Major heating issue please help..

[john cockshott]

I have a major problem and my plumber cannot solve it.

The radiators down stairs are cold, upstairs are hot, so far I have replaced the pump, replaced the switches, cleaned the system with a power flush, taken every radiator off to clean out and check water flow.The boiler has also been serviced and cleaned.
The downstairs radiators are still cold.
What seams to happen is the boiler turns off when it gets to a high temperature and then cools down really quickly and after a while starts up again, Therefore upstairs stays warms and down stairs remains cold.
Hot water is fine.
The heating system is open vented.
Does anyone have any ideas what is going wrong?
Thanks John

 

[rosiew]

Could be blocked cold feed

 

[john cockshott]

Hi thanks, how do I clean out the cold feed, is that not the same as completing a power flush?
Thanks

 

[Burnerman]

You haven't said if you have tried to balance your system (loads of advice in the FAQ's) but presumably you have bled your radiators?
If the cold feed to them is blocked, they won't bleed at all, as no water can be introduced to replace any expelled air.
John

 

[FiremanT]

How old is the system?
Gravity hot water?
Anti gravity (NRV) valve?
How young are your repair men?

 

[Agile]

I have a major problem and my plumber cannot solve it.

Thanks John

A simple circulation problem is hardly a difficult problem to fix! Nor would I rate it as "major" either.

Just how experienced and qualified is this "plumber"?

Is he a member of the CIPHE ?

Where did you find him?

Today I went to a system which was not providing much heat to any radiators and to me it was a routine job with a simple fix.

Tony

 

[john cockshott]

Hi, yes all the radiators have been balanced and no air pockets found. My plumber is in his 40's and been doing this all his life so experienced!

Yesterday when I turned the heating to 30 I started getting heat to the radiators downstairs but it took a while.

What seems to be the main problem is the boiler turns off every time it gets to about 67 degrees and then shuts off, therefore heat cannot circulate. Could it be an issue with the thermostat in the boiler recording the wrong return temperature

Thanks for the advice so far

 

[simond]

As above I'd be looking for an anti gravity valve. If you've had a PowerFlush the valve would be even more blocked than before.

It's particularly likely if the house was originally fitted with a floorstander with a gravity HW circulation circuit.

 

[stardanny]

What the pump speed? Does it make a difference if it is turn up?

Have you check that the pump valves are fully open

Daniel.

 

[john cockshott]

yes pump is on full and open and I have checked it is fitted the right way round
Thanks

 

[stardanny]

Have you got a diverter valve or zone valve?

Daniel.

 

[FiremanT]

To help, mlore details are needed . Can ypui post any pics - boiler & airing cupboard arrangement,unless you have a combi.

This is an "anti gravity valve":

but having reread the posts, and your reference to the temperature, which I assume you read off the boiler display, it is probably unliukely that you have a AGV

 

[john cockshott]

after all the comments and reading up on the system, i think it is a block in the heat exchanger in the boiler, does anyone have a comment on this?

 

[john cockshott]

hi no i dont have anti gravity

 

[FiremanT]

We could all supply a long list of comments or possible causes, but pretty pointless until you supply more specific details of boiler and system type.