Central heating problem - Radiators cold after powerflush - confused.

[winky1]

Hi,

New to this, so please go easy on me!

I would be very grateful for any help.....

3 months ago, British gas installed a new pressure vessel on my system as the one in the boiler had failed. Since then I have had nothing but trouble.

The following day, all radiators went cold, and the boiler kept overheating and shutting down (as it the water was not flowing around the system.

British Gas cam back and cleaned the heat exchangers (as the fault code on the boiler said heat exchanger blockage). no improvement.

British gas next replaced the pump (despite the limpet showing the pump to be fine!) that seemed to improve things for a day, but then the radiators went cold again.

As british gas told me that a powerflush was going to be over £700, I first tried a cold flush, which gave some improvement, but within a few days had got worse again, then 2 weeks ago I hired a powerflush machine from Travis Perkins and powerflushed the system. I had to connect it in place of one of the downstairs radiators, as there was no pump adaptor and my pump is inside the boiler. I also forgot to put inhibitor inn the system once I was finished.

The powerflush seemed to work, every radiator was too hot to touch, and it stayed fine - until last night, when they all went cold again. I tried a cold flush, and that again solved the problem for a few hours, but now they are cold again.

Is it likely that there was sediment in the radiator i removed in order to connect the powerflush? has sediment built up in the last two weeks since i powerflushed the system, because I didnt use inhibitor? Or should I be lookiing at something else?

My system is a sealed system with a combi boiler and no hot water cylinder, and is only 5 years old. the boiler is a Jaguar (rebadged Glowworm)

[buildersmate]

You need to replace the inhibitor PDQ, but that can't be the reason for them all going cold. Something is still blocking in the pipes - and it is in part of the pipework that is common to the whole heating circuit. That means the section of pipe around the boiler heat-exchanger and pump - my guess it that it is around the pump.

[winky1]

Thanks for that - how do I go about unblocking that section?

[AlBags]

Where is the pressure vessel? In the boiler or remote from it?
Can you bleed anywhere above the connection into it?
Is boiler and pump running when rads go cold?

[winky1]

Hi, the new pressure vessel is external to the boiler, on the return circuit, teed off just outside the boiler, and i have a drain tap just before the new pressure vessel. pump and boiler will both run, but cut out due to overheat, without rads or return pipe warming up. Thanks!