Radiators not staying hot

[zulujuju]

I have a potterton boiler that's around 12 years old.

When it comes on with the timer the radiators get hot but after about an hour
they go cold.

The boiler is giving us plenty of hot water. We have bleed the radiators but they didn't have any air in them.

The boiler comes on and off as it should and if I turn the thermostat up, it
clicks on.

Any ideas why they aren't staying hot?

Thanks

 

[seco services]

Maybe the room has reached it's temp so stat has clicked off.
You say you turn the stat and it clicks on again.

 

[zulujuju]

Yeah I've turned it up to 28c but they are not getting hot.

I don't think they have reached temp, house is concrete build so takes
a lot to get warm.

The boiler is on a timer at night from 4.30 to 10 pm but they are only
hot for an hour out of this time

 

[Armo74]

Where is the room stat?
Are there any other heat sources in the same room?

 

[zulujuju]

It's in the hallway, no heating in there