I'm looking for some advice of the possible reason for why my central heating rads don't really seem to get hot. I've a theory but I'd like someone more knowledgeable to comment.
We have a Vailant Ecomax 625E boiler, the system is quite large: 22 radiators (some doubles) split 11 ground floor, 11 first floor. It was installed about 11 years ago by a professional heating company.
The symptoms are as follows, while the flow pipe for the rads gets very hot the return is barely lukewarm. I've attempted to balance the radiators (12C difference between flow and return) but it became impossible after the first half dozen as the difference was always higher. In fact the radiators at the far end of the circuit have their LSV and thermostatic valve fully open and they're only lukewarm when the system has been on all day.
The boiler has a modulating pump, I've tried adjusting the output but it didn't seem to make a noticeable difference.
The hot water is heated without any issue.
My suspicions are that the water is preferring to circulate around the hot water circuit rather than the rads. In the airing cupboard there is a bypass pipe before the servo with a pressure relief valve. The body of this value is constantly very hot, even when both the hot water and central heating servos are open. I've tried adjusting the valve, it has numbers from 1 to 6, but that makes no difference.
I'd order and replace this valve but as they're 50 quid I want to know that I'm on the right track first. I'm happy to pay for a professional to fix this but I have problems finding someone reliable and that actually answers their phone to make an appointment.
This has been rather a long first post, thanks for reading this far.
Simon
We have a Vailant Ecomax 625E boiler, the system is quite large: 22 radiators (some doubles) split 11 ground floor, 11 first floor. It was installed about 11 years ago by a professional heating company.
The symptoms are as follows, while the flow pipe for the rads gets very hot the return is barely lukewarm. I've attempted to balance the radiators (12C difference between flow and return) but it became impossible after the first half dozen as the difference was always higher. In fact the radiators at the far end of the circuit have their LSV and thermostatic valve fully open and they're only lukewarm when the system has been on all day.
The boiler has a modulating pump, I've tried adjusting the output but it didn't seem to make a noticeable difference.
The hot water is heated without any issue.
My suspicions are that the water is preferring to circulate around the hot water circuit rather than the rads. In the airing cupboard there is a bypass pipe before the servo with a pressure relief valve. The body of this value is constantly very hot, even when both the hot water and central heating servos are open. I've tried adjusting the valve, it has numbers from 1 to 6, but that makes no difference.
I'd order and replace this valve but as they're 50 quid I want to know that I'm on the right track first. I'm happy to pay for a professional to fix this but I have problems finding someone reliable and that actually answers their phone to make an appointment.
This has been rather a long first post, thanks for reading this far.
Simon
