Downstairs radiators cool

Hi, I would appreciate some advice on this.

I have just moved into a house with a pressurised heating system and a SIME 80 boiler (about 3yrs old).

The downstairs rads only get luke warm while the upper ones are hotter but not really hot. The hot water seems fine.

In the airing cupboard I have two motorised valves and the hw tank with pressure expansion cylinders etc.

I have bled all of the rads and there is no air in them.

The pump seems to be running ok - (I can feel it vibrating).

The boiler regularly fires up to maintain the flow temp but the downstairs rads only get luke warm. I have tried increasing the boiler flow temp to near max but this doesn\\\'t help.

I reckon the problem may be:-

1. Sludge in the pipes - a plumber recommended a Powerflush for £250 which is expensive. Is this necessary or can I drain/flush the system myself?

2. Pump problem - but it seems to be running ok?

Beyond that I am stuck.

Any suggestions greatfully received !

David

A £250 powerflush is pretty cheap!

Is the motorised valve for the heating circuit opening properly and does the heating come on OK independently from the hot water?

Also, is the cylinder temperature satisfied easily enough in good time?

I seem to have found a partial solution to this problem. After getting a plumber round, he pointed out that the valve controlling the bypass circuit was fully open. He closed this leaving it open about 1 turn and the downstairs rads are now heating up much better.

Hopefully I wont need the Powerflush

He mentioned that I should replace the manual bypass valve with an automatic one.