Water Heater Closet - Ceilings?

Old 04-20-14, 06:40 PM
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Water Heater Closet - Ceilings?

Hello from southwest Oklahoma.

I've certainly not seen a million water heater closets, but most that I can picture in my mind have been unfinished with no ceiling. Well, this house I just bought that I'm doing a complete remodel of (built 1960), has two water heater closets and both have holes drilled in the bottoms of the doors and neither has a ceiling in them. However, both have solid ducts that go up to the roof and vent, of course. They burn natural gas, by the way.

I've been doing a lot of work to make the house more efficient, which obviously no one has done since it was built. The attic had 3" of insulation and the walls had no insulation whatsoever and the windows are the original wood framed single panes. Well, I've blown in 19" of cellulose into the attic and have dense packed the exterior walls with cellulose and my new double pane LowE366 argon-filled windows will be in this week. Not to mention brand new energy star furnace and A/C, blah blah blah.

Got to thinking, seems like these two water heater closets will be gigantic sources of energy loss. Can I put ceilings in them? Or do they HAVE to be open and vented like that for combustion purposes, etc. etc.? It's got a vent to the roof, what the hell more could it need?

Thanks for the help!
Old 04-20-14, 07:39 PM
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No, all that is required is a place for them to access combustion air, which is the purpose of the vent in the door. You must maintain clearance around the exhaust duct pipe with a non combustible product including any framing you put in.
Old 04-20-14, 07:52 PM
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You will need a thimble and double wall pipe...

Then you will need to calculate the door opening to make sure you have enough combustion air. Roomsize and btu's are needed for the calculation.

If not then addition air vents need to be cut in. One high one low. And or a louvered door...
Old 04-22-14, 01:39 AM
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Fire needs fuel and air. Without enough air it wont mix right. The exhaust needs to escape the house with enough draft or it will kill you.

The open ceilings and the suggested openings in the doors/walls are there to give the heater enough air to 'breathe right'. Without enough combustion air the heater will run lean, much like a car's carburetor out of alignment. Also, consider how much energy it takes for your furnace to heat the air to 70' in your house and then you send a bunch of that nice warm air straight up the chimney of your water heater. Depending on the climate, you may be able to arrange for the heater to draw it's 'breathing air' from the of the outside of home, or the crawlspace, or the attic, or both. If you are subject to freezing temperatures you want to be sure you don't pose a freezing pipe problem to the room. There are specific codes that govern how much air must be drawn into the room for the specific btu requirements of that particular heater so be careful. This is important to get right.
Old 04-22-14, 02:30 AM
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As you make your house more energy efficient the use of naturally drafted combustion appliances can become a problem. I assume that the new furnace is a direct vent, meaning it has abandoned the natural draft approach and so should your water heaters. A direct vent water heater is designed to draw its combustion air from the outside and and thus no longer inside air.

The added benefit for all of that cellulose is a tighter house. The down side is that kitchen, bath, and window exhaust fans can pull the house into a negative pressure and backdraft those water heaters. If you keep them you should have a worst case draft test done to be safe.

Old 04-23-14, 04:54 AM
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Thanks for the replies, guys!

I'm having trouble finding a calculator to figure on how much space I need and/or if I need additional vents.

I know from a friends personal experience that carbon monoxide is certainly not something to be taken lightly. Long story short - they got a new roof, contractor didn't hook up exhaust vents, house filled up with carbon monoxide (unknown to them, of course), husband woke up extremely ill, and wife couldn't be woken as she was in a coma and VERY near death. Both are fine today, thank goodness, but it was a very close call.

That being said, I do want to do this the right way and I will also definitely be installing monoxide detectors!

Makes sense that the current way of combustion air for these water heaters is not very energy efficient. I like the idea of taking air from the crawl space and/or the attic. I am, however, subject to 110 summer and as low as -5 winter.

As far as the furnace being a direct vent, I don't know yet because it's not technically installed yet. You caught me! Haha I've got a company that's supposed to come and get me taken care of. Don't know what's going on there, but that's another story I guess. Maybe when they're there dealing with that I can ask about the water heater requirements. They ought to know local laws and codes pretty well....I hope!

I'm hoping now that the water heaters I bought could be used with a direct vent setup. How can I tell?

Thanks so much again, ya'll

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