Just made an account just for this question. I'm doing some work in a commercial kitchen with 3 60 gallon water heaters. It is a closed system and there were no expansion tanks installed on the water heaters. Theres a random RO storage tank [www.freshwatersystems.com] in the mech room. My question is will this also work as a thermal expansion tank if I set it to the right PSI and install it on the cold line before the water heaters.

you don't set the pressure on an expansion tank. its purpose is not to caLL a well pump on/off but to absorb excess pressure.
why not just put a seperate tank and be done with it ??

I'm sorry, there are 3 100 gallon water heaters. They just put them in to commission and they are having all sorts of issues with leaks now. My question is, does the storage tank act in the same way as an expansion tank. They both have air chambers and bladders right?

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If the leaks you are referring to are coming from the WH TPR valves then your thinking about needing an expansion tank is likely correct. You could hook up the RO tank and see if it does something for the problem. If it doesn't you could then switch out the RO tank with the recommended expansion tank, most of the connection fittings would already be in place by then. But since it is a commercial installation you may not want to jack around, they'd probably like for the problem to be fixed quickly and you don't want any callbacks, that's not good. If the RO tank is just laying around they may give it to you, then you can connect it at home or at another private residence to see if it performs like an expansion tank.



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Yes, that tank will work.

That's assuming it is in good working order.

What if it was removed due to bad bladder or a leak? It isn't new, may be several years old. I wouldn't trust it on a commercial job unless I knew its history and that it is good. If still new in the box then maybe.



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