House radiator not working, ideas?

[Burdekin]

I have a problem child radiator that isn’t working and gone through probably the obvious things.

The rad to start with was totally cold and both pipes.
I bled it and some air came out but no difference.
I turned off all other rads and didn’t make a difference.
I replaced the control valve and no difference but some jelly muck did come out, not a lot.
Both valves seem to work but isn’t a lot of flow but seems normal at the top bleed nipple.
I isolated both valves, removed the plug fitting the bleed nipple screws into and then opened each valve individually and got a big expel of air and gassy water from each. Refitted thinking maybe a big air lock was the reason but still not hot, but the line in is now warm, not hot but warm. The exit line and valve is still cold and the rad is not warm.

Could it be just a gummed up rad and I should replace or is it worth replacing the lock shield valve first?

Any other ideas. I’ve bled all the other rads and they are toasty warm. The one not working is upstairs and furthest from the boiler.

 

[DanZac]

If you can isolate it, drain it down, and take it off the wall, you could take it outside and connect the garden hose to it, which will wash any muck that's in there out.

Be careful though as its likely to be full of filthy dirty water which you'll never get out of the carpet if you spill any.

 

[Burdekin]

If you can isolate it, drain it down, and take it off the wall, you could take it outside and connect the garden hose to it, which will wash any muck that's in there out.

Be careful though as its likely to be full of filthy dirty water which you'll never get out of the carpet if you spill any.

Yeah that’s worth a try.

 

[angellonewolf]

not trying to say how to suck eggs but

im assuming you mean controll valve the therotsatic valve ?

if the water and air coming out is spluttering it should have a nice stream of water with no splutter or there air in there and as your bleading make sure these enough pressure in the system

was the valves one or both side turned down or off over the summer ?

 

[Dave-sparks]

Turn all the other radiators on the system off, turn the problem one up to full on both valves.
You'll probably have to bleed it a few times but this normally gets the problem radiator hot.

Once it's got hot turn all the others back on and balance it all up.

 

[Kayos]

Turn all the other rads off, preferebly at the lockshield end, whack the boiler on high and see what happens. Try bleeding the problem rad as well

Sounds like an airlock, is it piped from above?

 

[Onoff]

No.2 daughter's bedroom rad was cold the other day. A while back they'd turned it off. The collar on the TRV was loose. Then the little spring pin wouldn't return.

I tightened the collar & gave the fitting a few knocks with my leatherman and job done.

 

[minimutly]

Not unusual this time of year. Sometimes the trv valve sticks - you have to take the top off and tap the t*t sticking out repeatedly, with the pump on max and all other rads off.

 

[Burdekin]

Thanks guys. I’ve done/tried all the suggestion. Going to flush out, make sure feed and return lines have no air and then fill and see what happens.

 

[Onoff]

The cold double rad here, I bled and no air came out, just water. Only when I freed up the trv did it get hot.

 

[Burdekin]

The cold double rad here, I bled and no air came out, just water. Only when I freed up the trv did it get hot.

I replaced the TRV. I checked the pin on the old one as well and was working.

 

[Onoff]

I replaced the TRV. I checked the pin on the old one as well and was working.

I gave all the fittings feeding the rad a few taps each.

 

[armalites]

I've been re-piping my system as I've fitted a twin coil solar tank, one bedroom had some issues since I installed Honeywell Evohome a year or so a go. After I had refilled the system I found that radiator had the flow coming to the lockshield end. It's the longest run radiator so the lockshield is fairly well open and with a normal thermostatic valve it work ok. I swapped the feed/return around and things improved. I also moved my pump setting from speed 1 to 2.

I also bought one these Thoroughflush systems and although I though my system was ok and I had a Magnaclean the amount of crap this flushed out was amazing. You tap into the flow and return, connect to mains water and a pipe into a drain/sink. You shut all bar one rad down and the system allows you to flush in both directions, reversing the flow does dislodge stuff. I've included spurs with valves next to my boiler isolation valves so I can tap straight into my system with disturbing anything. By using various valves in my system I can isolate/flush boiler,hot water and radiator circuits. The stuff that came out of the boiler for the first few minutes looked like ink. It's not cheap but it comes with just about every fitting you could need to connect to a system and does a really great job and flushing radiators.

Thoroughflush - Central Heating Flushing & Water Quality - VDI2035

Thoroughflush - the leading mains powered central heating flushing system in the UK. Providing all you need for flushing heating sytems effectively.

www.thoroughflush.co.uk

 

[armalites]

How old is the system? Does it have a differential bypass valve(opens the path from flow to the return when the radiator valves all shut) maybe set a little to low.

Balancing a system perfectly can take time, in an ideal world all radiators would get warm at the same time/rate but in older houses the path of pipework can be quite convoluted. Quick way is to start with the shortest run and wind that one down until you get 10-12 degree drop and move to the next, fluid will take the path of least resistance so a better way to do it is open all the rads fully and both sides when they are cold and run the heating and note the order they warm up in because you can't assume the shortest run provides the least resistance. Start balancing at the one that warms up first and work your way down the list.

I was chatting to a colleague about balancing because he has some rads that don't peform as they should, when he checked every one of his lockshield valves were wide open, I am surprised he didn't have some totally cold rads given he has rads in basement,ground and first floor

It seems fairly common having rogue radiators even in new builds, we had some friends who lived in a new build where one rad never got warm and they had multiple people out to look at it. I would love to have gone and had a play but they lived a few hours away and moved before could arrange something

As @Kayos says shutting down all the other rads at the lockshield valve should ensure the rad gets some heat which will at least prove the path to and from the rad is ok

If shutting all the other rads completely down doesn't get it hot then either the flow has another path back or the radiator is blocked

 

[JOEPRO]

My house was originally built in the mid 70s. Oil boiler. System was always crap for as long as I can remember with certain rads always cold etc. The old boiler leaked last year so I fitted a replacement condensing boiler.

I also flushed individual rads and used central heating cleaner a couple of times and drained whole system several times.

The thing that really helped was fitting a strong central heating magnet. I cleaned this every few days then weeks for the first while and the stuff it collected was shocking. Any debris which would otherwise move around and settle in the middle of a rad were picked up and trapped by the magnet.

Regular maintenance is key so I am going to check and clean this magnet again shortly.

 

[Burdekin]

Had another go this morning but still not working. The in feed line probably only has about 1/2 the flow as the out line by the looks. Air in the system, blocked line, kinked line maybe issues? Even with all the other rads off it’s not getting hot. I turned all the other rads back on and the in valve gets hot but not the rad. I get flow in and out of the rad so it’s not blocked. Bit of a mystery.

 

[JOEPRO]

Had another go this morning but still not working. The in feed line probably only has about 1/2 the flow as the out line by the looks. Air in the system, blocked line, kinked line maybe issues? Even with all the other rads off it’s not getting hot. I turned all the other rads back on and the in valve gets hot but not the rad. I get flow in and out of the rad so it’s not blocked. Bit of a mystery.

Did the rad ever get fully hot in your experience? Or was it always troublesome and never got fully hot years ago?

I had a strange one at my house. A rad that never got hot at far end of house from boiler. Checking all pump sizing guides said it was OK. But after exhausting balancing etc I upgraded the circulator pump in my house and after that the rad that was always cold for 20+ years was piping hot and problem solved.

I am not saying the solution here is to change your pump but just think carefully has it ever worked properly because if not then it could be a pipe issue, balancing or pump issue. Pump comes last if all else fails.

Also - is your pump a smart pump or regular pump? They all have adjustable speed so try adjusting that too and see if it changes anything.

 

[Burdekin]

Did the rad ever get fully hot in your experience? Or was it always troublesome and never got fully hot years ago?

I had a strange one at my house. A rad that never got hot at far end of house from boiler. Checking all pump sizing guides said it was OK. But after exhausting balancing etc I upgraded the circulator pump in my house and after that the rad that was always cold for 20+ years was piping hot and problem solved.

I am not saying the solution here is to change your pump but just think carefully has it ever worked properly because if not then it could be a pipe issue, balancing or pump issue. Pump comes last if all else fails.

Also - is your pump a smart pump or regular pump? They all have adjustable speed so try adjusting that too and see if it changes anything.

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It use to work, honestly can’t remember when stopped. I bled it and checked the rad pin etc last year. There’s two rads in the room and the other gets toasty hot. I’m not sure what type of pump is fitted, I just get it serviced by the Worcester Bosch tech annually and have a service contract with them. Pump could be the issue, it is the furthest away.

 

[Kayos]

Had another go this morning but still not working. The in feed line probably only has about 1/2 the flow as the out line by the looks. Air in the system, blocked line, kinked line maybe issues? Even with all the other rads off it’s not getting hot. I turned all the other rads back on and the in valve gets hot but not the rad. I get flow in and out of the rad so it’s not blocked. Bit of a mystery.

Sounds like a pipe blockage but I wouldn't rule air out just yet

 

[Blobber]

Had another go this morning but still not working. The in feed line probably only has about 1/2 the flow as the out line by the looks. Air in the system, blocked line, kinked line maybe issues? Even with all the other rads off it’s not getting hot. I turned all the other rads back on and the in valve gets hot but not the rad. I get flow in and out of the rad so it’s not blocked. Bit of a mystery.

Did you turn the hot water circuit off as well as the rads? went to a system once and could not get a rad going, in the end I made an adaptor up to fit the vent plug and shoved a hose with mains water pressure on it, that got it going and never had to go back! you do need to keep an eye on the header tank though as it can fill quickly