Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Expansion tank Question

Can (or do you see a problem with) Tieing a HW system, and a closed loop condensor water system into the same expansion tank if the systems will be at the same glycol percentages, and pressures. The is a chance of the two systems to be runnning at the same time in the fall, and spring months. Whem sizing the expansion tank they would be both the same size.


  • Paul Pollets
    Paul Pollets Member Posts: 3,509
    Expansion tanks

    Each system should have its own expansion tank. The (open) potable expansion tank uses different materials than a closed-loop (boiler) expansion tank. They cannot share a common tank because you would be mixing non-potable with potable. If you mean a "condensing boiler system", the closed loop system has it's own expansion tank. The tank(s) should be sized according to total system volume.
This discussion has been closed.