noise in baseboards

hoop

I am getting a knocking noise in the baseboards. the noise only starts when the boiler gets up to the limit temperature 179 deg f. It is a gas fired Wiel Mclain cast iron boiler, 20 years old with 3 zones. It is hard to hear the noise at the boiler but clear in the upstairs rooms.It does not sound like air or rushing water. A heating person recommended descaling the boiler. could it be the water is boiling or the flame is too high. It does not make the noise when the pumps first start up, only when the temperature gets high 

Steve Whitbeck

knocking

sounds like the boiler may need to be descaled.

If you lower the max temp to 170* does the noise go away?

STEVE PAUL_3

NOISE IN BASEBOARDS

You say the noise is in the baseboards when the boiler water gets to 179*. Scale or dirt in the boiler would possibly cause noise in the boiler, not in the base boards. It sounds to me like the problem you are having is from expansion noises in the baseboards and/or the connected piping. Look for piping rubbing against framing or where it passes through drilled holes. You could also turn down the water temperature about 10* and see if that helps.

To paraphrase Dan

 "IF THE NOISE AIN'T IN THE BOILER, THEN THE BOILER AIN'T THE PROBLEM"

JStar

Also.

Check your expansion tank and fill pressure. If the water is reaching higher than normal pressures, you can get a lot of ticking noises in the baseboard.