Gas Water Heater -- Fresh Air Intake Ducts

[bergs54]

Hello,

I am planning to replace my current gas water heater with a 38,000 btu unit. I've noticed that the installation instructions as well as the building / plumbing code (I'm in California) require sufficient air for combustion. The water heater will be in a laundry room that is about 8x8x8, which, based on my calculations, means I'll have insufficient combustion air. So, therefore, I believe I need air intake vents. My question is -- what are they going to look like coming out of the interior wall -- just an open round metal duct that goes through the wall to outside connected to a vent hood? Or, is there a specific kit / part that I can purchase the make the intake duct look a little more finished? Thanks.

 

[Daniel Collick]

Does the room have a gas/electric dryer? If so, you'll need lots of ventilation. I ran into something exactly like this, and with the door to the room closed and BOTH the water heater & dryer operating at the same time the dryer was prohibiting the exhaust from the water heater from exiting through the vent properly. Created some pretty high carbon monoxide levels. May be easier to remove the door to the room, but I'd recommend lots of ventilation. You'll need a low vent and a high vent. I may be wrong, but I think they need to be within 12" of the bottom & 12" of the top of the heater. A register through the floor into the crawl space and one through the ceiling into the attic.

 

[Sponsor]

 

[hj]

quote; I think they need to be within 12" of the bottom & 12" of the top of the heater.

12" or less above the floor, 12" or less BELOW the ceiling. The size of the room is somewhat immaterial. It depends on whether it is sealed or has sufficient 'leakage" to supply the air.

 

[bergs54]

Thanks for the tips. Yes, there is an electric dryer in there. I think it w said 1 square inch per 1,0000 BTU's so 38 sq. inches just for the water heater (have to look at dryer specs) So, are we talking a simple register like those used for heating / cooling or is there special air intake register that is used?

 

[Daniel Collick]

Thanks for the tips. Yes, there is an electric dryer in there. I think it w said 1 square inch per 1,0000 BTU's so 38 sq. inches just for the water heater (have to look at dryer specs) So, are we talking a simple register like those used for heating / cooling or is there special air intake register that is used?

I prefer metal registers. They obstruct less of the overall free space needed. You can attach a length of duct to the registers, long enough to penetrate through the layer of insulation. Attach some bird screen, or something similar with holes small enough to prevent unwanted pests from crawling in but not too small, to the opposite end of the duct. Insert one assembly through your floor into the crawl space and another assembly through the ceiling into the attic and secure the registers in place appropriately. Oversizing your registers may be entirely appropriate for your situation.

 

[bergs54]

Thanks for the info. Your approach makes a lot of sense.