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Turning a Pantry into a Water Heater / Furnace Closet

ForrestM | Posted in Building Code Questions on

I am splitting an old pantry into a half bath and hot water heater/furnace closet. Both appliances run on natural gas. I live in Washington State Seattle area climate 4c I believe. I am planning on framing a solid wall in between the two spaces and having the door to the HVAC room open into the hallway and the door to the bathroom through the kitchen.

My questions:

Since the door would not not be to a bedroom or bathroom, does it have to be self-closing and weather stripped etc etc as per code? Or can it just be a standard interior door? The closet is 42 and 1/2 in wide and roughly 4 feet deep. A tight space for sure. Could I install double doors 20″ each half for proper access to the units?

I have an atmospheric style hot water heater, I think it’s around 36,000 BTUs. It still works but is old. What do I need to do to make sure the intake system for the room is adequate? or should I invest in a new hot water heater? I’m not sure of my furnaces btus but can find out of course.

Renovating my first house, appreciate all the help I can get.


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  1. Expert Member
    PETER Engle | | #1

    If you get a new furnace and water heater, they should both be sealed combustion units that get all of their combustion air from outdoors and vent all of the products of combustion outside. Then you need no special treatment for the furnace closet. You will still have to watch clearances to combustible materials and other space requirements from the manufacturers of the equipment. If you are not using sealed combustion appliances, then you need to ventilate the room, again per manufacturer's requirements. The mechanical section of the International Residential Code, or just the International Mechanical Code each have sections on the requirements for venting, but they should be the same or similar to the appliance manufacturer's installation information. Since you will now be bringing exterior air into the space, the closet is essentially "outside." The floor, ceiling and walls must be insulated and the door should be insulated and weatherstripped.

  2. paul_wiedefeld | | #2

    Another option would be transitioning to electric: it would solve the makeup air questions, add AC, and be a less carbon intensive option.

  3. JC72 | | #3

    My gas water heater is passively vented and located in a second floor interior hallway. The door is louvered.

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