Central heating!

[moliver34]

Ive a problem with my central heating! The up stairs radiators get hot, but down stairs remain cold.
Ive tried turning off all the up
stairs radiators in hope it will force the flow through...nothing happened!

Ive turn the circulation pump up to 3...still nothing!

I drained down the radiator futhest away from the boiler, disconnected the valve from the 'flow' pipe, leaving the other valve closed.

On the flow valve I put a hose to the valve and ran it out side; guess what all the down stairs radiators get hot!

Question; is there a blockage in the return pipe to the boiler or a air lock.

Any suggestions would be helpfull.

Ps. The boiler is oil fired! and the system is gravity pumped!

 

[Dan Robinson]

What state was the water in? It could have just been an airlock.

 

[moliver34]

the water is clean; no sludge in there

if I reconnect the flow pipe to the radiator, all the rads go stone cold down stairs!!

The up stairs remain hot!

 

[Dan Robinson]

Do a search on balancing systems.

Other than that there could be a blocakge.

 

[gas4you]

I would check that there isn't a stuck anti gravity valve in the heating ciruit to the downstairs rads.

 

[moliver34]

could there be a non return valve located in the down stairs circuit? if this is stuck in the closed position, would it cause this problem?

The system was converted from gravity to fully pumped a while ago!

 

[gas4you]

It would cause this problem. The check valve would have been installed to prevent the upstairs radiators getting hot through gravity circulation when hot water only was selected and as you say hot water was via gravity.

It could even be that since changing to fully pumped the flow is now going the 'wrong' way so the valve is 'checking' the flow.

 

[bobthebender]

If you got water coming through the flow as you said then why not switch the heating off and see if you get water through the return
That way you will know if there is an air lock/blockage in the return pipe.
Thats what i would do

 

[moliver34]

Many thanks Dave! Any ideas where this valve may be located...ie near the boiler?

Or could it be any where?

 

[gas4you]

Unfortunatley it could be anywhere, but usually IF you have one it would be fitted in the flow to the rads above where the old boiler used to be.

Don't dismiss the air lock theory completely though.