Adding a Honeywell CM67RF to a ferroli modena 102

[jonnybegood]

Hi all,

I currently have no room thermostat attached to my ferroli combi boiler, out of 11 rads there are 8 that have TRVs fitted.

Firstly are the wireless devices reliable?

I have the Ferroli manual and the Honeywell installation manual, its seems fairly straight forward fitting the thermostat, but is the Honeywell compatible with the boiler and if so could someone with that bit of knowledge of Ferroli boilers explain the best way of doing things.

The current set up is the boiler has a 3amp fused plug to power it, I assume I would need to T off this supply to run the honeywell receiver, it mentions in the ferroli manual that the connections on the board for the thermostat are voltage free.

Note - When connecting a room thermostat or external timer, do not link the power supply of these devices to the
switching contacts. The switch contacts must be voltage free. Any mains powered devices must utilise mains power
solely to drive the timer motor.


Can someone explain this little bit for me.

IT currently has a built in timer on the front panel I assume this could just be left on 24hrs and leave the honeywell do the switching on and off as needed.

Thanks in advance for any help

A.S

 

[clf-gas]

As a budget room stat I fit this one, http://www.tfc-group.co.uk/assets/graphics/static/STT RF.pdf

Easy to wire in from D/P fused spur.

Fitted £75, I pay £40 for these you might have to pay that little extra, or do you have the Honeywell already.

Wiring as you say is easy and the HW you may have will work with your boiler.

 

[D_Hailsham]

The current set up is the boiler has a 3amp fused plug to power it, I assume I would need to T off this supply to run the honeywell receiver, it mentions in the ferroli manual that the connections on the board for the thermostat are voltage free.

Note - When connecting a room thermostat or external timer, do not link the power supply of these devices to the
switching contacts. The switch contacts must be voltage free. Any mains powered devices must utilise mains power
solely to drive the timer motor.


Can someone explain this little bit for me.

Here is the wiring diagram from the CM67 Install Manual

You will see that for a normal boiler (diagram a) there is a link from the L terminal to the A terminal. In this case the switch when closed will put mains on to terminal B.

In diagram b, the Combi boiler, there is no link from L to A, so the switch between A and B is just connecting two terminals on the boiler together. This is what is meant by volt-free switching.

Hope this explains the difference

 

[gas4you]

I thought the CM67 has been replaced by the 900 series

The Ferolli should have some volt free terminals to connect external controls to. Thes should be connected to the switch side of the receiver (right hand block if I remember correctly) the mains is just connected to the L & N in the receiver.

 

[jonnybegood]

D_Hailsham

here is the installation guide from the ferroli manual

What would be the best cable to use to connect the receiver, would I need 2 single cables or just 1 twin if possible.

Thanks

A.S

 

[gas4you]

0.75mm heat resistant flex. I would use 5 core personally.

 

[gas4you]

0.75mm heat resistant flex. I would use 4 or 5 core personally.

 

[jonnybegood]

0.75mm heat resistant flex. I would use 5 core personally.

Why would I need 4-5 cores, having opened up the connection box and look at the diagrams it seems only 2 cables are required from receiver to boiler.

I will be spurring off the boiler power supply cable which is plugged into a 3A fused socket, would you suggest the same cable be used for connecting the L&N to the receiver, can you see any problems doing this.

 

[gas4you]

In this instance I would take the L & N from the boiler 240V terminals and the volt free ones for the stat switch.

This way you know that everything will be dead when mains switched off without question.

4 core with brown sleeved earth, or 5 core and ignore the earth.

 

[D_Hailsham]

What would be the best cable to use to connect the receiver, would I need 2 single cables or just 1 twin if possible

The receiver needs four cores: L, N, A and B. It does not need an earth.

It might be easiest if you think of the receiver replacing the clock in the above diagram.

Terminals 1 and 2 of the clock are equivalent to the L and N terminals of the Receiver. So you could feed the receiver from X2/1 and X2/2, instead of spurring off from the main switch. Make sure you get the polarity right.

Terminals 3 and 4 (item 72 - the volt free switch) are equivalent to the A and B terminals of the receiver. You will find that they are linked together. Remove this link and connect A and B to these; polarity does not matter.

If you wanted to disable the clock entirely, connect X4-1 to 72/3.

Before you do any wiring check the reception of the receiver from the proposed location of the control unit. Honeywell say that the receiver should be at least 30cm from metal objects, such as the boiler. When I installed mine, I connected the receiver to a long flex plugged into the mains. I could then experiment with different positions until I found the best one.

 

[jonnybegood]

What you are basically saying is that where the 3A supply feeds into the boiler terminal blocks, take a L&N from there to the receiver and use the other 2 spare cores for the voltage free connection from receiver to boiler, i.e black & brown (Live and neutral) and red and blue for voltage free to stat.

 

[gas4you]

nearly. Brown & blue L & N, black and whatever else volt free, brown sleeve if using earth.

You must have old flex/cable if it has red in it.

 

[jonnybegood]

nearly. Brown & blue L & N, black and whatever else volt free, brown sleeve if using earth.

You must have old flex/cable if it has red in it.

No the cable is new, just a figure of speech so that I follow what your saying, I have just had another look after reading D_Hailsham comments so I could either wire the L&N to the receiver from the terminal block where the 230V supply comes in, or replace X2/1 and X2/2 with the connection from the receiver instead of the clock.
The second option is going to mean disabling the clock (even though it is no longer needed) or would it be possible to feed both from X2/1 and X2/2.

 

[D_Hailsham]

I have just had another look after reading D_Hailsham comments so I could either wire the L&N to the receiver from the terminal block where the 230V supply comes in, or replace X2/1 and X2/2 with the connection from the receiver instead of the clock.

Correct, though I would chose the X2/1 and X2/2 option

The second option is going to mean disabling the clock (even though it is no longer needed) or would it be possible to feed both from X2/1 and X2/2.

I can't think of any reason why not - the current drawn will be negligible. Though why keep the clock running if you are not using it? I would set the clock to midnight and disconnect it (I might even remove the clock completely). What you do not want is to have other people confused as to which clock is controlling the boiler!