Why can't I get Upstairs radiators to work independently

[FredChild]

Hi, wonder if anyone can give some advice. Recently moved into a new property. It has external OIL combi boiler which is new and works well.
Downstairs has underfloor heating - which works well.
Upstairs has wall radiators - which work well - but ONLY if the downstairs thermometer is calling for heat.
So if downstairs is up to temperature on the Danfoss thermo and FP715Si programmer - then no matter what I change the upstairs Drayton Digistat to the radiators won't come on upstairs (unless I up the temperature downstairs)
So the set up is a FP715Si Danfoss Programmer (located downstairs - with a Downstairs thermostat).
Upstairs there is a Drayton Digistat. If I up the temp on the Drayton controller I get the flame indicating it is calling for heat and also get the "ON" light on the Digistat SRC downstairs - but again the upstairs radiators won't come on unless the downstairs thermostat is set past the downstairs temperature.
We have a woodburner downstairs too - so if we wanted to cook it up downstairs we won't be able to have upstairs running radiators at the same time without having the heating on at same time as woodburner...
Any help welcome. Kind regards Fred

 

[SimonG]

Needs an experienced heating engineer to have a look and diagnose.

 

[Murdoch]

Definitely sounds like a wiring issue.

as above you need to find somebody competent in fault finding