Hi,
I wonder if some central heating wiring expert would be good enough to give me a helping hand.
I had the following:
Greenstar 24i system boiler
Grasslin QE2 controller – set to Fully pumped)
Fully pumped system with 2 x zone valves (one for CH and one for HW)
Room stat
HW tank stat
The Motorised valves seem to function normally. The room and cylinder stats both seem to work normally with testing.
Programmer set to on 2x per day for both CH & HW as follows
HW on 5am-7am
CH on 6am-9:30am
HW on 3pm-6pm
CH on 5pm-10pm
The QE2 was fine for 5 years and all was well and working as expected. It then decided to start locking up, particularly after a powercut – talked to grasslin and they told me it was most likely the battery backup had given up the ghost of a faulty unit (5+ years old). Before the QE2 going mad all was well. HW and CH were both fully independently working and life was good.
Decided to replace the QE2 with a Drayton LP722 which is equivalent and should be a direct wire replacement (both N L 1 2 3 4). All programmed up fine (including the mid program phantom 12:00-12:00 on/off as I only need 2x on/off) and the jumper set at back for Fully pumped. I thought it was working fine but an odd thing is happening with the HW
1. IF the HW is on and in demand and the CH is off on the controller then HW is delivered to tank and CH is not (as expected).
2. IF the HW is on and in demand and the CH is on and in demand then HW is delivered to tank and CH to rads (as expected)
3. If the HW is on and in demand and the CH is on but “satisfied” (thermostat set low) then the HW refuses to work when going into demand or going into satisfiled.
As soon as I then turn the CH to off and back to on (even if it is still satisfied) then the HW works normally again (ie when satisfied it turns the motorised valve off and when in demand it turns the valve on).
It is like cycling the heating to off and then on seems to kick the HW normal operation back into life as long as the HW is on. I can then turn the hot water to off using the programmer, turn it back to on and we are back to the call for HW being ignored again if the cylinder stat calls for HW.
I don’t understand why it was all okay with the QE2 but with the LP722.
To get around this I can set the on/off times for the HW not to overlap or fall within the CH on/off times but I am keen not to have to do that.
Any thoughts ??
Thanks
Paul
I wonder if some central heating wiring expert would be good enough to give me a helping hand.
I had the following:
Greenstar 24i system boiler
Grasslin QE2 controller – set to Fully pumped)
Fully pumped system with 2 x zone valves (one for CH and one for HW)
Room stat
HW tank stat
The Motorised valves seem to function normally. The room and cylinder stats both seem to work normally with testing.
Programmer set to on 2x per day for both CH & HW as follows
HW on 5am-7am
CH on 6am-9:30am
HW on 3pm-6pm
CH on 5pm-10pm
The QE2 was fine for 5 years and all was well and working as expected. It then decided to start locking up, particularly after a powercut – talked to grasslin and they told me it was most likely the battery backup had given up the ghost of a faulty unit (5+ years old). Before the QE2 going mad all was well. HW and CH were both fully independently working and life was good.
Decided to replace the QE2 with a Drayton LP722 which is equivalent and should be a direct wire replacement (both N L 1 2 3 4). All programmed up fine (including the mid program phantom 12:00-12:00 on/off as I only need 2x on/off) and the jumper set at back for Fully pumped. I thought it was working fine but an odd thing is happening with the HW
1. IF the HW is on and in demand and the CH is off on the controller then HW is delivered to tank and CH is not (as expected).
2. IF the HW is on and in demand and the CH is on and in demand then HW is delivered to tank and CH to rads (as expected)
3. If the HW is on and in demand and the CH is on but “satisfied” (thermostat set low) then the HW refuses to work when going into demand or going into satisfiled.
As soon as I then turn the CH to off and back to on (even if it is still satisfied) then the HW works normally again (ie when satisfied it turns the motorised valve off and when in demand it turns the valve on).
It is like cycling the heating to off and then on seems to kick the HW normal operation back into life as long as the HW is on. I can then turn the hot water to off using the programmer, turn it back to on and we are back to the call for HW being ignored again if the cylinder stat calls for HW.
I don’t understand why it was all okay with the QE2 but with the LP722.
To get around this I can set the on/off times for the HW not to overlap or fall within the CH on/off times but I am keen not to have to do that.
Any thoughts ??
Thanks
Paul