Cold Radiator - Have Tried a Lot

[mbga8mjb]

Hi All

Got a problem with a radiator in my hallway (where the stat is).

The radiator is cold, and only ever gets lukewarm when some of the other radiators in the circuit near it have turned off via the TRVs. I thought this was a balancing issue, so worked out the radiator order and amended the lockshields across the system. I have the lockshield on the dodgy radiator wide open, and most others across the system at only half a turn open.

This has had no affect.

I did try turning off ALL the other radiators on the system (less the bathroom one for bypass) and the radiator got really hot, for once.

My CH pump is on position 2, tried position 3 but this makes no difference in "normal operation" apart from additional noise.

The radiator in the hallway isn't the original one (it was moved and re-piped I suspect to allow for a door to be put in to a garage conversion) and where the pipes are also has pipes which I assume go to the radiator in the garage conversion (also not original part of the system - this radiator is always red hot, lockshield only one half turn open).

Near the front door is a piece of coving I assume carries this part of the circuit from upstairs (I have a Thermal Store). Only when the front room and downstairs WC TRV Shut off does it ever get lukewarm. Therefore I have these set low to compensate (i.e. they shut off quite early).

My plumber who changed my boiler couldn't resolve the issue. He was close to replacing the radiator assuming it was blocked, but didn't when it got red hot one night in early autumn, when I assume most of the TRVs on the system had shut off.

I wonder if the amendment to the system has meant they've tapped/teed off another radiator (downstairs WC) perhaps, but even then, if I turn that off completely, it doesn't get warm in the hallway (and the one in the garage room is blazing hot...this is a bigger radiator)

Please help as the stat is in the hallway and it is noticably colder in there all the time, meaning the system doesn't switch off as I'd like and we have to keep doors closed.

Thanks in advance.

I'd even consider offering a plumber to come around on a no-fix no-fee basis and only pay them if they resolved it on a cost plus basis. Any takers (preston area)

EDIT: Radiators are all bled
EDIT 2: TRV pin on affected radiator OK
EDIT 3: When boiler replaced (problem existed before and after) system was cleaned.

 

[mbga8mjb]

Out of interest - I mentioned the Thermal Store. I'm not a gas fitter or plumber but my day job is a Fluid Systems Engineer (Fuel) for Aircraft so I know a little about moving liquid through pipes.

All advice or guidance is valued.

Thanks

 

[dominoman]

It still sounds like a balancing issue to me.

You say it works when other radiators are off, so its not a blockage.

It may have been put on narrower pipe, or a longer path, when it was moved for the garage conversion.

You may need to adjust other lockshields a lot more than turning them half off. In my house I have several lockshields turned on by less than a quarter turn in order to get equal heat to my front room radiator (which is fully open).

 

[MANDATE]

Relative had radiator that did not get hot and decided to remove it and clean it.
It made no difference.
When I got involved it was noted the problem radiator was the furthest away from the boiler. Also attention was drawn to the bypass valve setting, thinking the water would rather go back to boiler via the bypass valve than the problem radiator.
Closing the valve slightly was partially successful. Radiator got warm but not as hot as others.
At this point the pump give up and decided to replace it.
On removel the inlet and outlet orifaces which should have been about 20mm were partially blocked and reduced to about 6mm.
New pump solved problem.