Heating not working unless hot water is on

[<marc>]

Hi been called out this morning to a pellet boiler there are 3 two ports one doing underfloor the other two operating radiators in the different units. The pellet boiler wont fire unless the Hot water (water jacket which forms part of the boiler) is turned on with the programmer its a Horstmann channel plus series 2 model h47XL. The motorized valves operate when they are selected on the programmer and all turn on the pump but not the boiler is this likely to be a faulty programmer???

thanks

 

[lame plumber]

get your multi meter out and test everything is working properly, youll find the fault along the way that way.