no hot water circulating to upper loop

[rmeyer]

I have a 2 loop system that uses 1 pump on each loop and 1 pump that circulates between the 2 loops. The power to the house was temporarily shut off for 3hrs and now only the lower loop is circulating hot water. The hot water will only go as far as the pump on the 2nd loop and it stops. I have changed out the 2nd pump thinking that was the cause but it didnt make any change. I also tried to purge the upper loop to get any air out that might be locking it up but still no change. The system ran for 3 years without any problems.

[jadnashua]

It's likely that there's still an air block in the upper loop. It depends on where you have purge valves, how best to clear that. Are you sure that the pump is getting power? While they are quiet, it is often possible to hear them running if you listen carefully. Is there a zone valve anywhere that is not opening? If so, they usually have a manual open lever. When the power is off, things cool off, the water shrinks, and if there is any leak anywhere, it can suck air into the system.

[olivia751]

It's likely that there's still an air block in the upper loop. It depends on where you have purge valves, how best to clear that. Are you sure that the pump is getting power? While they are quiet, it is often possible to hear them running if you listen carefully. Is there a zone valve anywhere that is not opening? If so, they usually have a manual open lever. When the power is off, things cool off, the water shrinks, and if there is any leak anywhere, it can suck air into the system.

Hey
Yeah I agree with jadnashua. rmeyer it may be the problem of pump or your upper loop may be choked so i suggest you to make sure pump is runnig and listen carefully sound of running water in loop.