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Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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How do I wire in a Horstmann 425 diadem to replace potterton

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How do I wire in a Horstmann 425 diadem to replace potterton mini minder
Hi , how many motorised valves do you have ? Two or one three port?
Customer: replied 2 years ago.
No motorised valves, it is a gravity hot water with pumped heating via a room stat. The Potterton mini minder had 6 terminals, N.L. power supply to N and L. The three "Control" leads went from N.3.and 4. The Horstmann 425 Diadem has 8 terminals. N.L. The L terminal has linked wires to terminal 2and terminal 5. I have connected the power supply to N and L and the three "control" leads to N.4.and 5. but the boiler will not light. One "control" lead must go to N. where do the other two leads connect to?
Hi in the hortsman .
Erth , neutral and live.
1 hot water on , 4 CH on
Customer: replied 2 years ago.
Nearly there, with the "control leads" moved to terminals 1. and 4. the boiler will not light when Hot water is switched on, but instantly lights and pump starts when CH is switched on. What should I try next?
OK hot water on , should go to the wire that was hw on with the mini minder connection 3. This will just be a live straight back to the boilernot including the pump
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