New Hot-water heating system

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ratzfatz

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Hi,
I am planning a new hot water heating system for my house. We have 2 bathrooms that are fairly far away from each other supplied by a gas-powered heater. In the far bath, it takes about a minute to get hot water which I want to fix. I am looking for a convenient, energy-efficient system that provides hot water instantly. I also want to go gas-less so it needs to be an electric system. We have a whole house water filtration system I can do the plumbing/electricity myself so cost won't be a big issue.

I am considering two alternatives:
a) 2 Stiebel Eltron Tempra Plus electric tankless heaters, one for each bathroom, repipe with PEX and I should be able to limit maximum pipe length to 6 feet or so.
b) leave the existing copper-pipe centralized heating system in place, exchange gas-heater for an electric heat-pump, add a recirculation pump and insulation to all hot-water pipes

I don't like the idea of continuously heating and circulating water through the system for energy efficiency reasons. Then, on the other hand, the heat pump should be more efficient energy-wise than the Stiebels.

My questions:
- How well do these re-circulation pump systems work? What do I need to do to get instant hot water at all faucets/fixtures? Do I need to install a full loop? or multiple pumps?
- How much energy do I waste if I re-circulate continuously for 16 hours per day?
- Any other pros/cons of the two alternatives? which one would you prefer?
 
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breplum

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You need a full loop. The most efficient system would be user activated push buttons or motion detectors in the area of the fixtures. And yes heat pump is the ideal solution both energy efficiency and greenhouse gas wise.
ACT D’mand Is a well-known company that has the pump and pushbutton set packaged. But you got to size the pump correctly. Wireless or wired are available. I haven’t had to deal with it in a while so I don’t even know if they’re still around.
On the other hand a Navien NPE 96% efficient gas tankless (.96 UEF) with built-in recirculation and the smart button push buttons that you can daisychain all over your house to your hearts content it’s mostly what we do.
 
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ratzfatz

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Thanks breplum!
Push button controlled re-circulation pumps may be efficient but they don't provide instant hot water. Are those recirculation pumps still efficient when running them continuously from 7am-12pm ? are there some ways/rule of thumb to calculate the efficiency/cost of these different systems?
 

Twowaxhack

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The cost associated with recirculating is

1) initial cost of equipment and install
2) maintenance cost
3) cost to heat the water then losing that heat to the surrounding environment

The cost to run the little pump isn’t significant.

I prefer to have my source of hot water close by.
No pumps, no wasted water down the drain.
 
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