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.

Baxi 380 heat exchanger leaks

ccaissie Member Posts: 1
I have replaced the o-ring/gaskets on this unit several times. I do not know how this fails, but periodically there must be a pressure spike and it blows out the rubber donut, causing a mis-fit against the exchanger surface. Each time, I find one of the donuts has been distorted, and replacing the set fixes the issue ...for a while.

I cannot find any reason for the failure...pressure spike? WHY? I have replaced and re-checked the expansion tank, pressure relief valve 2x, descaled and refilled the system with inhibitor, and most recently added a 1/32" thin gasket to the face of the exchanger to compensate for any distortion/dimension change....after a month of fine operation, client came home to a pool of water, AGAIN.

Since the pressure relief valve is set at 30psi (2 bar) and the system operates at 1 bar, the replaced and pressure adjusted expansion tank (12psi) should handle any pressure rises, right? And if not that, the relief valve should pop @ 2 bar.

So why does the pressure relief valve occasionally drip, and why does it blow the exchanger seals? Could I add another hard piped expansion tank in the line?

thanks for any insight. I plan to replace the exchanger, as the front sealing face seems not perfectly flat...maybe all caused by an overtorque in the past? the unit had been serviced before I came on the scene...



  • hot_rod
    hot_rod Member Posts: 22,144
    are you pumping into the HX?
    What size circulator, adding how much delta P?
    Scaled or partially plugged HX?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream