Y plan wiring / Hot water

[ETradesmen]

Good afternoon all, just a quicky.

Ona Y plan system can anybody tell me why there is a switched live from the cylinder stat back to the programmer (Also connected to the grey on the MV)?

Why does the programmer need to know that the cylinder has hit the required temperature?

FYI I installed a new nest smart stat and have never actually thought about why the programmer needs such thing.

All the best, Michael

 

[Ian1981]

Because a Y plan has only one motorised valve sharing the heating and hot water if you’ve only got a one zone heating system.

The grey on the MV is actually a permanent live supply and not a switch live

 

[Leesparkykent]

Because a Y plan has only one motorised valve sharing the heating and hot water if you’ve only got a one zone heating system.

The grey on the MV is actually a permanent live supply and not a switch live

The grey on a 3 port isn’t a perm live. The grey will only be live if the hot water is satisfied or the HW on the programmer is switched off.

 

[Leesparkykent]

 

[Ian1981]

Too sharp for me Lee

 

[gof1]

Hi Y plan don't like them never reliable, always ask plumber to make it S plan, if there are problems you only loose 1 thing not 2.

 

[PEG]

Hi Y plan don't like them never reliable, always ask plumber to make it S plan, if there are problems you only loose 1 thing not 2.

...unless that problem is water,electric or mechanical...

 

[davesparks]

Why does the programmer need to know that the cylinder has hit the required temperature?
l

It doesn't, the valve requires a signal from the programmer when hot water is set to off and one from the stat when it is satisfied.