Which is the best Tado set up for a new Vaillant ecoTEC VU 446/5-5 48kw system boiler?

Davell

I have recently had a a new Vaillant ecoTEC VU 446/5-5 (48kw light commercial) system boiler fitted. We are in a victorian house over 3 floors and a converted basement. There are 21 rads on 2 heating circuits controlled by 2 x Honeywell CM907 wired thermostats, 1x UFH circuit controlled by a separate thermostat and a hot water cylinder. The Honeywell thermostats are connected to a Horstmann Channelplus H37XL that controls the heating and hot water. Ideally I want to fit smart TRVs in all the rooms. I'm a bit confused as to what the best interface would be to replace the Horstmann controller as I would like to get the benefit of the controllers telling the boiler how to modulate (I think this is via EBUS??) Any advice much appreciated. I have also provided Tado with all this information and am waiting to hear back.

policywonk

Need to take this slowly. Dont worry about the Horstmann H37, thats a dead simple 3 channel controller. According to this page Are there any restrictions on tado° X devices per room/Home and rooms per tado° Home? | Help Center: tado° X - the X range should be able to handle this.

The challenge is to establish a completely EMS BUS, or Opentherm compatible environment which allows you to control output to the HW cylinder. If that can be addressed, the rest should be within reach. Tado dont do an EMS-BUS connectable HW thermostat. An obvious, silently avoided fact.

Need to check a few things with you.

1. Those wired thermostats - do they only add value in controlling the zone valves, ie when you've placed TRVs everywhere and put smart heads on them, will you really need those wired stats any more?
   1. Suggestion is, if this makes sense, replace them with automatic bypass valves,
   2. Remove their existence from the wiring centre so that the Horstmann controller only serves as a programmer, directly authorising the boiler and the pump rather then routing the authorisation through the zone valves.
2. Contact Vaillant and ask them if they have a wiring centre which allows you to fit their recommended, EMS compatible thermostat or EMS thermal sensor to handle the zone valve needed for the HW cylinders.

Come back. Will take it another step.

Davell

Thanks for the advice and I'll contact Vaillant as suggested.