CH Pump not working

Recently replaced mine with a Grunfos UPS3. Very happy with it so far.

Tim

Is power getting to the pump? A quick check with a voltmeter would establish that. Does the rotor actually move when manually turned with the screwdriver? It would be unusual for it to be supplied directly from the fused spur. The whole CH system (boiler, pump and switched values) could be powered from the spur but the power to the pump is likely to be also controlled/routed via the boiler or a controller.

If replacing the pump be aware that the isolating valves either side of the pump may be shot and, depending on age, either seized or leak when opened again after replacing the pump. While the fixing centres of various pumps may be standard the length of the isolating/service values may not. I found that when I last replaced a pump I also had to replace the isolating valves plus modify the pipe work because the replacement valves were shorter than the ones I removed. The original valves were possibly 25+ years old.

My CH had a replacement pump branded DAB/EVO/EVOSTA which was much cheaper than Grundfos models (from toolstation) and for the past couple or three years has proved to be very quiet and reliable. I purchased the model with 3 off fixed speeds and proportional differential pressure settings and is suitable for a direct replacement in older systems.

My electrician friend arrived this morning and managed to get it started. It must have been the fuse. He didn't explain, just repacked his magic wand and cloak and carried on working outside.

I think the system will need replacing in the not-too-distant future so thanks for all your advice.

Alan

I (well my plumber not me) replaced my 10 year old Grunfoss with a newer model Grunfoss. You would not believe the amount if crap in the old pump. The impellor is a strange design, with very narrow passages for the water to pass though and they were almost totally blocked by hardened sludge. Took some heavy handed scraping to clear, but now I have a spare pump! As another person said, the old isolating valves also had to be replaced, so it was a drain down and replumb job. The system works so much better and quieter now!

Interesting. I would normally have said that an obviously hot pump body would have indicated no fuse failure, your "rotor won't turn" check gives you the single fault that you need to give your symptoms. I wonder whether the electrician just applied sufficient torque to the rotor to free it up. I think your "days are numbered" analysis is probably correct.

About 20 years ago I got a Grundfos Alpha based on a recommendation here. It's still running.