Time control - faulty :roll: Honeywell time control ?
Is the system correctly wired .?here quick check :
Set dhw and ch to 24hrs ,
turn down dhw stat min -turn down ch stat min ,
Boiler-pump should now be off .
turn up ch stat max -boiler pump on *turn off stat boiler+pump off...
try balance both the radiators i would think the radiator above is linked too one below try forcing the water down into this radiator by reducing the flow into upstairs radiator ,
I assume you don't have thermostatic radiator valves installed - on either radiators ?
Over heat stops your boiler from ,transforming into a pressure cooker *
if the main boiler stat fails or is wrongly located within the boiler.
all sealed systems must have a overheat safety device , *
don't Diy :
Get the system checked by a corgi engineer you could save yourself £,s in the long term .
*The pump turns on when i turn on the boiler stat* :? :?
On the msv actuater there is a leaver ,push the leaver over too one side there will be some resistance ,move the leaver in a upwards direction .
Push the leaver into the recess position located on the valve.