Fixing a radiator - DIY advice please.

philstanbridge

philstanbridge

philstanbridge

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I have a fairly large radiator in our lounge that is not heating up - I have removed the thermostat, and tried pressing the valve down manually, and it does appear to heat at the top, very briefly, then goes cold within seconds. It did that once, now it's not warming at all. I've tried bleeding it, but it hasn't helped. When I put the thermostat back on it doesn't appear to work at all. Any ideas what can be at fault? I've got the same apparent problem with another (much smaller) radiator in a different room. The house is 5 years old.
 
I've got a similar kind of problem (with most of my radiators) and i've been told it's possibly a balancing problem. The radiator closest to my boiler heats up fine, but the others are a bit lacking/not warm at all.

Bleeding has made no difference - I think the next thing I need to try, is adjusting the valves on each, until they're evenly heated (although i'm not sure why this has suddenly happened).
 
Yeah - I don't think it's anything major, but I don't really know enough to rectify it if you follow. Think I need the help of an expert. My bro in law is a heating engineer by trade but he lives 400 miles away. He said it might be the valves on these rads - they can stick quite easily or wear out too. He also said that if you have any furniture enclosing the space around a radiator the rads can just stop working. Something to do with the thermostats he said. I don't know, frustrating stuff :(
 
The problem isn't the thermostat valve, it's the valve on the outlet side of the radiator.

Pull the covers off and wind down all the valves till they are shut, they wind them out 1/2->3/4 of a turn. Then run the heating and see if the cold radiator gets heat.

Basically the systems dumps the heat as quickly as possible, if the first few rads on the loop are flowing very quickly, they will dump all the heat in the water before the water gets as far as the end of the system.

Had the same problem in our new place, plumber had left all the outlet valves wide open, meaning the first few rooms were roasting hot and the reast of the house was cold.
 
You've got a valve at either end of the rad, the one with the numbers at the inlet end (sometimes thermostatic, sometimes not) the other end sometimes has a white cover, this covers the outlet valve, the bit that controls how fast water can get out of the radiator.

Could be a bit of much has blocked the outlet valve on the cold radiator, trying opening and closing it a few times to get things flowing again.

Not a clue as to why it would start now, but you mentioned you had air in the system, so maybe something has happened elsewhere in the system.
 
Okay thanks for the explanation. I have checked the valves and they were all tight. So I opened up the main rad valve just to see if that made any difference and unfortunately not.
 
All tight? All the way in tight, or all the way out tight? (all the way out is bad for balancing)
 
SB118 said:
All tight? All the way in tight, or all the way out tight? (all the way out is bad for balancing)
Click to expand...

The valves were wrench tight, all of the ones I checked. I opened up one to see if it would let more water in the rad, thinking this was the problem, but it hasn't made a jot of difference. I will tighten it back up again. I hope we're not at cross purposes here. I'm talking about the valves under the little white caps that screw clockwise/counter clockwise. Not the valve that you press down to release etc.
 
That's the ones i'm talking about. They shouldn't be tight in either direction. If they are tight in, then no water can flow, if they are tight out, too much water can flow, messing up the balance.

It doesn't alter the amount of water in the rad, just the speed if passes through.
IE, if you've got water at 60 degrees in the system and the rads are flowing flat out, you could be dumping 20 degrees in the first rad, 20 degrees in the second rad, 5 degrees in the third rad, then there is no more heat to passed out into the air.
On the other hand, if the rads are flowing slowly (valves screwed all the way in, then out 1/2->3/4 turn) you would only dump 10-12 degrees from each rad and the heat in the water would reach around the whole system. Usually find the rads furthest away from the pump need the valve to be open a bit more than the others.

Probably teaching you to suck eggs, but it might help the next guy who searchs for a thread on radiators! :D
 
Had a simlar problem with one of mine, in the end put down lots of sheets and a large tray and opened the air valve side, not just the little valve but the complete valve, end result you get massives of water coming out. DONT panic, if you start with black or off coloured water that quickly runs clear. Then put the airvalve back on your get a splash of water doing it but better to accept it and do it quickly. Once done any air blockage or sludge should be shifted.

It's not the best method but sometime you have to bite the bullet. I did it with hot radiators but I suggest you dont cause it can burn you. And water can seem to get everywhere.

WARNING if you burn your self or hurt your self you should have paid a plumber to do it. Don't blame a forum
 
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