Have I bought the right kit? Tado "Whole home bundle" + Baxi 830 boiler

stevek_wales

Hi there,

I'm completely new to Tado but was sold on it when there was an offer on Costco a few months back. We've just bought our new house and are having a new boiler and radiators installed.

The plumber is recommending a Baxi 830 boiler.

The kit I've purchased is:

https://www.costco.co.uk/Appliances/Cooling-Air-Treatment-Heating/Smart-Thermostats/tado-Whole-Home-Bundle-Wireless-Starter-Kit-with-8-x-Universal-Smart-Radiator-Thermostats/p/374926

I've also purchased a couple of extra TRVs.

Can anyone in the know tell me if this will all work well with the Baxi?

I've seen some threads suggesting that some of the tado stuff sold here in the UK isn't fully functional with OpenTherm?

Any pointers before I open any of the boxes Costco supplied would be so welcome.

Thanks,

Steve

GrilledCheese2

It depends if you're getting a Baxi 830 Combi or Baxi 830 Heat Only. The latter is used with a hot water cylinder.

If you have a hot water cylinder then you definitely have the correct kit as you will need the twin relay control for CH and HW. If it's a Combi then you won't be able to use Opentherm with that variant of the wireless receiver. Opentherm has a benefit over relay control, but it's not significant.

johnnyp78

If you want to use Opentherm it will need to be a combi boiler rather then a system (hot water tank) boiler. You’ll need to get either the EU extension kit or the old single button one. Otherwise use what you’ve got with 230v relay. You’ll need to if it’s a system boiler anyway

stevek_wales

Thanks to you both for your comments.

It is the Baxi 830 Combi (without a hot water tank).

I am so new to this stuff - can anyone give me a basic explanation of what features I'd be missing if I used the current kit I have versus ordering the EU Extension kit?

GrilledCheese2

With relay control the heating system is either fully on or fully off. The boiler has no idea what the room temperature is and is just blindly responding to the thermostat. If your heating engineer sets the CH water flow temperature to 60°C then the boiler will always aim to supply water at this temperature to the radiators.

With Opentherm the thermostat is communicating to the boiler by telling it both the room temperature and the required temperature. The boiler will modulate/adjust the CH water flow temperature to suit the conditions. So when the room is cold the boiler will set the CH flow temperature to a high temperature to get the radiators hot and to heat the room quickly. But when the room temperature approaches the required temperature the boiler will reduce the CH flow temperature (e.g. 40°C), which reduces the the radiator temperature and avoids the room temperature exceeding the required temperature. Better temperature control gives better efficiency, plus the lower flow temperature will increase the condensing of flu gases.

However, smart thermostats learn the characteristics for heating a room/home and use a control mechanism called TPI to mange the relay switching on and off. The end effect is the smart thermostat is predicting when to turn the boiler on and off to avoid the temperature overshoot associated with the old manual thermostats.

The best thing you can do is reduce the return temperature for water going back from the radiators to the boiler. The cooler the return temperature the more condensing will happen. For a gas boiler condensing will not happen above 56°C. Lowering the boiler's CH water flow temperature and balancing the temperature drop across each radiator will lead to a lower return temperature. Set the flow temperature too low and your radiators will not get the room up to temperature on a cold winter's day.

stevek_wales

Thank you so much @GrilledCheese2 for explaining that so thoroughly.

Phil_Taylor

Yep, it will work with that kit perfectly.

I have a totally oversized Baxi 800 in my house, so good for hot water.

The other replies are correct, for some reason the UK models don't have Open Therm, but my 7 year old Honeywell did. Maybe it's one of those mystery Brexit benefits?

If you have an older house with existing radiators you may find they were based on a home with single glazing, no cavity wall insulation and single glazing. You may find that you can actually run your new boiler at 55 degrees, forcing it to condense, and save fuel. It certainly worked for me with my new install from February.

One gadget you should certainly get your plumber to fit is the Baxi IFOS weather compensation sensor. You can pick them up at Toolstation, Screwfix for around £30, they pay for themselves quickly, and are easy to fit when installing a new
boiler:they are a bit fiddly when one is already fitted. Baxi have a few videos on them, and plenty of stuff on YouTube, you will also find a bit on the Heating Hub channel about flow temperatures. It seems you can save about 10% using the IFOS, but people seem reluctant to quote figures due to variables.

Tado TRVs, consider when rooms are in use, and set the temperatures accordingly. Each radiator can call for heat independently. Each one can have a separate programme, for example my bathroom is only on for one hour in the morning at 21, my bedroom heats for when I wake up and 1 hour at night. You can have setback temperatures, so that rooms at certain times will not get too cold.

Early start can start very early, and I suspect the UK systems have no learning capability. I set mine up to turn on in a phased manner, 90 minutes before I need a room, it starts the heating ramping in 4 .5 degree steps, if the room is already near temp, it only turns on for the last
one. Remember to give a squirt of WD40 on all the pins on the valves when fitting them

Set a good schedule, use the app, and you won't need the subscription service if you have a set routine

A bit left field, but you might be able to run the whole house on valves, ignoring the thermostat!

Buy a digital thermometer, and set the offsets based on where you sit in a room.

Good Luck

johnnyp78

From what I’ve read here, early start is actually designed for underfloor heating, which takes much longer to heat up, though Tado doesn’t publicise this for some reason. I know when I tried it on my rad system it was ridiculous - started heating about an hour earlier than the scheduled time.

Dgibs

Thread hijack because similar question and same boiler

Combi, Baxi 830.

Aiming for opentherm control.

Can i but the discontinued Wired extender (with the 2 relays and wireless) and connect to the boiler.

then just get a wireless thermometer and some smart radiator valves.

job done?

GrilledCheese2

Yes, you can purchase the old Wireless Extension Kit for Opentherm control and then pair other devices of your choice. Remember you'll need a Bridge for the system to work. You'll have to buy the extension kit from a third party but I still see new unopened devices advertised.

Beware of sellers with the new Wireless Receiver, but wrongly describing it as the Extension Kit.

johnnyp78

If you want to make sure, the extension kit serial number starts BU and has a single button on top and one indicator light. These are the ones you want for Opentherm.