Slow Rads

[richw1977]

Could anyone advise on the following problem please!!

I have got 2 rads that take about 3 hours longer than the others to get hot, the boiler ( BAXI SOLO 2PF) was serviced 2 weeks ago and everything is fine, the pump is fine, they have all been flushed out and balanced.

I have 3 rads downstairs that get hot, 3 upstairs that get hot soon after the heating comes on, and 2 downstairs that are stone cold, even the inlet pipes are cold, they used to work fine up until Saturday, I have bled the whole system but with no effect.

I would be grateful for any advice.

Many thanks.

 

[taydo]

when did they get flushed out and balanced, were they working when the system was balanced,are they on the same pipe run.

it could be an air lock.

Brian

 

[richw1977]

Brian.

They were flushed and balanced around 3 weeks ago, they did work afetr they were balanced, like I said they worked fine up until Saturday, and they are on the same pipe run.

 

[MANDATE]

Hi richw.
The circulation into the radiator is prevented by either air lock, sludge or the inlet/outlet valves.
If the radiators are on the same pipe run as others that are ok then I would rule out the air lock.
Why not try opening both the lockshield valve and the inlet valve fully, the lockshield valve may be closed too much or some sludge restricting the flow.
To help get the flow going you could close some of the radiators that are ok. If the inlet valves are TRVs, then they apparently have problems sticking in the closed position.
If they do get hot but a lot later as you say, it sounds as though the hot water is finding its way up into the rad very slowly and it makes me think 'valves'.
Another tip that might give an indication is to close one of the valves then then bleed off a little water and feel the bottom of the radiator near the open valve. Then repeat with the valve positions reversed, from this you may be able to work out which valve is restricting the flow.