Tankless electric

[MendoDave]

Has anybody had experience with a Tankless electric water heater? The one below runs on 240.



I have to do a bathroom remodel at some point on the rental and I saw tankless electrics by Rheem at Home Depot. I thought to myself "Self, you could avoid re installing gas service over there and it solves your space issue. But does it work?"

That is the question.

[ducpainter]

No fhe but...

how much volume do you need?

[MendoDave]

Mostly just the shower. I thing 4 gal a min should be more than enough.
Its a 1 bedroom cottage and it has a kitchen sink, dishwasher and washer, but you wouldn't want to run them all at once.

[ducpainter]

Mostly just the shower. I thing 4 gal a min should be more than enough.
Its a 1 bedroom cottage and it has a kitchen sink, dishwasher and washer, but you wouldn't want to run them all at once.

Not with a tankless...

The boiler/water heater combo I'm putting in the house only delivers 3 gpm at 70 deg delta T. I figure that we don't need to run more than one faucet at a time.

If you can actually get 4 from an electric it would be plenty.

[MendoDave]

This one claims 37deg above ambient at 4.5 GPM Min and 92deg at 1.50 GPM with variations at different flow rates.
A low flow shower head should ensure good hot water.


http://www.amazon.com/Stiebel-Eltron-24-Electric-Tankless/dp/B003N3NRY2/ref=pd_sim_sbs_hi_3

[triangleforge]

I haven't used an electric, but we use a whole-house natural gas tankless here and are generally pretty happy with it. There are a couple of issues that would cross over to electric models as well, so worth mentioning:  

We've got very hard water here, so deposits building up on some of the sensors can affect the operation. Even more notable, we've actually got a lot of sand in the water service, to the point that I have to clean out the faucet screens every four to six months when I notice the flow is significantly diminished. We just had to replace the shower head because it was so full of sand and other crud after three or four years - the flow had become low and irregular enough that it would sometimes trick the aquastat in the heater into turning off mid-shower.   I suspect that also has a bit to do with the length of the run of plumbing between the heater & shower for us, which is not a problem for what you're considering.

I'm guessing a tankless would be a great option for your application.

[ducpainter]

Do you know at what temp the water enters the house? Low flow shower head is a good idea anyway.

That thing does draw 60 amps...

That's a ton of kw

I haven't used an electric, but we use a whole-house natural gas tankless here and are generally pretty happy with it. There are a couple of issues that would cross over to electric models as well, so worth mentioning: 

We've got very hard water here, so deposits building up on some of the sensors can affect the operation. Even more notable, we've actually got a lot of sand in the water service, to the point that I have to clean out the faucet screens every four to six months when I notice the flow is significantly diminished. We just had to replace the shower head because it was so full of sand and other crud after three or four years - the flow had become low and irregular enough that it would sometimes trick the aquastat in the heater into turning off mid-shower.  I suspect that also has a bit to do with the length of the run of plumbing between the heater & shower for us, which is not a problem for what you're considering.

I'm guessing a tankless would be a great option for your application.

The guy I got my boiler from suggested a filter to protect the DHW side.

[MendoDave]

Do you know at what temp the water enters the house? Low flow shower head is a good idea anyway.

That thing does draw 60 amps...

That's a ton of kw
The guy I got my boiler from suggested a filter to protect the DHW side.

Probably about 35 to 40 degrees. The alternative is to have the gas hooked up again but this is going to require the lines to be moved a few feet and some digging to be done. I'm not going to do it this year, but the whole bathroom is going to be demolished and rebuilt, to be a bit larger. I find the whole thing to be inadequate. The kitchen got a nice remodel a few years ago. actually there was no kitchen at all, but now there's a nice one in there and a nice sunroom that serves as the living room.

I have pictures somewhere...

But that bathroom has to go.

[ducpainter]

Probably about 35 to 40 degrees. The alternative is to have the gas hooked up again but this is going to require the lines to be moved a few feet and some digging to be done. I'm not going to do it this year, but the whole bathroom is going to be demolished and rebuilt, to be a bit larger. I find the whole thing to be inadequate. The kitchen got a nice remodel a few years ago. actually there was no kitchen at all, but now there's a nice one in there and a nice sunroom that serves as the living room.

I have pictures somewhere...

But that bathroom has to go.

I bet it's higher than that.

Even if it is as low as 40...

100 ish degree DHW is plenty so you're looking at roughly a 60 degree deltaT.

That will put you in the 2.5 gpm range.

Should be plenty.

[ducatiz]

We needed a new water heater a year after we bought the house and put in a tankless.  Absolutely no regret whatsoever.  Ours is NG and the difference in gas usage is noticeable, like 10-15% lower every month.  Ours is a Rheem with something like 9 or 10 gal/min. 

No regrets at all and besides the lower gas bill (our highest gas bill was $97 last year -- 2 gas ovens, gas cook top, gas space heater in the garage and gas furnace too), I got a whole closet back since there was no longer a 60 gallon water heater there.

[MendoDave]

There is a Bosh LP gas tankless at my Dads place and it works great. I had to clean the inlet screen once, that was pretty easy.
When this Hot water heater goes out here at my place I plan on replacing it with a NG Tankless. That should save lots of space as well.

[ducatiz]

There is a Bosh LP gas tankless at my Dads place and it works great. I had to clean the inlet screen once, that was pretty easy.
When this Hot water heater goes out here at my place I plan on replacing it with a NG Tankless. That should save lots of space as well.

While you're doing it, put a water filter in front of the supply for the heater.  You can get them for reasonably cheap and it will make the heater last longer.  If you just do the feed for the heater, you can use a smaller one and it will actually last 6-9 months on a filter cartridge.  I use plain charcoal filters.

[77south]

If you have a whole home humidifier* hooked up to your forced air heating system, running hot water to it will increase its performance.  Sadly tankless water heaters do not work for this purpose, as they don't use enough water to activate the heater. 

*like an Aprilaire model 600 for example.  Disclaimer I work for Aprilaire, and used to work in the customer support call center, so I am speaking from experience.