Fitting a Wireless Thermostat to my Ariston Micro Genus Comb

[davelunt2]

Hi guys.

I have puchased a Horstmann Programmable Room Thermostat from Screwfix for my Combi Boiler.

My boiler is a Ariston Micro Genus (Instructions http://www.ariston.co.uk/uploads/doc493fb61e1ad05.pdf)

Thermostat Instructions http://www.horstmann.co.uk/download...ermoStats/RF Programmable Room Thermostat.pdf

Below is how I think the thermostat needs to be installed, could anybody please comment if they think it sounds right.

Thermostat
NC (Not Closed) Not Used
COM - Live Feed to Boiler's External Thermostat Loop
NO - Switched Live to otherside of Boiler's External Thermostat Loop

L - 230v Permanant Live Feed
N - Neutral - I think I need to wire these to where the main power cable enters the boiler.

I also believe that I need to unplug the boilers built in clock from the P.C.B.



One thing I do not understand is switched live, is the thermostat being wired for volt free application and I therefore need to remove the wired link on the thermostat? I inparticular do not understand points 6 & 7 of the below instructions.

The Instructions for my Boiler are as follows:

To connect a room thermostat, it is necessary to:
1. - Open the control panel as indicated in section 3.3.
2.- Remove the link “A” from the terminal block on the reverse of the control panel.
3. - Insert the thermostat cable through the cable grommet and fasten it by means of the
cable-clamp provided.
4. - Then connect the thermostat wires to the terminal block.
5.- If a remote time clock is to be fitted, disconnect the integral time clock from the P.C.B.
6. - Using a volt-free switching time clock, connect the switching wires from the time clock following points 1-4 above.
7. - If using an external time clock and room thermostat, these must be connected in series as points 1-7 above.

Note: Only a two-wire type room thermostat can be used.
An anti-frost device is built-in to the appliance’s electronic regulation
system.

Any help would be greatly appreciated.

Thanks in advance.

David Lunt
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[D_Hailsham]

Thermostat
NC (Not Closed) Not Used
COM - Live Feed to Boiler's External Thermostat Loop
NO - Switched Live to other side of Boiler's External Thermostat Loop

L - 230v Permanent Live Feed
N - Neutral - I think I need to wire these to where the main power cable enters the boiler.

Correct. L and N power the electronics in the thermostat. COM and NO turn the boiler on/off

Follow the diagram on page 10 (volt free)

I also believe that I need to unplug the boilers built in clock from the P.C.B.

I think this is correct but, as you say, the mfr's instructions are confusing.

The wires from COM and NO go to the two terminals which have link A between. (Remove link A!)

I suggest you disconnect the internal clock and see if the boiler lights and the new stat takes control. If it doesn't, reconnect the internal clock and set it to constant, i.e on 24 hours, and check the new stat does its job.

One thing I do not understand is switched live, is the thermostat being wired for volt free application and I therefore need to remove the wired link on the thermostat?

The link on the stat must be removed as the boiler uses "volt free" control. All the thermostat does is to make a connection between the two terminals on the boiler. It does not matter which way round the connections are.

 

[davelunt2]

Thank you so much for your relpy, it nice to have some confirmation that what I was thinking was correct.

I did think I needed to remove the switching wire on the thermostat.

Could I use 2 seperate 2 core cable from the thermostat receiver

i.e. one piece of 2 core cable for the power and one piece for the external thermostat loop?

 

[D_Hailsham]

Could I use 2 separate 2 core cable from the thermostat receiver

i.e. one piece of 2 core cable for the power and one piece for the external thermostat loop?

That's OK, but you should be using heat resistant cable for any wires connected to the boiler, so a four core may be easier and cheaper. (That's four core plus earth; the earth is not used.)

 

[davelunt2]

Thanks once again, I'll order some 5 core heat resistant then, is 0.5mm okay?

http://www.tlc-direct.co.uk/Products/CA0dot5HR5.html

 

[D_Hailsham]

0.75mm would be better.