# Heating hot water



## Dennis Alwon (May 9, 2009)

100 amp service with a 28kw heater. Did you do the math? It will use more than 100 amps. I am assuming single phase.


----------



## HARRY304E (Sep 15, 2010)

Dennis Alwon said:


> 100 amp service with a 28kw heater. Did you do the math? It will use more than 100 amps. I am assuming single phase.


He must have meant 2.8 KW.


----------



## Dennis Alwon (May 9, 2009)

HARRY304E said:


> He must have meant 2.8 KW.


Not for an instant heater.


----------



## HARRY304E (Sep 15, 2010)

Dennis Alwon said:


> Not for an instant heater.


What do they typically draw? never looked into doing one of those before.


Of coarse now i will get a ton of calls for them..:blink::laughing:


----------



## oldtimer (Jun 10, 2010)

Clarky said:


> Have a customer that's looking into an electric instant 28kw water heater what do you think? Can't use his pellet boiler and doesn't have gas on site.
> Is this his best option? His house has a 100 amp. service I'm not sure can handle this, although it is a momentary use item.
> Taking any suggestions
> Keith





Just a joke!! Why do you need to heat HOT water?


----------



## HARRY304E (Sep 15, 2010)

oldtimer said:


> Just a joke!! Why do you need to heat HOT water?


Because otherwise it would come out of the pipes "cold":blink::whistling2::laughing:


----------



## Dennis Alwon (May 9, 2009)

HARRY304E said:


> What do they typically draw? never looked into doing one of those before.
> 
> 
> Of coarse now i will get a ton of calls for them..:blink::laughing:


I have never done an instant electric but I hear they are 17kw-28kw. I also heard some negative comments on them in terms of efficiency. The gas ones however seem to do better and only need a circuit for controls & fan.


----------



## Southeast Power (Jan 18, 2009)

Clarky said:


> Have a customer that's looking into an electric instant 28kw water heater what do you think? Can't use his pellet boiler and doesn't have gas on site.
> Is this his best option? His house has a 100 amp. service I'm not sure can handle this, although it is a momentary use item.
> Taking any suggestions
> Keith


I really do not understand why people would want something like that. It is electrically nothing more than a water cooled welder.
Most fully electric houses have a 30 gallon, heavily insulated storage tank with a 4500 watt dual element system. Both elements do not come on at the same time. ever.
Assume that you will soon be charged an extra multiplier to use electricity during peak hours. Wouldn't it make sense to heat water during "off peak" times and use it during peak times. Wouldn't it be a disaster to heat your water with one of those water cooled welders during peak usage hours.

We have a local condo that had a handyman install several of these units throughout a condo building. He was eventually caught and it was discovered that the service on the building could only handle one or two of the tankless units on each floor. Some floors had several. 

My heater 4.5kw heater operates about two to three hours a day. This costs me less than $50 per month or max about $600 per year. 

Assume the tankless operates only 30 to 40 minutes a day at a 15kw where are the savings? Where is the payback on the installation?

Am I missing something about these units? If so, please educate me.

Considering what I know about these units, I think they are something that work better as a gas appliance.


----------



## oliquir (Jan 13, 2011)

main breaker can handle it for few seconds if he shuts off everything else since it draws about 116 amp


----------



## Cletis (Aug 20, 2010)

*On Demand*

Yeah, we do those all the time here. It's great because your going to get a 200 amp upgrade on top of the install. Make sure you call your local POCO and tell them about it so they can upsize their transformer if needed, or the customer will get dimming lights everytime they use hot water. 

Good Luck


----------



## Dennis Alwon (May 9, 2009)

oliquir said:


> main breaker can handle it for few seconds if he shuts off everything else since it draws about 116 amp


It sounds like you are endorsing this install. It is not compliant in any situation with a 100 amp service.


----------



## oliquir (Jan 13, 2011)

Dennis Alwon said:


> It sounds like you are endorsing this install. It is not compliant in any situation with a 100 amp service.


no i dont, i was sarcastic :whistling2: maybe i should have put some smilies


----------



## Dennis Alwon (May 9, 2009)

oliquir said:


> no i dont, i was sarcastic :whistling2: maybe i should have put some smilies


Good.... :thumbsup:


----------



## jmsmith (Sep 10, 2011)

Math and service size aside... Does HO have small children? Just a thought here, 'cause I would have to think on if the install is worth it to me! Youngin's have no earthly idea of what "instant" hot water is !

Sent from my iPhone using ET Forum


----------



## macmikeman (Jan 23, 2007)

I had to hook up about a half dozen in my travels. The other half dozen I talked em into getting a gas instant heater instead. The thing about gas ones is some are better than others. Some gas ones don't provide very even heat output, it goes hot, warm, hot in sequence. Not much fun if you like long showers. Good plumbers know what brands suck and what brands are problem free, so work with the plumbers on that one.......


----------



## dronai (Apr 11, 2011)

Iv'e done a lot of the small ones that go under the kicthen sink. They take a 20A dedicated circuit.

I also provide power to a lot of tankless waterheaters. (Gas) , but I had one the other day, that they were trying to use electric, because it was a Condo, that didn't have gas. I calculated the KW, and it would have taken over 100A, the same size as their small panel. Not practical !


----------



## jmsmith (Sep 10, 2011)

I have also installed the under-sink style in a couple of kitchens and in a few jobsite office trailers... So may have been out-of-line with my first response. Am not familiar with a whole-house model. Do they have the same style max temp controls that a conventional tank water heater?

Sent from my iPhone using ET Forum


----------



## RGH (Sep 12, 2011)

Maybe check out smaller point of use units for kitchen and/or baths. Then you could use smaller unit for main. Overall if it was my place I would go to propane lol, water input temp in vermont in January is what 45? ouch watch that puppy spin!:no:


----------



## Amish Electrician (Jan 2, 2010)

Looks like it's time to cross 'craft' lines and learn a little bit about another trade ....

Folks talk about changing over to an 'instant' water heater as if that was all there was to it. That's just not true ... and bad design leads to unhappy customers.

Even in the past few years there have been major changes - or, should I say, many little changes with big effects- regarding 'instant' water heaters.

For the electrician, the easy part is hooking the things up: just look to the nameplate and supply what it needs. The hard part is selecting the correct unit.

You see, the 'instant' heaters are very, very affected by the flow required. "Bigger" is NOT better, and the idea of a single, central water heater might no longer be smart.

An "instant" heater is rated in terms of the maximum amount of flow it will heat up enough. The first error folks make is that they assume too warm a temperature for their ground water, and get a heater that can't heat the water up enough. Fortunately, many manufacturers have corrected the misleading sales copy they formerly used.

Minimum flow is also a big deal. With 'low flow' shower heads, it's very possible that taking a shower will not draw enough water to turn the water heater on at all. The larger the heater, the more flow is needed to get it going.

For myself, these details led to a complete re-design of the plumbing in my house. I have a 5-gal tank under the kitchen sink for those small loads, and a modest 'instant' heater to provide the walk-in tub and laundry with large amounts of hot water on the (somewhat) rare times I use them.

Finally, the hot water is 'instant' only if the heater is very close to the point of use. If there's fifty feet of pipe between the heater and the faucet, that's fifty feet of cold water you still need to dump before the hot water arrives.


----------



## jwjrw (Jan 14, 2010)

Most of the all electric ones we have done were smaller than 28kw. They took two 40 or 60 amp breakers. Or maybe we did one of each. In most cases an upgrade is required. Tell the customer to see if they make one that uses propane or sell him a service upgrade...


----------



## jwjrw (Jan 14, 2010)

jmsmith said:


> Math and service size aside... Does HO have small children? Just a thought here, 'cause I would have to think on if the install is worth it to me! Youngin's have no earthly idea of what "instant" hot water is !
> 
> Sent from my iPhone using ET Forum



It does not supply INSTANT hot water. You need a circulating pump to accomplish that. They give you continuous hot water not instant hot water.


----------



## jwjrw (Jan 14, 2010)

dronai said:


> Iv'e done a lot of the small ones that go under the kicthen sink. They take a 20A dedicated circuit.
> 
> I also provide power to a lot of tankless waterheaters. (Gas) , but I had one the other day, that they were trying to use electric, because it was a Condo, that didn't have gas. I calculated the KW, and it would have taken over 100A, the same size as their small panel. Not practical !



All the under sink ones I have done recommend a dedicated citcuit but did not require one. All have been 1300 watts I believe though. You may have installed larger ones.


----------



## jmsmith (Sep 10, 2011)

jwjrw said:


> It does not supply INSTANT hot water. You need a circulating pump to accomplish that. They give you continuous hot water not instant hot water.


Thank you sir... Remember a chromalox heater that I wired in a church baptistry. The water was piped via a circulating pump, and in the dead of winter had to run about 6 hours before use, or people were fixing to see a preacher turn instant blue! lol! Thank you for the comeback, I guess I'm still thinking in industrial mode!

Sent from my iPhone using ET Forum


----------



## Clarky (Sep 25, 2011)

Thanks for input No I'm not indorsing this, I think a gas set up is what he should go with or just stick with his current electric set up which I think that's what he has.In Vermont the pellet boilers are becoming popular but I don't think people think about how they heat there hot water. Everyone is trying to get away from using oil or gas so pellets are being used but they are still a manufactured product that requires storage, no easy answers.


----------



## stars13bars2 (Jun 1, 2009)

one advantage is that you can run a discotech the under the incandescent lights that will be flickering the whole time the hot water is being used.


----------



## kinglew (Mar 16, 2008)

*on demand*

suggest propane on demand .i install one 14 months ago. save me 40 percent on my propane bill 1st year over my power vent hot water tank i replace when it die .noritz top brand no issue


----------



## Vintage Sounds (Oct 23, 2009)

Last post in this thread before you guys came along was on 10-08-2011.


----------



## five.five-six (Apr 9, 2013)

Why would you heat hot water?


Sent from my iPad using Tapatalk


----------



## backstay (Feb 3, 2011)

five.five-six said:


> Why would you heat hot water? Sent from my iPad using Tapatalk


To make it hotter!


----------



## chicken steve (Mar 22, 2011)

We did a 38KW EMax for a large multi-unit resi/commercial structure last year.

It required a 200A commercial service , the poco changed the Xformer from backpack to buick size, and the usage tipped the metering scales over to a higher KW per hr rate.

ya can't fix stupid!:whistling2:


~CS~


----------

