Originally Posted By: kshepard
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Today I looked into a small (approx. 6’x8’) room with a boiler and water heater in it. Both are gas-fired.
One wall is exterior concrete foundation wall and the vent (taped to the top of the burn chamber with aluminum tape, no draft diverter) vented out the wall above grade.
Another wall backs up to the garage (firewall). The other two walls back up to living space.
There is no combustion air supply except the oversize hole they chipped to route the vent to the outside, maybe and inch all the way around. The door fits tight to the carpet. 10 minute CO reading was 12ppm.
If they bring two 12 inch ducts directly into that little room, those water pipes are going to freeze and burst when it hits 20 below this coming January. If the ducts come in through the heated garage and run for say, 12 feet before going through the wall into the mechanical room the air will warm considerably but the one-hour rating of the firewall will be compromised. Joists run the wrong direction to run through bays.
Any suggestions on how to provide combustible air without freezing the pipes?