room stat

[333rocky333]

Any advice appreciated

When changing a room stat on a y plan

I put power on to trace live wire and found with timeclock C/H off and H/w on, the load side was also live.

Is that normal

I have looked at wiring diagrams but not sure, could it just be possibly going through the valve contacts etc, and somehow returning via the white wire

Aside from the sundial /honeywell, site info, does anyone know of any info regarding the grey and orange, internal switch wires and positions,in relation to the actual valve positions

Not sure either the function of the grey to the cyl stat and in what state the stat gives an output (ie Tank hot or cold), in the diagram it also looks like the grey becomes live when the H/W timer is off.


Thanks

 

[Paul Barker]

You make it sound very difficult.

The easy way to think about CH wiring is this.

You have two main types nowadays s plan and y plan. s plan is easiest as it is simply two channels in which a feed is passed along a chain when conditions are met. All neiutrals and cpc's are common. Only phase is interupted,

Phase leaves timer when timed to be on arrives at stat if stat not satisfied it is forwarded to zone valve when that has moved into place it progresses to instruct boiler to fire, boiler passes on same instruction to pump (when an overrun is required, if not boiler and pump receive phase simultaneously)

With Y plan which u have, the phase for heating only comes from the mid position valve via hot water off and via the cylinder stat satisfied connection. So all you have to remember that in y plan as opposed to s plan you must send 3 phase conductors from the timer and 2 from the cylinder stat, to power the heating only when hot water is satisfied.

It is a huge area of installation error, vertually all y plans you go to require hot water stat to be turned up high or heating won't come on and the twit who first fixed didn't put sufficient conductors in to rectify it.