on demand water heaters, am I missing something? - Page 2 - Electrician Talk - Professional Electrical Contractors Forum

Mountain Electrician · 10-29-2009, 07:12 PM

I've wired one...(3) 40A circuits, did require a service upgrade...and yes, it did dim the lights..even when it was the only load turned on. I have a propane on-demand water heater. The lights don't dim when they come on.

fraydo · 10-29-2009, 08:28 PM

I looked into one when my old w/h gave out since i was in the market for a new one anyway. Three 40-A 2-poles and all I have is a 125-A service! Forget it. I just bought a regular one. As for the timer, I have always had one installed. It turns on in the morning 30 minutes before we wake up and shuts off 30 minutes after we leave. That and two hours in the evening is all I need in the house. If I had gas service I would consider it.

Protech · 10-29-2009, 11:41 PM

If installed correctly, a modern electric heater losses very little heat. Installing a 24hour timer will do little or nothing in the way of energy savings. Now if they are gone for the weekend every weekend then I could see using a weekly timer.

Just to give you an idea of how long a heater can hold heat……I have repiped houses where the heater was off for 2 days and when the water was turned back on (but not the breaker) the water was still hot. It had only dropped a few degrees. This is only true for modern heaters with insulated pipes and heat traps. Older heaters will lose quite a bit of heat though due to poor insulation.

Quote:

Originally Posted by egads

A timer on a regular tank type is always a good idea. I wonder how many folks with electric water heaters in vacation homes forget to turn them off when leaving?

Toronto Sparky · 10-30-2009, 12:24 AM

I have been told over and over again that the "On Demand" water heaters are ok for showers and baths , but not near hot enough for dish washers or even clothes washers (to a lesser degree)
Dish washers need to be up around 160-180 degrees to sanitize plus the detergent will not desolve at lower temps.

Toronto Sparky · 10-30-2009, 12:26 AM

The timers on water heaters are for us folks that have "time of day" "smart meter" billing.

JohnJ0906 · 11-01-2009, 06:32 AM

Quote:

Originally Posted by Mountain Electrician

I've wired one...(3) 40A circuits, did require a service upgrade...and yes, it did dim the lights..even when it was the only load turned on.

I had the same experience.

Protech · 11-02-2009, 02:55 AM

Yeah you can save a little by being on a "load shifted" billing setup with one.

Quote:

Originally Posted by Toronto Sparky

The timers on water heaters are for us folks that have "time of day" "smart meter" billing.