I have a single boiler that heats radiators in my house. The upstairs and downstairs can be seperated but are both controller by a Horstmann controller. There is also a digistat thermostat connected. Both are switched on at the controller. The downstairs are working fine but i have not heat upstairs. Non of the pipes going into the upstairs radiators are hot so i think it must be something to do with the control. I am stumped Any Ideas?