DIY Doctor UK DIY Forums

Hi guys/girls
I have 1 radiator that will not heat. It is the furthest from the boiler. I have checked the pin on the thermostatic valve and it moves freely. I have shut off all other radiators and still no joy. Yesterday i decided to move out the box a bit and removed the bleed nipple completely, letting water flow freely out of it. This gave me a nice hot radiator with both inlet/outlet pipes becoming hot, which led me to believe that it was not a blockage problem (all other radiators still open and working). As soon as i put the bleed nipple back, 1 pipe cooled off pretty quick, the other cooled off slower and of course the radiator cooled off at an expected rate. The Radiator is approximately 40ft (piping length) from the boiler.
It is a radiator that was put into an extension we had built, the engineer used existing supply pipes to a radiator that did work (although there was a radiator about another 20ft away from that which did not work), but reduced from 16mm pipe to what looks like about 12mm pipe which runs under a concrete floor and is approx 10ft further away.
Any thoughts???
Many thanks, in anticipation

radar,
Check that the lockshield valve is fully open.
Make sure you have a thermostatic valve which works with flow in both directions.
Have a look at the pump and see if you can up the speed settings.
end

Also balance the system.

Hi Stoneyboy, thanks for the response,
Ok, lockshield valve is fully open. Valve is a 'Myson TRV 2 way' and as stated before, the pin is moving freely. The pump is a 'Wilo GOLD 50' on speed setting '3'. I did try it on speed setting '1', thinking maybe less speed would give it more 'grunt' but made no difference.

Have been pricing up new pumps just in case someone could tell me that is def the problem and have a question, if you could possibly answer ---
most pumps I have looked at seem to have some sort of designation such as 'ups 15-50 130' and then what looks an identical pump designated 'ups 15-60 130'. I know the 130 is the dimension across the screwed fittings but whats the difference between the 15-50 and the 15-60?? is it a power thing or flow rate or somrthing else??

thanks in advance and happy new year.

Hi Steve the gas
Im no expert on balancing the system but have basically gone round each radiator in sequence. I opened the lockshield valve on 1st radiator just a 'gnats', then each subsequent radiator I opened the lockshield a touch more than the previous. All other radiators are working perfectly.
The only reason this is a problem is because this radiator is at the end of the living room where the patio door and access to the garage are, so the cold air isnt being warmed and its making the whole living room a little chillier than the rest of the house.

radar,
My best guess is that you have an air-lock in the pipes to/from the radiator. With the heating off, close both valves, remove the bleed screw, open each valve in turn (not both together). If you have or can borrow a wet vac this is ideal for catching the full flow you should get from the bleed valve.
The pump ratings are for the maximum head the pump will achieve in a no-flow situation - 15-50 a 5m head and 15-60 a 6m head.
end

stoneyboy,
thanks, will give that a go.
I just thought that, because both pipes fully heated up when i let water flow through the bleed screw, that meant there was no blockage or air lock. but, hey, what do I know, just an educated guess on my part, but get the feeling that parts of this heating business is a bit of a 'black art' !!
will give it a go tomorrow, cheers

radar