Not very period radiator question

[a twig]

At my wits end - got a radiator that is stubbornly refusing to flow.

Radiator is bled, no bubbling etc and water is clear so doesn’t hint at internal corrosion.

TRV appears to function as when heating is on, when I’ve fully opened the TRV and then opened the bleed valve hot water does slowly get into the radiator.

Lockshield is fully open (anti-clockwise so fully up). Winds up and down so doesn’t appear to be seized.

It’s on the ground floor, I’ve tried shutting off the other rads in case it was a balancing issue but doesn’t seem to help.

I’m out of ideas and at the point of replacing the rad but no one seems to make cheap 1750mm wide panel rads so loathe to spend £600 on a new one until I’ve definitely ruled everything else out.

Any inspiration on something I might have missed?

 

[montyjohn]

I would isolate both ends of the radiator.
Drain it down.
Then in turn, open each valve into a bucket and check you get decent flow from both the "in" and the "out" valve.

Once this is confirmed, next your are down to balancing.
I've never had a situation where balancing is so bad that one radiator gets no flow, but if you have a particularly long and bendy pipe run to this radiator vs the others maybe it can happen?

 

[Stevers]

Sounds like one of those mysterious 'air locks' that you really hope you don't have to deal with. When refilling my system I run the pump flat out while bleeding the rads in the hope of avoiding one!

 

[Cubist]

Maybe a silly thought or two but:

1. Is this radiator sited in a traditional circuit or is it flow controlled through a manifold?
2. Is the rad sited at a high point in the property?
3. If its is part of a traditional circuit system have to checked that the valves are open in all the predecessor rads? Also, have you confirmed there are no airlocks in the earlier rads?
4. If the rad is connected via a manifold have you checked for blockages/locks there?

 

[my_name_is_slim_daisy]

(Sorry to hijack this post.. is there a thread you can recommend that explains the steps to remove and replace a convection radiator? Want to attempt this myself, but dont want to flood the property and also misconfigure a newly installed vaillant combi boiler)

 

[Cubist]

They are all 'convection' radiators. Is yours a wet CH system, or are they electric. Electric rads are easy but can be heavy. Wet radiators too can be relatively easy but potentially very messy if they are not drained down properly. If yours is a wet system would you want together rid of the feed and return pipes and valves too?

 

[noj]

Back to the original post.

You can check the operation of the TRV to a certain extent by removing the head and manually depressing the pin, seeing how far it travels and how it pops back up. Compare with a known working one.

If it is sticking down then you could try the pliers that you were pushing down the pin with to give it a sharp tug to release it - this is a BAD THING to do... Tapping may help though

 

[my_name_is_slim_daisy]

They are all 'convection' radiators. Is yours a wet CH system, or are they electric. Electric rads are easy but can be heavy. Wet radiators too can be relatively easy but potentially very messy if they are not drained down properly. If yours is a wet system would you want together rid of the feed and return pipes and valves too?

Hello

Yes it’s a wet system. I’d plan to keep the flow and return pipes and respective valves. Mainly because my mind can’t comprehend radiators without flow and return pipes (completely new to radiators here - I’ve lived on electric radiators my whole adult life. I’ve only just learnt that rebalancing radiators isn’t as mind boggling as it sounds ). I’d be interested to know how and why you would/could/should remove these pipes though.. I’m here to learn and hopefully not make expensive mistakes!

 

[a twig]

Maybe a silly thought or two but:

1. Is this radiator sited in a traditional circuit or is it flow controlled through a manifold?
2. Is the rad sited at a high point in the property?
3. If its is part of a traditional circuit system have to checked that the valves are open in all the predecessor rads? Also, have you confirmed there are no airlocks in the earlier rads?
4. If the rad is connected via a manifold have you checked for blockages/locks there?

Ground floor, about 300mm above the lowest rad in the house.

No manifold - traditional circuit.

All other rads function correctly. Tried opening / closing TRVs and lock shields on others but no dice.

TRV pin wiggles side to side and rotates but is fully up and is very difficult to push down. Clearly lets something through when messing around with the bleed valves which makes me think it’s the lock shield side or the rad that could be the issue.

Rad is very old and quite whiffy when bled despite there being no air coming out which leads me to think it’s the rad. Lock shield and TRV replaced 5 years ago so reasonably confident in those

Have whacked everything with hammers to no avail

 

[Cubist]

If you don't plan to replace the radiator then it's sometimes wise to remove the old pipework back to safe and unobtrusive locations rather than leaving the valves and pipe tails hanging in space. To do this though it's necessary to drain the entire CH system before cutting the feed and return pipes in the desired locations and then installing end caps to each - end caps are available in various fitting types. The system is the re-filled and tested for leaks.

The procedure to dismount and remove a wet CH radiator is reasonably straight forward but there are some risks that need to be handled. The first is that once the radiator is separated from the feed and return pipes the water content can drain out very rapidly as the radiator is lifted off the wall support brackets - particularly if it is tilted toward either the fill or return ends as its lifted. Before physically lifting the rad off the wall, it's a good idea to tape a couple of plastic bags over the flow and return outlets - the black water in the rad can make a dreadful mess. The second issue is that, while water filled, the radiator can be dreadfully heavy and awkward to move around - even small radiators may need two people. Best to have a large plastic sheet on the floor and a good sized bucket available to drain the rad asap.

 

[Cubist]

Ground floor, about 300mm above the lowest rad in the house.

No manifold - traditional circuit.

All other rads function correctly. Tried opening / closing TRVs and lock shields on others but no dice.

TRV pin wiggles side to side and rotates but is fully up and is very difficult to push down. Clearly lets something through when messing around with the bleed valves which makes me think it’s the lock shield side or the rad that could be the issue.

Rad is very old and quite whiffy when bled despite there being no air coming out which leads me to think it’s the rad. Lock shield and TRV replaced 5 years ago so reasonably confident in those

Have whacked everything with hammers to no avail

Has this rad been used in the house before or is a new install for it?

 

[a twig]

It’s about 40 years old and has worked fine historically

 

[a twig]

It used to be behind a sofa so was turned down but worked fine. This winter it just hasn’t come back to life though following the summer CH turn off

 

[a twig]

Got a chap coming to do the annual boiler service soon so might just outsource the problem and crank the wood burner up in the meantime

 

[Cubist]

My only thought would be that if theres no blockage inside the rad and theres good flow from the supply side then is the onward flow to the next rad in the circuit constrained impaired in any way?

 

[my_name_is_slim_daisy]

(@Cubist thanks for the info. The deal is sealed then - I am no longer considering removing the radiators myself!

Good to know though. I’ll probably observe how the plumber does it when I eventually get round to finding one that isn’t trying to ask for an arm and leg)!

 

[Cubist]

Did you see that? Not a bird, not a plane...coo a Biggles Porker.

 

[a twig]

Right - well in disgust this evening I opened all the downstairs valves to maximum and topped up the CH pressure by another 0.3 bar.

Some clunking and gurgling happened then the boiler had a hissy fit, threw a low pressure error and dumped a load of water into the waste pipe.

Topped the CH back up, reset the boiler and after much heavy breathing from the boiler everything seems to be working now so seems like it was just an annoyingly persistant airlock after all - hurrah!

EDIT: Spoke too soon - rad only partially heating but it’s progress! Will have another go tomorrow

 

[paulc]

The procedure to dismount and remove a wet CH radiator is reasonably straight forward but there are some risks that need to be handled. The first is that once the radiator is separated from the feed and return pipes the water content can drain out very rapidly as the radiator is lifted off the wall support brackets - particularly if it is tilted toward either the fill or return ends as its lifted. Before physically lifting the rad off the wall, it's a good idea to tape a couple of plastic bags over the flow and return outlets - the black water in the rad can make a dreadful mess. The second issue is that, while water filled, the radiator can be dreadfully heavy and awkward to move around - even small radiators may need two people. Best to have a large plastic sheet on the floor and a good sized bucket available to drain the rad asap.

Having removed a few radiators, residual water (even after draining the system down) is a problem. However, I use blanking plugs/caps rather than plastic bags. Less risk of picking the one bag with a hole in it.