# Parallel or in series 2nd hot water tank



## Guest (Apr 16, 2004)

I have decided that the best course of action is to install an additional gas hot water tank giving us two 50 gallon tanks. I have talked to two different plumbers and one has recommend to put them in parallel and the other has recommended to put them in series. Does anyone have a good argument for one or the other?


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## Bjd (Dec 19, 2003)

You could use what I do and it seems to work, they get sorta tied together, to work in series. However in the event of a failure they are also tied in in a parallel fasion.

In series one tank is used as a preheater, the 2nd tank is they only use to raise the temps up about 40oF works out pretty good give it a try.

Bernie


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## Teetorbilt (Feb 12, 2004)

I have a ranch style house with a water heater at each end, in parallel. It works by demand although the water slowly gets hotter as the flow from the second heater warms up. One of these days I will isolate the two.
In your case I would just get a single, larger heater. A lot less to go wrong. The only thing wrong with my 80 gal. was that it took too long for the water to get to the other side of the house, capacity was never a problem.


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## Bjd (Dec 19, 2003)

Teet; Why not just put a small circulator in the set up to retun the water back to the heater. You then would have plenty of hot water.

Bernie


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## Teetorbilt (Feb 12, 2004)

I live in an older house and the pipes are not insulated. I was mainly concerned with thermal loss.
My last house had that system and it was tied into a solar heater. That was great!


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## Bjd (Dec 19, 2003)

Well you could use a piece of Pex, the loss is really not that great from that and it would be easy to install as well.

Bernie


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## Teetorbilt (Feb 12, 2004)

You're talking about replumbing the entire house and I am not a Pex fan. I know too much about it. Technically, I'm an engineer. BSE, ME, PE, PHD fluid dynamics and hydrodynamics. Dad was a GC and, eventually, I went back to my roots.
P.S. I'm an old guy.


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## Mike Finley (Apr 28, 2004)

Just about to get this project put in. Decided to go with 2 in series. The old main heater will now become the secondary one, the new one will be a high recovery version and feed the house, with the old one now feeding the new one. They will be plumbed so that each can be isolated in case of a failure, ensuring hot water until the failure is delt with. This should allow us to keep the new main at the temp we desire and turn the 2nd down much lower, saving gas.


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## plumber79 (Jul 8, 2004)

Bjd said:


> Teet; Why not just put a small circulator in the set up to retun the water back to the heater. You then would have plenty of hot water.
> 
> Bernie



I agree with Bernie, but, put a timer on the circ pump so it only operates 10 or fifteen minutes before you wake up and just before showers etc. and then stay off the rest of the time. A lot less energy, in my opinion, is used as you will have instant hot water,or close to it, and not running water down the drain waiting for it.


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