Yeah, me neither, even with a surfeit of Solar capacity, it seems to me the high current draw is somewhat anti-solar friendly.
But then I'm still struggling with the thermodynamics of indoor air sourced heat pump water heaters during the winter. I mean I like the concept of a heat pump water heater...like geo thermal for example, but transferring heat from the air in my house during the heating season seems like a double whammy to me! Summer? Seems great...winter? Heck my basement is already cool enough!
Nope, not significant. But the basement does get fairly chilly (60 degees?) in the winter if you are really making a lot of hot water. I mitigate that by changing to a setting that is biased toward resistance (element) heat setting than a heat pump one.
I heat with a air source heat pump and propane. So I am moving heat from outdoors to indoors then to water, which isn't the most efficient, but it is still better than resistance heating elements. The proof is my overall electric usage dropped $30 a month, with no noticeable propane use increase.
We have two tankless, propane Rinnai water heaters at our home in Maine (two buildings). The property was lived in full time for a couple of years, then was vacant for about a year, then our vacation property for a year, and now we've lived there full time for over a year. Both heaters have been flawless throughout, with well water that has very high iron but no other mineral content. The filters were not great when the previous owners had the place (we've addressed that). Other than waiting a few seconds for the water to get hot, we think they're great. We save a bundle on energy, and maintenance has been almost non-existent (probably need to look into doing that this fall). I'd definitely consider them.
We currently have two 16-year old, electronic-powered hot water heaters with 50-gallon tanks in our attic. We had plumbers come out last week and they claimed I'd need 3 tankless units to cover the house (5500 sq ft with 6 bathrooms). Seems excessive, but given the mixed reviews I've read in this community about tankless, we've provisionally decided to replace the tanks with 2 new 50-gallon tanks -- these Rheem/Econet units. I'm also going to relocate the units to the garage from the attic. Having 100-gallons of water in my attic makes me nervous.
I'm also thinking about adding recirculation pumps for instant hot water that I can control with a smart outlet.
Finally I used this web site to discover our water is high in minerals and contaminants so we're also going to install an EWS water filtration/softening unit.
Will gladly accept any feedback or ideas! FWIW, we're in an area that is mild in the winter and hot/humid in the summer. This is not my area of expertise.
For those who have had good experiences with saving money on your electrical bill by turning the tank off for select periods each day.....
How do you reconcile that with the concern about Legionnaire's disease. I can see that @aaiyar drains and treats his tank once or twice a year. Is that the tradeoff with regularly lowering/raising your water temperature?
The temperature of the water in the water heater reaches 140 degrees (the temp stated to kill the bacteria) every morning when it comes back on from being off. I'm not too concerned myself lived in this house for over 25 years have never flushed the water tank once (replaced it a few times now after that long) and haven't been hospitalized for the disease yet.
I generally agree with @waynespringer79, but I want to add some comments here from a microbiological perspective to indicate why his choice is safe.
Even if Legionella grows in the tank, it will only affect those who are moderately to severely immunocompromised. That eliminates 99.9% of humans.
If you have a large hot water demand, meaning a family of 4 using the same 50 gal water heater, then even if Legionella grows in the tank, it isn't sticking around - but will be flushed/diluted out regularly.
If you change water heaters every ~10 years, that also diminishes the likelihood of Legionella becoming an issue.
It is really an issue for someone like me. I live alone. My hot water use is minimal. And I'm a type 2 diabetic which increases my likelihood for certain infections, including Legionella.
To add to this, both my tanks are old (but well-maintained). One of them just hit 20 years and the other is 13 years old. They're in my attic, so I have no desire to replace them - and maintenance (including replacing the anode rod) is simpler than replacing the entire heater.
There is something else simple that one can do to minimize the possibility of bacterial growth in a water heater. Use Zinc or Aluminum anodes instead of Magnesium anodes.
I have no experience with powered anodes but that would be an another alternative to magnesium anodes.
I have 3 Full Bathrooms in my house, and 1 of those has two shower heads (well, 4, but only 2 are ever on). My water temp is in the 40-50F range (as I recall), and my 11+ year old Rinnai can run 3 shower heads simultaneously with no issues (although due to proximity, one bathroom and the kitchen faucet have "priority" in the grand scheme of things, and can cause a pressure drop in the master shower). Admittedly, they are newer shower heads so probably run at less than 3 GPM, but I can't think of any reason that you would need 3 tankless water heaters for 6 bathrooms, unless you are running a youth soccer team through your 6 showers simultaneously, OR you have 2 water heaters already in different physical locations, servicing separate bathrooms.
If they aren't, then a paired set of Tankless like @Madcodger is using would be sufficient in all but the most extreme circumstances (e.g. extremely cold ground water -- such as glacial sourced water like you may find in the mountains, or a LOT of simultaneous use of water).
Cost wise, however, it's hard to recommend dual tankless on propane-- like the comment about Solar earlier in the thread, if you're seeking "payback" it'll be hard to get to a "paid back" status on 2 or more propane burning tankless water heaters. Natural Gas? Sure. Propane? Not so much.
The cost of a RUR199iP (Propane, Indoor, 3-6 Fixtures) ~11 GPM is ~$2200, significanly more than the Rheem Heat Pump Water Heater linked ($1742) so with that -- unless the space/unlimited hot water capability is high on your priority list,
The tanks you chose will be the easiest solution for sure.
It all depends on the assumptions of simultaneous bathing and other use like laundry.
I can easily deplete hot water on my 2x 50 gal water heaters in my 4 bath house if multiple people take hot/long showers (or fill the bathtub) while the washing machine is running. Has happened many times.
The right amount/# of water heaters all depends on use.
A gallon of 1% bleach. Or 3% hydrogen peroxide. For 30-40 minutes is amply sufficient (bacteria settle in the tank). Then fill the tank with cold water and run about 30-50 gallons out a bathtub (takes about 30 minutes) through the hot faucet before turning the water heater back on.
This is specific to Legionella - it happens to be particularly sensitive to oxidation. Other bacteria are less sensitive, but also not as much of an issue in water heaters.
