Heating not working in morning timer period

[kingofrp]

We have a Valiant Ecotec boiler which has just been serviced by a Valiant engineer. Subsequent ignition problems revealed a faulty diverter valve, which has been replaced by a plumber. The heating is timed to come on twice, morning and evening. In the evening all seems to be well and functioning normally, but in the morning the heating will not come on properly (hot water is fine). The light is on the timer indicating it should be on, but error messages on the boiler are coming up intermittently, either S.30 (no heating demand), or S.7 (pump over run), occasionally S.4 (heater ignited), but that for only a very short time. I have tried turning the thermostat up high, but this does not work.
Does this strange problem indicate a boiler malfunction, or perhaps faulty timer?

 

[wull67]

S is not a fault code but a status code of what the boiler is doing, if the s.30 code is showing the boiler is not getting a signal from controls, Ps fault code on that boiler would begin with F. If it works ok at night I'd be checking the controls first

 

[kingofrp]

Thank you. That's very helpful