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Can a water heater be installed between two apartments and wired to both apartments' breaker boxes, effectively splitting the bill between the two? It's a 220-volt heater, and this is a retrofit wiring.

Bob and Trish
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    Unless you can find a dual-element water heater meant for sharing (not the typical top/bottom dual elements since they aren't used equally), I think the only way to do what you want would be to install a separate meter for the water heater and split the bill, or wire it into one apartment, then use a power meter of your own to measure the power and split the bill. There are some electronic home energy monitors available that can email you with usage. You'll still face issues of "fairness" over which apartment uses the most hot water, though I guess you could measure water usage too. – Johnny Jan 19 '16 at 23:03
  • If it can be, there's a major flaw in that one side could simply flip their breaker to off. They could still share the hot water, but not have to feed it electricity. – DA01 Jan 20 '16 at 16:10
  • That's why there are lockable panels. Oh by the by, someone called me a bad name & the moderator decided my list & your comment should be deleted on the other question...in case you were doubting. – Iggy Jan 20 '16 at 17:34
  • There is a separate question regarding [why this is dangerous](http://diy.stackexchange.com/questions/82622/how-can-it-be-dangerous-to-feed-a-water-heater-from-two-separate-panels). You don't want to do this. – Nelson Jan 21 '16 at 03:37

2 Answers2

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No, no, no! Not only would it totally not do what you want, but would make the cost splitting even worse, as one tenant's other load would wind up on the other tenant's bill, simply due to the way electrons seek the path of least resistance.

It would also create neutral and ground loops that would make heat in unexpected places, and your circuit breakers wouldn't protect you from that. It could burn the building down.

A less-unsafe way of doing that would be seek out a water heater with two separate heating elements on 2 circuits. For instance larger on-demand heaters have this. Put one circuit on one service, and the other circuit on the other service. If they operate together, that would split the cost. Check with the manufacturer to see if they do that. However there'd still be an issue of ground. If the apartments are served by 2 service panels, each getting their grounds from different locations, then you would be entangling grounds from two different systems, and my gut reaction is code would prohibit that. If there's an exception to be found, or a way to rejigger the panels' grounds to make this safe, a proper electrician could tell you better.

In the apartment business, the normal way that's handled is by a third meter for commons areas.

Harper - Reinstate Monica
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    +1 for a third circuit and split or flat billing. A technical solution to a **billing** problem needs to be simple. – blaughw Jan 20 '16 at 19:38
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    i would tend to agree. Frankly our genius is wasted trying to help this skinflint avoid a couple of hundred bucks for a second water heater: done. Nothing we can come up with will be cheaper than that, and none will be nearly as fair. – Harper - Reinstate Monica Jan 20 '16 at 21:32
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In short, no. Wiring issues and code aside, the real issue isn't how the electricity is metered - it's how much hot water each side uses. The electricity is simply the input energy required to raise water to the set temperature, and the amount used is based on how much water you take out that has to be re-heated.

Let's assume that you go with a two element heater with each element metered. If your neighbor is running hot water 24/7 and you only use cold, you're still footing half the bill for your element.

Comintern
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  • @Iggy - I'm not making a recommendation at all. I'm answering the question as to whether it would "effectively split the bill between the two". – Comintern Jan 20 '16 at 23:19