Baxi Solo 3PF - overrun operation

[sprocker]

Morning all... Please can someone help explain the operation of the 'boiler overrun' facility, I understand that it come's under the control of the Boiler PCB.

Let me explain my son has/is moving to a new house (built in the 60's) it has a Baxi Solo 3PF boiler with a pressurized Telford Copper Tempest Cylinder 125lts.... I've repaired a leak on the indirect cylinder heating coil connection so all is now water tight and leak proof !? The CH rads all have TRV's fitted but does have a boiler bypass v/v fitted this being just a 1/2'' gate v/v....now this begs the question regarding the 8min boiler overrun pcb timer... is the gate valve left cracked open and how much ( instruction refer's to an installed locksheild v/v 1turn open ) or do both of the 2 port mov's (CH & HW ) also come under the control of the pcb overrun timer and stay open (mmmmmm... would work in the HW case but not for CH if and when all TRV's are closed ) what you think folks....joe

 

[sparkytim]

Normally the overun is only controlled by the internal boiler stat via the PCB and kicks in when ALL external control has ceased to call for heat, this is to ensure that the latent heat within the boiler is disipated out via the system. It is considered good practice to have at least ONE radiator with NO TRV within the area covered by a room stat. If no bypass is open then the pump will be pusing into clsoed Zone valves.