Honeywell T63660B 102B upgrade to Heatmiser PRT Wifi

[LOGIK1]

I'm looking to upgrade a Honeywell thermostat with a fancy wifi one... I must say that I'm a little baffled by the wiring on the Honeywell as there only appears to be 2 wires as well as earth... the Heatmiser PRT wifi's state that they need 3 wires as well as earth...


I've included pictures here of what my current wiring looks like... How is this thermostat talking to the combi-boiler? Is there a hidden wire connected to pin 4 that I can't see?

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• LOGIK1
• 21 Oct 2012
• 1

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• LOGIK1
• 21 Oct 2012
• 1

Thanks in advance for any help and advice!

 

[EFLImpudence]

No, terminal 4 is live when the thermostat is used to call for cool so is not used.

 

[EFLImpudence]

Do you realise that the wired part of the new thermostat can be positioned near the boiler or wiring centre location?

The thermostat wireless part will presumably be at the present location where the wiring will not be required.

 

[LOGIK1]

Do you realise that the wired part of the new thermostat can be positioned near the boiler or wiring centre location?

The thermostat wireless part will presumably be at the present location where the wiring will not be required.

I think you misunderstand... I want to fit a Wifi thermostat, not a wireless RF thermostat... Its wifi in that it connects to my wireless network and I can control temperature from my phone or PC. Something like this one (there are several different model though) http://www.ebay.co.uk/itm/Heatmiser...arden_Hearing_Cooling_Air&hash=item337c77c955

Product states "It requires 230v (L,N) to power the thermostat, and then it offers a volt free changeover contact for the heating circuit. In simple terms, if your existing thermostat has three wires, excluding the earth - you can upgrade."

Still a little baffield by the wiring though, nothing is connected to pin 2? I'm starting to think that these arent drop in replacements?

 

[EFLImpudence]

Ok. My mistake about the wifi.

However, as you require a 'neutral' for the new one a new cable, 3 core & earth, will have to be run.

 

[EFLImpudence]

Had a look at the manual and see that it has a 'heat anticipator' and 'RFI supressor'.

I presume that it is just a mechanical thermostat and without the neutral (terminal 2) these features do not work.

 

[LOGIK1]

Had a look at the manual and see that it has a 'heat anticipator' and 'RFI supressor'.

I presume that it is just a mechanical thermostat and without the neutral (terminal 2) these features do not work.

Theres a similar model that has RF link to the boiler... I guess I could go with this... its a little pricey though to say the least!

http://www.ebay.co.uk/itm/Heatmiser...arden_Hearing_Cooling_Air&hash=item4d05b39d45

"What are the wiring requirements of this thermostat. A: It requires 230v (L,N) to power the thermostat "

 

[LOGIK1]

Anyhoo, im still baffield by the wiring in my current setup... It looks like I have mains cable? Earth+L+N?

I dont understand how it talks to the boiler...

 

[EFLImpudence]

Another point to consider is that the wiring may not be 240V.

It could be Extra Low Voltage (24V) and just connecting two terminals on the boiler circuitry.

 

[EFLImpudence]

Anyhoo, im still baffield by the wiring in my current setup... It looks like I have mains cable? Earth+L+N?

No. It's just live (240 or 24V) and switched live.
Just because it's black doesn't mean it's neutral, it's not.

I dont understand how it talks to the boiler...

It's just a switch which connects two terminals.


Regarding wireless, this one is considerably cheaper.
I fitted one in my daughter's house and have had no problems
http://www.screwfix.com/p/horstmann-hrfs1-programmable-room-thermostat/93829

As said, the receiver is fitted near the wiring centre or boiler and the sender unit just hangs on the wall anywhere you wish.

 

[LOGIK1]

Oh right, I see all these wires come from the boiler... switching off the boiler also cuts the power to the thermostat.

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• LOGIK1
• 21 Oct 2012
• 1

Thanks for the link to the cheaper versio. I do still feel that I really want a wifi version that lets me tweak the settings without having to stand in the hallway pressing buttons on a clunky interface... we seem to be constantly tweaking the settings and this makes more sense... but it is a tad expensive!

 

[Lectrician]

Your wiring is no good for the Heatmeiser one, you do need the neutral for it to function. They do the RF version too which would sort your issue.

These are brilliant - Once setup and connected to your WiFi, you can setup your port forwarding in your router, and access the stat from any PC, anywhere, and also using a smartphone app - I got one of these very cheaply when they first came out as part of an evaluation drive.

The wired version requires a 35mm deep flush box behind it, not sure on the RF version.

Screen shot from the iPhone app:

 

[LOGIK1]

Yes, the heatmiser wifi looks to be the dogs dangly bits.

According to the boiler wiring diagram, I have Live, Neutral and Switched live... The neutral is wired into the earth socket on the Honeywell.

 

[LOGIK1]

Chaps, finally managed to find the manual for the Heatmiser PRT... As far as I can tell the 3 wires I have are enough?

The heatmiser has "volt free contacts", which is just a fancy way of saying that it has a relay in it... Running a wire link from L to A2 like in the diagram and then connecting the Switched Live to A1 achieves what I need, does it not? From the heatmiser website :

"Our digital thermostats have volt free contacts and this means that we can switch anything from 12-240v. If you have three wires (not including earth) then you are switching 240v and the connection will therefore be live and neutral to power our thermostat and a third being the switch wire to the appliance. We call this "mains switching""

Heatmiser PRT-TS diagram

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• LOGIK1
• 22 Oct 2012
• 1

My boiler diagram (Worcester Bosch 35CDi)

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• LOGIK1
• 22 Oct 2012
• 1

 

[Lectrician]

No.

Your earth conductor in your twin and earth cable must be used for earth and earth only. You have the earth in the stats earth terminal, the red in the stats live terminal and the black in the stats 'call' terminal. You don't have any neutral connection. Your terminal 2 in the old stat should have a neutral connected (it wont be particularly accurate with out it).

Your current stat should really have a three core and earth cable to it, and your PRT stat would require this too. The relay output would be linked to the live supply to provide a sw live out, requiring just three cores PLUS earth.

As I said before too, the PRT stat needs a 35mm box to be flushed into the wall.