Central heating problems

[Primotomb]

We have warm radiators upstairs, but the downstairs radiators are no longer heating up. We moved in in December and they've always taken longer than the ones upstairs to heat up, but now they are just not heating up at all.

Boiler (downstairs) is old (15 years old) but in good working order, as is the central heating pump next to the hot water tank (upstairs). Both boiler and pump were checked by a boiler engineer at the weekend.

His only suggestion was to try timing the water and central heating to come on at different times (I.e. not both on together). We've tried that, but not made any difference.

Anyone got any other suggestions?

Any suggestions?

I would try bleeding them, they might be full of air.

Tried that, no air

It could be that they’re full of sludge & need flushing through

It could be an airlock.

You could try turning the radiators that ARE working off and see if the downstairs radiators get warm.

Or turn ALL the radiators off and put one on downstairs, and assuming that one does get warm turn it off and then turn the next one on etc.

My sister in law had that issue and had the system flushed, which solved the problem.