twin hot water heaters

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My installer put in twin 86 gallon Propane hot water heaters and it appears that the cold water feed goes into the first unit and then out into the second unit. I have a sometimes small hot water load and during the heating seasons I will have a larger load for my radiant heating.

I would think that the first unit would work very hard and the second unit would only be receiving pre-heated water and would not work hardly at all.

I also have a recirculation pump that keeps instant hot water that feeds into the second hot water heater.

Information on the best way to have these units installed is limited at best; especially considering the needs of my hydronic radiant heating.

Any suggestions on how these units should be configured?

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
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indianapolis indiana - land of the free, home of
installed in series

I suppose these propane hot water heaters are

doing your potable needs and your radiant heating too


they are hooked up in series and its always the way I hook up

two heaters together......

usually setting the first one on low and the second one on med to high

seems to work the best and you have better flow rate through

both of them than tieing them in parrell...

this is something you might have to turn up higher during the winter months

but it is the best way to do it...

I wonder how economical propane radiant heating with
those heaters will be??

Spaceman Spiff

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Salt Lake City, Utah
I have two hooked up like you say and the first makes warm water, the second hot water. Because of the recirc pump the second kicks on ocassionally w/o water use (to reheat the cooled recirc water), but the pair kick on almost at the same time when someone runs the shower or bath. The thermostats are set like MPM says. With a little tuning it should work quite well...
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