OK let me give some background in the hope someone can help me with this old system:
S plan fully pumped CH & HW controlled via 2 single actuator valves.
Boiler installed 1998 and given pretty much trouble free service with the exception of the gas valve replaced around 2005, the Drayton SCR receiver failed and was replaced about 3 years ago and the fan packed up last year but was an easy swap. I maintain the system pretty well with an annual flush, inhibitor and bleed and know it inside out.
Earlier this year I noticed that when the heating turned off the pump would pulse on/off for around 30 seconds and give up but worked perfectly at all other times.
As I am pretty confident with electronics and plumbing I decided to diagnose myself and worked out that it was probably a bad PCB but as a few items were dated I decided to replace the actuator heads myself first, they are all working fine and did not solve the issue.
I then bought a brand new like for like PCB and fitted in the boiler and this solved the problem instantly but...
I have noticed that when the CH or HW turns off the pump stops immediately and then restarts about 10 seconds later and only runs for about 30 seconds.
There is no other issues at all like lock out etc. and HW and CH works well.
Is this normal over run behavior on these boilers?
I would imagine that pump over run should last longer than 30 seconds?
From the boiler manual I cannot see that the over run is triggered or stopped thermally and it is a very simple boiler but there may be some logic built in that the over run is only triggered if the temperature in the boiler is X degrees?
Have I got an issue or is this perfectly normal?
S plan fully pumped CH & HW controlled via 2 single actuator valves.
Boiler installed 1998 and given pretty much trouble free service with the exception of the gas valve replaced around 2005, the Drayton SCR receiver failed and was replaced about 3 years ago and the fan packed up last year but was an easy swap. I maintain the system pretty well with an annual flush, inhibitor and bleed and know it inside out.
Earlier this year I noticed that when the heating turned off the pump would pulse on/off for around 30 seconds and give up but worked perfectly at all other times.
As I am pretty confident with electronics and plumbing I decided to diagnose myself and worked out that it was probably a bad PCB but as a few items were dated I decided to replace the actuator heads myself first, they are all working fine and did not solve the issue.
I then bought a brand new like for like PCB and fitted in the boiler and this solved the problem instantly but...
I have noticed that when the CH or HW turns off the pump stops immediately and then restarts about 10 seconds later and only runs for about 30 seconds.
There is no other issues at all like lock out etc. and HW and CH works well.
Is this normal over run behavior on these boilers?
I would imagine that pump over run should last longer than 30 seconds?
From the boiler manual I cannot see that the over run is triggered or stopped thermally and it is a very simple boiler but there may be some logic built in that the over run is only triggered if the temperature in the boiler is X degrees?
Have I got an issue or is this perfectly normal?
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