Wireless Programmer Advice

[Last plumber]

So, I think by volt free that doesn't mean there's no voltage on the contacts, just that the voltage is separate from the mains voltage. So, a solenoid that is switched open and shut by the 230v mains, but the contacts on switch are separate and therefore can be any voltage you need? Am I thinking about this correctly?

Therefore, if the boiler takes 230v on the switch you can just link the 230v of the supply to the solenoid to the common, and that way it will send 230v up it when it is closed? However, if the device to be switched need a lower voltage, you instead apply that to the common terminal so that the correct voltage is returned when it is closed?

I think I'm slowly getting my head around this, it's the naming of "volt free" that threw me off.

Why would a boiler not want 230v on the switch, I mean, why would a boiler need a 24v return to switch it? Can you give me an example of a boiler that uses this so I can download the manual and take a look?

https://www.google.co.uk/url?sa=t&r...47.pdf&usg=AFQjCNEEZPLuEg435Gdc-mejUBX16zKfbg

Have a look at Vaillant. All three ideas/methods are available with those.

There's 230V, 24V and ebus. ebus is specific to Vaillant.

As far as volt free goes, that is a funny thing to get your head around. I always think of it as a circuit that doesn't actually run anything by itself, directly.

In my case a volt free circuit normally includes a PCB. So the switching is done via components on that board like transistors, relays etc. Things like volt free switching on a room stat would just close a circuit for the board to recognise.

Some say that volt free is Free, as in Free like non specific.

 

[hightower]

Well I read one article that said volt free just means the relay contacts are separate (free) from the supply voltage. Then I read another article saying volt free means exactly that, there isn't a voltage sitting present but some circuit board wizardry is watching the cable for continuity - and when the switch is closed it picks up on the continuity and acts on it.

 

[hightower]

Thanks for that link, very helpful. Just looking through and on page 27 it says not to use 7,8,9 (20v) terminals in the UK.

 

[Last plumber]

Thanks for that link, very helpful. Just looking through and on page 27 it says not to use 7,8,9 (20v) terminals in the UK.

Wizardry ......Yep that's it.
another subject all together.

 

[Leesparkykent]

The controls should really be fed from the LS terminal within the boiler so they are protected by the internal fuse. This way its connected in accordance with the manufacturers instructions.

 

[Last plumber]

The controls should really be fed from the LS terminal within the boiler so they are protected by the internal fuse. This way its connected in accordance with the manufacturers instructions.

Not all MF's say that and the only thing that should be supplied via that particular circuit is the switching of it.
So in the case of a Programmer, you wouldn't run the L N supply to a programmer from the boiler and definitely not from that source, so you wouldn't be protecting the control itself with the internal fuse anyway !
The switch circuit ( in this case Lr Ls ) is to tell the board to fire the boiler. The boilers internal functions and components e.g. Pump, fan etc are powered via the permanent live supply.

 

[Leesparkykent]

Not all MF's say that and the only thing that should be supplied via that particular circuit is the switching of it.
So in the case of a Programmer, you wouldn't run the L N supply to a programmer from the boiler and definitely not from that source, so you wouldn't be protecting the control itself with the internal fuse anyway !
The switch circuit ( in this case Lr Ls ) is to tell the board to fire the boiler. The boilers internal functions and components e.g. Pump, fan etc are powered via the permanent live supply.

Hightower says its a worcster bosch 25si so yes the programmer should be fed from the LS/230V out terminal if you follow the manufacturers instructions/diagrams.

 

[Last plumber]

Hightower says its a worcster bosch 25si so yes the programmer should be fed from the LS/230V out terminal if you follow the manufacturers instructions/diagrams.

It does say that, you would however be running the Programmer via the board which I personally don't like the idea of for numerous reasons.
I prefer the programmer to take it's supply from the system wiring. If you ring Worcester tech, they'll tell you its a suggested way of doing it, not a must. It is a provision they make. There is more than one way to skin a cat. There is no harm in feeding a switched live to the boiler Lr.