Ventilation Rqmt in Mechanical Room

[BC Eagle]

Hello pros,
Appreciate any advice you offer. We are remodeling a basement in our 10 year old home by adding a bedroom to an open space that includes a furnace and water heater on one end. The furnace is a HE gas Trane unit with intake and combustion air vented outside, that was added last year by the previous owners. The 80k BTU gas water heater has an electric blower on top, but I believe the combustion air comes from the room. This new downsized mechanical room is about 9' x 11.5' with a 9' ceiling. There was conditioned air delivered into the room before the remodel started, but that has now been sealed.

Today our contractor said he needed to add an air passage vent from one of the adjacent living spaces to the mechanical room. Do we really need to do this? Can adding a replacement conditioned air vent meet this need?
Brian

[beshvac]

No, you need the properly sized pass thru grills (ceiling and floor) to communicate to a large enough space to provide combustion air.

[beenthere]

An 80,000 BTU gas fired appliance needs a free air volume of 4,000 cubic foot. So yes, you need to have combustion air added to that room.

[BC Eagle]

I was afraid that would be the answer. We'll make it work. Thanks for the help!
Brian

[tedkidd]

Kick the low efficiency pig to the curb. Install a 98% efficient sealed combustion on demand water heater and you can leave the room alone.

[second opinion]

Make sure they follow IFGC section 304 and IMC section 702.3,---702.3.1 and 702.3.2

also IFGC section 303

[motoguy128]

Kick the low efficiency pig to the curb. Install a 98% efficient sealed combustion on demand water heater and you can leave the room alone.

+1. If the hot water heater is the original builder grade unit, it's worth replacing. I'd get a HE unit as mentioned above. One AO Smith unit has enough output capacity that it can provide almost continous hot water almost like a on demand system. I plan to install one of those in the next few years to get my flue out of my chimney... or rather to stop using my 86 y/o brick probably unlined chimney as a flue.

[Gross]

Hello pros,
Appreciate any advice you offer. We are remodeling a basement in our 10 year old home by adding a bedroom to an open space that includes a furnace and water heater on one end. The furnace is a HE gas Trane unit with intake and combustion air vented outside, that was added last year by the previous owners. The 80k BTU gas water heater has an electric blower on top, but I believe the combustion air comes from the room. This new downsized mechanical room is about 9' x 11.5' with a 9' ceiling. There was conditioned air delivered into the room before the remodel started, but that has now been sealed.

Today our contractor said he needed to add an air passage vent from one of the adjacent living spaces to the mechanical room. Do we really need to do this? Can adding a replacement conditioned air vent meet this need?
Brian

omg yes! its the only sure way to do it. cutting a hole in a wall doesnt mean air will go into that room.

[dandyme]

No, you need the properly sized pass thru grills (ceiling and floor) to communicate to a large enough space to provide combustion air.

are you suggesting taking ventilation air from inside the structure/living ares?

An 80,000 BTU gas fired appliance needs a free air volume of 4,000 cubic foot. So yes, you need to have combustion air added to that room.

even a 90+ 2-pipe?

[vangoghsear]

Isn't it true that transfer air can be through openings or mechanically induced through a fan? The problem I see with the A/C vent is that there is no guarantee that the unit will be running to bring in air when the gas water heater is firing.

Couldn't a dedicated supply fan be used to blow air into the room, either a constantly running or interlocked with the water heater, as an option?

[boilerman856]

You are not allowed ato put a non sealed combustion gas water heater in a bedroom, I would think you shouldn't take combustion air from that room through grilles either. Better call the code enforcement officer or fire chief on thar one first

[jpsmith1cm]

You are not allowed ato put a non sealed combustion gas water heater in a bedroom, I would think you shouldn't take combustion air from that room through grilles either. Better call the code enforcement officer or fire chief on thar one first

Boilerman856,

Read and follow AOP forum rules.

You should apply for Professional Membership.

[genduct]

Boilerman856,

Read and follow AOP forum rules.

You should apply for Professional Membership.

Although there is a good reason to have and follow rules, even if they are newly instituted, I would like to point out that what boilerman said, in no uncertain terms, is what secondopinion referenced in his post.
Clearly boilerman has been very forthright and correct in warning the OP with his remarks and is right in doing so in a potentially dangerous situation.

So I think if your post could have begun with a thank you, agreed with him and then invite him to apply. The OP might have gotten the idea that boilerman's concerns were not valid.
NO GAS APPLIANCES IN SLEEPING AREAS ALLOWED
We would like to see the occupants wake up in the morning