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My existing water heater is electric and is likely to need replacing soon. The heater is in a converted garage that I use as a guest room.

As the house is piped for gas, I'm considering the purchase of a gas water heater to replace the electric one. Is there any hazard with a modern gas water heater being used near where people are sleeping? (I'm more concerned here with fumes than the possibility of explosion.)

Aarthi
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Will Shaver
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3 Answers3

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The amount of oxygen consumed by a hot water heater is negligible. The risk of the gas heater sucking all the oxygen out of the room is zero. Now that does not mean that it's code to have it in a bedroom, but there is no safety issue from consumption of oxygen.

The safety issue is on venting of the carbon monoxide (CO) from the hot water heater. In order to make the install safe, ensure that the new gas water heater is properly vented through the ceiling. There are lots of resources online about properly venting gas appliances. Here's a reasonable one to start with.

Obviously since a gas hot water heater requires adding a vent, it's more expensive to install. You may find that an electric water heater still makes financial sense once you consider installation costs.

As noted in the comments, be sure and get a CO detector for the room. These are relatively inexpensive and you can get them at your local hardware store or order through Amazon.

JD Long
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  • +1 for the reason they're usually banned. There was a case in Greece (or one of the Greek islands) a couple of years ago where the children in a family died due to faulty heater and CO poisoning. – ChrisF Jul 28 '10 at 20:58
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    Your answer is good, but missing one critical thing: make sure you have a CO detector! (probably on the other side of the room from the water heater) – gregmac Jul 29 '10 at 15:59
  • @gregmac, very good point. I added the CO detector to my answer. – JD Long Aug 02 '10 at 14:57
  • Can you provide a source for your statement that the amount of oxygen consumed by a hot water heater is negligible? I'm not trying to be a jerk but we are talking about something that can kill people here. – Mike Powell Aug 02 '10 at 18:50
  • @MikePowell it's not the consumption of O2 as such - it's the production of CO, which can be fatal in very low concentrations – Rory Alsop Jul 16 '12 at 18:17
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    I know of no model code that allows a fuel burning water heater in a bedroom unless it is a direct vented type. Installing a CO detector anywhere there are fuel burning appliances is a good idea. But it is foolish to tempt fate by installing a fuel burning water heater in your bedroom, and relying only on a single electronic device to save your life. Don't risk it! – bcworkz Jul 17 '12 at 00:30
  • @RoryAlsop My point was that the statement "there is no safety issue from consumption of oxygen" is a bold one to make without giving any source. I realize CO is a greater risk, but it's only an issue when something's malfunctioning. In contrast O2 depletion in a tight room is something that could potentially occur even with everything in perfect working order. I still haven't seen anything to back up JD's claim that it's an issue that can be dismissed completely. – Mike Powell Jul 17 '12 at 03:11
  • For what it's worth I completely agree with @bcworkz's comment above as far as the original question goes... – Mike Powell Jul 17 '12 at 03:13
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Pretty sure codes prevent using a gas appliance in a location where it will get it's combustion air from a bedroom. The reason for this is that if the heater is burning up all the oxygen in the room and it can't be replaced quickly enough through natural air flow through the house, you'd end up being asphyxiated in your sleep.

I think there's an exception though if you use a direct-vent model that gets it's combustion air from the outside. So you would need to make sure whatever hot water heater you buy is rated for that kind of installation.

Eric Petroelje
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CO is dangerous as it has not odor, It is best not to take risks.

You can place a gas water heater outside in a metal closet with the proper ventilation.

This is much safer. I also currently have an electric heater, but when I put in gas pipes a couple of years ago, I put one outside so one day I can set up a gas heater in a safe way.

Sruly
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