Baxi 380 heat exchanger leaks

ccaissie

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...

Thanks,
C

hot_rod

are you pumping into the HX?
What size circulator, adding how much delta P?
Scaled or partially plugged HX?