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WAPA Bills-Savings From On Demand Water Heaters


Advanced Member
Joined: 13 years ago
Posts: 319
September 21, 2011 10:19 am  

Energy office continues to promote ENERGY SAVINGS. Sometimes we all wonder whether the upfront cost is worth it in the long run. Just ran a test, two empty units from Aug 1 -31---the same time period of WAPA service period.

Unit 1 Unit 2
Energy Star Fridge Energy Star Fridge
2.5 electric hot water heater Titan on demand water heater(regular plug)
Everything unplugged Everything unplugged

The only difference is the water heater.

Cost of Electricity

Unit 1 Unit 2 Difference

$65.41 $27.43 $37.48

Monthly Savings On Demand Heater Yearly Savings Cost of On Demand Heater(GBH, Ganetts, Home Depot)

$37.48 $449 approximate $275

Self installed(minor plumbing and available electric outlet).

Test above was an actual---no other usage at both units , doors locked and no tenants. Seems like a no brainer to install ON DEMAND HOT WATER HEATERS.

Trusted Member
Joined: 14 years ago
Posts: 929
September 21, 2011 12:50 pm  

Interesting, however if both units were empty, and there was no water usage, then what is this test really showing? That you can save more money when not using hot water if you have an on-demand heater? That's kind of obvious as the unit is not having to keep a quantity of water at a set temperature.

More interesting would be how much energy each water heater utilized under normal water usage situations. I wonder if the VIEO has any monitoring eqiptment that could be applied in a real-life usage situation.

Advanced Member
Joined: 12 years ago
Posts: 495
September 21, 2011 4:15 pm  

Thanks, Inn, but IslandHops has a point: to be a valid test, the "on-demand" heater needs to be used under realistic conditions. (actually they both do). But it is interesting to note that it cost almost $40 to keep 2.5 gallons of water warm for a month.

Advanced Member
Joined: 12 years ago
Posts: 164
September 21, 2011 9:12 pm  

Has anyone an opinion regarding on-demand hot water heaters vs. a timer on a regular heater? My timer is set to produce hot water for only one hour a day, which is more than enough for one person from my 40 gallon tank -- and I'm wondering about the value of amortizing an on-demand heater.

East Ender
Joined: 18 years ago
Posts: 5404
September 21, 2011 9:39 pm  

I have heard of problems with on demand water heaters working with water pumps, higher altitude (third story) etc. They are meant to have steady water pressure like in Big America...

Advanced Member
Joined: 15 years ago
Posts: 44
September 22, 2011 12:52 am  

With electric water heaters, a kilowatt is a kilowatt. The only difference would be heat loss through insulation. Electric resistance heaters are all 100% efficient by design.

Now, propane might be a better way to go. Propane is one of the few things that's actually a good deal on STX. In the states, propane costs a little more than natural gas and electric, but not 5 times more which is what we're paying for WAPA. Even better would be propane with a heat exchanger connected to your A/C system. The hot gas discharged by the compressor runs as high as 190°F and is normally just thrown away. A heat exchanger uses that to heat your water and it can be added to a propane hot water system.

Of course solar is a no brainer, really. Just my 2 cents.

Trusted Member
Joined: 17 years ago
Posts: 541
September 22, 2011 8:17 am  

I installed an on-demand system in my home. Worked well at first but I'm having problems now. The heating elements do not always turn on. Still investigating but I suspect it is an issue of inadequate water pressure. When I installed it I noticed the pump pressure reading was a the absolute minimum required for my heater...

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