Mr Heater Questions

[kmacht]

I am finding myself not going out to the garage since it is too cold to work so I am thinking it might be time to finish insulating and add a heater. My garage is 24x24 but has a 2nd floor loft with a full workshop up there. That makes it 1152 square feet counting the second floor or 576 square feet if you only count the first floor and think of it as having 20' ceilings. So my first question is what heater do I need assuming the walls and ceiling are insulated with R13 and I add foam to my two currently uninsulated garage doors. I live in CT so winter temperatures are usually in the 20 to 30's. I don't need the garage warm enough to work in short sleeves but being comfortable in a sweatshirt would be nice. I don't plan on running the heater unless I am out working in the shop. Will the Mr Heater Big Max 45,0000 unit be big enough or do I need to go to the 75,000 unit.

The second question is hooking it up. There is no gas service to my house so I am going to have to use a tank. I was thinking of getting a 100lb tank and putting it outside the back of the garage. Do I need to somehow plumb this with black gas pipe or can I use some sort of rubber flexible hose like my gas grill uses just longer. I can get the tank outside within about 10 feet of where the heater will be located. Should the tank be located inside or outside the building? I was thinking that if it was inside I wouldn't have to worry so much about a rubber hose deteriorating and I can shut the valve off on the tank when I am not using the heater. Outside would take up less shop space in an already crowded garage though. Thoughts?

Keith

 

[DPelletier]

OK, here's my thoughts;

- 1) to properly size a heater, a full heat loss calculation needs to be done. That being said, few seldom take the effort and expense to have one done. A cheap and dirty calculator is here: http://www.ultimategarageheater.com/propane-garage-heater/search.php I would consider it a 576 sq. ft space with 20' ceilings rather than an 1152 sq ft space with a much larger foot print; your heating needs will be far less than two stand alone shops of 576 sq ft. Is your shop really full size? attic trusses?

- 2) do NOT try to store your propane tank inside the building.

- 3) code for gas piping and connections vary from place to place, hire a gas fitter but yes, you will likely need sched 40 blk iron pipe.

- 4) keep in mind that the BTUH ratings on equipment is usually INPUT, you need to compare your needs to the OUTPUT of an appliance which will be a percentage less than input based on AFUE.

Dave

 

[kmacht]

OK, here's my thoughts;

- 1) to properly size a heater, a full heat loss calculation needs to be done. That being said, few seldom take the effort and expense to have one done. A cheap and dirty calculator is here: http://www.ultimategarageheater.com/propane-garage-heater/search.php I would consider it a 576 sq. ft space with 20' ceilings rather than an 1152 sq ft space with a much larger foot print; your heating needs will be far less than two stand alone shops of 576 sq ft. Is your shop really full size? attic trusses?

- 2) do NOT try to store your propane tank inside the building.

- 3) code for gas piping and connections vary from place to place, hire a gas fitter but yes, you will likely need sched 40 blk iron pipe.

- 4) keep in mind that the BTUH ratings on equipment is usually INPUT, you need to compare your needs to the OUTPUT of an appliance which will be a percentage less than input based on AFUE.

Dave

Yes, the shop upstairs is really full size. The garage has a gembral style roof and a wall between the two bays downstairs that allows me to have a full weight bearing floor upstairs with a ton of head room.

The link above doesn't let me put in above 12' ceilings. I doubled the square footage and put in 10' ceilings and it still only came out to around 40,000 btu. So it sounds like with good insulation I would be fine with the 50,000 unit but if I want heat quicker I wouldn't be too oversized with the 75,000 unit.

 

[DPelletier]

Yes, your total BTUH requirement is only around 40k. I would avoid going too big for several reasons; increased inititial cost, more over/undershooting setpoint and shorter cycling which is harder on the equipment. If you want to include a "fudge factor" because you're guessing, then I'd recommend a small increase, not 50% more...of course the equipment that you're looking at may not have a 60,000 BTU unit.

Dave

 

[dave67fd]

If you are only heating the lower section the 50k will be more than adequate.

The 45k units are also no longer manufactured by Mr. Heater. If you purchase the new 50k units, they have new venting requirements as a class III heater.

Read and learn the manual before you purchase one so you can install properly and to code.

http://www.northerntool.com/images/downloads/manuals/27457.pdf

 

[kmacht]

The heater will have to heat both the upper and lower floors as there is a staircase connecting the two and no way to close the upper floor off from the lower one.

I have looked at the manual for the heaters and I think I understand the requirements. I would be doing a horizontal vent so it has to be between 3 and 5' long with a 1/4" per foot pitch up, a condensate drain, 12" past the structure, and 4' from any window or door. Anything else I am missing besides proper thimble for going through the wall and the proper end cap?

Keith

 

[nwav8tor]

Ar the condensate drains only required for commercial installations?

Paul

 

[dave67fd]

Ar the condensate drains only required for commercial installations?

Paul

A condensate drain is not required for residential installations. The 1/4" rise per foot is required for the heater to burn off the condensate.