heating code question?

[DRH1175]

I have a furnace that I am installing in my garage. What is the code as far as how far it has to be off the ground or what has to be done so it is to code? The previous owner had it about 1 ft off the ground and it was red flagged by the inspector? Someone with heating code knowledge please help!?

[18 inch Crappie]

Might be different with each city, give them a call to find out.

[MNice]

2000 IFGC (International fuel gas code) section 305.2. 18'' above floor for any source of ignition.

I'm a plumbing/HVAC inspector for a TC suburb, don't hesitate to ask anything cod related.

[DRH1175]

So I don't have to box in a seperate room with fire rated sheet rock? I have been told that is what would have to be done. The previous owner had it red flagged. The bottom of the furnace is about 8" off the concrete.

[MNice]

Assuming the furnace only heats the garage, no separation would be required, it can sit right on a platform, provided the 18" is met. If the furnace heats the house and located in the garage, a mechanical room would be required. Assuming it is a single family home, 5/8" type X rock on the garage side is no longer a requirement, 1/2" is OK on the walls, 5/8 on the ceiling if there is living space above.

[DRH1175]

It is a detached garage about 75' behind my house. It will heat only the garage. Two rooms my workshop. And then the main garage where I store my boat and will work on my cars etc... It is nice to know all I have to do is jack it up another foot or two and it would be to code. I was told by Air Mechanical that I have to build a fire rated room around it. Was hoping not too since it will take up some valuable space that I could use for other stuff. Thanks for your help. Last question? is there anything I have to do to the ductwork to make it code? Was going to run the Plenum up and then run round insulated vents to each side of the garage. Thanks for your info.

[MNice]

Sounds like your duct work would be OK. Keep in mind you need 2 sq. inches of duct on the supply & return minimum per 1000 BTU of output. IE if you had a 100,000 BTU 85% efficient furnace, your output is 85,000. 2sq in x 85 = 170 total square inches of duct. This is to provide enough air to keep the heat exchanger from getting to hot.

[DRH1175]

Does this involve length too or cross section of duct? Also is there a minumum # of registers I will need? My furnace is a 80% 75,000 BTU Comfort Air Furnace. Was planning on running the Plenum up to a tee duct which would run to each room. Than off of the tee branch a few ducts to the other side of the rooms, both work shop and main garage. To get the heat around. Not too complicated of a system pretty basic.

[DRH1175]

okay doing the math I got the sq inches figured out. 60,000 total btu X 2 Equals 120 so I would need like a 10x12 duct on the supply and return correct?

[MNice]

correct, remember that is the minimum, you can go a little bigger if you wish. Most return air drops are in the 10 x 20 size. Don't worry about being over sized, just don't go way over or you will lose velocity. A couple of 8 X 12s on the supply and 1 return would be fine. Good luck.

[DRH1175]

MNice Thanks so much for your info it was needed and much appreciated. Last question what is the code on burrying the Gas line outside? 18" or 24"? is it the same as electric service?

[MNice]

I'm at home now, but it's either 6 or 8 inches. I can check the code Monday for sure. Personally, I'd go with 16-20 inches. I'm assuming you're using copper.

[DRH1175]

Yes copper what is recomended soft copper or what?

[MNice]

Yep, soft copper is OK. Also, burial is 12" min. I was thinking wrong at home when I said 6-8, it's 8" to an outside appliance, like a pool heater, or grill, but to a building would be 12". Sorry about the misinformation.

[DRH1175]

Thanks I was going to go 18" to be safe. Thanks again for all your help!