potterton 24he. boiler wiring?

[antran]

I wonder if anyone can help. I am wiring in a potterton promax 24he combi boiler. My gas installer has fitted a bypass and said the unit needs to be permanantly live with the pump connected for overrun.
The only external connections on the boiler are S/L, N, E and P/F. Where would the permanent live connection need to go?

 

[stem]

Are you sure it's a combi?

The wiring for the heat only version is as you describe, but I would expect a combi have built in by-pass, controls and pre wired pump. Also I wouldn't expect it to have a switched live, but a permanent supply from an FCU

Based on that I'm assuming it isn't a combi, so, the following information applies to the heat only version. Please check your installation instructions to make sure that your boiler is the same.

S/L = Switched Live from the external controls
N = Neutral
E = Earth
P/F = Pump feed (live)

There is no permanent live.

If the external controls are still calling for heat, and you have radiators fitted with TRV's then the boiler contains a flow switch to control the pump. To use this feature connect the pump live to the P/F terminal.

The boiler itself does not need a by-pass, so the pump can be stopped at the end of the heating period.

 

[antran]

thanks for this, on looking at the manual, it is heat only. Slightly confused as to why my installer would fit a bypass if not required. I rung potterton, but they were unwilling to divulge any details, but the tech guy mentioned something about connecting a permanant live on the capacitor on the pcb?
seems like i am looking into this too much. will wire up as you have suggested.

 

[stem]

The boiler doesn't need a by-pass, but there's no problem fitting one if the radiators have TRV's. If there is a by-pass, you can connect the pump to the S/L terminal and not use the flow switch. As you seem to be lacking information, I've found you a manual click here See page 10 for the by-pass information.

 

[antran]

thankyou. appreciate your time.