UK Plumber Forum

[David]

Hi, I have a radiator upstairs not working, I took it off and flushed it out in the garden till clean water came out, before I put it back I checked valves. The lock sheild side there is no water coming out and the Trv works on temperature, I think. So I used a wet/dry hoover to suck air lock out, but this never worked. I thought maybe the lock sheild was at fault so I started to drain the system and I noticed there was water coming out of it, put everything back and turned central heating back on .. no joy and no water coming out of lock sheild, any advice?

[REDSAW]

slacken off small nut in top of lock shield and re pack it with some ptfe tape then tighten down, might need to do it a couple of times.
when flushing out a rad we leave the valves on wide open, turn rad upside down and belt it with a rubber mallet severall times over all over. take of valves and bleed screw then do it again.
lock shields are only a couple of quid so best change them for best practice if there old any way!

your Trv has knacked and the fluid is depleted. unscrew the top off and see if rad works this will replicate wide open stat with full flow, if not then its the lockshield or sludged up rad ports. you can just swap the head for new one with the right lock ring size.
other wise- turn off all other rads on that floor and leave the smallest rad on elsewhere, this will push any blockage through system, if boiler makes to much strain-noise then take off rad and check it and the valves are working again

[David]

Hi have not put rad back, flushed it out to clear water,only couple years old any way .I have even switch off all radiator left the one that's not working that didn't do anything. What I need to do get water flowing out of lock sheild, then I can sort out tvr valve thanks for your reply

[REDSAW]

did you drain down the system?

lockshield valve collapsed-change to new one.

[David]

To flush system ,you turn heating off leave radiators on I have a hose with drain by boiler just let it run out . Am i right so far, then I will replace lock sheild and Tvr valves . Will the water come out of the lock sheild when I put everything back .I will check any way fingers crossed . Thanks for your advice

[REDSAW]

yes, supposing you have drained out water to a level below the rad tails. hard to give proper advice without seeing it.
do it methodically with a try beneath rad valve to catch any water then have new valve ready to slip on in the off position

[David]

Hi changed valves Tvr and new lock sheild put everything back ,tries to work still no good ,feels warm sometimes as though it's worked but then it just goes cold .Pipes on the valves our hot then air radiator, still no good thanks any way

[REDSAW]

when you took off the rad did you jet out the bleed pin? when you bled rad did any air come out, has the bleed hole been freed off from blockage?
if heat is felt on the feed pipes to valve one side, then the valves are not working- theres air in the rad or the return pipe is blocked. failing all that then the rad is starved by other rads for heat flow. turn others off or down to low.

is it microbore??????

[David]

Yes did all that .Before I took rad off I even connected hose to bleed valve and flushed out ,lowered other radiator down so heat would hopefully go to this rad,still no joy . May be if I get a cleaner to unblock pipe if any ,may be that could work .Fed up with it at the moment Thanks for reply .Certainly is a mistery? Working fine last year.

[Craig0787]

Hi David, it may as mentioned above be a faulty lockshied valve or the pipe feeding the lockshied could be blocked. Is the radiator fed by 8/10mm pipes or 15mm pipes?

[REDSAW]

Hi David, it may as mentioned above be a faulty lockshied valve or the pipe feeding the lockshied could be blocked. Is the radiator fed by 8/10mm pipes or 15mm pipes?

one way TRV ?

[Craig0787]

Hi David, it may as mentioned above be a faulty lockshied valve or the pipe feeding the lockshied could be blocked. Is the radiator fed by 8/10mm pipes or 15mm pipes?

one way TRV ?

Could be but he said it worked fine last year and going back to him saying no water came out the lockshied (which has now being changed) I can only assume blockage of some kind.

[David]

So would you say a cleaner is the answer. I have renewed the lock sheild and the Tvr valves .I have gone through everything else .It funny that everything else is working fine all the other radiators ,water .Just the one radiator?

[REDSAW]

going to be one of those jobs that would take me less than 30 mins to figure- if i was there lol.

take rad back off, connect hose to valve then open valve with hose in bucket or out window obviously! do that both sides and all will tell where problem lies.

you still need to answer what system and pipe bore its on, makes a diffrence?????

[David]

I've done that had small tap connecters both sides, bucket turned lock sheild on no water .Water comes out of Tvr side ,no water comes out of lock sheild side .Gravity fed central heating system 15m pipe .Got to be cleaner next has it .Where is the best place to apply this . Cleaner is the last thing I can do ?

[REDSAW]

did you try it with heating on?

ive had a lot of success with calchem 3in1, just feed into rad.

[David]

Just tryed it before lots of air coming out ,water moving about inside Tvr side gets red hot sometimes lock sheild side cold ,then Tvr side goes warm then hot again still air coming out takes ages for water to come out or nothing at all of bleed valve .The side of the tvr that gets hot inside rad but not all of it ,then goes cold off and on.... weird ? . The cleaner you mentioned goes in the top of rad ? Bleed valve

[REDSAW]

Just tryed it before lots of air coming out ,water moving about inside Tvr side gets red hot sometimes lock sheild side cold ,then Tvr side goes warm then hot again still air coming out takes ages for water to come out or nothing at all of bleed valve .The side of the tvr that gets hot inside rad but not all of it ,then goes cold off and on.... weird ? . The cleaner you mentioned goes in the top of rad ? Bleed valve

anywhere you can get it into system!
now you have something flowing it may now work. is the lockshield fully open?
sounds like there is an air lock, jamb off completely all other rads and try agian bleeding all time for an hour with stat on 30 deg + also take off that TRV head & check there is water available in the header tank
https://www.toolstation.com/central-hea ... gKo__D_BwE

[David]

Hi back again tried that turned all other radiators off left the one on ( with pump left on) went up to rad ,release bleed valve ... nothing.. waited no sound no heat both sides give good time for something to happen nothing. So turn rads back on went back to radiator bleed valve air coming out .The water sounded like it was going in the two sides hot tvr hot lock sheild. But the air never stopped coming out ,waited and waited for it to finish for water so I could tighten bleed valve. . air . Got cleaner you mentioned sounds easy enough to do .How long does it take for any signs about .THANKS again

[REDSAW]

Hi back again tried that turned all other radiators off left the one on ( with pump left on) went up to rad ,release bleed valve ... nothing.. waited no sound no heat both sides give good time for something to happen nothing. So turn rads back on went back to radiator bleed valve air coming out .The water sounded like it was going in the two sides hot tvr hot lock sheild. But the air never stopped coming out ,waited and waited for it to finish for water so I could tighten bleed valve. . air . Got cleaner you mentioned sounds easy enough to do .How long does it take for any signs about .THANKS again

start a day or two and improves over a week. you just leave it in.

does your rad pipe go up into loft? as it sounds like theres a big air lock in the pipe!
i would just keep doing what you have done until no more air comes out as thats being replaced by water.
what happens is water pulls water to make a cicuit if theres no pressure but water flows.

BTW, a good tip to try is undo bleed nipple and put wet vac over it to draw the water.

[David]

Thanks I have done something similar when I first started, before I took off rad.I put a connection to bleed valve with hose to draw water 2 big buckets of water ,put it back did not work done it again 5 big buckets of water still did not work .I have also put wet /dry when rad was off to valve, that did not work .. . The pipes go down stairs not from loft ..Can this cleaner go in when central heating is on ?

[REDSAW]

Thanks I have done something similar when I first started, before I took off rad.I put a connection to bleed valve with hose to draw water 2 big buckets of water ,put it back did not work done it again 5 big buckets of water still did not work .I have also put wet /dry when rad was off to valve, that did not work .. . The pipes go down stairs not from loft ..Can this cleaner go in when central heating is on ?

chemical can go in any time, best make sure you dont drain it out though.
i presume you had both valves open when you sucked it out into the bucket?

[David]

Well at that time I left both valves on ,just thought if I do this before I do anything I would try this first .Heating was on and I didn't think it was going to be a big deal .... So wrong. I'll give this cleaner a go and give it time see if there is any change .. Thanks will let you know in a week or so.. thanks for all your help

[joni os]

Connect hose to lockshield valve with other end connected to ourside tap or cold water washing machine connector, then open lockshield valve and back flush with mains pressure water. Only do this for short burst because otherwise F&E tank will overflow.

[David]

Hi its Dave again putting cleaner in fed tank ...did not work back to where I started . I have another problem with a radiator down stairs I had to renew bleed valve a while ago because would not tighten up so I put a solution can't remember what it was called but it worked ,but now with the trouble I have had with turning them off and on ,the bleed valve wont tighten up .I have renewed it as well thinking the thread had gone on it but the new one is the same,tried this plumbing silicone around thred never worked Thanks

[REDSAW]

think you need a decent heating eng David
some jobs take little time when seen and a good idea of whats going on in real time.

have you tried @joni os -idea with the garden hose? i always revert to that if it a stubuorn blockage- failing that then its head scratching time.

[David]

Yeah tried that..pardoned the pun fed up with it now probably end up getting plumber to look at it .Will let you know sometime .thanks for all your replys on it .