Central heating problem

[Homeowner125]

Hi hope someone can help me. In September after my central heating off all summer I employ a gas registered plumber to do the annual check on my Worcester Bosch greenstar condensing boiler. He told me he could not complete the full check as he could not keep the boiler on long enough to get a heat out put reading. He showed no interest in helping diagnose the problem.

I got another plumber in who said it was the control white box on the Drayton 3 port value. He changed the control unit and the boiler came on ok, but 3 rads at the furthest point on the pipe run would not heat up. Here recommended a power flush which he did and was very successful with all rads banging out heat. Plumber said leave heating on constant for 24 hrs at about 19degs then go back to normal timed running.

The heating ran normally for about 24 hrs then because it was warmer it was not needed for about 3 days. When I neeeded heating back to all rads not heating up and boiler cycling again.Plumber returned said he did not know what the problem was and left.

I got another plumber to take a look and do some diagnostic checks he asked if the flush plumber had checked the contents of the F and E tank I said I did not think so. He checked it and said it had a load of gunk in it that would be sucked into the system and recommended a clean of the tank also changed the actual 3 port valve which was gunged up as was the pipe from the pump to the valve. he seemed to think the gunk had come from the the F and E tank. He also suspected gunk elsewhere in the system and put a cleaner product in the system. said it would take about 4 weeks to clean gunk back to the magnafilter.

I see the logic but I am having trouble getting the rads to heat up. I am suspecting almost no circulation in system can get 2 rads on at a time but that all. I suspect problem in return pipe as all inflow pipes to rads hot but outflow still cold would expect them to be lukewarm at least. Any one any ideas please I am suspecting a complete reflush. First flush seemed to go well he was using all the right gear and system water was very dark brown at first then after about 3:hours ran clear.

[moderator2]

whilst you can still edit the post please break down your block of text into paragraphs. It's currently difficult to read.

[Homeowner125]

Thanks for feedback unfortunately software telling Mei cannot edit now

[moderator2]

Thanks for feedback unfortunately software telling Mei cannot edit now

I've broken down the text for you.

[aeromech3]

Seems strange the power flush 'Plumber' did not check and clean the F & E. If you have a Magnafilter then that should stop the worst, the chemical cleaner will break down any gunk in the system if it is running and hot, but it still needs to be removed and an inhibiter added.
I do my system at least every 2 years when it is in regular use, to keep the fine particles moving instead of clogging up and the gunk will be in the filter (iron) and in the F&E.
If access to F&E is reasonable what I do is close the mains cock, take a couple of plastic buckets up (torch or roof light) scoop out the water and muck with a plastic container (empty cut down milk bottle) wipe around with an old sponge/rag, open water and check it shuts of with the ball cock when about half full, empty buckets in toilet and add inhibiter.
If the in pipes to the rads are hot, then I suspect they need a bleed.

[Homeowner125]

Thanks for this Aeromech3. I have bleed all rads. No air at all just clear water

[Razor]

Sounds more like the pump is weak. What number is it set on?

[Homeowner125]

Hi Razor thanks for the come back. The pump is on the factory setting. It is a Grundfos Ups3. Seems like only one speed but depends on constant or pressure. The green light is on and the next two yellow lights. If I take either of the yellow lights of the pump seems to slow down.