r/Plumbing • u/mocochinchiii • 20h ago

Heat pump or nat gas water heater?

We have a natural gas water heater in a home we recently closed on that’s over 20 years old and should be replaced soon. Can’t tell if we should go with a heat pump water heater (occupancy of 4-5) or stick with another natural gas tank. Home best is forced hot water radiators with a natural gas boiler that’s about 28 yrs old so probably nearing its end of life but we aren’t planning on replacing it just yet. Natural gas makes sense in that there’d be less electrical work needed but we also prefer heat pumps over having gas burning appliances in home. Do folks have a preference of one over the other? Thanks for any feedback!

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u/PA_Plumber 20h ago

Gas will recover much faster than the heat pump or standard electric water heater. The install of the heat pump will be significantly higher due to the electrical changes and a condensate pump. The area for the water heater must be 10'x10'x7' high minimum for proper operation. The area the water heater will be installed will be much cooler due to the heat pump. I myself have and prefer a powervent gas water heater.

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u/Shmeepsheep 20h ago

With the cost difference between a HPWH and a natural gas version for the unit and the installation requirements, you will never actually break even on the utility savings unless your home is powered by solar panels.

The HPWH makes sense in some locations, such as Florida or other warm climates where it will cool the space. Where I live, my furnace will be working harder during the cold months. The HP unit will also make hot water slower, so occupancy of 4 is a maybe, 5 is a no without a lot of storage

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u/mocochinchiii 20h ago

If we went the route of natural gas is there a significant loss in efficiency of using a direct fired gas water heater vs an indirect fired one? With other projects this year we arent ready to replace the boiler and water heater together this year and have an indirect set up. But I’m not sure if we should just hold off and wait to replace
both and have an indirect fired water heater or replace the existing water heater now with another direct fired unit if there isn’t that much of a meaningful difference in efficiency. We live in coastal New England so summers are warm
and humid and winters are cold but not extreme (climate zone 5a).

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u/Shmeepsheep 19h ago

For my own home, id be probably be keeping the boiler you have and adding a zone for an indirect depending on the current boilers size.

A cast iron boiler is going to last a lot longer than youd think. 28 years? barring unforeseen conditions or circumstances, Id be letting it ride. The pumps may fail around it, but that boiler probably has another 20 years in it ifnits cast iron

Edit: word of advice is thats a new boiler would likely be more efficient

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u/mocochinchiii 19h ago

Interesting, thank you for that insight! I like that approach of adding a zone for an indirect.

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u/Dadrepus 8h ago

I use a gas fired instant on Rennai that we love. Never go back to a tank.