Why aren't my radiators heating up?!

kmmr

Hi,

I was wondering if anyone could help me diagnose a problem with my radiators.

We have 3 radiators in the flat, and underfloor heating.

Two radiators are like this:


and one is a vertical more fancy one. Anyway, the two like the image above have stopped heating up properly. The boiler turns on at 6am, and one of them heats up very slightly, and then stops. The other seems to still be completely cold.

The UFH and third radiator warm up fine - but very little from the two other radiators. Sadly one of them is in the bedroom, so it's making for very chilly mornings.

From time to time, it will heat up properly, so I know that it CAN - but it seems like the sensor is somehow telling the radiator that it is warm enough. Can anyone let me know what I can look at too see if it is a problem with some kind of sensor? Or what else it might be?

I'm happy to get an engineer out if necessary, but I would like to have an idea what might be wrong as it makes the conversation with the engineer a bit easier.

Thanks!

HappyMJ

Bleeding needed? TRV's faulty? Take the TRV's off the radiator and move the pin up and down on the radiator under the TRV. It may be stuck down.

kmmr

I don't think it's bleeding, as it can heat up if it wants to.

Can I just twist off the TRV? Presume I don't need to drain the system or anything?

WestonDave

The TRV is normally held on with a clip with a screw in it to tighten it - if you undo the screw slightly the thermostat head bit (the "handle" will just come off. You should then see a small pin sticking out of the bit still on the radiator inlet - those pins sometimes stick in which means the radiator stays off. The "head" part expands in the heat and pushes the pin in to turn the radiator off and then contracts to let the pin pop back out. So if the pin sticks and doesn't come back out the radiator won't heat up.

kmmr

when you say a clip.. I can't see anything to go at with a screwdriver. It's this TRV



It has a large metal band around the bottom (I can't think of the right word for it). Do I just loosen that?

HappyMJ

kmmr wrote: »

when you say a clip.. I can't see anything to go at with a screwdriver. It's this TRV



It has a large metal band around the bottom (I can't think of the right word for it). Do I just loosen that?

Yes just loosen it...it'll come off.

WestonDave

Obviously slightly different to mine but if the band immediately below the white plastic will loosen then that will probably allow the head to come off without releasing water. Gently does it - its possible to pull the lower end of the chrome fitting away from the copper pipe which will cause a leak.

kmmr

ok - I just have to wait til DH is out of the house... otherwise he will shout at me if it leaks! I'll give it all a go later today. Thanks for the help, and will update results.

Is the sensor either on or off? At the moment it giving low level heat, but could that mean the sensor is working - just that it is set at the wrong level?

Anyway, I'll give it a go later and hopefully get a bit of decent heat. It definately used to be much warmer.

lesalanos

not the best video out there but this shows what is under the plastic housing

http://www.youtube.com/watch?v=nyCBMz6U6ZU