I have a Glow-worm 38cxi combi boiler (very happy with it by the way) and
I've decided to install a programmable thermostat. The one I've decided on
is the CM67 RF NG, not least because of the good reports it gets on this
group.

Now, the installation guide for the CM67 relay (HC60NG) is a bit sparse.
Basically the mains wiring is OK, but it shows 2 wires leaving the relay
going to a symbol which I take to mean the boiler to 2 switches marked T1
and T2 as follows...

HC60 A B C D E
| |
BOILER T1 T2

But on the diagram there is a little picture showing switching between A and
B and A and C...

HC60 |------------|
| / \
A B C

So T1 on the boiler A can be connected to B or C either of which is directed
to T2 on the boiler.

This text is also printed on the picture...

24-230V
A-B:10(3)A 0..30 deg C / 8(3)A 0..40 deg C
A-C: 5(3)A

Now I have a couple of questions.

1) The 38cxi boiler doesnt have any switches labeled up as T1 or T2. The
installation guide shows a programmer/thermostat only connecting via 1 wire
in the central position of a 3 way block for mains voltage connections. I
assume the HC60 is a mains voltage controller. What wires do I need to
connect from the HC60 to the 38cxi?

2) What switch setting is required between A and B or C within the HC60?

Any help would be gratefully received.

--
====================================
Swap nospam for bluerose to reply personally.

I think I may have found the answer to this. The HC60 is voltage free
and so it can just be connected to the votlage free controls terminal
on the combi. No problem their but I do have another question.

Do I need to make the connection between A and C terminals within the
HC60 myself (ie by adding a piece of wire between them)?

The reason I ask is because the diagram on the application guide shows
just such a connection, but the accompanying text says "just connect
terminal A and B to two boiler terminals and the job is done", which
implies there is no need to manually make the A-C connection.

If this doesn't make sense, here is a link to the application guide
supplied (it's a PDF). Look at page two and the text and accompanying
diagram.

http://content.honeywell.com/uk/homes/files/pag114.pdf

Thanks.
Dean Lawrence wrote:
I have a Glow-worm 38cxi combi boiler (very happy with it by the way) and
I've decided to install a programmable thermostat. The one I've decided on
is the CM67 RF NG, not least because of the good reports it gets on this
group.

Now, the installation guide for the CM67 relay (HC60NG) is a bit sparse.
Basically the mains wiring is OK, but it shows 2 wires leaving the relay
going to a symbol which I take to mean the boiler to 2 switches marked T1
and T2 as follows...

HC60 A B C D E
| |
BOILER T1 T2

But on the diagram there is a little picture showing switching between A and
B and A and C...

HC60 |------------|
| / \
A B C

So T1 on the boiler A can be connected to B or C either of which is directed
to T2 on the boiler.

This text is also printed on the picture...

24-230V
A-B:10(3)A 0..30 deg C / 8(3)A 0..40 deg C
A-C: 5(3)A

Now I have a couple of questions.

1) The 38cxi boiler doesnt have any switches labeled up as T1 or T2. The
installation guide shows a programmer/thermostat only connecting via 1 wire
in the central position of a 3 way block for mains voltage connections. I
assume the HC60 is a mains voltage controller. What wires do I need to
connect from the HC60 to the 38cxi?

2) What switch setting is required between A and B or C within the HC60?

Any help would be gratefully received.

--
====================================
Swap nospam for bluerose to reply personally.

In an earlier contribution to this discussion,
wrote:

I think I may have found the answer to this. The HC60 is voltage free
and so it can just be connected to the votlage free controls terminal
on the combi. No problem their but I do have another question.

Do I need to make the connection between A and C terminals within the
HC60 myself (ie by adding a piece of wire between them)?

The reason I ask is because the diagram on the application guide shows
just such a connection, but the accompanying text says "just connect
terminal A and B to two boiler terminals and the job is done", which
implies there is no need to manually make the A-C connection.

If this doesn't make sense, here is a link to the application guide
supplied (it's a PDF). Look at page two and the text and accompanying
diagram.

The stat has change-over contacts - because it can be used for heating *or*
cooling. You're just using it as a switch - so you only need to use 2 of the
3 contacts - common and normally closed. The boiler will then run when the
room temperature is below the stat setting, and will switch off when the
room gets up to termperature, and the stat operates.

Hope that makes sense!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Sort of! But I still don't understand whether I need to put in the link
between A and C terminals (as per the diagram) or not (as per the
text).

Set Square wrote:
The stat has change-over contacts - because it can be used for heating *or*
cooling. You're just using it as a switch - so you only need to use 2 of the
3 contacts - common and normally closed. The boiler will then run when the
room temperature is below the stat setting, and will switch off when the
room gets up to termperature, and the stat operates.

Hope that makes sense!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
wrote:

Sort of! But I still don't understand whether I need to put in the
link between A and C terminals (as per the diagram) or not (as per the
text).

There *isn't* a link between A and C. What the diagram shows is the
*internal* workings of the thermostat switch. When the room temperature is
low, A is connected to B - so the boiler runs. When the room temperature is
high (above the stat setting) the contacts change over and A is connected to
C instead. Forget about C - that is only needed if you use the stat to drive
an air conditioner - so you need it to come *on* when the temperature is
high. For your purposes, just think of it as a switch between A and B which
is ON when it's cold and OFF when it's hot.

Does that make any more sense?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Ahh! Yes, that makes perfect sense. The diagram is a representation of
the thermostat switching in response to the temperature (what you buy
one for really). Yes, I understand now. Thank you very much for your
help. All I need to do is connect the two wires from terminals A and B
on the HC60 to the voltage free terminals on the boiler and away it
will go.

Don't you just love those lightbulb moments. Thank you again.

Set Square wrote:
There *isn't* a link between A and C. What the diagram shows is the
*internal* workings of the thermostat switch. When the room temperature is
low, A is connected to B - so the boiler runs. When the room temperature is
high (above the stat setting) the contacts change over and A is connected to
C instead. Forget about C - that is only needed if you use the stat to drive
an air conditioner - so you need it to come *on* when the temperature is
high. For your purposes, just think of it as a switch between A and B which
is ON when it's cold and OFF when it's hot.

Does that make any more sense?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
wrote:

Ahh! Yes, that makes perfect sense. The diagram is a representation of
the thermostat switching in response to the temperature (what you buy
one for really). Yes, I understand now. Thank you very much for your
help. All I need to do is connect the two wires from terminals A and B
on the HC60 to the voltage free terminals on the boiler and away it
will go.

Glad to be of help!

One other thing - *please* post your replies *below* the message you're
replying to - *never* above!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.