Recent content by evb222

Ok, I had another plumber over, and he thinks that the problem may lie in the incorrect positioning of the bypass valve resulting in the boiler pumping against itself if only 1st floor circuit is open. I drew a scheme of the boiler connections. Can anybody point out what's wrong with it...

The downstairs circuit on its own functions just fine: normal long burn from the boiler, the radiators get hot everywhere and stay for as long as thermostat is asking for it. The upstairs circuit on its own runs with the same problems: boiler starts up at the lowest power for 15-30 seconds...

Yes. Different valves, different thermostats, etc.

The downstairs is zoned out from the upstairs via another two port valve. Whethe the downstairs is on or off makes no difference for the upstairs. Regarding the blockages - I have no idea where to start looking. Does this mean lifting all of the carpets and floorboards?

Checked, even the flow and return pipes swaped over to get around a potential non-return valve somewhere in the system. Same issue, irrespective of the flow direction and no blockage near the two port valve.

Upstairs rads add up to 9.1 kW. Downstairs is about 11 kW. 17.99 kW for the whole house.

D_Hailsham, Thank you for your reply. I will check as you suggested, but here are some initial thoughts. The circuit upstairs is roughly the same size to the circuit downstairs. The downstairs circuit functions without any issues. Also, the new boiler is capable of modulating to a lower...

Old boiler - Vaillant 835 (Combi), which has had a corroded heat exchanger and was more economical to replace (clearly not in the hindsight) New boiler Atag A325EC (also Combi) Pump - which ever one is built into the boiler, so don't know really know.

Symptom: Boiler fires up for 30 seconds, raises the flow temperature too high and then cuts out. The return pipe eventually gets to just barely warm (after hours of the repeating cycles like that). The first 2 – 3 radiators upstairs heat up ok, with the following 2 – 3 being just barely worm...

I am planning to replace my current combi boiler with Atag a325ec (after lots of reading from the posters on this forum). I also want to install a two zone UFH in 2 rooms downstairs. Can someone help me to understand how the boiler/radiator control (if there was no UFH) would integrate with UFH...