Cold Radiators Downstairs

[Jonathan@9]

Ok so I have standard 3 bed house, boiler downstairs, pump and tank on the first floor, working with 30 year old mircobore pipes, the radiators have twin entry valves.

The radiators are hot upstairs, cold down. Last week I turned down the heat on the radiators upstairs and saw an immediate improvement downstairs. This did not last...

On Friday night I turned all the lock shield valves down a turn on the upstairs radiators to force more water downstairs, no result then - but yesterday morning (Saturday) good hot radiators downstairs, today cold or luke warm again...

I have lots of hot water - the central heating out pipe is very hot..

Any help appreciated

 

[Dotty]

what boiler have you got?

 

[Gray0689]

Is pump running ok

 

[Jonathan@9]

Potterton Flamingo...rather old

 

[Jonathan@9]

Sounds good, can hear it running

 

[Dotty]

needed to know if you had internal or external pump.

Pump's failed.....

 

[Gray0689]

needed to know if you had internal or external pump.

Pump's failed.....

I'd agree too

 

[Jonathan@9]

External pump Grundfos Selectric sounds like its running, if it wasn't would the upstairs Rads also be cold?

 

[Dotty]

No. Hot water rises by convection.

 

[Jonathan@9]

How can i double check the pump? has a large silver screw head on the front and a white control on the side, this is a little hidden due to the position - what does this control do?

 

[GasmanxxxR1]

check resistance across the L & N terminals on the pump WITH THE POWER OFF

120 to 250 ohms is ok, if not replace

 

[GasmanxxxR1]

also remove the screw when pump is working, carefully and gently insert a screwdriver to feel the shaft spinning, a small amount of water will come out, this is normal, if its tons of water then pump is also knackered

 

[Jonathan@9]

removed the screw and inserted a small screwdriver and the felt the pump turning ok...not looking like a pump issue...

 

[Dotty]

removed the screw and inserted a small screwdriver and the felt the pump turning ok...not looking like a pump issue...

Doesn't mean the impellor's not connected.

 

[Jonathan@9]

Ok so i removed the screw on the pump, felt it working, replaced the screw and my wife shouts these radiators downstairs are rather hot. We have a result, maybe a short term one, but seams like maybe the pump has issues.

 

[Killy Bing]

Did you get air bleed out as you undid it?

 

[Jonathan@9]

Yes, was that good or bad...

 

[GasmanxxxR1]

Yes, was that good or bad...

good, air in pump = no worky

 

[Roger Welton]

pump was just airlocked, job jobbed.

 

[Killy Bing]

You could have freed the pump up or it could have been airlocked depending on its position. Could you post a photo of the pump installtion please?

 

[Jonathan@9]

Great - thank you.