Gas Heat Make Up Air

[SuperD]

Well, you can sure tell winter is coming with all the shop heater questions!
My shop is 26' X 26' with 10.5' ceiling and I will be installing a 50,000 BTU Maxx Gas furnace heater, I will use propane because of my location. I will vent the exhuast with a 4 inch cat 3 pipe as per my local code requirements. My questions are about the requirements for fresh air make up for the combustion. I hate to think all of the work I have gome thru to make the building air tight and well insulated and insulated doors and then require 12- 14 square inches for the fresh air supply. I know about the sealed combustion type furnaces and the 95% high efficency condensate furnaces but the cost is 2-3 times as much.

Any suggestions regarding the fresh air supply (negative air pressure sensor?) or even modifications to pipe in fresh air for the combustion are appreciated.
Thanks in advance

 

[zmaxmotorsports]

I normally just use a dryer vent piped into the furnace area for combustion air.

 

[SuperD]

I have to install it to code, new home and new garage. I was hoping someone with furnace installation experiance might have some suggestions. The 50,000 btu furnace-heater is on sale at Princes Auto until Oct 2.

 

[zmaxmotorsports]

I have to install it to code, new home and new garage. I was hoping someone with furnace installation experiance might have some suggestions. The 50,000 btu furnace-heater is on sale at Princes Auto until Oct 2.

Have you read my profile? Ive been doing this for a long time.
Heres a picture ,not exactly how I do it but it should give you an idea anyway.

 

[SuperD]

Great idea, I like the idea of the dampener as it allows fresh air in for the furnace combustion, I will check with the gas permit branch. Thanks!

 

[smalltown]

I was wondering the same thing after insulating my garage, and making things tight.
I had thought about a drier vent installed backward so the louvers would only open when the heater was running. Just haven't come up with how to make the outside look finished.

I haven't come across a product like the thumbnail you posted, but I'll be looking.

 

[Mike007]

I have to install it to code.

If you need it done to code, you need to find out what the code is where you are. The jurisdiction may allow what the install manual calls for in regard to make up air.

 

[rlitman]

Just haven't come up with how to make the outside look finished.

Use a dryer vent with a bird screen, and rip out the flapper damper (because it is facing the wrong way. Then glue in some window screen to keep the bugs out.

In my install, I put two vents back to back. The interior one kept the flapper. The exterior one had the flapper ripped out and replaced with hardware cloth.

 

[smalltown]

Thanks rlitman. I try that if I can ever get my Sterling ceiling heater piping correct.

 

[Brian_WK]

You can put a trap or a "J" on the bottom of the inlet pipe or a motorized or barometric damper that comes on when the furnace is fired. Any of these will stop drafts but make sure that what ever you use that it is to code.

Brian

 

[SuperD]

I will check further if i can use a dampener. I need 1 square inch per 5000 BTU, so a 3.5 inch inside hose or pipe meets that requirement with a 50,000 btu heater.

 

[tinker rick]

Check into seperated combustion venting or maybe concentric venting. It worked well for my sterling heater.

 

[Jackfre]

your other option would be a Tjernlund Enforcer. They interlock with the burner and only provide CA when there is a call for heat. Good equipment!