Troubleshooting rad problems

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hello!

One of my radiators is not working and I wonder if anyone has any tips for trouble shooting & resolving? Basically it doesn't get very hot - but does get mildly warm at the top of the radiator.

What have I tried already?
- switched off most other radiators to focus the flow through those remaining - and this one acted exactly the same - the others felt like they were going to melt!
- because of the above - I don't think my boiler is under-rated, and there seems plenty of flow.
- it's 2nd or 3rd in line from the boiler out of about 20 rads - most of which are fine.
- my boiler pressure is 1 1/4 bar when cold, rising to about 1 3/4 bar.
- the flow pipe into the radiator gets red hot - but the return never feels more than luke warm.
- I have recently drained and refilled the system for unrelated work - the radiator had the problem before the refilling which makes me think it's not an airlock - and also makes me doubt it's a sludge - the radiator wouldn't have emptied otherwise


I rekon it's one of the following - but wondered if how to determine which - or if there is something I am overlooking.
1. faulty TRV (when I take the TRV off and press the button, it does start/stop the flow - but still could be partially blocked)
2. faulty lockshield/balancing valve - as above. opening it wide did warm the rad a tiny bit - but I am not sure if I felt it because I wanted to!
3. blocked radiator/pipes with gunk - stopping the heating water flowing through - but then why did it drain down OK?
4. airlock - as above, probably in the return pipe - but then I have recently drained and refilled, so unless it's a piece of susceptible pipework...
5. some wierd combination of the above!

Are there any non-intrusive tests I can do - ideally without lifting floorboards & too much carpet!

Cheers - and apols for long post!

whitling2k
 
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Any rad can be completely blocked on one side and drain through the other.

The obvious thing is to do the bucket test.

See the FAQ for detals.

Tony
 
Yes - I thought of that when I had got my post written down!

I missed the FAQ - there seems to be three different sources of FAQ/Info on the site - in addition to the forums.

I've had a read through the various FAQs and sections - some good stuff in there.

Next step: disconnect the radiator, clean it and test the valves.

I have some old 1/2 inch/15mm isolating flexible hoses that fit other rad valves perfectly. I'll repressureise the system with those in place to see if the valves/pipes are faulty.

Cheers

Whitling2k
 

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