Pipe from gas boiler making loud noise (link to sound)

[tundea99]

Hi,

I have gas baseboard hot water heat with two taco zone valves. One zone in particular makes a loud knocking noise whenever the thermostat calls for heat. The noise is coming from the first part of the zone right where the zone valve is. I've been in the house for one full winter and I've never heard the noise until last week. I've had a guy come and drain the system as he thought there might be air in the system but that didn't solve the issue. Does anyone have a suggestion? Here's a link to the noise:

 

[Geofd]

There is a lever on the zone valve that's basically a bypass if the zone valve fails I don't know alot about them but you could try that lever then return in to normal and see what happens

 

[Geofd]

There is a lever on the zone valve that's basically a bypass if the zone valve fails I don't know alot about them but you could try that lever then return in to normal and see what happens

I also read a thread that said to remove the head and spray wd-40 the thread said it worked

 

[mark3885]

Sounds like the pipe expanding as it rubs against the floor joists.