Some radiators and pipes are cold

[les80]

About 23 months ago I had my system power flushed and sealed,as none of my radiators were getting warm.

My boiler is a Baxi back boiler and I live in a Park Home, with a Calor Gas supply.

One of my radiators, with a pipe that is taken into the open air, is often cold and takes a very long time to heat at all. This has been like this since it was fitted. Before that I had no radiator in that position.

My conservatory radiator went cold a couple of months ago, then three weeks ago the bedroom one started to go cold, or only be luke warm. Now it is cold and so are the pipes too and from it.

Three radiators, closest to the boiler, are hot, one so hot that I can't touch it for long. This radiator is connected directly tothe pump andboiler, as isthe cold bedroom one. All others are on spurs.

At one time the bathroom radiator was cold at the top, but now it is reasonably hot. A couple of days ago I bled the radiators and got air from two of them, but no water when the air stopped.

Today I tried to unscrew the cap of the pump to check if it is working, but can see nothing. However, some water leaked out. The pump has no bleed screws.

Can anyone give advice? I have very litle time to work on this and myhusband can't do anything with water.

 

[gas chap]

see if you can locate the header tank first,

the smaller of the storage tanks, and see if there's any water in there.

 

[JohnD]

After the power flush, do you know if an anti-corrosion chemical was added to the water?

 

[les80]

The header tank does have water in it.

When the system was flushed I was told that chemicals were added.

The three hot rads are closest to the boiler and pump and the both pipes are hot until the last (and hottest) of these. Then both pipes are cold.

The pump is about three years old

 

[JohnD]

This may be a balancing problem (hope so, as easy to fix) . Try turning off the hot radiators, and see if this causes the heat to flow to the colder ones. If it does, tinker with the lockshied valves on all the radiators so that the heat is shared out between them.

See also http://www.diydata.com/projects/centralheating/balancing/balancing.htm

and //www.diynot.com/forums/viewtopic.php?t=37170

 

[les80]

I'd already tried turning off the bathroom rad, but the other hot ones had seized valves. So, WD40 allowed me to turn one off, but the hottest needed a gentle application of mole grips to get it started.
With all 3 hot rads off, the bedroom rad started to get hot, then cooled down. Bled it and now the top is cooler but it's getting hot.
So for that rad at least it seems to be balancing.
I use a thermometer at work with dual thermocouples, so need to bring it home to measure inlet and outlet temps while balancing.

I'm not sure what order to do some of them though, because most of my rads are on spurs. A spur from just after the pump, and a long outdoor run to one rad, a spur for the conservatory, spur for bathroom and spur for hall. Only two of my rads are in a direct line.

 

[chrishutt]

a long outdoor run to one rad

 

[JohnD]

Good thick insulation (Climaflex foamed polythene) is more than an inch thick (so about three inches in diameter)

 

[les80]

Got that. Proper thick insulation on that rad. Sometimes it works a little, sometimes not at all.

But just by turning valves down and bleeding,as well as pressurising to almost half a bar (red needle was set by engineer at half a bar when the system was sealed) we have heat in the bedroom rad, although it's still cold/cool at the top. Conservatory spur got warm for a little while, then cooled. I keep having to go back and bleed air, but at least some rads now have water coming out when the air has been bled.
Seems as though there is air in the system still, I bleed, ok for a bit, then needs bleeding again.

I've not attempted balancing yet because I don't have the thermometer, and this is a very complex system of spurs. But balancing is certainly needed.