Leo
New Member
Allied Engineering Superhot MG-75 Nat gas boiler (14 years old) for hydronic home baseboard heating losing water from PRV. Found 2 gal exp tank had no air charge and full of water. Installed Maxtrol EX-15 exp tank with 14 PSI precharge, new 30 PSI PRV, and a new boiler 1/2" drain gate valve. I purged air from all 5 zones and from the boiler circuit. I have 14-16 PSI reading on tridicator so pressure reducing valve is working correctly, (I brought it down from 19 PSI as only have 14 feet of lift). I have twice lit the pilot, warmed the heat exchanger, then fired up the boiler. 2-3 minutes and I'm at 180 F and 29 PSI and climbing so had to shut down. WTF? I have a circulator at the boiler on the return side. Any ideas? What is the circulation pump supposed to sound like?
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