volt free contact inside electric heating boiler

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Discuss volt free contact inside electric heating boiler in the UK Electrical Forum area at ElectriciansForums.net

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Kev2632

http://www.electric-heatingcompany....0/03/electric-boilers-tech-install-manual.pdf

Go down to page 8 of this document, you will see it asks for the contacts to fire the boiler up to be volt free, now i do finally understand i think what this means, it means that those two contacts R+P are independently volt free from the power being supplied to boiler, now what i cant understand with the way the booklet is telling you to wire the boiler up is, when wiring a normal 2x 2port valve set up, we supply either the orange or grey with 240 and the micro switch closes sending 240v down the other core, how can this boiler work when there will be no voltage at all applied to either orange or grey cores?? and is it possilbe to feed 240 volts onto one side of the R+P volt free contact at all ? and have 240 come out the side of either R+P ??

thanks again guys
 
In this case R&P are in parrallel with the microswitches on on the actuators and just simply cause a short on the o/p and i/p of R&P and signal the boiler to switch on.

There will be more than likely be a 0v 4-20 ma signal source supplied from either R or P which will simply feed back into the boiler when switched. If you short the R & P out to test it with the boiler switched on, it should fire up. If not then check the voltage rating of R&P and check with manufacturers if voltage needs to be fed to them. Sometimes the term "volt free" is mis used by some manufacturers in different industries.
 
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chilliwilly said:
In this case R&P are in parrallel with the microswitches on on the actuators and just simply cause a short on the o/p and i/p of R&P and signal the boiler to switch on.

There will be more than likely be a 0v 4-20 ma signal source supplied from either R or P which will simply feed back into the boiler when switched. If you short the R & P out to test it with the boiler switched on, it should fire up.
Click to expand...
okay yea i understand here, so is there anyway at all you can put 240v into one side of either R or P connection, like a light switch for example? or does this type of volt free connection not allow you to put 240v near it at all??
 
so i take it some case " volt free" can be used in such a way that you can feed 240v into one side of the connection and it then leaves the connection on the other side, or sometimes " volt free" can be just a case of using that connection as signal wire purpose is that right ???
 
Without more spec from manufacturers, I wouldn't risk it. Test each o/p for voltage between and to earth and see what you get, then use a peice of wire for now and see if it works.
 
Do not put 240v into r or p or your pcb is gonay have a bad time and it'll cost you a fair bit of money. I've wired boilers up by simply putting a two core flex into these connections and into a light switch. The light switch just breaks the loop stopping the boiler, once it's been switched on the loop is reinstated and boiler fires up.......


hope that makes sense.
 
paul_h said:
Do not put 240v into r or p or your pcb is gonay have a bad time and it'll cost you a fair bit of money. I've wired boilers up by simply putting a two core flex into these connections and into a light switch. The light switch just breaks the loop stopping the boiler, once it's been switched on the loop is reinstated and boiler fires up.......


hope that makes sense.
Click to expand...

Yea that makes sense thanks, so i take it there is different types of "volt free" connections is that correct?? just depends of manufactures instructions is that right??
 
paul_h said:
Do not put 240v into r or p or your pcb is gonay have a bad time and it'll cost you a fair bit of money. I've wired boilers up by simply putting a two core flex into these connections and into a light switch. The light switch just breaks the loop stopping the boiler, once it's been switched on the loop is reinstated and boiler fires up.......


hope that makes sense.
Click to expand...

http://www.myson.co.uk/static_files...V_Wiring_Centre_Installation_Instructions.pdf

like with this underfloor heating set up, it has volt free contacts on it, but i assume its possible to supply one side of this volt free contact with 240 volts is that right????
 
Kev2632 said:
so i take it some case " volt free" can be used in such a way that you can feed 240v into one side of the connection and it then leaves the connection on the other side, or sometimes " volt free" can be just a case of using that connection as signal wire purpose is that right ???
Click to expand...

Yes but in the event of uncertainty refer to manufacturer instructions, or just test the o/p and i/p between and to earth or short out the output o/p with the input i/p, and see if there's a function or change. That way you will know if whether or not a 4 - 20 ma signal is being used that needs feeding back in by switching or shorting, or whether a common feed is required to cause a function.
 
chilliwilly said:
Yes but in the event of uncertainty refer to manufacturer instructions, or just test the o/p and i/p between and to earth or short out the output o/p with the input i/p, and see if there's a function or change. That way you will know if whether or not a 4 - 20 ma signal is being used that needs feeding back in by switching or shorting, or whether a common feed is required to cause a function.
Click to expand...

thanks for your help, could you just have one last look at that other post i put on for the under floor heating, that also has "volt free" does that mean this set up will allow me to put 240v into one of the " volt free" contacts on the boiler and pump " volt free" connections ??? is that correct??
 
Kev2632 said:
now i do finally understand i think what this means, it means that those two contacts R+P are independently volt free from the power being supplied to boiler,
Click to expand...

No, that's not what the manufacturer means when they say volt free.

VOLT FREE is free of any EXTERNAL voltage being applied to those appliance connections that also includes no external Neutral and No external earth connections.

The boiler control puts a voltage, nowadays usually low voltage onto the terminals and is looking for an external (volt free) closed contact to energise a circuit.

Re the other post DON'T put any voltage onto connections labelled Volt FREE.
 
snowhead said:
No, that's not what the manufacturer means when they say volt free.

VOLT FREE is free of any EXTERNAL voltage being applied to those appliance connections that also includes no external Neutral and No external earth connections.

The boiler control puts a voltage, nowadays usually low voltage onto the terminals and is looking for an external (volt free) closed contact to energise a circuit.

Re the other post DON'T put any voltage onto connections labelled Volt FREE.
Click to expand...

for the underfloor heating manifold, i was told that those volt free contacts you can supply 240 volts into one side of and take another out of it ( like a light switch) is that right???
 
Yes that's right, the RHS top section shows the L & N being fed into the board, then the boiler and pump relays which are volt free, can be looped off to feed the Live side and switched internally.

In the case of the boiler, the manufacturer is calling R & P volt free, as some do? But there will more than likely be a neglegible voltage to drive a 4 - 20 ma current to switch or signal a component on the pcb.

As previously commented, check the voltage with a bench meter, or short out the i/p and o/p and see if you get a function?
 
chilliwilly said:
Yes that's right, the RHS top section shows the L & N being fed into the board, then the boiler and pump relays which are volt free, can be looped off to feed the Live side and switched internally.

In the case of the boiler, the manufacturer is calling R & P volt free, as some do? But there will more than likely be a neglegible voltage to drive a 4 - 20 ma current to switch or signal a component on the pcb.

As previously commented, check the voltage with a bench meter, or short out the i/p and o/p and see if you get a function?
Click to expand...

yea i thought i was right about the underfloor heating manifold, so if i was too loop of the live side to one side of the "volt free" connections, i assume then i will take a switch wire from the side of that switch to the boiler and pump is that correct???
 
I was telling you different because I believe you are wrong (mainly because it says about 10 times do not put a voltage across) I was trying to find a link for you but could not. Do yourself a favour tomorrow and phone the tech line If I am wrong you have lost price of a phone call. On every boiler I have ever done there has been volt free and 240 side but your call.
 
stuartcourt said:
I was telling you different because I believe you are wrong (mainly because it says about 10 times do not put a voltage across) I was trying to find a link for you but could not. Do yourself a favour tomorrow and phone the tech line If I am wrong you have lost price of a phone call. On every boiler I have ever done there has been volt free and 240 side but your call.
Click to expand...
Well that other guy told me right there, so it must be true, and I've heard that's how it's done as well you can apply 240v to that volt free connections on the underfloor heating manifold
 
Just because the underfloor heating diagram points to that has nothing to do with your boiler, but I am not trying to make life hard, as I said your call.
 
Kev, they'll be tears if you put 230v on those contacts. The underfloor heating has nothing to do with the boiler you're working on and just to clarify the situation (as I see it) volt free inputs (I/P) are just that, for the likes of normally closed (n/c) or normally open (n/o) contacts (basically signals provided internally) on the other hand (as found on the underfloor heating you mention) volt free outputs (O/P) are normally open (n/o) contacts for you to supply a voltage (in this case 230v) to feed whatever that needs feeding (can't be bothered going back and having a look, but could be a fan, light, pump etc!)
I hope that makes some sense.
So take the advice given before you damage anything!
 
I was browsing about the internet there, and i noticed you could use a relay to provide volt free contacts to a boiler how does that work? when there is 240v supplying the coil ???
 
Voltage free contacts is a term given to contacts which you apply your own voltage signal, or signal or 4-20ma etc.
Voltage free contacts as in a relay or microswitches will be rated and shown with max amps and max voltage. IE 2amp/230v or 24volt dc/5amp etc etc.
This boiler manufacturer seems to have used unfortunate wording in their description of R and P. I read it like has already been stated and is 4-20ma (with 10 volts to carry it) or 24volt etc. Looks to me like they have had a lot of returns/faults which are site based and so the emphasis on warning after warning.
The easiest to explain it is if you think of P as power (leaving the boiler at whatever voltage) and R as return (going back to tell the boiler to go). Therefor self contained and no voltage to be applied by your wiring.
 
stantheman said:
The voltage only appears across the coil, the contacts are independent.
Click to expand...

okay so i could feed the coil with 240volts and take a two core from the relay contacts to the boiler is that correct yea, and that will provide "volt free" contacts to the boiler correct yea??
 
Boydy said:
Voltage free contacts is a term given to contacts which you apply your own voltage signal, or signal or 4-20ma etc.
Voltage free contacts as in a relay or microswitches will be rated and shown with max amps and max voltage. IE 2amp/230v or 24volt dc/5amp etc etc.
This boiler manufacturer seems to have used unfortunate wording in their description of R and P. I read it like has already been stated and is 4-20ma (with 10 volts to carry it) or 24volt etc. Looks to me like they have had a lot of returns/faults which are site based and so the emphasis on warning after warning.
The easiest to explain it is if you think of P as power (leaving the boiler at whatever voltage) and R as return (going back to tell the boiler to go). Therefor self contained and no voltage to be applied by your wiring.
Click to expand...

Thanks Boydy :)
 
stantheman said:
The voltage only appears across the coil, the contacts are independent.
Click to expand...
okay so i could feed the coil with 240volts and take a two core from the relay contacts to the boiler is that correct yea, and that will provide "volt free" contacts to the boiler correct yea??​




 
Kev2632 said:
okay so i could feed the coil with 240volts and take a two core from the relay contacts to the boiler is that correct yea, and that will provide "volt free" contacts to the boiler correct yea??
Click to expand...
Yes on both counts! But are they actually asking for you YOU to provide the volt-free contacts i.e. are the terminations available or are they internally provided by the boiler/controls themselves? Without looking I can't say!
 
If you study the wiring diagram on page 8 you will see that the greys of the valves are connected to R and the oranges are connected to P.
These are connected when the valve is opened.

It is (unusually ?) using the valve as 'volt-free' contacts for the boiler terminals (R and P) and has no connection with the 240V supply.

The valves are powered by the browns at 240V from the thermostats.

You do of course need 240V L,N,E on the terminals where it says Boiler Main Supply even though the wiring is not shown.
 
There's no doubt.

The valves are being used as a relay with a motor rather than a coil.


However, if wired correctly as per the diagram it doesn't really matter how it works.
 
agree, if you follow geoffsd post 34, this is a common way for connecting many Grant air source pumps that require volt free contacts.
 
Just phone up monday morning and ask tech support they will tell you in about 5 seconds and that is a risk free option, Its what they are there for
 
Phone the helpline as we are all guessing here and they will have the definitive answer, it will be a lot cheaper than making yourself a very expensive door-stop!
 
We are not all guessing Strop.
Those of us who have read, and understood the manufacturers diagram have provided the necessary info.

Boydy
 
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