Weird Hive issue with scheduling

[Hkphooey]

Hi guys
Weird one this, when boiler is firing and heating water if my scheduled rad heating come on also it doesn't heat my rads...
BUT here's the weird part if I BOOST the heating the at same time scheduled water is on then it works?

 

[Gasmk1]

priority hot water do you have a s or y plan system

 

[Hkphooey]

priority hot water do you have a s or y plan system

Single valve bud... I take it y plan

 

[Deleted member 120897]

priority hot water do you have a s or y plan system

Would that still be the case though? OP states it works if boosted. I suspect a setup/wiring fault. @Hkphooey can you post some photos of valve(s) and wiring of Hive?

 

[Hkphooey]

Would that still be the case though? OP states it works if boosted. I suspect a setup/wiring fault. @Hkphooey can you post some photos of valve(s) and wiring of Hive?

I know strange isn't it... Was thinking valve stuck, but will at boost

 

[Gasmk1]

Single valve bud... I take it y plan

Possibly wired wrong then or faulty valve. Is it mid position type which model of valve as said photos of set up would be ideal

 

[Hkphooey]

Possibly wired wrong then or faulty valve. Is it mid position type which model of valve as said photos of set up would be ideal

Thanks bud for your input... To be fair it's been in place years, without any issues with my hive set up.
Yes I will get a picture uploaded, does sound like a valve issue doesn't it.
Trouble is BG take about 3 visits and 3 different engineers to get it diagnosed.