Glowworm Fuelsaver MkII (Model 50R) Tepid Radiators

[Johnglav]

Hi,

I've got a gas Glowworm Fuelsaver MkII (Model 50R). An approximate sizing has shown that the boiler output is just enough (theoretically) for the original radiators and a double panelled one added recently.

The central heating has been poor for a while with downstairs radiators being warm/cold. When the system was drained, cleaned with Fernox and refilled the problem moved between radiators, but remained.

A friend helped me to power flush the system, which triggered a fault with the thermal cut out. However, thanks to the guys on this site we got it going again.

The boiler has now been serviced, but the radiator problem persists. Recent advice from a plumber was that the motorised valves were working OK, the pump sounded OK, but the boiler seemed to be 'cycling', an indication of poor flow. He also commented that the power flush should have been done at the pump and not at a radiator. I've since manually flushed each of the downstairs radiators with a hose, but with little improvement. The radiators do get warmer if the hot water is off, the thermostat on the hot water tank has also been replaced.

Any advice would be gratefully received.

 

[Johnglav]

Please?

 

[Johnglav]

Just to close this thread, I did eventually resolve this problem.

As a last resort I planned to repeat the power flush (from the pump location) and at the same time fit a new central heating pump. However, it seemed sensible to replace the pump first, since it was the lower cost of the two and easy to access.The difference was immediate and remarkable, every radiator in the house is now too hot to touch.

The old pump had been working at least well enough to heat some of the radiators and was not noisy. Examination did not reveal any obvious fault, it is not blocked and the shaft spins ok.

Ah well, at least it's fixed