We're planning to build a new house in SE Michigan this year and geothermal heating/cooling is near the top of our options list.  We assumed we'd be able to add a desuperheater to use with our planned natural gas water heater but the contractor says an electric water heater should be used instead.  What is the rationale for using electric instead of gas?

Apologies if this has been asked and answered before.  A quick search didn't turn up anything specific.  Thanks.

Get a buffer tank.  You crazy to do a single tank. If the electric goes out you will still have hot water with the gas unless you have one of those extreme high efficient ones with a electric blower for the exhaust. If you ever go solar hot water the buffer tank is already there.

For me the desuper heater only is used during the AC mode.  For winter and non-heat/ac mode the gas water heater does the job more efficiently than a regular electric hot water tank with my electric rate (50% is wind generated, checkout cleancurrents.com)

Chris in MD

In SE MI (my AO) Nat gas is cheaper than electric hot water.
j

Desuper without a dedicated unfired buffer / storage tank is almost certainly a waste of money. Properly buffered, a desuper can feed any other type of finishing heater; storage or demand, any fuel.

contractors here are feeding the on demand propane heaters via buffer tanks for storage and are very happy with the performance.
Eric

When we built our house last year, my wife did not want anything gas in the house.  We had a Marathon 85 gal electric water heater tied in to the desuperheater from our geo system.

It works just like I was told it would.  The geo produces 50 - 65% of the hot water in the summer months and about 25 - 35% of the hot water in the winter.

Although true, if I lose power, no hot water. But on the other hand it does take awhile to use up the 85 gallons.  Besides, when I wired the house, I set up a sub panel for my backup generator and added the hot water circut to the panel for that purpose.

Posted By nhgeo1 on 27 Apr 2011 07:04 AM
We had a Marathon 85 gal electric water heater tied in to the desuperheater from our geo system.  It works just like I was told it would.

We an 85 gallon Marathon as well, 2 DSH's tied to it (from 2 geo units), and a water heater timer.  Works well for us in VA.

Posted By nhgeo1 on 27 Apr 2011 07:04 AM
But on the other hand it does take awhile to use up the 85 gallons.  Besides, when I wired the house, I set up a sub panel for my backup generator and added the hot water circut to the panel for that purpose.

And the Marathon only looses about 5*F per day, so it holds heat very well.  We're working on a generator project now, initially considered to keep our sump pump running, but it is capable of running our water heater, and more, as well.

There are reasons folks don't want gas in their homes (risk of CO, fire, burns conditioned air requiring replacement air from outside).
I'm usually inclined to use gas where it's available.
groundsquirrel have I seen your project?
Joe

Posted By joe.ami on 27 Apr 2011 08:14 AM
...groundsquirrel have I seen your project?
Joe

No, we're still planning, and trying to vet the recommendations we've seen.

Thanks for all the useful replies.  It sounds like there's no technical reason a natural gas-fired hot water heater couldn't be used, but that a buffer tank should be part of the system.  Frankly, I was surprised when the contractor specified an electric (52 gal.) unit, as I've always thought that (in SE Michigan anyway) electric was a far costlier option for making hot water than gas. 

Nat gas is least expensive, but depending on whether you have consumers or DTE, electricity is cheaper than propane as you approach or pass $2/gal propane.
Joe

BTW while few endorse it here virtually every manufacturer continues to suggest you can use an electric tank and dsh without a buffer tank. None suggest unbuffered use with a gas water heater.
You may have met someone that's trying to save you a few hundred on the install, I wouldn't endorse the plan.
j