can anybody say what relay i need to provide volt free switching for an ethos combi the controls are wired as s plan 3 room stats 3 zone valves
relay for volt free switching
- Thread starter larrytheleak
- Start date
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chrisr
honeywell & boiler tech help say fit relay between orange on zone valves & boiler switch live which is on pc board
honeywell & boiler tech help say fit relay between orange on zone valves & boiler switch live which is on pc board
No doubt this is because it has a PCB which is fooled by the 70v or so kicked out by a Honeywell 3 port...... so much for Dr drivel saying they were designed for the UK market. Suppose if he'd fitted one he would have known.
Any relay will do, Drayton make an ugly one in a box (is it called an RB1?).
Alternatively, go and buy a contactor in a box, see http://www.tlc-direct.co.uk/Products/WYMESB20.html and http://www.tlc-direct.co.uk/Products/HGIU2.html
Any relay will do, Drayton make an ugly one in a box (is it called an RB1?).
Alternatively, go and buy a contactor in a box, see http://www.tlc-direct.co.uk/Products/WYMESB20.html and http://www.tlc-direct.co.uk/Products/HGIU2.html
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thanks for info simond got hold of rb1 relay today had a quick look at wiring layout any advice regarding connecting up
I don't have a diagram but you need to power the coil with the switched live output from the motorised valves you would normally use a the boiler switched live. NB: Most people use the orange MV wire for this.
The other side of the coil needs to be connected to neutral. Thus, when the valves are open the relay coil will energise..
Then you choose a pair of switch contacts (from memory the Drayton has more than one pair), put the boiler volt free out on one side, and the volt free in to the boiler on the other. Either way round makes no difference, obviously.
Thus when the coil energises, the boiler will get switched on.
You can do this with just the pin switches on the valves (eg: no relay) but it would confuse someone working on the boiler at some future point.
The other side of the coil needs to be connected to neutral. Thus, when the valves are open the relay coil will energise..
Then you choose a pair of switch contacts (from memory the Drayton has more than one pair), put the boiler volt free out on one side, and the volt free in to the boiler on the other. Either way round makes no difference, obviously.
Thus when the coil energises, the boiler will get switched on.
You can do this with just the pin switches on the valves (eg: no relay) but it would confuse someone working on the boiler at some future point.
B
BigBurner
Volt free contacts are normal for most combis as you just switch it with a volt free wall stat or stat programmer. This sounds like a problem with Honeywell zone valves if they send 70v through a voltage free end switch contact. Thanks for this as I would use another make of zone valve.
Wiring it, well I would take a permanent live to each volt free end switch on each zone valve. The other side of the end switch take to the coil of the relay. That is the three ed switches switch the coil of the relay. The volt free side of the boiler, which normally is switched by a stat but not in this case, just runs through one of the switches on the relay. The relay contact replaces the volt free room stat. The zone valves should be energised by time clocks or room stats or stat programmers.
Using proper zone valves that do send 70v down a volt free contact, it is a matter of taking a wire from each zone valve end switch back to the terminal of the volt free contacts on the boiler. Very simple if proper zone valves are used.
Wiring it, well I would take a permanent live to each volt free end switch on each zone valve. The other side of the end switch take to the coil of the relay. That is the three ed switches switch the coil of the relay. The volt free side of the boiler, which normally is switched by a stat but not in this case, just runs through one of the switches on the relay. The relay contact replaces the volt free room stat. The zone valves should be energised by time clocks or room stats or stat programmers.
Using proper zone valves that do send 70v down a volt free contact, it is a matter of taking a wire from each zone valve end switch back to the terminal of the volt free contacts on the boiler. Very simple if proper zone valves are used.
I do not see any reason why the volts free contacts in a zone valve should not be used.
Presumably this 70v is just whats measured on a high impedance DVM as a result of the capacitance in the connecting cable.
I would not have expected that would affect many boiler stat circuits.
Tony
Presumably this 70v is just whats measured on a high impedance DVM as a result of the capacitance in the connecting cable.
I would not have expected that would affect many boiler stat circuits.
Tony
B
BigBurner
I don't know anything about why this 70v is put down a so called volt free contact. I suspect it is the magnetic field of the zone valves coil which is doing this. Maybe putting some kitchen foil around the contacts in the zone valve may sort this out. Someone who knows more of this can comment. I would expect a major maker like Honeywell to have got this right.
The 70v was mentioned if you are using a three port. There is no problem with 2 ports, obviously.
I can only assume that Ethos want a belt and braces approach to protect a fragile PCB and demand the fitment of a relay.
I would expect this functionality to be in the boiler rather than needing a pile of other bits, seems like a poor show to me.
I can only assume that Ethos want a belt and braces approach to protect a fragile PCB and demand the fitment of a relay.
I would expect this functionality to be in the boiler rather than needing a pile of other bits, seems like a poor show to me.
Zone valves as in two port valves have a microswitch to operate auxillary equipment such as a boiler.
In the case of the Honeywell this microswitch is totally volt free on/off arrangement which is normally off on the 22mm version. The 28 version has an exytra wire so aux switch is a changeover device. Replacement heads have this extra wire.
The 3 port valve is a different kettle of fish because the way they work. The internal (to valve head) circuit and the auxillary switching is combined with the internal positional control so are NOT volt free.
In the case of the original post you can either use the valve internal microswitch which is volt free to control boiler dirrect or use this switch to operate a relay which in turn operates boiler. The second probably being better as it would be easier to keep the volt free connections isolated from the mains voltage within the wiring centre.
Get a 240Volt relay, base and box from Maplin, Rapid Electronics or similar.
In the case of the Honeywell this microswitch is totally volt free on/off arrangement which is normally off on the 22mm version. The 28 version has an exytra wire so aux switch is a changeover device. Replacement heads have this extra wire.
The 3 port valve is a different kettle of fish because the way they work. The internal (to valve head) circuit and the auxillary switching is combined with the internal positional control so are NOT volt free.
In the case of the original post you can either use the valve internal microswitch which is volt free to control boiler dirrect or use this switch to operate a relay which in turn operates boiler. The second probably being better as it would be easier to keep the volt free connections isolated from the mains voltage within the wiring centre.
Get a 240Volt relay, base and box from Maplin, Rapid Electronics or similar.
Larrytheleak, I have only looked at the first post by you and my take on that is you have three zones wired as S plan. Well, S plan uses two port valves. Auxillary switches in the two port valve can be used as voltage free switches or any other way you so desire.
Voltage free switch is needed on some boilers because the source voltage on the 'heat demand' connections on the boiler is not 240 volts. It does not matter anyway, because one of the connections on aforementioned terminals will have a voltage that has to be applied to the other terminal to start the boiler.
Have been to boilers which when switched off at the front panel are still live because some idiot has 'sourced' 240 for the auxillary switch from elsewhere when it shoould have been derived from 'terminals 3 and 4' commonly used on some boilers
Voltage free switch is needed on some boilers because the source voltage on the 'heat demand' connections on the boiler is not 240 volts. It does not matter anyway, because one of the connections on aforementioned terminals will have a voltage that has to be applied to the other terminal to start the boiler.
Have been to boilers which when switched off at the front panel are still live because some idiot has 'sourced' 240 for the auxillary switch from elsewhere when it shoould have been derived from 'terminals 3 and 4' commonly used on some boilers
It's an Ethos Combi.
I found it in the cunningly concealed first sentence from the OP.
If the manufacturer says they want a relay on the volt free line who am I to argue.
Who are you to argue? I thought you knew that boilers have to be installed to MIs?
I found it in the cunningly concealed first sentence from the OP.
If the manufacturer says they want a relay on the volt free line who am I to argue.
Who are you to argue? I thought you knew that boilers have to be installed to MIs?
If you have a combi, you can't have an S-Plan; that description is used for a system where you have a zone valve for the hot water circuit and one or more zone valves for the heating circuit.
I can't see why you would need a relay! It's just a case of how you wire up the zone valves. Connect all grey wires, which usually go to terminal 1 in the wiring centre to get a 240V supply, to an unused terminal. Connect all the orange wires, which usually go to the boiler on an S-Plan, to another spare terminal. Then connect these two terminals to the boiler volt-free control terminals.
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