In series gas and electric water heater

Old 10-18-18, 02:48 PM
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In series gas and electric water heater

I recently moved into a new home and noticed I have two water heaters, a 40 gallon gas and 40 gallon electric. Looks to me the electric water heater was added afterwards when the basement was finished and a large whirlpool tub was installed. The way it's setup is cold water flows into gas water heater, water then flows from hot water side of gas heater into cold side of electric heater than the hot from electric goes out to the rest of the house (so they are setup in series). I'd really like to shut off the electric water heater because it uses much more energy to heat the water and is more expensive than natural gas. But I'm assuming if I turn it off it won't work correctly since it is the 2nd heater in the series correct? Can anyone tell me what my options are or what would be the best setup between the two? Thanks
Old 10-18-18, 07:31 PM
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The issue with shutting off the electric heater is you will have to run 40 gallons of water before you get any hot water. Easiest thing to do would be to just bypass the electric heater. It would likely be a fairly easy job with just a few fittings and a tubing cutter. Post a picture of what you have and I'm sure we can help you figure out what needs to be done.
Old 10-18-18, 08:49 PM
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If it's running on natural gas...... send the electric one packing.
If it's propane.... there may have been a monetary reason for that setup.
Old 10-19-18, 03:14 AM
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If you use the tub you will need both water heater I know from experience.. Have a large tub and had to add second water heater to keep up.
Old 10-19-18, 06:04 AM
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Originally Posted by dollabillz217
I'd really like to shut off the electric water heater because it uses much more energy to heat the water and is more expensive than natural gas.
But, with the setup you describe, that electric heater isn't actually heating the water,
It is maintaining the temperature as a "warmed storage" tank.

The gas water heater is bringing the water up to temperature, the electric tank is holding it at temperature, the electric tank only has to keep the already heated water from cooling down.
So, make sure that once the water is heated by the gas water heater, it doesn't cool down.

I would insulate the gas water heater and the hot water lines to the electric water heater,
and try a lot of insulation around the electric heater (e.g. wrap in R-30 and then drape a 100-gallon trash can liner over it, repeat with a second layer of R-30 and liner for a ridiculous amount of insulation...)

See what happens, insulating will be much less work, time and money than rerouting the existing piping, and might get you what you need- lots of hot water for little money.

Last edited by Hal_S; 10-19-18 at 07:03 AM.

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