One cold radiator!

[dave2410]

We have 8 rads on our system, 5 upstairs and 3 downstairs. Each rad downstairs is on an inverted loop. All the rads get hot except for the one in our dining room, which at best only gets luke warm at the top. I have read various posts of similar problems and the answer would seem to be a build up of sludge and to flush out the system, add X400 or similar, leave for a few weeks then flush out again and refill with inhibitor added. My dilemma is that in the new year we are having bathroom/toilet knocked into one and renovated. Part of the work will involve removing a rad from the bathroom and replacing/resiting the one in the toilet with a towel radiator. This will involve draining down the system, therefore I do not want to do this now to resolve the cold rad problem and to add X400 and inhibitor and then do it all again after bathroom work has been completed.
Having explained my situation, this is my question: Can I close the valves either end of problem radiator, drain and remove and flush through and then refit rad? Or is there another/better option for the time being?

 

[buck51]

Do some more research, there are loads of things you could do before removing the rad,

 

[Agile]

Has the system been balanced?

Tony

 

[D_Hailsham]

Turn off all rads except the problem one.

If the problem rad now gets hot, it's a balancing problem. If not, it's a blockage or air in the system problem.

Have you tried bleeding the rad? (Do it with the boiler off)

 

[dave2410]

When you say turn off all the other rads do you mean just from the trv's or the lockshields also? Hope that's not a daft question but thanks anyway.

 

[dave2410]

Hi Tony,

When you say is the system balanced I assume that it was originally and I have not done anything to unbalance it. On the rare occasion in the past when I once removed a radiator for decorating purposes I made a point of how many turns it took to close the lockshield and then opened it by the same amount. I have checked the pin on the trv and that moves freely. I have bled the radiator and water comes out straight away. Heat can be felt on the "radiator side" of connection to trv but heat is not travelling around the radiator, at best it only gets luke warm at top of radiator and cold at bottom.

Dave

 

[buck51]

JUST TURN THE OTHER TRVs OFF &POST THE RESULTS

 

[xr4x4]

Just turn them off at the TRV, also make sure the hot water is off at the programmer.

Also if it's a vented system (small tank in the loft) make sure that the level drops when you draw some water off, this will check the cold feed to the system.

 

[dave2410]

I closed all rads except for the dodgy one, it did get hot but only around the edges and along the top the rest of the rad was quite warm but nowhere as hot as sides and top. Does this sound like a balance problem or build up of sludge?

 

[jackthom]

......Can I close the valves either end of problem radiator, drain and remove and flush through and then refit rad? Or is there another/better option for the time being?

Yes do the above and while it's off do the "bucket test" to briefly check how quickly water squirts out of each valve, which should help identify any pipework restriction due to sludge.

 

[45yearsagasman]

Stuck and partially closed TRV anybody?

 

[dave2410]

Hi Jackthom,
What is the bucket test and what should I be looking for if there is a problem?
Following the advise given yesterday, with all the other rads turned off the problem rad got hot around the edges and along the top (could only leave hand there for about 4-5 secs) but in the middle and bottom it could only be explained as very warm (hand could be left on indefinitely). This morning after all other rads had been turned back on the problem rad is once again cold all over?

 

[jackthom]

With the radiator removed place a bucket alternately under each valve, turn the valve on full for a short time and see how fast the water (and any other black stuff) squirts out. It should be reasonably obvious if either feed is partially blocked.

 

[dave2410]

From details and advise given so far are you of the opinion that this is likely to be a blockage rather than a balancing issue? If so I guess I know what I will be doing this Saturday. Thanks for everybodys input so far.

 

[D_Hailsham]

From details and advise given so far are you of the opinion that this is likely to be a blockage rather than a balancing issue?

The fact that the rad is hot at the top and sides, but cold in the middle and at the bottom suggests there is sludge in the rad.

The fact that the rad is getting hot when it's on by itself suggests a balancing problem.

So you have two jobs to do on Saturday.

PS if you have a TRV on the rad, it may not shut off completely when turned to the lowest setting. If this is a * (frost setting), you should set the head to max, remove it, then insert a small round disk, e.g a small coin, in the head and replace it. Now wind the head down carefully until it stops. The valve is now closed. Some cloths under the joints are still a sensible precaution.