I have a Potterton Promax 12 SL, it is the original boiler, installed in 2011, it is in good order & has just been serviced with no issues found.
My system is S plan, I have a Grundfos alpha 2 pump which had been left on fixed speed 3, after some experimenting this has now been changed to PP2.
Pressure when system cold 1.0 bar, rising to around 1.6 when CH heating fully warmed up (12 rads in total), if only the HW is on the gauge rises to around 1.4/1.5 bar.
Many of the parts of the heating system are original so I have had the following parts replaced over the last couple of weeks:
18 Litre HW expansion vessel - partial drain down to install.
12 Litre CH expansion vessel, PRV & pressure gauge - partial drain down again but on a different day.
Automatic air vent - pressure just dropped enough to swap the vent, again on a different day.
2 leaking radiator bleed valves - individual radiators isolated at LS & TRV to enable the valves to be changed.
Radiators balanced.
Now when the boiler first starts you can hear the sound of running water inside the boiler, as the boiler fires the sound begins to fade, after around 20 (ish) seconds the sound has gone, other than this new noise the boiler is working as expected, the HW is being heated to temperature, the radiators are performing better than ever following the balancing, the boiler flow & return temperatures are consistent. When the boiler shuts down you can also hear the sound of water again, but only for a few seconds, the pump shuts off as soon as soon as the boiler goes off, the pump does not run on.
I have checked all the rads & they are free of air, I ran the HW & CH at the same time to create a full open circuit, I have tried cycling the pump through the various speeds while the system was warming up in a bid to try & dislodge any air in the system but so far no luck.
Any thoughts or suggestions?
Thanks in advance.
My system is S plan, I have a Grundfos alpha 2 pump which had been left on fixed speed 3, after some experimenting this has now been changed to PP2.
Pressure when system cold 1.0 bar, rising to around 1.6 when CH heating fully warmed up (12 rads in total), if only the HW is on the gauge rises to around 1.4/1.5 bar.
Many of the parts of the heating system are original so I have had the following parts replaced over the last couple of weeks:
18 Litre HW expansion vessel - partial drain down to install.
12 Litre CH expansion vessel, PRV & pressure gauge - partial drain down again but on a different day.
Automatic air vent - pressure just dropped enough to swap the vent, again on a different day.
2 leaking radiator bleed valves - individual radiators isolated at LS & TRV to enable the valves to be changed.
Radiators balanced.
Now when the boiler first starts you can hear the sound of running water inside the boiler, as the boiler fires the sound begins to fade, after around 20 (ish) seconds the sound has gone, other than this new noise the boiler is working as expected, the HW is being heated to temperature, the radiators are performing better than ever following the balancing, the boiler flow & return temperatures are consistent. When the boiler shuts down you can also hear the sound of water again, but only for a few seconds, the pump shuts off as soon as soon as the boiler goes off, the pump does not run on.
I have checked all the rads & they are free of air, I ran the HW & CH at the same time to create a full open circuit, I have tried cycling the pump through the various speeds while the system was warming up in a bid to try & dislodge any air in the system but so far no luck.
Any thoughts or suggestions?
Thanks in advance.