What else could cause my radiator not to heat up?

11 Nov 2004
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United Kingdom

Looking for some advice.

We had a rad in the hall not heating up (just a little heat at the top with lots of heat at the entrance into the rad).

Pipe heated up to the TRV and the bit of panel next to the inlet but not much else.

Tried taking off rad, flushing with water - lots of little black flakes came out but did not fix the problem.

Have now installed new radiator but only heating alittle at top with both TRV and lock shield fully open (also tried closing abit as well) but nothing worked.

Opened the lock shield valve into a bottle with a good flow of water squirting out.

Hot water is getting into the radiator as the bottom bit of the rad where the water goes in is roasting.

So if water is getting into both sides of the rad, what could be the answer for a lack of heat?

Had to give up as well on the whole fix so no pressure for hot water as the lock shield connection to the microbore was leaking loads. Not a successful Sunday.

Any thoughts welcome.

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Microbore exit line probably blocked somewhere down the line.

Remove radiator and fit drain hose to exit lockshield valve. Then open valve to backflush the return line and hopefully remove blockage. Do same with inlet valve to confirm flow into radiator.

You say black flakes came out of radiator. Clearly system has corrosion products (sludge) due to lack of inhibitor. Whole system needs flushing and inhibitor solution filled.
Thanks for quick reply jackdae.

Should have added.

I dont have a lockshield valve on the return side at the moment. It kept leaking badly today, probably due to the amount of times we have kept opening and closing. Therefore removed.

I got a new 8mm valve from the merchants yesterday but the nut won't fit onto the microbore. Dont know if this is because there are two grooves on either side of the pipe, probably where the previous nut was tightened on. Could i sand these grooves off easily to allow valve nut to fit?

It has been disasterous today.

We dont know how to put the old valve on without it leaking and the new one wont fit.

We have replaced all rads except for one (no easy access in kitchen), we put inhibitor in 3 years ago and will put fresh in after flushing once we get the rad in hall to heat. It is old pipe work from 1980's with combi boiler installed 7 year ago.

Woukd it be advisable now to get a plumber to just repipe to this rad? Assuming we can get access under the floor as laminated in hall.
Is there any play on the pipe ? If there is just pull it up enough to cut the grooves off and fit new one. Fit a hose to the new valve and open filling loop and let run for a while to clear crud. Depending on how bad it is it may require a chemical clean/flush and a filter fitted.
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Hi gigz

Thanks for the reply.

Prepare for a stupid DIY'er question:

How do I fit a hose to the valve and achieve a seal?

Looking a the the end of the valve which will screw onto the radiator, the connection seems too big to secure a bit of hose over it - or am I just having a blonde moment?

If running water through does not fix the problem, will new pipe solve it if this is the only problem rad?

Hope so.

Short piece of 15mm pipe, olive and nut. Tighten onto valve, then hose over pipe (secure with jubilee clip).

There's various ways to fix this but try this first.
That is so logical - I have no common sense whatsoever.

Thanks gigz
Short piece of 15mm pipe, olive and nut. Tighten onto valve, then hose over pipe (secure with jubilee clip).

There's various ways to fix this but try this first.

Sometimes, washing machine hoses will fit too.

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