Nest thermostat E installation Baxi duo tec 2 combi
Posted: Tue Mar 16, 2021 5:26 pm
by Nate500
Hi there recently acquired a nest thermostat E, and would like to install myself, I've followed the guide so far but am pretty stuck already ! I have dual zone heating, a baxi duo tec 2 combi and a myson wireless thermostat currently, I get to the stage where it says to replace the wireless reciever with the heat sink and this is where I'm stuck I can't seem to find one! All I can find is two myson power extras under the boiler, I just wondered if anyone could point me in the right direction or wondered if I needed to hire someone to install this for me, please see photos below
Re: Nest thermostat E installation Baxi duo tec 2 combi
Posted: Mon Mar 22, 2021 4:48 pm
by ericmark
The Myson power extra is a zone valve, the normal method is a thermostat controls a zone valve and the zone valve controls the boiler so boiler can't turn on until zone valve is open.
So orange and grey on zone valve turn on the boiler and the brown and blue work the zone valve, so normally there would be a thermostat some where which makes and breaks the supply to the brown wire on the zone valve.
There are some devices designed to work with two zones, EPH do special thermostats which work as master/slave and Drayton Wiser does a three channel programmer with a combo you would only use two channels. But the boiler does not seem to have any OpenTherm or ebus option so any pair of thermostat will do the job.
But you do need two thermostats, one would hope if you trace the two leads from the two motorised valves you should find the bases for the Myson thermostats.