Strange radiator problem

[LindseyS]

Hi all,
I am hoping someone can give me some advice - I have a strange problem with some of my radiators being cold.
I rented out my cottage while working away, and the tenant decided to turn off all the radiators at the valve. The boiler (gas gravity system running 7 radiators) I know is fine, as it just went through a landlord annual safety check and service right before the tenant moved out. However, when we switched the boiler back on and turned the valves back on, four of the radiators heated up fine, but three were stone cold.
There doesn't appear to be any air in the system, and the whole radiator is cold, so it's not that they need bleeding.
It's been suggested that they might need desludging, but someone else has since suggested that a sludge problem would give a similar effect to air in the system and the radiators would be partially warm.
If you push in the valve you can hear the flow change, so there does appear to be flow. Also the pipe going to each radiator is hot.
I know a bit about plumbing but not enough to work this one out - I am totally baffled. Any suggestions would be really welcome.
Many thanks
Lindsey

 

[ShaunCorbs]

trv pins might be stuck / not open full or as you say sludge

can you feel any warmth on the return pipe work out of each rad?

 

[rpm]

Welcome to the forum Lindsey.
Could it need balancing guy`s & girls?

 

[ShaunCorbs]

Welcome to the forum Lindsey.
Could it need balancing guy`s & girls?

could be but depends if the tenant has just turned the trv heads off or messed with the lockshield as well

 

[rpm]

could be but depends if the tenant has just turned the trv heads off or messed with the lockshield as well

Which we don`t know hence why I threw it in.

 

[ShaunCorbs]

Which we don`t know hence why I threw it in.

not shooting it down mate hell they might even be shut off seen that a few times

 

[rpm]

not shooting it down mate hell they might even be shut off seen that a few times

Know you didn`t shoot it down Shaun, guess I`m getting involved where maybe I shouldn`t but like I say just threw it in after the welcome along.

 

[Swizz]

Worth balancing the radiators and testing all TRV pins... Take it easy though as the pins can spring out and you'd get a little sprinkle all over your lovely carpet!

 

[ShaunCorbs]

Know you didn`t shoot it down Shaun, guess I`m getting involved where maybe I shouldn`t but like I say just threw it in after the welcome along.

its good advice your ok

btw im catching you

 

[chris watkins]

Hi Lindsey
You say you have "gas gravity system running 7 radiators " do you have a pump on the heating pipework or is it indeed a gravity system? if so who fitted the TRVs?

Either way have you tried turning off the rads that are getting hot?

 

[LindseyS]

Thanks guys!
This just gets weirder - some changes seem to have happened while I was out at work today!
The lounge radiator is now cold on inlet and return pipes, but that may be because I've hd to turn the gas fire on in there, just turned the main thermostat up to see what happens.
Spare room radiator is as it was - radiator stone cold, inlet hot, return cold
Bathroom radiator is now hot at both inlet and return, and has stumbled up to lukewarm.

The valves seem to be moving fairly freely on both the lounge and bedroom, the bathroom one does feel a bit sticky. I guess feeling free and being free are two different things though!

 

[joni os]

On cold rads, fully open lockshields, (opposite end to TRV) then close all rads but one and see if it gets hot. Do this for all cold rads. If cold rads become hot by this method turn on all rads and balance system.

 

[LindseyS]

The central heating does have a pump (sorry my terminology's not great, I about know the difference between gravity and combi)
Chris, we did turn off the ones that were hot to increase pressure to the others when we first came back on Thursday, but it did nothing - I will try it again now though as the bathroom rad is hinting at signs of life.
The system was in when I bought the house in 2014, I know it was professional fitted but not who by.

 

[LindseyS]

Thanks Joni, trying that now.

 

[rpm]

btw im catching you

Now you`ve lost me.