How do multiple TRVs work?

ChrisMac

Existing system: Roomstat and timeswitch with two switching periods per day, manual TRVs.

Proposed Tado system: To have a smart TRV in each room each with its own schedule.

What happens when the schedule for one TRV says 'off', does it change its setting to 0 degrees? If not does another TRV saying 'on' turn on the boiler thus overriding the schedule of the first TRV?

Adzyp

Battery life will dependent on how often your schedules changes. More commonly used rooms will likely use up batteries quicker but ours are moving multiple times a day and only have to change once a year for the quieter rooms, maybe longer, slightly more often for busier rooms.

I just use rechargeable batteries and keep some as backup ready to go

hugbilly

If the TRVs are assigned to a zone controller then each can call for heat. As you say when the schedule for one is off then the TRV closes and the boiler stops firing. If another TRV then calls for heat it opens and activates the boiler.

ChrisMac

Thanks. So valves could operate several times per day. How are they powered?

hugbilly

Yes they can, the V3 valves use two AA batteries . . .

wateroakley

Hello @ChrisMac Welcome. The Tado V3+ system is very flexible.

Two modes of radiator heating operation with a TRV::

• Attached to a 'Zone Controller'. Time and temperature schedule that will 'call for heat'.
• 'Independent. A smart 'dumb TRV' for time and temperatuire schedule that relies on another device to 'call for heat'.

The TRV maintains the temperature setting for it's schedule.

There an 'away' setting: 'Off', 'eco', 'balance' or 'comfort'.

There is an 'early start' e.g. for UFH.

Sorry, I dont know the intracacies of the newer Tado 'X' system.

ChrisMac

Again, thanks.

So when the schedule for a particular TRV indicates 'off' the TRV will close it's valve. I wonder how long the batteries will last as I've seen different reports? A typical valve in my current system requires a down force of around 2kg to move it, is this typical?

davidlyall

Many factors will affect battery life

• Type of batteries
• Construction materials of property
• Distance from tado bridge
• Number of valve operations

Not sure about the force required but that will certainly also have a bearing on battery life. 2Kg sounds like quite a bit but perhaps it's normal. @Emcee, can you advise if Tado has a specification around the max force that the TRVs can apply to the valve pin?

For a real life example, I have 7 TRVs in my small (100m2), timber frame, 2 storey, 3 bed house. Some TRVs last up to 2 years while the shortest battery life has been around 10 months. Smart thermostat and wireless temp sensor appear to last even longer but I don't seem to have saved the battery alerts for those

eezytiger

You can use rechargeable AA batteries. Eneloop 1900 mAh are recommended, NOT the larger capacity Eneloop Pro. This is due to the physical size of the batteries and very tight tolerance for battery diameter within the valves.

Note that Ikea Ladda 1900 mAh rechargeable batteries seem to share identical performance characteristics with the Eneloops, but at a much more competitive price. I use them myself.

https://www.ikea.com/gb/en/p/ladda-rechargeable-battery-hr06-aa-1-2v-00509814/

ChrisMac

Again, many thanks for all your help.

I now have a fully functional system but not without one or two problems on the way.

Changing the Danfoss timer to the Tado Wireless Receiver was easy as the only change to my wiring was to bridge the switched feed to the wired thermostat back to its return in the junction box. In actual fact to test the system I just set the wired thermostat to a silly high value so that its contacts remained closed at all times. The wireless roomstat then worked correctly.

I fitted one TRV which did what it was supposed to do but with one unhelpful side effect. There is only one loop of central heating pipe so when the boiler is switched on by the TRV hot water flows through all the other radiators as well. The wireless thermostat may want to stop the heating but cannot do so until the TRV turns off, result, very hot rooms. Solved by fitting TRVs to all radiators. Everything fine.

As the roomstat was redundant I de-registered it.

My hot water ceased working, indicated 'on' but the 'test' button had no effect and no LED lit up. In this wonderful community site I found that a roomstat is required for the hot water to function. A reason given by Tado was that there must be a manual method of turning on the hot water. I can see that this function could be provided by a wired thermostat but not a wireless one. Anyway I registered the wireless thermostat and everything works, it is a strange requirement which is not mentioned, at least I could not find it, in the installation guides.

Heating-wiring.pdf