way more than that to install something better and a 6 to 10 year payback.

I could easily run my big buddy heater into my shop and run it on high to warm my shop up quickly. I simply don't want the moisture.

Try to remember this is a 12 x 20 ft space. It doesn't take much to heat. I'm not heating a house.

$300 a year isn't a heavy burden. Definitely not worth $2000 in debt to cut that in half.

 

[Bone Head]

For winter I have a torpedo heater than has a cut-off when it gets around 80 or so. No rust or condensation problems so far. I can tolerate temp changes fairly well, and whoever built my house insulated it like the house.
Summer I can keep the overhead door closed above 80 and be fairly comfortable. I discovered that on80 plus days a simple cool-it-down=quick-trick is to open the overhead door to the attic. Heat rises. Temperature drops fairly quick and I can definitely feel it.
Gets to 'teens and I stay in the house and do stuff.
You other fellows that are planning to build a stand alone garage, look into radiant heating in the poured floor of the building. Neighbor did that to his pole barn he recently built. On a particularly cold day last winter he was working in shorts and a t-shirt.

 

[rabler]

Generally heat flow (loss) through a wall depends linearly on temperature difference from inside to outside. So it will cost twice as much to maintain twice the temperature difference. How long it takes to heat it up depends on thermal mass of the shop, and size of the heater.

It is a little hard to determine what information you're looking for, if any. If you're looking for a straight answer to how much more it will cost to keep your shop a bit warmer when you're not using it without changing your heating scheme, the simplest answer to that is going to be to try it and see. Otherwise it depends on too many things that are hard to know, from insulation level to how often you are in the shop, and personal factors like comfortable temperature and budget.

Being simplistic, but one thing that may help, it doesn't really cost more to use a second electric heater to help heat it up faster. Either way it needs the same number of watts of electricity to raise the temperature a certain amount. Of course the machines and such will only warm up so fast.