Which electrics will remember temp setting across power outages?

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Scott9

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I've searched all over the place including here and can't find this information. Which tankless electric POU heaters will remember their temperature setting across minor power outages?

The situation is that I had a 7kw constant temp rise unit that failed. I'd like to replace it with a temp regulated unit of the same capacity. It's mounted in a rather inaccessible location. Thus, once I set the max outlet temp I don't want it forgetting it or staying off after minor power outages, which we have quite frequently. I'm ok with it forgetting if the power is out for more than a few hours, but it has to be able to remember across all those .5-5sec outages we get. Of the units I've looked at, none make mention of this in their documentation (if you can call it documentation) or sales literature.

I'm also considering replacing our aging propane tank type heater with a larger electric tankless in the 15-18kw range. Same requirement applies.

Can anyone please point me in the right direction?

Thanks,
---Scott.
 

Reach4

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Which tankless electric POU heaters will remember their temperature setting across minor power outages?
I would be surprised if there was one that will not do that.
I'm also considering replacing our aging propane tank type heater with a larger electric tankless in the 15-18kw range. Same requirement applies.
What are your objectives? Save space?
 

Scott9

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In the reviews for one (don't remember which one) one of the complaints was that it didn't remember and turned off. That got me worried, so it became an issue. I just got an answer back about the iHeat HS-7 and the dealer said it doesn't remember. I currently have a query with Rheem about their RTEX-06.

Yes, I'm a bit surprised. This is trivially easy to accomplish either with NVRAM or a supercap on regular static ram. Heck, my $60 AC thermostat will retain its programming for longer than our power has ever been out (multiple days). This is old tech and there's no excuse for these water heaters not to have it.

As to a large unit for the house, no particular goal here. It needs replacement, at 25y I'm on borrowed time. I can go either way electric tank/tankless or propane tank. Propane tankless is out because of the venting issues and supply line. More work and expense. Getting the closet space back would be nice, but not necessary.
 
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Jadnashua

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Your inlet water temp in FL may be high enough to deal with an electric tankless system, but while efficient, they often don't heat that much volume. A 17Kw unit equals about 58K BTU. Keep in mind, most whole-home gas-fired units are nearly 4x that big at 199K BTU...that should give you and idea of how much hot water it can provide. I wouldn't even think about trying to fill a tub, but you might get by taking a shower if nobody else is trying to use any hot water at the same time.
 

Scott9

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Just a followup on what I ended up doing. Rheem got back to me on the RTEX-06. Their website was incorrect. It said that the RTEX-06 had adjustable (regulated) output temp. It does not. It's a constant rise unit with a temp display. I've decided to buy another of the exact same unit that failed. I've put up with constant rise for 20 years and can continue. It's also my least expensive option and it will be a drop-in with no plumbing changes.

The house will be done with a propane fired tank unit.

Thanks.
 

Cacher_Chick

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An alternative would be to power the controller through a UPS, but making the connection would depend on how the unit is wired.
 

WorthFlorida

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...The house will be done with a propane fired tank unit.....

If the electric unit meets your needs I would shy away from propane. In Florida propane probably will be more costly as compared to electric. I had FPL for 27 years and for the most part the electric rates were fairly steady for most of those years and now I'm in Orlando with OUC and the rates are less or about the same. Check with your electric company and look for rebates offers. They come and go of various kinds and usually they are not advertised.
 
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