Worcester heatslave highlow

[Zehroni]

Dear All,
I have just moved to a house where it has an old boiler, it is Worcester, heatslave highlow type. When I tried to switch it on from the mains, after lighting the pilot, I could hear a lot of rattling nose from the pump as well as the timer. Consequently, I managed to install, new pump, new two port valve, and new timer. It is now working perfectly, but pump seems to be always working, whether the CH on or off or the DWH on or off. In my opinion the pump should come on when either the CH or DHW is on demand, any other time it should not be running, am I right in assuming this? Is there any relay stuck on the PCB, can someone advice of where I can get a manual for it, any input or advice from anyone would be highly appreciated.
many thnaks

 

[Gas2Air]

Was the problem present before? If not you have wired the 2 port permanent live wrong or pcb isn't working correctly for pump overrun. I'd check the wiring first to the 2 port.

 

[Zehroni]

Yes it was, when I switched the boiler on from the main (electric switch) I could hear the pump making loud noise. This is before I replace any of the parts. Furthermore I marked the two terminals of the new port and connected them to same connections of the old one.

 

[Gas2Air]

Well the pcb pump overrun is shot, needs replacing.

 

[Zehroni]

I do believe the pcb is working because the boiler working perfectly it dose what I am expecting it to do, the 2 port valve behaving as it should opening both ports when both CH and DHW is required, giving priority to DHW closing on port when either CH or DHW required as appropriate. one more thing the boiler is highflow not highlow as it stated in my first post

 

[Zehroni]

Gas2Air,
Many thanks for the advice; do you mean the whole of the PCB or the part that operates the pump on the pcb? if so, any idea where to get it

 

[Gas2Air]

Yes i know it's a Highflow, the pcb contols many things on that blr and a small side of it controls pum poverrun, if this is faulty it will cause the pump to run without demand. Does the blr fire with no demand?

 

[Zehroni]

The boiler does not fire with no demand , it only fires if either the CH or DHW or both are on demand.
I take it that the side that control the pump is embedded within the pcb and the whole of pcb need to be replaced, is it?
The pcb does not look very sophisticated and certainly smaller then the modern boiler I have seen so far.
Is the pcb obtainable? considering it is about 20 years old boiler

 

[Gas2Air]

Yes it is a direct replacement pcb and they're still available.

 

[Zehroni]

any idea where to get one and how much would it cost?

 

[Zehroni]

Gas2aire,
Many thanks for the advice, it was the pump over run pcb. I have replaced it today and the pump cuts off after few minutes it does not keep running 24 hours as it was before.