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Rick Ridley
Rick Ridley, UK Heating Engineer
Category: UK Plumbing
Satisfied Customers: 1561
Experience:  30 Years on the tools, now retired, Ex CORGI
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I have two Potterton Suprima 100 boilers in parallel. They

Customer Question

I have two Potterton Suprima 100 boilers in parallel. They were wired to the pump through a Drayton RB1 relay. When the relay failed a replacement was bought but two successive plumbers have advised that a relay is unnecessary and appear to have wired the LH boiler only direct to the pump, by-passing the relay. The brown live wire wire from the LH boiler is attached to the pump live wire via a separate connector. The blue neutral wires from both boilers are wired directly to the pump blue wire. The brown wire from the RH boiler is connected to terminal 8 of the relay and is the only one connected to the relay.. A symptom is an occasional lockout of the LH boiier.: the pump continues running and the boiler can be started by tapping the PCB (whereupon the pump stops) and then pressing the reset button whereupon both boiler and pump start..
JA: How long has this been going on? And how severe is the problem?
Customer: Can you advise how the b
JA: Do you plan on doing the work yourself?
Customer: Yes. I would just like advice as to which wires to connect to which terminals on the RB1relay.(numbered 1 to 8) I think the relay must be used in order to avoid the lockout problem. Grateful for any advice you can give.
JA: Anything else we should know to help you best?
Customer: Don't think so.
Submitted: 1 month ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 1 month ago.

Is this what you are after?$FILE/DS21685_1205.pdf

Customer: replied 1 month ago.
Thenks.I have this diagram. What I need to know is which of the wires from the two boilers and to the pump go into which terminals on the relay.

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