I have a fully pumped CH system with a timer control panel on an ideal classic boiler (boiler and water tank are 5yrs old). When the heating is set to come on it only does so for 40mins and then goes off and the pump stops working. At the front of the pump is a nut which i think is used to bleed it, i've tried to remove it but it just keeps rotating after a while (with a tiny bit of black water coming out).
Does anyone have this style of pump and know how else to access it so I can see if it's siezed. The pump has 3 settings and it's on 3.
Or does anyone know what else maybe causing my heating to stop after 40mins?
Thanks for reading.