Radiators go cold after 20 minutes

[Chris54321]

Hi

All of my radiators go cold after 20 minutes once the boiler stops firing. Could it be a faulty wall thermostat?

 

[ShaunCorbs]

Any more of an explanation/ background

As they normally do go cold when the boiler isn't firing / heating them

 

[Chris54321]

Any more of an explanation/ background

As they normally do go cold when the boiler isn't firing / heating them

Okay so I have a tank in my airing cupboard, not a combi system. No radiators have trvs. My potterton suprima boiler fires up fine and all radiators get hot. Then after 20 minutes it stops firing and all radiators start to get cold. The boiler led is orange meaning no call for heat. All the radiators used to stay hot for a long time. If there was a problem with a component in the boiler surely it would not fire up to start with?

 

[ShaunCorbs]

Great

Is your programer calling for heat when the rads are off ?

 

[Chris54321]

Any more of an explanation/ background

As they normally do go cold when the boiler isn't firing / heating them

Yes they would get cold when boiler stops firing. But my thermostat should sense a drop in temperature as it is set to 30 but my boiler won't fire up again for hours.

 

[Chris54321]

Great

Is your programer calling for heat when the rads are off ?

Yes

 

[ShaunCorbs]

Click your thermostat off eg lower temp then up again does your boiler fire back up ?

 

[Chris54321]

Click your thermostat off eg lower temp then up again does your boiler fire back up ?

No it won't. If I try again hours later then boiler fires up.

 

[ShaunCorbs]

could be a few things eg pump etc

Best to have a local engy have a look at your system

 

[Chris54321]

could be a few things eg pump etc

Best to have a local engy have a look at your system

Pump seems to be fine. Might try facing a fan directly on the thermostat and then see if boiler stays on.

 

[Harvest Fields]

Pump seems to be fine. Might try facing a fan directly on the thermostat and then see if boiler stays on.

Seems?

 

[Chris54321]

Seems?

Had a plumber fit a brand new one last winter.

 

[Harvest Fields]

Had a plumber fit a brand new one last winter.

That does not mean much If there is a lot of sludge in your system!

 

[Chris54321]

That does not mean much If there is a lot of sludge in your system!

The radiators would be cold at the bottom in this case but there not.

 

[Harvest Fields]

I have had pumps almost blocked but the rads still get relatively warm all over.

 

[Chris54321]

I have had pumps almost blocked but the rads still get relatively warm all over.

My rads get hot to the point where you can barely touch them.

 

[Harvest Fields]

Probably not the pump then

 

[Chris54321]

Probably not the pump then

Nope. The boiler gets up to temperature fine but then it just stops and rads get cold and it won't fire up again even after temperature in the house has dropped.

 

[ShaunCorbs]

Probably not the pump then

Could be if it's not getting the heat fast enough from the boiler

And the boilers shutting down from being upto temp

 

[Harvest Fields]

Could be if it's not getting the heat fast enough from the boiler

And the boilers shutting down from being upto temp

That’s what I was thinking. But if that was the case surely the boiler would be cycling on and off until the rads were hot?

 

[SavageW]

Check your 2port or 3port valve is still open when the boiler shuts off an they start to cool,this should tell you wether the thermostat is still calling for a demand,could be worth checking with multimeter your getting 240 on the orange in your wiring centre.
*just re read you said the boiler LED is continuously orange which would indicate the call for heating has gone,what room thermostat do you have?

 

[Chris54321]

Check your 2port or 3port valve is still open when the boiler shuts off an they start to cool,this should tell you wether the thermostat is still calling for a demand,could be worth checking with multimeter your getting 240 on the orange in your wiring centre.
*just re read you said the boiler LED is continuously orange which would indicate the call for heating has gone,what room thermostat do you have?

Yes the led is continuously orange once it stops firing. Green whilst it is firing. I have a Honeywell room thermostat, a very old one mind. It is in the living room. I do have a very small 1 bedroom house which only has 3 radiators.

 

[Chris54321]

Yes the led is continuously orange once it stops firing. Green whilst it is firing. I have a Honeywell room thermostat, a very old one mind. It is in the living room. I do have a very small 1 bedroom house which only has 3 radiators.

Sorry is the 2 port valve on the boiler or airing cupboard?

 

[SavageW]

Would normally be in your airing cupboard, small box looking thing with brass body underneath it after the pump. May have A & B written on it (little lever should be on B if programmer and room stat still calling for heat) or if it’s an metal looking box check the lever is loose which would mean it’s open. I don’t think it would be this as the boiler led goes continuous orange which means you now have no demand for heating.

 

[Chris54321]

Would normally be in your airing cupboard, small box looking thing with brass body underneath it after the pump. May have A & B written on it (little lever should be on B if programmer and room stat still calling for heat) or if it’s an metal looking box check the lever is loose which would mean it’s open. I don’t think it would be this as the boiler led goes continuous orange which means you now have no demand for heating.

Think I know the one, it is a metal box which is on auto.