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Whole Home instant hot water heater #168217 08/29/07 01:24 PM
Joined: Aug 2006
Posts: 11
sprynda Offline OP
Junior Member
Hello to all,
I have a customer that was thinking about a whole house instant hot water heater. I did some research and looked at the bosch and SEISCO units. The customer wants the electric unit not the gas unit. The thing that concerns me is that both units require 3 40 amp 220 circuits. The customer has a 200 amp service. The main panel is filled except for 4 slots with all 220 breaker for electric heat and includes a 100 breaker for one sub panel and one 60 amp for a second sub panel. I just feel that there is too much on the panel to add this type of devise. Has anyone ever used this type of heater and if so i would like some comments
thanks for the help

Work Gear for Electricians and the Trades
Re: Whole Home instant hot water heater [Re: sprynda] #168218 08/29/07 02:04 PM
Joined: Apr 2002
Posts: 7,235
HotLine1 Offline
Seems that a good load calculation is in order. Better may be installing a recorder for actual readings.

Gut feeling is....service upgrade

Re: Whole Home instant hot water heater [Re: sprynda] #168220 08/29/07 02:41 PM
Joined: Jul 2004
Posts: 783
LarryC Offline
Whole house instant hot water heater? I thought Instant DHW heaters were point of use devices? How does a whole house become a point of use?

Larry C

Re: Whole Home instant hot water heater [Re: LarryC] #168221 08/29/07 02:50 PM
Joined: Aug 2006
Posts: 11
sprynda Offline OP
Junior Member
these units are bigger that the point of use. i have installed several of those units in kitchens or baths, but then i foynd these whole house units. i just have not found anyone that hsa one to get feed back from

Re: Whole Home instant hot water heater [Re: sprynda] #168227 08/29/07 05:06 PM
Joined: Feb 2003
Posts: 939
frenchelectrican Offline

I allready install few whole house instat waterheater and unforetally most place where they have 200 amp service they useally really pushing pretty hard with the rating.

from my experince i genrally expain what will happend when they get the whole house instat waterheater i have to warn them they will have to hevey up to 400 amp service and the cost as well.

anyway few did have it hook up in few months later they asked me to remove it and get the standard electric waterheater or go with gas version of whole house instat waterheater

the other thing is that from my exerince i am sure few will ring in here as well

1] the lights will be more noticeable flicker when the IWHWH cycle [ just like turn on and off 3 electric range at the same time or run in stages ]

2] many POCO will get little ticked off becuase if this transfomer feed few homes and burn up the transformer. [ try that on very hot summer day when everyone crank up A/C and the IWHWH kick in with overloaded transformer]

3] the whole house instat waterheater is very senstive to the water flowage it can be anywhere from lukewarm to pretty hot [ if you have very cold water supply it will make it lukewarm ]

i will let other peoples fill in their experince with this as well

Merci , Marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Re: Whole Home instant hot water heater [Re: frenchelectrican] #168250 08/30/07 12:46 AM
Joined: Feb 2006
Posts: 144
napervillesoundtech Offline
I stayed in a small (5-room) hotel that had one of these on a 200 amp panel. The flickering lights were almost unbearable, as the unit turned on and off as each guest turned their water on and off. In my opinion, a 200 amp panel would be way too small.

Re: Whole Home instant hot water heater [Re: napervillesoundtech] #168267 08/30/07 03:06 PM
Joined: Oct 2005
Posts: 40
gibbonsseabee80 Offline
We are installing some commercial grade three phase, tankless water heaters in some of our buildings. Check out this company, they make a nice product. I believe there are some units that can be fed with one 2pole breaker instead of three 2pole breakers. If you go with tankless water heaters, make sure they have replaceable elements. Some manufactuers sell some models where, if you blow an element, the whole unit has to be replaced. Just a nice company to check out. Thanks, Brian

Brian Gibbons
Re: Whole Home instant hot water heater [Re: gibbonsseabee80] #168295 08/31/07 08:54 AM
Joined: May 2007
Posts: 169
ChicoC10 Offline
I haven't seen a whole house electric unit but from what I have seen of the point of use elements I wouldn't install any of them in my house, nor recommend them to a client.
I've installed a 30A and a 50A unit. The 30 was worthless above flow rates more than a trickle.
The fifty was installed where the ground water gets cold and the house had a loooong overhesd service drop.
Result was to pull the mains down about 9% while providing just enough rise in water temp at an almost tolerable flow rate to wash your hands. I checked out the one in a friends office restroom and it was the same story. 50A, dimming lights, poor rise in temp at any kind of flow rate.

I have wired a couple of houses that use gas whole house on demand units. Both houses were long kinda long in design.
Both houses have 2 units feeding the hot water line at opposite ends of the house. One of the units didn't even need the receptacle I installed for it because it used a flow powered generator for ignition. I was impressed with the performance of these systems and the homeowners seem happy with them.
If you can go gas and think about 2 units if you have long hot water pipes.

Re: Whole Home instant hot water heater [Re: ChicoC10] #168303 08/31/07 12:24 PM
Joined: Jul 2002
Posts: 717
macmikeman Offline
If you end up having to go with the electric whole house heater, MAKE the customer sign papers that clearly outline the forseen problems with the install and release you from any responsibility for any voltage drop problems on either side of the meter socket. After he signs the paper, go ahead and put it in and collect the check for the job. My bet is he will give in at that point and opt for gas.

Re: Whole Home instant hot water heater [Re: macmikeman] #168346 09/01/07 08:35 PM
Joined: Jan 2007
Posts: 59
dilydalyer Offline
I agree with doing a load calc.

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