Every time my base board heating system starts up the baseboard in our master bedroom bangs for awhile. Loud single bang about every 20 seconds for several minutes then it will start.
Recently we had pressure relief valve on furnace replaced as it was leaking. Noticed today that it is leaking again.

Help

Thanks
Ed

What is the pressure of the water in the boiler, should be 12-18 psi. Pressure relief valve opens at 30 psi. Banging could be air or just expanding pipes from the heat.

What is the pressure of the water in the boiler, should be 12-18 psi. Pressure relief valve opens at 30 psi. Banging could be air or just expanding pipes from the heat.
Pressure is within 12-20. Relief valve is just leaking a little started today but banging has been going on for a while. Have cast iron baseboards, pipes are secure in basement, air bleed valves open on master bedroom baseboard.

Ed

Valve should not leak at ALL. It is designed to stay closed to 30 pounds.
Air still in system.

Valve should not leak at ALL. It is designed to stay closed to 30 pounds.
Air still in system.

Thanks to NorthernHeat and HVAC 1000 for the answers.
I'll contact the company that put in the relief valve and have it looked at more.
Ed

Just for giggles, check the clearance between the pipes going up from the basement and the hole they penetrate through. You may be experiencing a pipe rubbing on the wood and expanding quickly causing the bang. If you can get to the pipe and spray the pipe with a silicon spray it may help. Make sure your boiler is running below 200 degrees.