Is my boiler behaving normally?

[gemius]

I had balanced it best as I could. That is turning the first rad down to a crack and then opening each one up a bit more in turn but I still had the problem with the last two.
I don't want to mess about with things at this time of year as most of the house is still OK heat wise. I think I'll wait until the Spring and then take the rads off or perhaps get someone out to have a look at it, as I'm only an occasional plumber!

 

[D_Hailsham]

I had balanced it best as I could. That is turning the first rad down to a crack and then opening each one up a bit more in turn but I still had the problem with the last two.

How far open the lockshield valve needs to be depends on (a) the rad output, and (b) where it is in the system. You may find that the rad furthest from the boiler needs the LS valve open less than one that is much closer.

I understand your reluctance to possibly making things worse, but you could try setting every rad's lockshield valve to half a turn open and checking what effect it has. (Write down how many turns open it is now; then you can reset it if things don't improve.

 

[John D v2.0]

Given the last two rads don't even heat up when all the other are off completely (if I understand the op right) then it can't be balancing.
It would only be that if the furthest rads warmed up fine with the others turned off.

 

[Doggit]

That is turning the first rad down to a crack and then opening each one up a bit more in turn but I still had the problem with the last two

You would have; all the hot rads need shutting slightly, and the cold ones, opening up. By opening all of the rads apart from the 1st one, then you would have done nothing practical. I can understand your reluctance to mess around with the system, but if you have TRVs, then turn off a few non essential rads, and then open up the lockshield valves on the cold 2, and then see what the response is. If they get hot, then you've got a balancing problem, and if they don't, then it's blockage, or pump issue.

 

[Madrab]

If you can't warm them up by turning off all of them apart from those 2 then it's not a balancing issue, it's a circulation issue. Either water isn't getting to them because of a restriction in the pipework before those 2 on the run, their valves or the rads themselves have an issue with sludge or its a lazy pump that doesn't have enough guts to get it to them after 17yrs of hard work.

You or an experience heating engineer needs to work through each of those issues to find the problem.

 

[AGAS]

How far open the lockshield valve needs to be depends on (a) the rad output, and (b) where it is in the system. You may find that the rad furthest from the boiler needs the LS valve open less than one that is much closer.

you sure

 

[John D v2.0]

Certainly possibly in theory, if one radiator is a 3000w monster and another is twice as far but only a 400w towel rail.

 

[AGAS]

Certainly possibly in theory, if one radiator is a 3000w monster and another is twice as far but only a 400w towel rail.

hey you never know he could have towel rails in every room

 

[John D v2.0]

hey you never know he could have towel rails in every room

3kw towel rail would be so big it's a room in its own right

 

[D_Hailsham]

How far open the lockshield valve needs to be depends on (a) the rad output, and (b) where it is in the system. You may find that the rad furthest from the boiler needs the LS valve open less than one that is much closer.

you sure

Yes.

The closest could be a 2 kW and the furthest a 500W, so the closest will need four times the flow. So the LS valve on the 2 kW rad will have to be open more than the valve on the 500 W rad.