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Put your Central Heating System question in here.
By flexyboy
#13427
Y plan System description

Ideal Logic Heat 12 (heat only) Type 41-399-99 s/n XV20583700014230
Drayton LP722 2 channel timer/prog
Drayton mid position valve
Corgi room stat
Iflo 3 terminal cylinder stat
Danfoss circ pump

All the external components have been individually checked and tested and all are working to specification
All Wiring via the central connection center (junction box), has been checked to Ideal installation spec and individual component spec and is correct and in good condition


Fault

Call for CH only- display changes from 0 to c (with room stat not satisfied)
It is approx 10 seconds from CH call on programmer before boiler display changes from 0 to c, indicating the mid valve position has moved to appropriate position and has sent out the switched Live – orange to the boiler SL terminal
The boiler burner indicator lights for a couple of seconds then goes out and stays out


Switch on call for DHW, boiler lights and stays lit, flow water heats and sends hot water to cylinder AND rads OK
When HW cylinder stat is satisfied, boiler blue light extinguishes but display still reads c (because of call from CH side- room stat NOT satisfied)

In summary boiler will not operate DESPITE there being a call for heat (as indication on display panel) UNLESS there is a call for DHW simultaneously

The condensate drain is clear, and the internal trap is clear and full


Question

Why, when there is a call for CH only (display changes from 0 to c) does the boiler NOT stay lit, but will if there is a simultaneous call for DHW – indicating that the internal flow sensor ( and circ pump OK) , flow and return thermistors ok, and clearly the fan and ignition circuits are OK..

Surely when there is a c on display the boiler should fire up and it does NOT differentiate whether that is a DHW or CH only call, the control of DHW and CH is mainly controlled by the external components e.g. thermostats

Any thoughts would be much appreciated
Thanks

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