Grundfos circulator problem

Pat Justis_2

I have a 2 year old Grundfos UP 15-42F 115V circulator on a primary loop. It has worked beautifully on my 3 zone primary/secondary system. Yesterday I heard strange noises coming from the basement and discovered that my boiler was boiling water! I figured out that the Grundfos was not circulating. Then I let the system cool down and started it again. The Grundfos was working on startup when temps were below about 140F. But at some point around a primarly loop temp of 140F the Grundfos just quits. If I let it cool down it will start up again, no noise, no problem. I'm not sure what the problem is. I did make sure the strainer was clean. I know the Grundfos is rated for operation at over 200F, so I'm not sure what the problem is. Any ideas?
Thanks

Unknown

Pat,

could be a bad-one , just change it. Not expensive anyway.

Dave

hot_rod

If your boiler

is under pressure, let's say 12 psi or more, and it did in fact steam, first off you need to find out why it went to such a high temperature. At 12 psi the temperature had to go above 244 to steam.

Or if the circ cavitated for a length of time the water lubed bearings may have been ruined.

As Dave suggested, replace it, but also determine and fix the cause of the overshoot. And check or replace the pressure relief valve. They are also very cheap insurance.

hot rod

Pat Justis_2

Grundfos circulator problem-replaced it

Today I replaced the circulator and it is working fine. I think it was tripping due to defective overload protection when the unit got hot. Without circulation, I'm assuming the boiler could get water to 240F in a pocket or two but then would shut down a few seconds later. Anyway, thanks for the feedback. We'll see how this one goes. So far, so good.