Considering drastic action to get CHS working

[kate54]

I'm sorry if this has been posted somewhere else before, I had a scan but couldn't see anything similar.

Our central heating system was a gravity fed system using microbore pipes to all the radiators. When we moved in we changed all the radiators to ensure that they were sufficient for the rooms based on the various tables found on the internet. Last winter was awful and with the heating on continuous we didn't manage to get the house warm.

During the summer we changed the manifold and all the pipes upstairs to the radiators from 8mm microbore to 15mm pipes. The system was also made into a pressurised system. The downstairs pipes remain a combination of 6,8 and 10mm microbore pipes.

now we can get the radiators upstairs hot if we turn off everything else and if we virtually turn the upstairs off we can get downstairs luke warm.

The question is, should we replace all the pipes downstairs with 15mm pipes as well (I have been resisting as all the pipes are buried in the walls and the disruption would be awful) or could it be the pump or the boiler???

thank you for any help you can give us. our kitchen is currently 12 degrees when the heating is on continuous

 

[mario500]

Yes is the shorty answer. There is no point having upstairs piped in 15mm when downtairs is microbore. You would need some serious balancing to get downstairs rads to heat up properly.

Have you checked to see what the boiler output is on Ch? is it correctly sized?

Also What are the thermal insulation properties of the buliding fabric?

Have you got cavity wall insulation - loft insulation etc? to current building regulations?

Allan