Thread: Boiler Leaking
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      10-24-2019, 08:37 AM   #7
byroncheung
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Drives: e90 m3, 997.2 c2s, x166 GL450
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Quote:
Originally Posted by ToddBlack88 View Post
Two things can cause the relief valve to discharge. The auto feeder failing to lock up/shut off, or the expansion tank is flooded/failed.

If you shut the auto feed off and it stops leaking completely, even when it fires up, then that is your issue. If the valve only leaks when the boiler is firing, then the expansion tank is the problem.

25yr plumber/gasfitter/restricted electrician
sorry for thread hijacking - but i do want to ask, in my setup (have a navien tankless boiler), when the boiler isn't heating, pressure is about 13-14psi. when it heat, it would goes up to the twenties, say 22-23 etc. is that amount of increase normal or i need to have a look at my expansion tank?
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