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
--
Vass
'06 R1, '90 CBR1000F
www.doubleyolk.co.uk

"Vass" wrote in message
...
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

"John" wrote in message
...

"Vass" wrote in message
...
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.

so the receiver talks to the boiler via telepathy?

"Vass" wrote in message
...

"John" wrote in message
...

"Vass" wrote in message
...
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.

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

John wrote:

No, via radio (wireless) which is the whole point of a wireless stat. The
stat is the transmitter, the receiver is in the boiler.

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.

"Geronimo W. Christ Esq" wrote in message
...
John wrote:
I still needed to wire the wireless receiver to the boiler. That is the
point of a wireless stat.

exactly
--
Vass

"Geronimo W. Christ Esq" wrote in message
...
John wrote:

No, via radio (wireless) which is the whole point of a wireless stat. The
stat is the transmitter, the receiver is in the boiler.

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.

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.

In an earlier contribution to this discussion,
Vass wrote:

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

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.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Vass wrote:

[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.

Hi Roger
Apologies for poor sketch
can you make anything of this?
http://www.naldernet.plus.com/utils/boilerwires.JPG
thanks
--
Vass

On 2007-10-20, Vass wrote:

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Vass wrote:

[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.

Hi Roger
Apologies for poor sketch
can you make anything of this?
http://www.naldernet.plus.com/utils/boilerwires.JPG
thanks

According to http://www.sunvic.co.uk/tlxrrt.html the receiver box is a TLX
1206. It has one more pin (N L 1 2 3 4) than you write in your original
post. Can you check this. It's very important to get this right.

If the web page is right, replace the original room stat as follows:

1. connect the existing green N (neutral) wire to N on the new
receiver box

2. connect a *new* unswitched live lead from the L terminal block
to L on the new receiver box.

3. connect the existing black "switched live in" wire to the switch
commmon pin on the new receiver box. According to the web page
above that's pin 2.

4. connect the existing red "switched live out" wire to the call for heat
pin on the new receiver box. If the web page is right that's
probably pin 3 but it isn't clear. If the control works the wrong
way round (i.e. the boiler stays off when cold) then connect it to
pin 4 instead.

Given the need for safety please can someone check the above?

John
--
John Phillips

"John Phillips"

According to http://www.sunvic.co.uk/tlxrrt.html the receiver box is a TLX
1206. It has one more pin (N L 1 2 3 4) than you write in your original
post. Can you check this. It's very important to get this right.


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
--
Vass

On 2007-10-20, Vass wrote:

"John Phillips"

According to http://www.sunvic.co.uk/tlxrrt.html the receiver box is a TLX
1206. It has one more pin (N L 1 2 3 4) than you write in your original
post. Can you check this. It's very important to get this right.


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.

--
John Phillips

On 2007-10-20, Vass wrote:

"John Phillips"

According to http://www.sunvic.co.uk/tlxrrt.html the receiver box is a TLX
1206. It has one more pin (N L 1 2 3 4) than you write in your original
post. Can you check this. It's very important to get this right.


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

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.

--
John Phillips

In an earlier contribution to this discussion,
Vass wrote:

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Vass wrote:

[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.

Hi Roger
Apologies for poor sketch
can you make anything of this?
http://www.naldernet.plus.com/utils/boilerwires.JPG
thanks

I see from your later posts that you seem to have sorted it.

Yes, your drawing does make sense. You have a fairly conventional Y-Plan
system - fully pumped with a 3-port mid-position valve to direct the boiler
output to either the HW or CH circuit, or both at the same time depending on
demand. If you study the Y-Plan wiring diagram at
http://content.honeywell.com/uk/homes/systems.htm you'll see that it's
essentially the same as yours (albeit using different pins in the wiring
centre for some of the functions).

The wiring has been done in a way which is all too common - using whatever
cable is readily to hand rather than the proper stuff - so you've got the
neutral wire of a T&E cable used for live, and the unshielded earth wire
used for neutral! But hopefully you've now corrected that.

As I was saying in an earlier post, the neutral connection to the old stat
was purely to act as a return for the accelerator heater (which gets
slightly warm when the heating is on, and reduces the stat's hysteresis).
Digital stats need no such fudge, and the neutral wire must *not* be
connected to any of the switching contacts - otherwise in some condition or
other it will get connected to live and cause a dead short.

As others have said, the base unit of the new stat needs an unswitched L & N
feed from the left-hand end of your wiring centre, purely to power it - and
your existing black and red wires (or their replacements if you've rewired
that bit) must be connected to Common and Call for heat respectively.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Vass wrote:
"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Vass wrote:

[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.

Hi Roger
Apologies for poor sketch
can you make anything of this?
http://www.naldernet.plus.com/utils/boilerwires.JPG
thanks

Looking at the sketch, my understanding of the original leads is

unsheathed (green in diag) - neutral
black in diag - switched live
red in sketch - load

The black is a live feed to the original thermostat that is only
live during the times the timer switch is programmed to have the
heating on. This lead is connected to the input on the original
thermostat.

The red lead is the switched output from the thermostat. It operates
the valve which in turn operates the bolier. For the red output to
be live the timer switch must make the black live and the roomm
temprature must be below the trigger temprature of the thermostat.

So far, so standard.

I suspect that the unsheathed neutral is either not used or wired to
an anticipator circuit in the old thermostat. Basically a resistor
that heats up then the thermostat is on and triggers a slightly
early turn off.

Does this sound reasonable?

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

Vass wrote:
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

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

"Guy Dawson" wrote in message
...
Vass wrote:
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

Firstly, what are the model numbers of the old and new thermostats?


Old = Drayton T45

New = Sunvic TLX RFD (from QVS)
thanks
--
Vass

On Friday, October 19, 2007 2:52:08 AM UTC+8, Vass wrote:
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
--
Vass
'06 R1, '90 CBR1000F
www.doubleyolk.co.uk

On Friday, October 19, 2007 2:52:08 AM UTC+8, Vass wrote:
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
--
Vass
'06 R1, '90 CBR1000F
www.doubleyolk.co.uk