Looking for some advice please, new to forum.
Setup - I have a Glow-worm Flexicom 24HX heat only boiler with HW cylinder. 13 rads on system controlled by Hive thermostat. Eclipse 490920 pump set to level 3/3 speed. Flow temp on boiler set to 75C. Boiler output set to max 24kW. TRVs present on most rads except usual places, couple of little used rooms turned down to 2 or 3 but no rads are completely off.
Historically when thermostat called for heat the boiler would fire up strongly and reach the set flow temp within a few minutes, therefore all rads would be roasting in 20-25 mins max and target thermostat temp reached promptly.
However recently the boiler seems to be taking much longer to reach set flow temp, even from cold (e.g. first thing in morning). What seems to be happening is that the thermostat calls for heat, boiler fires up straight away, flow temp increases from say 35C up to maybe 55-60C, then after maybe 10 mins the flame will turn down (not off) and flow temp drops until it lingers around 45-50C, which it could do for up to 15 mins or so. In the meantime the rads are lukewarm at best and don't appear to get any hotter during this time. By this point the thermostat has been calling for heat for almost half an hour and the target temp has hardly moved (no good for setting CH to come on half hour before getting up in morning). Normally by this time all rads would have been roasting hot and benefit felt through house.
All rads do eventually get very hot but this is well over 30-40 mins after the thermostat started calling for heat. No air, no cold spots etc so wouldn't expect a circulation problem. I haven't touched any of the lockshields. No issues when the HW calls for heat - boiler reaches flow temp promptly. I'm not aware of any weather compensation being installed/enabled.
I understand the boiler should modulate as part of normal operation however this seems excessive, especially as it is doing it from stone cold so I'd have thought it would want to get up to flow temp as quickly as possible?
Any thoughts appreciated.
Setup - I have a Glow-worm Flexicom 24HX heat only boiler with HW cylinder. 13 rads on system controlled by Hive thermostat. Eclipse 490920 pump set to level 3/3 speed. Flow temp on boiler set to 75C. Boiler output set to max 24kW. TRVs present on most rads except usual places, couple of little used rooms turned down to 2 or 3 but no rads are completely off.
Historically when thermostat called for heat the boiler would fire up strongly and reach the set flow temp within a few minutes, therefore all rads would be roasting in 20-25 mins max and target thermostat temp reached promptly.
However recently the boiler seems to be taking much longer to reach set flow temp, even from cold (e.g. first thing in morning). What seems to be happening is that the thermostat calls for heat, boiler fires up straight away, flow temp increases from say 35C up to maybe 55-60C, then after maybe 10 mins the flame will turn down (not off) and flow temp drops until it lingers around 45-50C, which it could do for up to 15 mins or so. In the meantime the rads are lukewarm at best and don't appear to get any hotter during this time. By this point the thermostat has been calling for heat for almost half an hour and the target temp has hardly moved (no good for setting CH to come on half hour before getting up in morning). Normally by this time all rads would have been roasting hot and benefit felt through house.
All rads do eventually get very hot but this is well over 30-40 mins after the thermostat started calling for heat. No air, no cold spots etc so wouldn't expect a circulation problem. I haven't touched any of the lockshields. No issues when the HW calls for heat - boiler reaches flow temp promptly. I'm not aware of any weather compensation being installed/enabled.
I understand the boiler should modulate as part of normal operation however this seems excessive, especially as it is doing it from stone cold so I'd have thought it would want to get up to flow temp as quickly as possible?
Any thoughts appreciated.
