Radiant heat Pump Squels

[Eric Osborn]

I have a Grundfos Radiant in-floor heat pump that I am installing on a new in floor heat set up. I got the first pump and turned it on and it squeled really loud so I sent it back to the company and they sent me a new one. The second one does the same thing. The pump does have a check valve in it. I was running them dry but only for a couple seconds. What could cuase this?

[jerkbait]

Could be because it was dry. The fluid is the lubricant for the impeller inside. I have never ran mine dry and the are nice and quiet.Try running it with the fluid in the system.

[Eric Osborn]

I kept thinking that but did not want to get the system all pressurised and them have them still squel. Does your system have a check valve in the pump? Or anywhere?

[jerkbait]

On one of the pumps on the outdoor wood burner had a check valve, I did end up removing it though, no need to be there since those pumps run continously. The zone pumps do not have check valves. In order to find out what the squel is you will have pressurize. One option would be to make a short loop out of the floor just to check it out.