Only one radiator working

7 Jan 2022
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United Kingdom
Since I moved into my new home a couple months back only 1 of the radiators in my house works. I have tried searching online to find the solutions to what could be the problem but everything looks to be fine.

I've tried bleeding the radiators and water comes out immediately. I have tried turning the lockshield radiator valves open but that still doesn't do anything either. My boiler is a logic combi boiler and the pressure gauge is sitting at around 1-1.2 so I increased the pressure up to 2 but again nothing seems to be heating up every other radiator in the house.

Very strange as the radiator in my living room always seems to be boiling hot but the rest are freezing, even the ones with TRV valves turned up to 5 don't work.

Any help appreciated,
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How old is the install ... could be stuck TRV valve pins if they've been off for a while.

Pull the TRV heads off and see if the pins push down by a couple of mm and spring back up.
turn off the hot one. what happens to the others?
Thanks for the quick reply Rab,

I've tried that now and none of them seemed to be stuck and push down okay.

The house was only built in 2018, but there were previous owners before me
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Draw the system out and post up the picture here for the pro's to look at.

Perhaps a stuck valve or just a ****e install?
If one rad works then it's got to be a restriction in the pipework somewhere or valves that aren't opening. What happens when you turn the one working rad off, do any get even a little heat. Are they warm at the pipes at the floor/wall?
All the pipes are freezing cold Rab, except the working one obviously.

Turning the working rad off hasn't changed anything either.

Looking like an expensive one..
An idea to chuck into the mix....

Might the one working rad be a bypass, and only water heating is selected. Have you tried turning heating on at the timer and turning the wall thermostat up?
@Harry Bloomfield good idea, my bathroom radiator is thermo syphon rest are pumped. I was told bleed each radiator twice, once with only lock shield open, and once with only TRV open, if either feed or return blocked that should show it, and it also ensures no air lock in feed or return.

But one radiator only points to it being the heat sink radiator and some valve has not opened.
Given it's a combi, I wouldn't normally expect so but does your system have separate thermostats and zone valves ... or is there a hot water cylinder?

If not I'd be tempted to shut off one rads valves, drain the rad, top the boiler up to 2 bar and run the boiler, then crack open each end and make sure there's flow from both valves.
So I turned the working rad off, and guess what.. now that won't heat up again!

I have a Hive thermostat but even up at 22 degrees there is still no heat from any of the radiators, as for all the other answers I greatly appreciate but I think I've done as much as I can as I'm certainly no expert.
That's just sods law that is!!:mad:

I'm still leaning towards valves TBH. If it was anything else then usually it would be all or nothing.

You don't have any zone valves or similar??
OP post a pic of the valves and pipework under your boiler.

Just to rule out something silly like a partially closed iso valve.
We all relate to what we have come across before. I have lived in 4 houses each one different, this one likely the most complex, with one boiler heating main house and an annex or granny flat, so one boiler two pumps, two motorised valve two wall thermostats 14 TRV's of which 9 are electronic.

But back to basic, a boiler heats water, which is pumped around a set of pipe work, which heats up a selection of radiators, and we want the pump to always be able to circulate the water, so we include a by-pass so even if all TRV close there is still circulation.

So if that by-pass valve is stuck open, then not water through radiators.

So how to check? Well the by-pass may be inside the boiler or external, so it depends on which as to if hands on pipes can work out the water flow.

I am an electrician not a heating engineer, however it is really the same idea, a process of elimination, and hands on is the way to go, and I mean literally hands on, put your hands on pipes, and trace where the hot water goes or does not go.
Does the hot water work properly? (possible boiler pump failure or partial blockage)
Where is the boiler relative to the rads? ie boiler in bungalow loft.
Is the lounge rad at the top of the house, boiler on the ground floor.

Back to basics: the lounge rad did work, but after turning it off it won't turn back on. It's a 2018 house, so likely to be fully TRVed.
When you viewed the house before buying was the whole house warm?

I'll back Madrab's tip. Check again that the pins of the TRVs push down (have you taken the heads off?) and spring back up by themselves.
Do all the TRVs' pins react similarly?
At the other end of each rad, close each lockshield valve, then open each just 1/2 turn. Any heat to any rads now? Feel each of the pipes close to the rad. Is there heat there?

As for giving accurate and realistic symptoms, I suggest that reporting the rads as 'freezing' is nowhere near accurate.

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