Potterton Suprima 50 - No Hot Water

Hi,

Had BG over to fix my problem of no HW or CH. Thought it might be the dodgy PCB in the suprima, but turned out to be the circulation pump, which they replaced. Thought everything was ok, as boiler fired up and the CH started working again. However, noticed that there wasn't any hot water. So turned off the CH and tried the HW. Boiler did not fire up. Call BG and another engineer came out, he messed about with the lever on the underside of the motorised valve and turned up the temp on the immersion heater from 50 to 60. When the call for heat came from the HW, the boiler fired up. However, the boiler cuts out every 30 seconds and the reset button needs to be pressed on the boiler to get it to start again. Call BG again as the engineer had only left 10 minutes beforehand to try and get him back. Before he left, he had a look at the radiators downstairs as a few had not been warming up at all. He checked the valves and they all looked ok. Suggested that there could be a blockage to the radiators and suggested a powerflush. The call person at BG spoke to the engineer and he said that the reason for no hot water was that the system was blocked and a powerflush would fix it.

Swapped the suprima pcb for the newer version to test if this was causing the fault, and the same tripping occurs. However, you don't need to press reset as the pcb does this for you.

Would like your opinion on the few of questions below:
1. Would/could Powerflushing the CH system fix the no HW problem?
2. How likely is it that the motorised valve is faulty causing the no HW problem/boiler tripping? The BG engineer didn't look inside.
3. Any other suggestions?

Thanks in advance for any replies.

System could be sludged and dirty, but would have thought the first BG guy would have told you that when replacing the pump

Powerflush is an easy answer to all ch problems when you can't be bothered to check everything else first

I would suspect the zone valve sticking in the body first, I would also suspect th new pump might have stuck, never assume something new is working correctly.

Have you or anyone drained any water out of the system to actually check what colour or state it is in?

If not how can anyone GUESS a powerflush is needed.

It will probably be just an air lock in the pipework.

Try draining down again and refilling slowly bleeding rads as you go. look at FAQs about draining down/refilling.

gas4you said:

Have you or anyone drained any water out of the system to actually check what colour or state it is in?

Click to expand...

The 2nd BG engineer bleed one of the top radiators and when he closed the bleed valve the small amount of water that drained on the kitchen towel was dirty black.

Is this enough for an engineer to say that it needs a powerflush?