Switchmaster Wiring Diagram - This is one for those of you with a good memory.

[Hypersonic]

Hi All,
I'm a new member to this forum and I'm hoping that one of you with a good memory, or tidy records, will be able to help.
In short I'm looking for an old switch master wiring diagram, one that uses a mid position VA1 valve (6 wire) and SM300 controller.
Yes I know this kit is obsolete but my reason for asking is that my builder has got into difficulty because this old installation did not follow any of the conventions that other manufacturers followed for Y plan type installations.
Not only is the valve different from similar Honeywell examples (easily changed), but the controller and room thermostat wiring (2 wires only) cannot simply be converted to conventional Honeywell Y plan. In addition the current location of the pump and valve and tank are all remote from one another. Maybe I should have fitted a Combi rather than keeping the existing System layout with tank!! C'est la vie.
I have therefore decided to fit an entirely new control system but I need to understand what / where the existing wires go so that they can be repurposed. I traced all the wires some time ago before the boiler was changed but unfortunately I can't find my own paperwork and final revised diagram that I created, plus I am working at 200 miles from the site.
I intend using a roving RF controller (Glow Worm do a 2 channel Climate Pro) but I will need to do some (repeat) back office work to confirm which of the existing wiring can be used and use RF for the room stat thus removing the need to add additional wiring and thus avoid redecorating and worse!
I do hope one of you can help.
Best Regards.

 

[stem]

Does this help? I think it's for a VA1 valve, but I would check the connections with a multimeter to be sure.

There are various versions of the SM programmer and they were a bit before my time. In the diagram above 1=Heating On / 2=Heating Off / 3=Hot Water on / 4= Hot Water off.

 

[Hypersonic]

Hi Stem,

Thanks for the diagram.

Yes it must be a VA-1 Switchmaster mid point 3 way valve since it has 6 wires including Red & Orange and Earth.

It adds to the rest of the info I have amassed. I'm now sure that I have enough info to plot how I'm going to tackle this job.

A very helpful guy from Danfoss Controls (Vincent) today told me that in fact there is no need to replace the old VA1 valve with a modern Honeywell. In short Blue on the VA1 = Neutral. Red & Orange can be joined and connected to the Orange on the Honeywell Yellow on VA1 goes to White on the Honeywell and White goes to Grey.

So it looks like my difficult job has just become very simple and I don't even have to change the 3 way valve which is still working perfectly after 40 years..but I'm still concerned about taking advantage of Pump over run which is a feature on the new boiler but did not exist on the old one. The Danfoss guy told me how to do it but it needs an additional lead to the pump +ve.

Thanks again. Stuart (Hypersonic)