2 boiler complicated home

mystikmeg

Hello. I have an old cottage with a new extension part. There are 2 modern Worcester boilers with wireless thermostats. One boiler does the old part of the house, one boiler does the new part. We have water underfloor heating in the kitchen area that has a TRV located in the boiler cupboard which seems a bit naff. I’ve started off buying the wireless starter kit which I have connected to the first boiler that does the underfloor as well as most of the upstairs, what else so I need to be able to control at least the kitchen underfloor independently from the radiators. The old part of the house runs off the second boiler. I believe I need a wired receiver, do I buy a wired starter kit?

GrilledCheese2

@Andreplusplus that’s not true. Tado is designed to work with multiple heat sources on one system account. One bridge (starter kit) and two zone controllers is all that is required.

Rob2

"We have water underfloor heating in the kitchen area that has a TRV located in the boiler cupboard which seems a bit naff."

Don't touch that until you understand why it is there!

mystikmeg

Why is it there? I think the boiler would give it a false reading as it heats the cupboard ?

GrilledCheese2

@mystikmeg the device in the cupboard is unlikely to be a TRV. I expect it is a thermostatic valve for regulating the water temperature flowing into the UFH circuit. There’s probably a wire coming from the valve head that is attached to a sensor in the floor. As Rob2 says do not adjust it. You run the risk of damaging the floor if the water in the floor circuits is too hot.

If you have already purchased a starter kit then do not purchase a second one as you can only have one bridge per account. And you can only have one wireless receiver per bridge. Additional thermostats will need to be wired - look at add-ons for extra devices.

mystikmeg

So how do I get say, a radiator on boiler 2, to work if I don’t have anything wired into boiler 2? Do I need to have a receiver in boiler 2?

GrilledCheese2

You will need to mount a wired thermostat in the living area and run a length of cable back to the wireless receiver currently used for boiler 2. The wireless receiver will need to be disconnected and the wiring adapted to work with the wired thermostat. You won’t get advice from Tado on how to do this as they will consider it to be beyond the scope of Do It Yourself.

Andreplusplus

If you have two boilers, you need two drivers to control those. But then you need two accounts also, and two starter kits.

mystikmeg

Thanks! What do I buy for the ‘zone controller’ is it the wireless thermostat?

mystikmeg

How does the second boiler know how to shut on and off without the receiver wired to it?

GrilledCheese2

@mystikmeg the wired thermostat and wireless receiver are both zone controllers. The wired thermostat will switch on and off the second boiler. This may be done by a relay switch or using digital bus communication, depending on the configuration used.

mystikmeg

What do I need to connect the wired thermostat to the second boiler? It’s a new Worcester Greenstar 28CDi erp with Comfort II rF module.

GrilledCheese2

@mystikmeg the Comfort II uses the digital EBUS interface. You’ll need to confirm with Tado if they support your boiler model. If they do it’s an easy install and Tado will provide you with the instructions. Otherwise you’ll need someone to make a change inside the boiler to use the traditional switched live relay interface.

mystikmeg

Thanks again Cheese 👍🏻