Repeatedly blocked radiator

Joined
27 Jun 2012
Messages
288
Reaction score
14
Location
Leics
Country
United Kingdom
One of our radiators keeps getting blocked off. It is one in the sitting room. We have one under the bay window and a smaller one the other end - used to be dinning room and separate sitting room.

It is an old system that has had some upgrade work done to it over the years. I had this radiator off in isolation and noticed a lot of black sludge at the out flow. I thought that that was causing the blockage. I cleaned the valve and flushed the radiator through with a hose. I put it back on and it worked for a few days only to stop warming up again. So I drained the whole system and had this radiator off again, but this time there was no visible sludge. I have flow from both in and out flow. I added a sludge remover a couple of weeks ago before filling the system. Last night I notice the radiator being stone cold again. I guess some sludge is acting like a valve somewhere in the pipes. What else can I do in order to get the radiator working reliably??
Originally my plan was to drain the system again after 4 weeks and add inhibitor, but I think this will have to wait.
 
Sponsored Links
You mention one radiator is cold. Turn off ALL the others and perhaps you will get some flow through it. You may have a balancing problem. Have you turned up the pump speed?

Any radiator or pipe with no flow through it will not be cleaned by your chemical.

Draining it will not loosen sediment. Hosing out every radiator will shift some, but I'd suggest you start by adding Sentinel X400 which has a sort of detergent action. You circulate it for up to four weeks, then drain the system and rinse it, the loosened sludge will run out. Empty the F&E tank first and sponge it clean.

As yours is very dirty it would be helpful to hose out all the radiators as well, but this is more time and effort.

The X400 will only cost you about £15

If you can afford an extra £100 and can do basic plumbing, fit a system filter as well, if will trap the residual circulating particles (you can never get it all out)
 
Last edited:
Over the years, whenever we renovated a room, I fitted isolation valves to the in- and out flow pipes so I could just take one radiator off without draining the whole system.

When this radiator was off I opened the isolation valves and always had water gushing out under pressure. Before I refilled the system I put some of the descaler / sludge remover down both pipes and also filled this radiator up with it. It did circulate round the system and the radiator has been hot for the last 2 weeks. I know that I do not have a solid and permanent blockage in a pipe and I know that in our house there are pipes where the water can pool even when the system is "drained".

I used screfix's NoNonsense cleaner. The next step now might be a more aggressive Sentinel then.
 
Is one of the radiator valves a thermostatic valve ? It may be just sticking and need replacing. Try removing the sensor head ,make sure the pin below is moving freely up and down .leave the head off and see what the rad performs like.
 
Sponsored Links
One is a TRV, but both valves are freely moving. I checked when I had the radiator off the wall.
 
Leave the head off the trv and see how rad performs , it may be closing down when it shouldn't .
 
If the isolation valves you have installed are not full bore, you have restricted the flow of water, possibly below that required to give the heat you require.

Also, be aware that many isolation valves of the "screwdriver turn" type are not rated for central heating temperatures.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top