Shop Heater Sizing

[danho]

The pad for my 32x40 shop was just poured and I am looking at my heating options. Any recommendations on brands of propane heater and BTU's for Southern Oregon? I have done research and calculations and they are all over the place. The shop is 32x40 with 14' ceilings, will be wrapped and insulated with R-19 in the walls and R-38 in the ceiling. There will be an attic with a full set of stairs, so I am not sure if I will need separate heating sources for both levels or if sizing and placement of one unit will suffice.

Thanks all.

 

[gmcgeo]

Propane = Mr heater , Hot Dawg , Renzor. hanging units

Mini splits are an option as well

65,000 btu out put is about what you need to look at

 

[PoorUB]

What is you winter temp at the coldest?

In that climate you should only need 45,000 BTU for the main garage area. The upstairs heat will depend on the use. Storage? Man cave space? If it is just storage you might not even heat it. Man cave it will need a second source of heat, maybe AC too.

 

[danho]

I would say that 25 degrees would be the coldest for our area and that may not stay for more than a few weeks. The upstairs will be a combination of storage and he/she space for crafting and reloading. Keep in mind that I have a wife and 3 girls who all think the world is ending if it drops below 80 in the house, so I would like to be able to get some heat moving if needed. Also, Reznor has quite a few different models of heater, any insight on which way to go if I decide to purchase from them?

I appreciate both of you quick responses, thanks.

 

[klassenl]

10 watts or 35 btu /square foot is a good place to start. Perhaps a little more considering the high ceiling. It sounds like you mean to insulate to a good level which is as important as heater size.

 

[Twodawgs]

With the high ceilings, I would look at radiant tube heat such as Re-Verber-Ray

 

[PoorUB]

10 watts or 35 btu /square foot is a good place to start. Perhaps a little more considering the high ceiling. It sounds like you mean to insulate to a good level which is as important as heater size.

We always did 25 BTU per sqft in a decent garage, never got bit here in North Dakota on hundreds of shop heater installs and we get a alittle bit colder than southern Oregon. With him on southern Oregon you can drop that number even lower, but then add a bit for the 14 foot walls. My bet is 30K BTU will heat it just fine, but my **** puckered a bit and says 45K to be sure. 45K BTU will heat the lower level without a problem.

I agree with the radiant heaters because of the high ceilings. It just depends on what the OP wants to do with the space. If he parks a tall camper or motor home in there then no on the radiant.

As for the upstairs? If mama and the kids are going to use the space for crafts it will need to be comfortable, AC might be a good idea too, I might consider a mini split. Better yet a ducted mini split.

 

[klassenl]

We always did 25 BTU per sqft in a decent garage, never got bit here in North Dakota on hundreds of shop heater installs and we get a alittle bit colder than southern Oregon. With him on southern Oregon you can drop that number even lower, but then add a bit for the 14 foot walls. My bet is 30K BTU will heat it just fine, but my **** puckered a bit and says 45K to be sure. 45K BTU will heat the lower level without a problem.

I wonder how low you could actually go. I have almost 1000 sq ft and had to convince the guy I bought my heater from (good trustworthy guy, known him for years) that 45000 was a bit big. I think I have 30000 and it works no problem. we get -30 C and the garage is never cold. That being said I don't expect my garage to stay at room temperature.

Would we be able to keep that garage at 10 Celsius say 50 Fahrenheit with 20000 but or 15 or 1000 btu?

 

[nadogail]

Again, the answer depends on the Heat Load you expect the heater to handle.

 

[PoorUB]

I wonder how low you could actually go. I have almost 1000 sq ft and had to convince the guy I bought my heater from (good trustworthy guy, known him for years) that 45000 was a bit big. I think I have 30000 and it works no problem. we get -30 C and the garage is never cold. That being said I don't expect my garage to stay at room temperature.

Would we be able to keep that garage at 10 Celsius say 50 Fahrenheit with 20000 but or 15 or 1000 btu?

How low? North Dakota and we will see -30F and once in a while -40F. I guess when we get around those numbers C or F gets pretty close. My neighbor has 900+ square feet with 30,000 BTU and he will run it at 68 when he is out there. I sol him the heater and pretty sure he would say if it did not keep up. We talk all the time.

 

[Jackfre]

A Rinnai EX38 will handle that nicely. I have it in my 1000 sq ft shop a bit S of you in a shop with the same insulation specs and pretty much the same temps. The vent is included in the box and requires only a 2.75” hole through the wall. Programmable stat built in. They are not inexpensive but they are excellent in all regards…and they are quiet and cool to the touch. As to the upstairs, I’m not sure you want to have common air there, up/down stairs, but look at a Tjernlund Airshare. It can operate floor to floor. I’d do a mini-split upstairs. After all, in the summer months you are going to be hearing from the girls if they aren’t comfortable and it will get hot up there.

 

[danho]

The shop intent for the lower area is general parking and perimeter workspace, I plan to use the whole shop equally as I usually have several projects going on at once. The tallest item I would have, would be a 4 post lift (future purchase) that I may use as a storage option as well and park underneath. I am initially leaning towards a hanging ceiling unit as I do not plan to have anything hung above normal cabinet height so it won't be taking any wall space from me. 45k BTU seems to be the consensus, so thank you for that recommendation, and if you all have any models I should be honing in on please let me know, specifically the radiant units as I am in the dark on those entirely.

Here are a few units I am looking at for the main area, please let me know your thoughts:

Mr. Heater F260550 Big Maxx MHU50NG Natural Gas Unit Heater​

Reznor UDX-45 45,000 BTU Power Vented Gas Fired Unit Heater​

Hot Dawg 45,000 BTU Propane Gas Heater

The mini split (or ducted split) upstairs sounds like a good fit, but I haven't started looking down that road yet. Any quick thoughts for an attic that is 10'x40' with a couple of dormers?

Thanks again all....

 

[PoorUB]

As for a mini split, make sure what ever you get will heat well below zero. You will not need it to run that cold, but you will have full output at outdoor temperatures you will need to heat. A 9,000 BTU unit would probably do it, but to find a hyperheat you will probably need to go larger.
Becareful of units that are advertised that they will heat to zero. They will heat to the point, but maybe only 1/3rd output.

 

[My Old Tools]

We get lower than 25 regularly during the winter, as low as -8 last year. My shop is 30x40x12 with a 6/12 roof pitch, 22 feet to the top, conventional roll insulation, double on the roof. I put a 36k MrCool in two years ago. We see 100+ with humidity in the summer (20 yards to the lake). The MrCool barely gets above idle most of the time. I doubt it would have pulled 80 degrees when it was -8, but in any normal conditions it will. Remember, heat rises. I run a fan pointed down in the winter to pull the heat down to floor level.