Wiring help replacing a Drayton LP711 with a Solus DT500RF

[johndhuk]

Hi, I recently became a home owner and have been getting into my DIY. I have found a project where I want to be safe and make my first post in this wonderfully helpful community.

I'm looking to replace the existing Drayton LP711 with a Solus DT500RF on a Worcester Junior 28i Combi boiler.

I've sourced all the relevant diagrams, and taken a photo of the existing set up:

Boiler diagram:

Boiler wiring

• johndhuk
• 10 Mar 2016

Existing Drayton wiring:

Drayton wiring

• johndhuk
• 10 Mar 2016

Solus diagram:

Salus wiring

• johndhuk
• 10 Mar 2016

So current Drayton wiring is:
N = Neutral (Blue)
L = Live (Brown)
1 = COM (Black)
2 = No wire (would be OFF)
3 = ON (Grey)
4 = No wire

The Solus wiring diagram is:
1 = NO - Normally Open [N/O]
2 = COM - Linked Live feed (230V AC heating applications only)
3 = L - Live feed (230V AC)
4 = N - Neutral

Seems straight forward I just wire the existing L (live) and N (neutral) to 3 (live) and 4 (neutral) on the Solus.

Also 1 (COM) is 2 (COM) on the Solus. Does that mean I can just wire 3 (ON) on the Drayton to 1 (Normally Open) on the Solus? Is Normally Open N/O the same as ON?

Thanks in advance for any help! I'm keen to avoid frying any electrics by getting it wrong.

 

[stem]

Seems straight forward I just wire the existing L (live) and N (neutral) to 3 (live) and 4 (neutral) on the Solus.

Also 1 (COM) is 2 (COM) on the Solus. Does that mean I can just wire 3 (ON) on the Drayton to 1 (Normally Open) on the Solus? Is Normally Open N/O the same as ON?

Thanks in advance for any help! I'm keen to avoid frying any electrics by getting it wrong.

Correct, L, N & Com are the same on both units. 'NO' and 'ON' are different terms for the same thing. [NO = Normally Open, and it refers to the state of the switching contact when the Salus is de-energised. When it's energised the contact will close and the heating will come ON]

As you presently don't have the 'L' and 'Com' linked together on the Drayton, you won't need it on the Salus either.

I would recommend that you change the operating frequency of the unit from the factory settings using the jumpers and switches as per the instructions. It's easier to do this before it's wired up and these units are getting popular, I have seen two occasions where a property has had its heating switched by the controls next door because they were both left on the factory settings. It doesn't matter if you live on a remote farm, but can be a problem on a typical UK street.

 

[johndhuk]

Thank you very much for your help! Will be giving it a go when the unit arrives, fingers crossed it all works. Will definitely switch the jumpers, good tip.