Hot water but tepid radiators

[pmc123]

Hi,

Help!!

My central heating is faulty.
Lots of hot water but the boiler kicks out after only 2 minutes then restarts after about 10 minutes. The water going to the flow side of the boiler( ir to the radiators) is really hot....but the return from the radiators is very tepid.
The radiators are tepid as well.

My theory is that there is a blockage in the pipes somewhere hence the boiler just shuts down because the water is not losing heat at the radiators.

I wondered if anyone agreed and how the blockage can be sorted.

Thanks folks

 

[MANDATE]

Have you bled the pump and verified that it is working.
Has the system been drained and refilled causing an air lock.

 

[pmc123]

No i didnt know to bleed the pump?

It is a newish pump that was replaced on October 2007.

How do you go about bleeding the pump.......do you unscrew the massive big screw in the centre?

This cold radiatior thing has been a problem on and off for years.
My friendly gas man last time drained the system, put in a new pump and put in a valve to close slightly the water going to the hot water tank. This definitely worked for a few months and the radiators were great.

The radiators are all relatively new but the pipe work is about 15 years old.

Cheers,

 

[MANDATE]

It's just as important to bleed the pump as the radiators. If the impeller is turning in air, then water aint going anywhere.
Yes you unscrew the large centre nut to allow air to escape.
Even when you've bled the pump, there could still be air locked in the pipe work, that needs to escape or pushed forward to radiators where it can be bled off.
My pipes have been in 35 years so I don't think your blockage is sendiment.
You don't happen to have any motorised valves in your system do you?. You may want to look at the 'stickys' near the top the plumbing and central heat page, they cover quite a bit on central heating.

 

[pmc123]

Thx mandate you are very helpful

Tha gives me something to try

 

[Slugbabydotcom]

You haven't even read THIS have you?

Its like talking about a leg but not saying if the leg belongs to a table, an oil rig, a football tournament, a zebra or Charlie Dimmock!

PS Have you tried turning your pump speed up? If its a combi it should be on the fastest setting anyway.