Need help with Nest wiring to boiler and underfloor vent

30 Oct 2016
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United Kingdom
Hello all

Hoping to get some help here.

I just got a nest 3 to replace my existing system.

My boiler is Ferroli DOMIcompact F30B and a Danfoss thermonstat. I also have underfloor heating vents and fans controlled by a set of separate thermostat and control. Its a Danfoss clock thermostat connected to a Jaga Room Controller on DC to switch the fans on/off.

The idea is - when CH is on, the fan in the vent is on too. However it is controlled by a separate set of thermostat and I had to program both the boiler and fan thermostats to go on at the same time. It was annoying as most of the time they switch on/off at different times since they are operating on their own set of thermostats and temperature.

So yesterday I got the Nest 3 and hoped to link up both the boiler and fans to work together. I got the boiler danfoss thermostat replaced no problem. Nest is able to control CH via opentherm. But I couldnt figure out how to wire the fan controller to the heat link so that when CH is on, the fans in the vent are on too.

I am now running a L/N to the heatlink from a socket.
Connected the heatlink to boiler via the OT1 and OT2. Boiler/CH working great with Nest.
I have attempted to wire 2 & 3 from the heat link to the Jaga control but no joy. Not sure how.

Any idea to connect the fan control to the heat link too? Its a DC system.

Pictures attached.

Thanks in advance!



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20 Jul 2005
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United Kingdom
I have only ever seen a system like yours once and I'm not 100% sure it was a Jaga. Anyway, The controller will likely have the facility for remote control somewhere using a potential free contact. If so, if you use a relay, and connect the relay coil to the Hive 'Neutral' and 'Heating on' terminals, then you could use the relay's potential free contact as a remote control.

Alternatively, depending on how the system is configured to work, you might be able to use a relay with multiple contacts to switch the 24 v signals from the thermostat to control the heating and the vent.
Last edited:
28 Nov 2019
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United Kingdom
Hi AaronTTQ,

Did you end up finding a solution to your problem?
I have the exact same configuration (so much so we probably live in the same development), and was planning on making the following connections in addition to OpenTherm:
Jaga #5 to Heat Link #2
Jaga #2 to Heat Link #3

What I’m worried about though is that the Heat Link might not trigger the relay between 2 and 3 when operating with an OpenTherm boiler. Would you be able to shed some light on this?


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