Door Vent for HW Tank Room

[Verdeboy]

A building inspection for the house I'm working on cites that the small exterior room that houses the Gas HW tank and the breaker boxes must be properly vented. But they don't specify how.

I'm thinking of making a cut-out in the metal door and installing a 14"x12" passive vent.

Someone suggested that we need to install a new "louvered" door.

Which, if either of these, is correct.

The room is very small--maybe 6'x6'.

[statjunk]

I've done projects like this and all I did was open a large hole in the door and put a vent cover over it. I would say the hole I opened was about 2x3 on the lower part of the door.

I went to the hardware store and picked up the vent and cut the door to fit.

Tom

[jadnashua]

There's a formula, often in the installation manual, that describes how big it must be based on the BTU requirements of the device. They usually want two vents, one lower and one higher. This is an often overlooked thing for systems like tankless, furnaces, gas dryers, etc. They exhaust a lot of air and many of them don't use closed combustion. The air to burn has to come from somewhere. FOr example, while I did look into a tankless system, my basement was too small by a factor of maybe 2 to support it without some significant air vents to the outside. I didn't like the idea of introducing that much unconditioned air into my basement so I went with a different system (closed combustion). Keep in mind, while this isn't in the dwelling, that any combustion device, unless closed combustion, sucks a lot of oxygen and that air comes from cracks in the house bringing in dust, etc in the operation.

[jimbo]

You need two vent openings. One within about 14 inches from the floor, the other within about 14 inches from the ceiling. If you are getting the air from outside, each opening needs to be , if I remember correctly, 1 square inch per 4000 BTU. A 40,000 BTU heater would require 10 square inches, but I believe there is a minimum opening size specified which may be larger than that. You get the idea. I will try to pull out my National Fuel Gas Code book later and confirm these numbers.

[markts30]

I believe the UPC specifies minimum sizes of 100 sq in. (unobstructed)
A 10X10 louvre is LESS than 100 sq in of unobstructed airflow - most ventilation louvres will specify what they are rated at (ie 10X12 with substantial louvres may only be rated as 100 sq in)
You need, as mentioned, 2 - one within about 1 ft of the floor and one within about 1' of the ceiling...