Radiator not heating up

One Radiator not heating · Oct 15, 2023

Hi All,

We renovated our house in 2019 and put in completely new plumbing system and piping including new boiler and 9 radiators. Off those, there is one radiator in the living room which does not heat up at all. I have tried balancing myself and also had a professional come in to balance it but the radiator just won't warm up like the other 8 do. It is possible it may be the last one in the flow, but I have tried turning off all other rads and yet it refuses to heat up.

I have checked the lockshield valve and they are both fully on. One valve (which I assume is the flow) is burning hot, while the other valve remains cold.

My question is could this be a case of blockage in the radiator? If so, do I need to do a complete power flush or simply flushing the radiator in question would be enough? Any experts out there who can help? (Note: I am not a professional and will need professional help to get either of the tasks done). The original installers have suggested doing a complete power flush (they are charging £800 for that), while another one suggested flushing only the radiator in question. Any advise and pointers on this will be greatly appreciated!

many thanks,
Ash

Ben-gee · Oct 17, 2023

Have you tried waggling the pin on the trv?

Is it possible it’s been plumbed in with two flows instead of a flow and a return - this happens more often than you would think possible!

Can you trace the pipework to check this?

DAVE the old git · May 15, 2025

One Radiator not heating said:
Hi All,

We renovated our house in 2019 and put in completely new plumbing system and piping including new boiler and 9 radiators. Off those, there is one radiator in the living room which does not heat up at all. I have tried balancing myself and also had a professional come in to balance it but the radiator just won't warm up like the other 8 do. It is possible it may be the last one in the flow, but I have tried turning off all other rads and yet it refuses to heat up.

I have checked the lockshield valve and they are both fully on. One valve (which I assume is the flow) is burning hot, while the other valve remains cold.

My question is could this be a case of blockage in the radiator? If so, do I need to do a complete power flush or simply flushing the radiator in question would be enough? Any experts out there who can help? (Note: I am not a professional and will need professional help to get either of the tasks done). The original installers have suggested doing a complete power flush (they are charging £800 for that), while another one suggested flushing only the radiator in question. Any advise and pointers on this will be greatly appreciated!

many thanks,
Ash

If some of the rads are not Heating try nocking off the rads on the same floor this will let the heat to run around to the rads that are not heating .But if it is a new centeral heating system and I am talking about a new centeral heating system with all new pipe work but I would have my doubts if it is all new pipe work even if you did pay for a new heating system at the very least all centeral heating systems have to be power flushed before a new boiler is installed and this is stated in all manufacturer's instructions then when job is comishened anti corresen inhibitor installed in centeral heating But with most the new Rads on the market to day there are small water ways on the rad if these water ways get blocked the rad just will not heet but all is not lost connect a garden house to the rad that is not heating a flush it outside do it from both ends of Radiator but when the water is going through the Rad give it a with the handle end of a claw hammer this will loosen and sludge that is in the rad .I would not pay no 800uk pounds to have my centeral heating flushed that should of been done before job on new centeral heating was installed. hope this helps