Tankless Electric Water Heaters

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1

Originally Posted By: Bob Smith
This post was automatically imported from our archived forum.


Hello,


I have been asked to research the effects of tankless water heaters in relation to proper sizing of utility transformers
in the residential sector. Do you have any information/studies regarding how the electric utility companies are having to
make adjustments to handle any additional loading? Any information at will be most helpful. ![icon_smile.gif](upload://b6iczyK1ETUUqRUc4PAkX83GF2O.gif)

Sincere Thanks,

Bob Smith
Load Research Analyst
OGE Energy Corp

2

Originally Posted By: lfranklin
This post was automatically imported from our archived forum.


Welcome to the message board Bob.


I don't have any information on the load draw of a tankless heater.

I know they are new to the market around here and thought they had less of a draw. Was even thinking of my next one being a tankless heater.

Does anybody know what the actual draw between the two is ![icon_question.gif](upload://t2zemjDOQRADd4xSC3xOot86t0m.gif)

3

Originally Posted By: Bob Smith
This post was automatically imported from our archived forum.


Thanks Larry.


From what I've picked up so far, they come in two categories: Point of service units (smaller and located under skinks or close to the end use) and whole house (larger and replaces the conventional tank type heater). The whole house units is what has us at the utility concerned. They can be sized from 14KW to 35KW, typical being 22KW thru 28KW, a 28KW will require probably a 200 AMP breaker, it has 4 chambers each with 7000Watts. So if you have a home builder that is promoting the devil out of these and has a whole housing addition putting them in... well we may need to look at how the transformer sizing fits with the load diversity, I'm thinking it will be different than what we currently size for.

Any information is greatly appreciated, and thanks for the welcome!

Happy Holidays,
Bob.

4

Originally Posted By: dedwards
This post was automatically imported from our archived forum.


Bob,


I plugged in electric tankless water heater into Goggle. It has a slew of places but the one I looked up cause Im a curious kind of guy, was www.homeclick.com. There are several areas to choose from but it listed one called PowerStar. Replaces a residential 40 gallon tank and draws around 17.25 KW, single phase, 240 volt. Uses an 8 AWG wire. All the specs are on the site. Hope this helps.


Doug

5

Originally Posted By: Bob Smith
This post was automatically imported from our archived forum.


Hi Doug,


Hey thanks for the reply, I will go and check out those specs and see what I can learn.

I just spoke with our engineer on this project and found out that we're talking about an apartment complex that is total electric and will have tankless water heaters in every apartment. OK, at 18KV per unit, and 100 apartments.... hmmm when everyone gets up to shower before heading off to work, we better have a healthly transformer out there or someones lights are about to dim/flicker... you get the picture.... ![icon_idea.gif](upload://6VKizmOm2U7YYmfXNtFW4XTwFVy.gif)

Thanks Again, I really do appreciate it.

Bob.