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Woke up to a loud almost grinding noise coming from all the radiators/pips in my hot water heating system. It's intermittent, every few seconds but the system is generally running louder than normal.

I thought the booster pump might need oil so I added some. When I was doing so I noticed the 5 gallon bucket I keep under the pressure relief valve output was full and the boiler pressure was just under 10psi after just turning off the system (still hot.)

I opened up the pressure regulator to bring the cool pressure up to about 12psi and turned on the system again but still hear the noise.

It's snowing bad today and won't be able to get someone to look at it. Any advice?


I checked the radiators and one of them needed bleeding then I opened the pressure regulator to add some more water to make up for the loss. Ran the system and eventually the air worked out of it. Guess that's what was causing the noise.

Noticed a little bit of water in the bucket again today. Any thoughts on why that could be? There's an expansion tank (old type that's just a tank not a diaphragm). I think I need to check to make sure it's empty? Haven't had time to deal with it once the noise subsided. Trying to get my snow blower working before it snows again tonight.

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