Thoughts on a side arm for a water heater

[MNfarmer]

I've been trying to figure out ways to improve my system and have an idea but I wanted to see if you all thought it would work. I picked up two 80 gallon water heaters that I want to use to preheat the water going into our 50 gallon electric water heater. Can I use one side arm for both of the preheating tanks if I arrange the tanks so the T&P valves are facing each other? If that would work would it be best to hook the two 80 gallon tanks in series or parallel before going into the electric water heater? Any thoughts? Thanks.

 

[maple1]

Should work. My hunch is parallel.

Can't you just put a sidearm on your 50?

 

[MNfarmer]

Thanks. I could just put it on the 50 but we go through a lot of hot water.

 

[E Yoder]

Sounds like a flat plate heat exchanger would be more suited to your situation. They'll make an enormous amount of hot water on demand.

 

[maple1]

Thanks. I could just put it on the 50 but we go through a lot of hot water.

OK, not sure how much 'a lot' is, I guess someones 'a lot' is someone elses 'not much'.

When set up right & fed a steady diet of hot enough water, sidearms can make a fair amount of pretty hot water. Ours could make our 60 gallon tank 150° top to bottom overnight, and there is no way we use close to that in a day - mixing down to usable temperature almost doubles the 60. No idea your needs, but yes either more storage capacity, or maybe a flat plate as suggested would be worth considering.

 

[MNfarmer]

I had been thinking about a plate exchanger but I have a 35 gallon Royal indoor boiler and I didn't know if that small of a boiler would be enough for a plate exchanger. I'll give the side arm a try, thanks for your help!