Sending signal down output wire

[glnovice90]

Just a question, what happens if a live current goes down the orange wire on a not energised (position W) drayton mid position valve, not as an output but as an input?

 

[terryplumb]

Are you talking about voltage ,not current ??
If there is 230/240 volts present at the terminal that the orange wire is connected to, the boiler will fire up, as that's connected to the same terminal .

 

[glnovice90]

Are you talking about voltage ,not current ??
If there is 230/240 volts present at the terminal that the orange wire is connected to, the boiler will fire up, as that's connected to the same terminal .

I mean current from the live travelling up the orange wire. I'm gessing the orange wire only activates as an output when both white and grey are energised and an internal switch is activated allowing current to flow. If that presumption is true then that means any current flowing in the reverse should just hit a dead end if the white and grey aren't energiesed. I just want this to be confirmed

 

[RandomGrinch]

If that presumption is true then that means any current flowing in the reverse should just hit a dead end if the white and grey aren't energiesed. I just want this to be confirmed

Not quite.
If there were a dead end, there couldn't be any current flowing.
As @terryplumb suggests...

Are you talking about voltage ,not current ??

Here is a schematic of a 3 port valve (albeit a Honeywell), in its rest position...

Three port mid position valve - DIYWiki

If 230V was applied to the Orange wire, there would be an extremely small current draw from the motor windings, and the two resistors in series - I estimate this to be <1 mA.

 

[terryplumb]

I mean current from the live travelling up the orange wire. I'm gessing the orange wire only activates as an output when both white and grey are energised and an internal switch is activated allowing current to flow. If that presumption is true then that means any current flowing in the reverse should just hit a dead end if the white and grey aren't energiesed. I just want this to be confirmed

Current only flows when there is a load on the circuit.
I don't think you understand the relationship between AC ( alternating current ) and voltage.

 

[glnovice90]

Current only flows when there is a load on the circuit.
I don't think you understand the relationship between AC ( alternating current ) and voltage.

It would be under load condition

 

[glnovice90]

Not quite.
If there were a dead end, there couldn't be any current flowing.
As @terryplumb suggests...


Here is a schematic of a 3 port valve (albeit a Honeywell), in its rest position...

View attachment 378723

Three port mid position valve - DIYWiki

If 230V was applied to the Orange wire, there would be an extremely small current draw from the motor windings, and the two resistors in series - I estimate this to be <1 mA.

Thanks for the diagram.

I think it may be clearer if I provide context. This is my post where I explain my setup and what I'm trying to achieve https://www.diynot.com/diy/threads/room-thermostat-to-call-pump-only.641074/

I've set up my wiring to achieve this process flow:

I want to be able to control the max temp of the water in the system so boiler control can only be managed through the HW thermo. In CH call mode the default behaviour is to pull stored heat from the system via the pump and the boiler will only activate when the HW cylinder temp drops. Problem is, I'm worried that in HW only mode, the common HW thermostat terminal will cause the load to also travel back up the orange wire (in a reverse circuit) and I don't want to damage the valve.

 

[DP]

I mean current from the live travelling up the orange wire.

If you do not have voltage then there will be no current.

 

[DP]

If 230V was applied to the Orange wire, there would be an extremely small current draw from the motor windings, and the two resistors in series - I estimate this to be <1 mA.

Current flow in resistors will split after the diode as that switch is not made for HW call ( comes into circuit during heating only)
To motor to hold it in place
To call wire on appliance, the flow will, as you said, be very little

 

[DP]

I want to be able to control the max temp of the water in the system so boiler control can only be managed through the HW thermo. In CH call mode the default behaviour is to pull stored heat from the system via the pump and the boiler will only activate when the HW cylinder temp drops. Problem is, I'm worried that in HW only mode, the common HW thermostat terminal will cause the load to also travel back up the orange wire (in a reverse circuit) and I don't want to damage the valve.

The system you have is a gravity hot water system.
Water in cylinder is heated by convection currents. Seems some of this circulation is taking place to the rads due to plumbing issues ( there should be none)
Be careful wgphere you fit ant valve etc on hot water loop as those 22mm pipes will extends to F&E cistern. Any vave you fit will need to be such that there is clear uninterrupted pipe run boiler the header cistern for both feed and vent
Fail to see why you are opting for 3 port MV unless the system is being converted to fully pumped.