5 out of 9 radiators in house not working.

[Redding1985]

Hello all,

I am having quite the issue with the central heating in a house I recently moved into.

Upon moving in we have had this problem, unfortunately I have no background on what work was done prior to me getting the house.

There are 9 radiators in the house, 5 upstairs and 4 downstairs. 3 of the radiators work upstairs and 1 works downstairs. The ones that work are piping hot, the ones that don't are stone cold.
The house has an extension where one radiator upstairs as no air or water coming out of it when bled. All the other radiators give water when bled.

The 3 way valve was broken when I moved in so I replaced the whole unit. Some rad valves were weeping ever so slightly so they have been replaced.
After changing the 3 way valve and rad valves its still exactly the same.
2 of the rads that don't get hot (1 up and 1 down) the pipes to the feed valve will get ever so slightly warm when the hot water is on as well as the heating.
Aside from that I have bled the pump (which seems to be working fine) changed the speed of the pump to max, tried balancing the rads and tried turning all the working rads off to see if i can force the heat to the no working ones. Nothing.

A lot of gurgling happens when I change the pump speeds which suggest trapped air, but I cant for the life of me find it though bleeding all the radiators.

Any help or suggestions would be greatly appreciated.

Many thanks

 

[motorbiking]

Do they have Thermostatic valves? have you tried checking the valves are openning properly (ans also the return)?
If the flow gets warm but not the rad then the blockage is in the valve/rad
Are there any inline valves closed?
Do the cold rads release water when bled?

This does sound like air, I'd be tempted to bleed them when the system isn't running. And bleed a lot out (e.g. a couple of pints from each rad)

 

[45yearsagasman]

The house has an extension where one radiator upstairs as no air or water coming out of it when bled. All the other radiators give water when bled.

No air or water coming out might indicate a blocked cold feed or empty expansion tank in the loft. I'm assuming that your system is open vented, you don't say. A better description of your boiler/system would help.

 

[Redding1985]

Yes they have thermostatic valves. These all seem to be working fine, taken the tops off and the pins are moving ok.

Sorry for the vague info on the boiler system. It is open vented, the header tank is all working fine and is full.

Also another point I forgot to mention is the boiler (an old Potterton Suprima) cuts out when I have just the heating on, the thermostat is set all the way up to make sure its not hitting temp. It's like it detects there's a problem then cuts out, then cuts back in. Could this strengthen the air problem??

 

[Redding1985]

Also, it is just one radiator that has no air or water, all the rest give water when bled.

 

[gigz]

Have you tried closing the ones that are hot ?
Ahh just re-read op