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28kw tankless water heater

8.9K views 49 replies 22 participants last post by  Knightryder12  
#1 ·
Anyone here have experience with these babies? They take (3) 40 Amp breakers. That's big.

How do they handle on an existing 200 Amp services? Especially ones with all electric appliances?
 
#3 ·
If its for yourself, don't. Anytime you run hot water they take that power so you have to factor that in above what your house needs otherwise. I hooked up a 36KW for a guy in his shop, and depending on the volume of water and temperature setting it caused very bad flickering of the LED lights. I believe it was caused by an element being cycled quickly to maintain the temperature.
I've also heard they are a lot worse for temperature fluctuations when hot water is turned on elsewhere.


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#8 ·
It is time to sell a new 400a upgrade, talk to them about solar, battery storage, pre-wire them some EV chargers.

Do it now. I don't want any excuses about not working when you had the opportunity to sell this job.
 
#13 · (Edited)
Here's the guy I need to talk to.

OK, so my thoughts were to run a 125 Amp feeder and set a sub panel next to the WH. Then have (3) whips off (3) 40amp breakers to the unit. That seems more practical than running (3) lines.

Does this baby actually pull 120amps every time it calls for hot water?
 
#18 · (Edited)
I have a 36 kw unit made by Eco Smart. It's in my own house I'm renovating. It's perfect since when I first installed it, I wasnt staying there full time so would be in and out randomly when I had time to work on the house. Didn't have to keep a tank unit on all the time and still had hot water as soon as I got to the house after not being there in days/weeks.

4 40 amp breakers, well water, and the elements turn on sequentially one at a time based on demand.
200 amp service, small 900 sq foot house. Haven't had any issue what so ever, lights don't flicker.
No access to gas on the property, everything in the house is electric, including baseboard heat. Installing a multi zone mini split currently. So far, I'm a fan of the on demand heaters. Time will tell. It's been the only source of hot water there for about 2 years. No breaker or bus issues what so ever.
 
#21 ·
900sq ft? Probably not an enormous amount of demand on the electrical system. That sounds like a small 2bd 1 bath, right? Maybe 3 people there, 4 tops.

Wonder what that would look like on a 1500-2000 sq ft home...
 
#19 ·
Most of my customers that have these have gas fueled ones. They love them (according. to them...). Two were stubborn and insisted on installing the big electric jobs with 3 40's or 3 sixty amp 2 pole breakers. Then they wine about power sags. LOL. I covered everything in the proposals. Told em to call 1-800-Ainokea.
 
#20 ·
My newest mini split does a nice job of heating the area it covers. I’m not sure I’d rely upon it for the coldest of days but haven’t tried it either. I have two of the gas on demand units and as long as they are cleaned/maintained they do their job fine. I think if I was going to wire in one of these electric units and upgrade the service to handle it, I’d feel better installing a bolt in style panel. I’ve seen the larger car chargers wreck stab in panels, so I’d be a little leery of that.
 
#22 ·
Some laymen use the logic, "I got 220, why not. I won't have to buy gas."

The subject has come up a number of times. The only one who actually bought one wasn't all that sharp. His house was supplied by a 1940 vintage overhead service. A 15 KW transformer supplied 3 houses. His was supplied with an overhead service #4 aluminum. IIRC his was 127 amp load total in three stages. He saw no problem upgrading to 200 amp service until he heard the price. His 19 amp tank water heater started looking better.
 
#25 ·
Poco in my area doesn't want anyone back-feeding solar so one option i have been looking at is to convert my hot water heater to 24vdc and using it as a pre heater. Then i could install a tankless water heater to finish heating the water before use.
The power requirement of a tankless unit does make you scratch you head and wonder if its worth the hassle.
 
#24 ·
It sounds like it could work out like it is for the poster if it has limited use and the installation was done correctly. I find it difficult to compare costs, payback and so forth when trying to compare fossil fuel vs electric heat or hot water. The practical aspect of the install sometimes seems to be the driver. I noticed that it's been a long time since the property managers converted from electric baseboard heat. I'm sure there are a lot of factors in that decision. Several conversions to gas have been done from oil, possibly driven by underground storage tanks.
 
#27 ·
A quick Google Search shows at least a dozen different electric models and brands.

Ranging from 11kw to 32kw.

In fact one site says electric is so much better than gas models because you don't have to pay for the expensive "gas piping and venting". Lol. That's right...
 
#34 ·
Usually, they are used for areas where there is no continuous use of water in order not to continue heating water all day long as done in a normal electric water heater.
In regards to the solar heater, there are two types of solar thermal and PV.
Solar thermal is preferred in hot climates as PV efficiency is very low in hot sunny areas and they don't need batteries.
In general, for a sandy area just be sure that they can be cleaned or oversize it, to consider the dust accumulation in case it's an issue.
 
#39 ·
What about having multiple point of use units located throughout the home, like maybe a unit per water location? Bath 1, Bath 2, Kitchen, Laundry?

Cost of installation aside, I wonder about the efficiency of the system, both on the water use side and the power consumption side.
 
#46 ·
I like the small 30 amp or less ones at the sink. Those make excellent sense , especially for break rooms in other than dwellings.

Places with showers and bathtubs though out to go some other directions than electrical in use. Solar heat tanks are excellent in my location, they only need to rely on the house electrical backup supply maybe three or four days out of a year. The rest of the time it's an overabundance of hot water available for just the cost of the original installation and a bit for maintenance.