Y Plan 'Plus' (3 zones with 2 mid position valves)

[kevin]

Hi

Well the subject says most of it really :) I currently have a 2 zone (CH & HW) Y Plan system and am looking for electrical circuit layouts to extend this into a 3 zone system (CH, HW & Heat Exchanger for swimming pool).

I am looking to keep the existing mid position valve, and add another mid position valve in the 'feed' to the existing mid position valve. Now I know that makes my electrics more complicated, as I can't go to a relatively simple 'S Plan Plus' system, but it make my plumbing a lot easier.

Whilst I would like to go to a 'fully functioning' system with all 3 zones and combinations of those zones available, a simpler circuit that simply turned on swimming pool pump, boiler and mid position valve to 'Heat Exchanger only), at the expense of ignoring any demand from the CH or HW systems would be fine.

I have spent some time searching this group and google, finding the odd comment about 'it gets complicated', but never finding answers. With the number of people installing swimming pools, and the number of Y plan systems out there - many people must have done this before?

Thanks in advance Kevin

[kevin]

Thinking about this simpler option, I have a plan which I think is ok.

Take a feed from the mains isolator switch that currently supplies the boiler electrics, first through a time switch (the same as is done for the CH time switch and HW time switch currently), secondly through a thermostat for pool temperature control, then into a new wiring centre to make it easy to feed from this point the following 3 connections:

1) to the new mid position valve, requesting it goes to 'A only' (White + Grey?) 2) To the swimming pool pump that sends pool water through the Heat exchanger (Note 1) 3) to the boiler, or Orange wire of existing mid position valve to demand heat from the boiler (and circulating pump). (Note 2)

Note 1 - This is only 100 watts so not to much for the existing 3 amp fuse, but is outside so I need to make sure it has an RCD in the path. Note 2 - I had a concern about 'feeding back' the live from this new circuit into the existing 3 position valve via the orange wire, but this already happens via the Cylinder stat, so I believe it wont be a problem?

All comments welcome

Thanks Kevin

[Roger Mills]

Why is it so difficult to use three 2-port valves, and do it properly rather than cobbling up something with two 3-port valves?

The problem with 3-port valves is that the electrics for position control is all mixed up with the switching for boiler and pump control, whereas with

2-port valves the two functions are completely isolated from each other. Whilst a 3-port valve works ok (most of the time) in the specific application for which it was designed, things get very complicated if you stray outside of that application.

[<me9]

[snip]

[snip]

I used a system as proposed for several years. (Due to suppliers being out of stock of 2 port valves when the system was installed.) It was easy to set up with 3 port valves, once the wiring in the valves was understood.

However, I was forever changing micro switches in the 3 port valves. About 5 years ago I converted to 2 port valves. I haven't had an electrical failure since (one valve is weeping slightly and needs changing at some time).

If you want reliability in a non-standard system (and the ability of a corgi to understand it), stick to 2 port valves (S plan+).