by ericmark »
Sat May 09, 2020 12:04 pm
It does seem the new thermostat is for under floor heating, terminals 5 and 6 would connect to a sensor to stop floor getting too hot, as said your line and neutral are correct, and there will be a link line to either 1 or 2 and black wire to the other terminal.
Do be aware the wall thermostats job is to stop the boiler cycling in the summer, and with a wifi linked one also it can be used for geofencing, however for a boiler to work efficiently the return water needs to be cooler than 40°C, if you switch whole boiler on/off each time it switches on it runs flat out, until the return water heats up, and then it tends to over shoot, so you don't get the latent heat the boiler is designed to extract, so room temperature should be controlled with the thermostatic radiator valve (TRV) and you can now get reasonably cheap electronic programmable heads, the eQ-3 is a good example, at less than £10 I got the bluetooth version for £15, these gradually adjust water flow, so the return water gradually heats up or cools down and the boiler flame hight auto adjusts to suit (modulates). This allows the boiler to extract the latent heat.
I use a smart wall thermostat, but also a programmable TRV head in the same room set just slightly lower to the wall thermostat, so the TRV head does the controlling first, and only when weather warms up does the wall thermostat turn off.
There are linked systems like evohome, tado, wiser and hive, but the TRV heads are around £50 so I simply set the same schedule on the TRV and wall thermostat, and that seems to work nearly as good.
