Volt Free Contacts

[Lewis581]

I am new to this site so sorry if it is not how it should be.I was wondering could you please explain (as if i was a five year old) a volt free contact within a commercial boiler. I hear they are voltage free and not connected to the main wiring or the boiler if this is true how does it communicate with the boiler and what is its purpose?, and can it only 230 volts take coming in or only send 230 volts, and what would normally be used in this set up? Basically im clueless, any help much would be much appreciated

 

[warmadmax]

"volts free" normally means its low voltage DC from the boilers pcb (12v)

just means it's not mains voltage

 

[rjm2k]

there was another thread with exactly the same title about these about 2 weeks ago, the search facility should bring it up - I think the conclusion was they are not volt free in the sense you are expecting so don't touch!

 

[Lewis581]

Thanks......Sadly im still none of the wiser. The boiler supplies volt free contacts to enable a thermostat to connect to it?

1, What else can be connected to the volt free contact with in the boiler?
2, Are the volt free contacts actually connected to the boiler. to give information to what ever is connected to it? If not whats the point?
3, Can the contact only recieve 230v OR only send 230v?
4, would this be a fair example;- a BMS could be linked to the boiler via the volt free contacts, the boiler would send a signal via the volt free contacts that came from the PCB and that would then send a fault or run signal to the BMS?????

PCB - Volt Free Contacts - BMS??

Sorry to be hardwork!!

 

[warmadmax]

"volts free" isn't Volts Free.... simple as, don't read into the name.

at a very basic level, in a "volts free" thermostat, the "volts free" contacts behave like a light switch, it either allows flow of electricity or blocks it,
the electricity in this case comes from the boiler, normally low voltage contacts in it.
this is unlike a mains voltage one which would feed mains AC back down the switched live.


what do you mean by "BMS" ?

 

[Lewis581]

BMS - sometimes boilers are operated by a Building Managment System, this is of the case when working on projects of a larger scale, enables the building manager to have the ability to control Air con,heating etc from just the one panel. So volt free contacts would have voltage supplied from the boiler - in that case anything being connected to this, external from the boiler its self would have to be voltage free?? Which leads me to think that Voltage free is only "free" in the sense that the boiler will offer "free" voltage from the contacts?

Dont shoot me if i am wrong, help much appreciated!!

 

[CBF]

i am seriously worried why you are even asking this question when you can't even seem to understand the basics

 

[Lewis581]

Seriously wouldnt worry, its only a question!! If we all knew everything there wouldnt be such things as forums. Dont think what i have asked is out of the ordinary! Searching the net seems to come up with different types of terminology. where as all i am after is a direct response to the questions i have asked - got to start somewhere.

 

[Agile]

When asking these questions it sounds as if you are directly involved with commercial systems without the basic knowledge required.

The term "volt free" is a misnomer! All it means is that it must never be connected to 230 mains! Its a simple term for simple plumbers!

The boiler actually sends out a ( low ) voltage ( usually 24v DC ) and plain contacts on the controls do just the switching. Thats with on/off contacts in the controls.

Tony

 

[Terrywookfit]

Volt free contacts simply means "Not internally connected to any votage".

The contacts must be connected to the voltage requiring to be switched, whether that is 240, 50,24 ,12 orwhatever.

 

[CBF]

I'm worried because i can't understand why you would need to know, if you can't get to grips with any of these answers whatever you are doing or need to know the answers for you shouldn't be doing it.

 

[Agile]

Terry has replied in relation to something like a thermostat.

That can be confusing when the OP is asking about a boiler!

 

[Terrywookfit]

When asking these questions it sounds as if you are directly involved with commercial systems without the basic knowledge required.

The term "volt free" is a misnomer! All it means is that it must never be connected to 230 mains! Its a simple term for simple plumbers!

The boiler actually sends out a ( low ) voltage ( usually 24v DC ) and plain contacts on the controls do just the switching. Thats with on/off contacts in the controls.

Tony

An RF roomstat has V F C but is used to apply 240v to the motorized valve.

As most electrical controls are designed to be installed by "Simple Electricians".
I fail to see why the terminology would be used to aid "Simple Plumbers"!!

It must be something you were taught at the BBC!

 

[DP]

"volts free" normally means its low voltage DC from the boilers pcb (12v)

just means it's not mains voltage

Volt free means just that i.e. NO VOLTAGE on the contacts. That includes abscence of low or little voltage

Programmers (most not all) have an internal link that applies 240 volts to OFF contact when timer off and on ON contact when timer calling.

Simple timers often have three connections on a 'switch' not connected to any voltage i.e. three terminals free of voltage or voltage free. So you can connect a small battery to this switch, a car battery if you choose, 24 volts to it if you a bothered, 110 volts if you can find that voltage or 240 if you have taken you invincible pills.

A voltage free contact would be used if an equipment was supplying its own voltage be it small or large

 

[ChrisR]

The term "volt free" is a misnomer! All it means is that it must never be connected to 230 mains!

Misleading!
It could easily have mains on either or both contacts.


You're connecting a Thing to a boiler, ok.
The Thing may have a relay or switch in it which has contacts, but when you connect it to the boiler, The Thing mustn't have any volts on already onthe contacts. So they are voltage free.
The boiler itself will usually put a voltage, which could be 12VDC or 240VAC or anything else, on one of the contacts, and look for it on the other.