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5 'dial' Thermostats in House... Best 'Smart(ish)' Replacement Advice Needed

Postby matt_in_real_life » Fri Feb 07, 2020 3:08 pm


We're in a house which has underfloor throughout the ground floor and standard rads on the 1st and 2nd floors with a Baxi combi boiler and Salus 'wiring centre'. We have a total of 5 dial/analogue thermostats (4 downstairs to control each room, one on the 1st floor (to miraculously control 1st and 2nd floor rads)).

We're looking to replace the thermostats so that we have programmable control. Obviously the simplest thing is to replace with 5 x programmable thermostats but - as well as all we've seen being ugly as sin - we want to make sure we're not missing a trick by not going for (at least some) smart options.

Having looked around online at the big names (Hive etc), I can't understand why - with our set up - we'd need the hub and other ancillaries. In an ideal world, I'd like to replace the thermostats with programmable thermostats that have WiFi support so that they can be programmed (and overridden if necessary) from an iOS app which simply contains 5 rooms/zones. I think I've found some thermostats like this online around the £35 mark, but they have pretty poor reviews. Alternatively, I wondered if there was such a thing as replacing all the thermostats with room sensors and then having all control via an app or a dedicated piece of kit?

Any suggestions, thoughts or input?

Thank you!
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Postby ericmark » Fri Feb 07, 2020 8:28 pm

Under floor not so sure how it works but standard radiators with TRV I would say fit electronic heads first, and see if that is enough.

I have 4 wifi and 5 bluetooth heads, £35 and £15 the non bluetooth seen at £10 each. Easier to set up with bluetooth, but once set I walk into a room press one button to move from Eco to Comfort, nothing simpler.

If you want to add geofencing latter, then the Hive TRV head can be both used one their own and with the wall thermostat.

I use Nest as it allowed CH and DHW control with two wires between main house and flat under house where boiler is, it was not fitted for the occupancy detection or geofencing.

Boiler does make a difference, oil in the main don't modulate, so no point having opentherm thermostat, Bosch do not allow third party modulating thermostats, to connect to ebus you have to use their thermostat so one room only.

EvoHome opentherm is an add on extra, Tado I don't know how it works.

Non modulating boilers easy, with modulating boilers idea is not to turn off/on but up down, easy way to control up/down is return water temperature so the TRV is king.

Using the ebus with some boilers means the boiler turns down before it turns off, so less heat lost from flue each time it turns off, some have complex algarithums so will do same using return water temperature.

So the on/off thermostat is to turn boiler off in summer, in winter it does nothing. So in coolest room with no outside doors or alternative heating.

The under floor heating however can mess things up, we talk about the hysteresis and the under floor heating stores that much energy it can cause the boiler to switch off for too long.

How well the house is insulated and if morning sun can lift the temperature of selected rooms clearly makes a difference. In general easy to heat, harder to cool, so main thing is not to allow any room to over heat.

Look at the eQ-3 TRV head, there is also the Terrier i30 seen the former for under £10.

I found with mothers house the big advance was having a TRV and wall thermostat in same room (the hall) this goes against all advice, however it worked, when front door opened the TRV opened wide allowing quick recovery, but before it turned off wall thermostat it turned down allowing time for other rooms to heat up before turning off boiler, some times you need to think out of the box.
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