One cold radiator!

[dave2410]

Thanks for the valve tip D_H I will try and find something suitable before I tackle the problem

 

[dave2410]

Well what a day today has been! From the previous posts, the idea today was to remove the rad in question, flush out, replace and then balance all the rads. I closed the valves either end and then proceeded to undo nuts to remove rad. The nut near to trv was a beast to undo and resulted in too much movement of connecting pipes which led to a strong leak from the compression joint. As a result I had to drain the system down (something I was trying to avoid at the moment) and remove the faulty length of pipe and replace with new. When the system was drained I was surprised how clean the water was, no evidence of sludge or dirty brown water. Also, when the rad was flushed out this was clean also. It has taken me all day to repair and connect back up. As the system was drained down I took the chance to replace the trv with a new one which I happened to have. When I refilled the system I also added some X400 just for good measure and this will be removed in the new year when bathroom refurb is carried out.
From what others had said on this post I guess the next thing to do is to balance all the rads but for the life of me I do not know where to start? Most advice says to start with rad nearest to boiler and then the next and next until the furthest one has been done. I have a baxi back boiler behind fire in living room, the pump is in the airing cupboard in front bedroom. The closest rad to pump is in front bedroom about 4ft away, would this be the first rad?
As the heating system was put into this older house at a later time and has solid floors downstairs, the three rads downstairs are all on inverted loops with two pipes coming down from ceiling to each rad. Any advice on how best to balance rads will be much appreciated.

 

[D_Hailsham]

when the rad was flushed out this was clean also.

Sludge can be hard to dislodge!

Did you turn the rad upside down? If you don't, the water can easily travel straight along the bottom of the rad and miss all the sludge trapped in the water ways. A rubber mallet to 'tap' (fairly hard) the rad will also help shifting the sludge.

As for balancing, here's the quick way:

1. Remove all TRV heads and set all wheel valves to fully open.
2. Set all lockshield valves to 1/3 of a turn open from closed (fully clockwise).
3. Start boiler and allow system to warm up
4. Feel all return pipes (cooler one) to see how warm they are.
5. Select one which is midway between the hottest and coldest and use it as a 'standard'.
6. Any rad with a hotter return than the 'standard' should have the LS valve closed a tiny fraction.
7. Any rad with a cooler return should be open a tiny fraction.
8. Repeat 4 to 7 until all returns are approximately the same temperature.

Do no expect perfection. The adjustment each time is very small and you need to leave time (say 10 mins) between each cycle for the system to settle down.

When finished replace all TRV heads and set to required temperature. Set all wheel valves to required position.

 

[dave2410]

Hi D_H, yes I did turn the rad upside down and I gave it some welly with a rubber mallet. I think the neighbours thought there was a tone deaf steal drummer in the garden.
What do you mean by no.1 remove all trv heads and set all wheel valves to fully open?
Do you just mean turn the valve round to max so that it is calling for hottest water, or am I being daft and missing something?
Thanks for taking the time to reply.

 

[D_Hailsham]

What do you mean by no.1 remove all trv heads and set all wheel valves to fully open?
Do you just mean turn the valve round to max so that it is calling for hottest water

You need to make sure that a TRV or wheel valve is not interfering with the flow through the rad, i.e acting as a lockshield valve. That's easy with a wheel valve - you just wind it fully open. But a TRV on Max could start to close, so the safest thing to do is remove the head, which contains the temperature sensor. The valve then stays fully open.

 

[dave2410]

Ah that makes sense, will give it a try and update.