Evohome and Vaillent

[1animal1]

Hi, having fitted a full evohome system before using opentherm and underfloor, having moved into a new build recently, I've decided to fit it again, despite not being able to use OT.

I have a Valiant ecotec boiler which is quite far away from the cylinder. The set up is a 2 zone plus HW, so 3 zone valves. My plan is to remove the upstairs zone stat and fit the evohome controller in the position of the down stairs zone stat. I will be following the Y plan wiring schematic.

Couple of questions...

The Vaillant boiler I understand has a pump live feed, so in the wiring I'll connect the pump live to that.

The boiler also has the full mains plus an RT connection, which I presume is the switched live for the above circuit? The main live fitted as permanent.

Also, I presume I'm fine wiring the two heating zone valves together.

Thanks

Tim

 

[1animal1]

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[ShaunCorbs]

I think you mean s plan

Rt is switch yes and yes perm live as you have pump overrun

 

[1animal1]

I think you mean s plan

Rt is switch yes and yes perm live as you have pump overrun

Thanks! Yes sorry, S plan...

So the boiler switch in the diagram in my switched live, and I just add in a permanent.

Next question...

Does the high limit stat need wiring into the HW zone valve or the boiler live? Picture below of high limit and control star wiring...

 

[1animal1]

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[ShaunCorbs]

Always run the hot water stat before the zone valve eg live to stat live out of stat to brown on zone

 

[1animal1]

Always run the hot water stat before the zone valve eg live to stat live out of stat to brown on zone

So on the schematic above, does the stat go between the brown wire on the HW valve. I found the attached for the same stat... Presume common is the main live, and the 1/2 on the right is linking between the valve brown?

Sorry if I've misunderstood you

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[ShaunCorbs]

Common live from timer / hot water on
Load brown 2 port
Don’t need sat

 

[1animal1]

Common live from timer / hot water on
Load brown 2 port
Don’t need sat

Thanks Shaun! So the stat sits right between block 8 and the HW valve

 

[EvilDrPorkChop]

Should be on your HW BDR91,

Perm Live to A
B on the Relay to C on the High Limit Stat. (Remove link between 2 High limit and C on Temp Stat)
2 on the High Limit Stat to Brown on the HW motorised valve.