I'm working on designing a small cabin that is slab on grade with no garage and I need to place the air handler (with electric furnace) and the electric water heater somewhere. There are all sorts of codes about gas units since they use combustion, and require venting, etc. But I haven't been able to get a clear answer on what the requirements of such a utility closet would be, often with conflicting information in online searches.

I'm thinking it would be most economical to build one utility closet for the electric water heater and electric air handler/furnace and put them in there together if permitted. I know you can't do that for gas, but with both appliances electric...? Does anyone know if this is allowed? The code is IRC 2012 with no local modifications.

  • Is this an electric tank water heater? The reason I ask is that if this is a weekend cottage, then a tankless water heater has advantages for that application, but electric tankless heaters are limited in their size due to the extremely high power requirement when the hot water is being delivered. You mention electric furnace but don't mention a/c so I assume this is in a very cold climate. Where will it be located? Aug 28, 2017 at 18:31
  • The air handler has AC coils and electric heat and the blower for both. It get into the 40's (F) at night in the winter.
    – Nick
    Aug 30, 2017 at 11:39

2 Answers 2


It shouldn't be a problem, as long as there's enough working space around the units. See this answer for more details on how much working space you need, and this answer which includes a good graphic.

Here's a PDF from Mike Holt, that describes the requirements for space around the equipment (starting on page 16).

  • 1
    But the answer is yes they can be in the same closet.
    – Ed Beal
    Aug 28, 2017 at 15:49

As above it should be fine, Mike Holt is a very good source.

In terms of water heaters I am a big fan of tankless water heaters, some people do not like them however you have to take into account . I am a member of a heating forum where a a member was saying he had recently installed a Rheem model and as a result was saving 200 dollars a year on his energy bills. He said the site he was used to find his unit was http://tanklessheaterguide.com/

First is whether you need a gas or electrically powered unit, this will probably come down the the cost of these respective to your specific area, often gas is cheaper. Another advantage of gas units is that they tend to be higher capacity and more powerful, making them more suitable for larger families and big residences.

However electric units are becoming very advanced now with companies like Stiebel Eltron and EcoSmart really pushing the technology forward to the point where these are now very powerful units that can rival gas models. Other things to take into account are your budget as these units can be expensive and please remember to have your tankless water heater professionally installed to ensure you qualify for the warranty scheme of the manufacturer you opt, usually it will be void otherwise.

Hope this helps

  • I am a fan of tankless but most electric models large enough to heat the water for a home are horribly expensive to install because the service usually needs to be upsized for the massive load. Smaller point of use tankless electric water heaters make sense especially if a long distance from the main.
    – Ed Beal
    Oct 6, 2017 at 13:34

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