PJ

[Pejackson]

I have a baffling problem with my central heating if anyone can help?
I have no heat getting to two rads upstairs. I have had a power flush, new pump fitted and magnatec fitted. I have also replaced most of the pipes leading to both these rads the problem still persists. I thought i might be the rad valves, but when I went to change these I drained one of the rads and found I needed further equipment to carry on. I refilled the rad and bled it and immediately it filled and it got very hot. But this lasted a very short time before it got cold again. With both these rads the pipes get hot going up to them but not into the rad itself.
I am now starting to pull out what little hair I have left, can anyone help with this problem.

 

[WHPES]

Sounds like the pipework is airlocked.

Turn off your system, shut off the DHW cylinder feed (usually by the motorised valve and timeclock) and every rad other than one of the problem ones, turn your pump to max setting and switch on system and see if it forces the air out. You should hear air gurgling about. Repeat for the other, then put everything back as it was.

You may need to rebalance your rads as well (see relevant threads)

Alterntively it could be a stuck TRV if you didn't manage to change them.

 

[Puddle]

As above but make sure boiler thermostat turned down and maybe leave one rad slightly open if no byepass as we do not want pump pumping against nothing if it is not air lock or bad air lock or could damage pump

Take it rads used to work,do they have thermostatic valves on ?

Has problem occured since power flushing,if so balancing could need redoing

 

[Dsgas]

i had same problem mate it was the last 2 radiators in the circuit.the fix was adjusting the bypass closed a little to force the water to the rads.

 

[REDSAW]

i think diffrent,
i think you drained down the rad and sludge left in the rad has clogged up your valves,
come accross this dozens of times.
dont care if theve been flushed, i will take a bet their is still sludge in the 3mm fins of the rad.
is the pipes leading to these rads hot?.

 

[Pejackson]

Thanks for the advice I will try a few options. The pipes leading to the rads does get hot right up to the thermostatic valve.