radiator help needed!

[cocolepew]

I posted this in chat but was advised to come here.

3of my radiators keep going cold. A big one in the living room, the bedroom one above it and the bathroom one.

We have had loads of people out to look at them and everyone said the last resort was a power flush. It seemed to work, then shortly the same thing happened. The fella that did It said to put the heating up high and maybe turn the other radiators off. He said because it was working for a couple of weeks it should be ok. Turning the heating up worked.

But still its happening. The living room stays warmish at the bottom.

Its oil fired central heating.

TIA

did you turn the hot ones off, and did the cold ones then go hot?

did you observe how much sludge they got out?

I wasnt there when they were hosed but DH said it wasnt much gunge. Not heating if we turn the others off.

They were balanced as well.

what speed is the pump set to?

how did you choose the people who looked at it and made guesses?

what comes out when you bleed the rads?

Are both the flow and the return pipes on the boiler hot? What about after you turn off the hot rads?

Have you got a feed and expansion tank in the loft? What's in it?

2

Reccommnded, family firm very reputable DH got power hoser from phone book

water, clear

Need to check

No

You could try turning the pump up to 3

However if the people on site are competent, they should be best placed to find the fault. If the house is Zoned they are sure to have noticed, and verified that the motorised valves are operating correctly.

If the powerflush was done with a large machine, and they used a sludge-loosening chemical such as X800, and they spent about half a day on it, running round to open and close each rad individually, then I would be thinking about a bypass which is allowing to much of the flow to avoid the rads. You will detect this because the Return pipe is hot even when the rads are all cold. Some Bypasses are automatic with a spring release; and some are manually adjusted to allow a modest flow.

As you have no F&E tank in the loft, I presume you have a pressure gauge on the boiler. What pressure does it show; does the pressure drop over time, or does it change a lot between boiler hot and boiler cold?

Does water ever come out of the relief valve which ejects through the wall behind the boiler?

I presume the sludge that came out was black, not brown.

Thanks so much for your help. Ill check the pipes tomorrow. We haven't the heating on for weeks, DH was trying to dry his motorbike gear and noticed it.

Thanks again