My Weil-McLain boiler supplies hydronic heat to two zones. It does the job - all radiators get hot, including the ones in the attic. However, my pressure gauge on the side of the boiler reads zero, both when the boiler is cold or hot. The water supply valve is set to 15 psi, and even when I let it fill to cutoff, the pressure gauge is zero. The expansion tank gets hot on top when the boiler is running, and is cold on the bottom. I suspect that the problem is the gauge. Is the proper way to check by measuring the pressure in the expansion tank, which should be equal to system pressure?![]()
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