Radiators hot upstairs and cold downstairs

[nickypon]

I realise this problem has been posted before but you never seem to get the outcome at the end if the thread.

I have a vented heating / hot water system in a 2 storey house with tanks in the loft and hot water cylinder on 1st floor, boiler on ground.

The house was a reposession and heating system had been previously drained and unused for 9 months

When i switch the boiler on , radiators all become piping hot upstairs within minutes and stone cold downstairs .

I have checked the pump. Seems to be turning free and making a low vibrating noise. The pipe going in an out are both very hot.

I have bled all radiators and tried shutting of all upstairs and downstairs radiators apart from 1 downstairs to direct the flow so I could get rid if air lock if that was the problem.

None of this has worked and the boiler overheats after 5 minutes and cuts out .

Any ideas ? Thanks in advance

 

[nickypon]

BTW I made sure i refilled the system before switching on the boiler

 

[45yearsagasman]

Obviously a circulation problem or an air lock still remains. Just because the pump is making a noise is no proof that it is actually working correctly. There may also be blockages causing symptoms. Some dismantling would be required to get to the real cause. Checking the rotation of a pump is described in the FAQ's. Posting a pic of the pipework and pump etc in the airing cupboard would be useful.

 

[nickypon]

Thanks for the reply Pete. I will post a pic tonight of the pipework around the pump which is located underneath the hot water cylinder. There are 2 gate valves which in not sure if they should be open or closed. I'm not just going by noise on the pump . I opened flat head screw and made sure it wasn't seized up.

 

[nickypon]

Here is a picture of the pipework around the pump

Untitled

• nickypon
• 25 Feb 2013
• 1

 

[Whitespirit66]

Sounds like it maybe an airlock.

Try running the pump on setting 1 for a day, then turn up to max. Sometimes shifts it.

Or. Drain system, slide over and latch open lever on any motorised valves. Fill system with a hose pipe through lowest drain cock. Un-latch valves and turn on ch.

 

[MANDATE]

The valves without hand wheels either side of pump obviously should be open. Photo shows another gate valve with hand wheel to the right of pump which appears to be a by pass. Water will take the easiest path so if the resistance in downstairs circuit is more than the by pass it will go through by pass.
So you have to either decrease resistance in the circuit (opening lockshield valves a little) or increase the resistance in by pass.( closing the by pass valve more).
You could do with checking how much is the by pass valve open. If fully open then that would most likely give you the problem.

 

[duffin]

try bleeding downstairs rads. if you can bleed hot through but the rad doesn't stay hot, I'd say the pump's had it. not too bad.

 

[nickypon]

Absolutely great help guys . I manage to get everything going. Turned off all upstairs rads and sll downstairs apart from 1. then switched in boiler low setting and turned the pump on and alternated setting from 1 to 3 a few times. Went down stairs and bled radiators one at a time then worked round upstairs. All ok now. Defo an airlock. Glad it's not the pump. Cheers

 

[Whitespirit66]

Glad you got it all sorted. For some reason, just having the water lapping around the system on pump speed 1 for a while before turning up to max seems to break airlocks.

Now it's all working, don't forget to get some inhibitor in the system.