My old room theromostat had 3 wires L, N and one to pin 2 I guess for Call for heat
I have bought a wireless stat, but the wiring diagram to the backplate shows 5 wires L,N and pins 1,2,3 are all used.
Am I safe wiring the same backplate as my existing old stat or do I need to investigate the wiring from the spagetti in the box next to the boiler? TIA
Call me silly, but I thought the idea of a wireless stat was that there are no wires???
Our Alpha 7-day Wireless EasyStat (it controls our Alpha CD32C boiler that's up in the loft) is battery operated and has no external wiring to it at all.
John
You need to understand the *function* of each of the connections, and wire it accordingly.
I've never installed a wireless stat, but my guess is that L and N are to power the base station - and probably need a constant supply taken from the FCU. The 1,2,3 connections are likely to be the actual switch - operated remotely by the wireless temperature sensing unit - so one pin will need a live feed from the programmer (like the old stat) and one will be the switched live which goes to the boiler or zone valve or wherever, again as before. Assuming it's a change-over switch (most are) the third connection won't be used.[1] The two to use will be Common and whichever of NC and NO (definitions vary!) is connected to Common when the room is cold, and disconnected when the room temperature is above the set point.
[1] Don't under any circumstances connect it to N - unless you like fireworks! The reason for having a neutral connection on the old stat (as a return for the accelerator heater) doesn't apply to the new stat.
so the receiver talks to the boiler via telepathy?
No, via radio (wireless) which is the whole point of a wireless stat. The stat is the transmitter, the receiver is in the boiler.
John
These wireless stats are intended for boilers which don't come with a wireless receiver built-in, like yours apparently does.
Wireless worked out well here, otherwise I'd have had to track walls all over my house to wire the stat in. I still needed to wire the wireless receiver to the boiler. That is the point of a wireless stat.
exactly
Well in my case, the boiler originally came with a mechanical/electrical clock/timer thingy in the boiler. The clock comes out, three or four spade terminals on the back, and the wireless receiver is a direct replacement for that so yes, I agree, obviously wiring has to be connected to that.
Maybe I just read the OP wrong, but it obviously wasn't clear to me that Vass was talking about the receiver end. In fact, his first line states *My old room theromostat had 3 wires* so I assumed he was talking about that end of the equation, and I couldn't weigh up why he was wiring a wireless stat.
John.
Wall it was screwed to has been removed, cable pulled back to boiler that went originally to stat. now needs to go to "receiver" also in my OP
Firstly, what are the model numbers of the old and new thermostats?
For example I'm replacing a Honeywell T6360 with a Honeywell CM907 after an earlier poster put me onto the two subject of chronostats.
The CM907 is battery powered but is wirted up to a live feed which it switches between two outputs - call for heat and call for cooling.
I looked at the Honeywell CM927 (I think that's the model) which is basically the wireless version of the CM907 the base unit needs a L and N feed to power it and switches three connectors - an input with two outputs.
I decided against the CM927 because of the extra wires. Now, it's possible that I could have powered it off the wires for the T6360 as the supply to the T6360 appears to be a live, neutral and call for heat.
The live and neutral would be wired up to the CM927s L and N feed and the live to one of the three numbered terminals. The call for heat wire would then be wired to the appropriate numbered terminal. This would probably work but I was not 100% sure...
Guy
-- -------------------------------------------------------------------- Guy Dawson I.T. Manager Crossflight Ltd snipped-for-privacy@crossflight.co.uk
To be fair mate, I never saw any of the above paragraph in your OP. I guess Mr Mills has hit the nail on the head though.
Adam
New = Sunvic TLX RFD (from QVS) thanks
Apologies for poor sketch can you make anything of this?
According to
If the web page is right, replace the original room stat as follows:
Given the need for safety please can someone check the above?
John
"John Phillips"
yes sorry, pin1 has no metal connections, just 2, 3, and 4 the web link you give is exactly what I have and the wiring diagram matches the leaflet in the box
Then I believe the connections I proposed are correct. The only question is which way round the switch works and whether to use pin 3 or pin 4 for the red switched live out wire.
BTW are you sure that the green N wire to the existing thermostat in your diagram is actually connected to the neutral terminal block? That looks odd and you write something about an unsheathed earth that confuses things.
yes its horrible, am going to replace the cable with a 4 core now, and tag the green wire accordingly If I'm not back in an hour or two, it went wrong ;-)
Many thanks John for all your help Your first option for pin 2 and 3 was correct All works perfectly Many thanks again, would not have managed with you
WELL DONE THOSE MEN.
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