One radiator is not heating up

[Minchroadster]

Dear DIYnot.com,

I have a strange situation where one of the downstairs radiators on my CHS doesn't always work.

Sometimes it remains cold sometimes luke warm and then sometimes hot. I've noticed that if I turned the CHS off for 20 mins and then turn it on again the radiator seems to work fine( but not always).

Also all the radiators have thermostatic valves and on this particular radiator the hot feed into the radiator enters via the non thermostatic valve. Is this correct?

Should the hot water be entering via the Thermostatic valve?

I've bleed the radiators and all seem full of hot water?

Any ideas guys/gals?

Minchroadster

 

[superdupergasman]

Have a look at the pim that operates the water section on the Thermostatic valve. This will most likley be stuck down.

Remove head of valve and free off this pin, hopefully this should cure the problem.

 

[NEALDEAN]

I AGREE, THIS IS A COMMON PROBLEM BUT IT SEEMS ODD THAT ITS INTERMITENT BECAUSE IF THE PIN WAS STUCK IT WOULDNT WORK AT ALL, BUT GIVE IT A GO.

IF ITS A BI-DIRECTIONAL TRV THEN IT DOESNT MATTER IF ITS ON THE FLOW OR RETURN SIDE.

ALSO CHECK THAT THE VALVE ON THE OTHER SIDE IS OPEN.

YOU COULD ALSO CHECK THE RADIATOR BY FOLLOWING THIS...

RUN YOUR HEATING FOR ABOUT 20 MINS
LEAVE IT RUNNING
TURN ALL THE HOT RADS OFF AT THE VALVE
AFTER 10 MINS CHECK TO SEE IF THE FAULTY RAD IS HOT
IF IT IS THEN YOU ARE LOOKING AT A CIRCULATION PROBLEM

WOULD YOU SAY THAT THE FAULTY RAD IS THE FURTHEST AWAY FROM THE PUMP OR IF ITS A COMBI, THE BOILER ?

HOPE THIS HELPS

NEAL

 

[bengasman]

read FAQs

 

[Minchroadster]

I AGREE, THIS IS A COMMON PROBLEM BUT IT SEEMS ODD THAT ITS INTERMITENT BECAUSE IF THE PIN WAS STUCK IT WOULDNT WORK AT ALL, BUT GIVE IT A GO.

IF ITS A BI-DIRECTIONAL TRV THEN IT DOESNT MATTER IF ITS ON THE FLOW OR RETURN SIDE.

ALSO CHECK THAT THE VALVE ON THE OTHER SIDE IS OPEN.

YOU COULD ALSO CHECK THE RADIATOR BY FOLLOWING THIS...

RUN YOUR HEATING FOR ABOUT 20 MINS
LEAVE IT RUNNING
TURN ALL THE HOT RADS OFF AT THE VALVE
AFTER 10 MINS CHECK TO SEE IF THE FAULTY RAD IS HOT
IF IT IS THEN YOU ARE LOOKING AT A CIRCULATION PROBLEM

WOULD YOU SAY THAT THE FAULTY RAD IS THE FURTHEST AWAY FROM THE PUMP OR IF ITS A COMBI, THE BOILER ?

HOPE THIS HELPS

NEAL

Neal that's really helpful.

I unscrewed the TV handle and the pin was moving freely (are they on springs as it returned out quickly when I pushed it in?)

Silly question is there a way of telling whether the TV is bi-directional by inspecting it without removing it?

Will try the trick of shutting off the other rads when its next cold.

No it's not too far from the bolier and its a standard boiler not a combi.

If it gets hot when the other rads are shut off you suggest a circulation problem, any idea what sort of problem?

Cheers Neal and others for your time and advice,

Mark

 

[NEALDEAN]

do you know where your pump is ? if so is the faulty rad the furthest away from it ( taking into consideration the route of the pipework ).

you could be looking at the pump thats faulty or the system thats is sludged up therefore needing a power flush.

good luck !

neal