Honeywell Y plan.

[Mike']

Why am I getting 3 lives on my cylinder stat connections?
This should only be two, I have gone through the wiring guides and not found either faulty wiring nor products.
Honeywell technical closed for Xmas.

 

[gas4you]

What you mean all live at the same time?

Only 2 should be live together.

You must be getting a back feed from somewhere, test the 3 port valve, programmer, or it is not wired up correctly.

 

[EliteHeat]

First of all, are you experiencing a problem or are you just curious?

Secondly, what are the exact voltages to the various stat terminals?

 

[Mike']

We agree there should only be 2, this is the problem.
We do not know where the back feed is coming from.
We have a Vaillant 428 using a Siemens programmer.
Used the Y plan wiring guide using the boiler as master supply and pump overrun independant.

 

[Mike']

Elite;- 230 volts on all terminals

 

[Mike']

New MV head, new programmer, new boiler.

 

[ChrisR]

Don't bother trying to figure out the backfeed voltages!
Does it WORK?

 

[Mike']

Chris, CH works but not getting hot water. Roomstat controling the boiler. Only way to get HW is to remove MV head and manually position valve.

 

[EliteHeat]

Why don't you disconnect the grey - that way you will see where the voltage is coming from?

 

[gas4you]

I never use the boiler as the main feed for the ch, (sorry Simon)

I just run permanent live, switched live and pumped live from boiler back to wiring center.

Have you removed the link in the boiler between 3 & 4 on the pcb?

 

[Mike']

Dave, Vaillant recommend their boilers are the 1st on the power supply chain.
Link was removed between 3 & 4.

 

[Mike']

Elite,
removed grey but supply comes from programmer terminal 1 and boiler terminal 3

 

[gas4you]

Their engineers don't

 

[EliteHeat]

This isn't making much sense. The link between terminals 3 & 4 has been removed, if it wasn't then the boiler would run constantly.

The power to common on the cylinder stat comes from terminal 1 of the programmer.

The demand for heat should go straight to terminal 4 on the boiler.

The demand satisfied should go to grey.

Boiler terminal 3 should not be used at all.

 

[gas4you]

Looks like it's you and me in the wilderness out there then elite.

Are we the only 2 who fit like this properly