Replacing BDR91 with Hive mini dual channel receiver wiring

[ejigarpatel]

Hi All,

Apologies if this has already been answered earlier, but I cannot find a 100% confident answer.

I am replacing my old Honewell BDR91 with the new Hive Mini (dual channel) Thermostat. I have Baxi 400 combi boiler at home.

Attached image with my old Honewell BDR91 wiring, I have replaced it with the attached new Hive mini dual channel thermostat wiring.

I have replaced the old wiring:

A to 2: Heating off (NC)
B to 4: Heating on (NO)

is this the correct one?

Note - I don't have a hot water tank and using a combi boiler of Baxi (400)

Thanks,
Jigar

 

[bernardgreen]

The switch in the BDR91 connects A to B to command the boiler to fire up.

The dual channel Hive has an internal connection to the switches so that the switches connect Live to send commands to the boiler.

That internal ( inside the Hive ) connection of the switches to Live may mean a dual channel Hive cannot be used to control your boiler.

 

[stem]

You have the wrong version of Hive. The Dual channel is for a system with a hot water cylinder.

The BDR91 has the switching wires isolated from the mains supply, so change it for a Single Channel version then the wires in A & B go to terminals 1 & 3 (Common and Heating On)

You might be able to use the Dual Channel if your boiler is wired for 230V control with some modification to the wiring. If on the other hand your combi is wired for 24v control you can't, and if you tried, the results wouldn't be good. But you would never make any connection to CH off.

 

[ejigarpatel]

You have the wrong version of Hive. The Dual channel is for a system with a hot water cylinder.

The BDR91 has the switching wires isolated from the mains supply, so change it for a Single Channel version then the wires in A & B go to terminals 1 & 3 (Common and Heating On)

You might be able to use the Dual Channel if your boiler is wired for 230V control with some modification to the wiring. If on the other hand your combi is wired for 24v control you can't, and if you tried, the results wouldn't be good. But you would never make any connection to CH off.

Hi,

Thank you for your prompt reply, appreciate that.

I am not an expert here, so just to clarify, do I need to buy a single-channel version? Is there a way I can use this one?

How can I know if my boiler is wired for 230V control? also if I only connect old B to number 4 on the new Hive and leave the old A wire will this work?

Sorry for the silly question.

 

[stem]

They are not silly questions, but unfortunately without knowing what is connected to the other end of the wires in A & B it's impossible to tell if it's 24v or 230V. Looking at a Baxi 400 series manual I've found on line, and assuming yours is the same, it can be wired for either 'low voltage' (24v) or 230V, depending on whether the wires to the BDR91 are connected to X4 or X8

If, and only if the boiler is wired for 230V, quite possibly it might work by connecting B to number 4, but it might be A to number 4 depending upon which way around the original installer has connected the wires to the terminals at the other end. [It doesn't matter with the BDR or Hive Single channel, as they have voltage free connections the wires will work either way around]

If it is wired to X8 the link can be reinserted and the wires moved to X4

However, ideally, if you can, I would recommend changing it for the correct Hive, it removes all of the uncertainty. But even if the dual channel can be used with your boiler the app will show hot water control that won't be doing anything, which would annoy me but that's probably because I'm a bit OCD about these things.

Just a note that to access the wiring terminals of some boilers it involves opening up a room sealed compartment if that is the case this should only be done by an RGI who can carry out the necessary checks to make sure it is safely sealed again afterwards. I don't think yours is but can't be certain.

 

[ianmcd]

As @stem correctly says your dual channel hive CAN be used but only if wired into 230v switching at the boiler end, if it isnt you need to change it or you will damage the PCB a very expensive mistake, if you havent opened the dual channel hive return it and swap it for a single channel one and A&B go to 1&3 on the single channel hive and it wont matter what the wiring is at the boiler end

 

[ejigarpatel]

As @stem correctly says your dual channel hive CAN be used but only if wired into 230v switching at the boiler end, if it isnt you need to change it or you will damage the PCB a very expensive mistake, if you havent opened the dual channel hive return it and swap it for a single channel one and A&B go to 1&3 on the single channel hive and it wont matter what the wiring is at the boiler end

Thanks for the explanation, unfortunately I have already opened and fit the new Hive one, so wanted to seek options to work around for dual channels.

 

[ejigarpatel]

Does anyone suggest Tado instead? https://www.screwfix.com/p/tado-v3-...-hot-water-smart-thermostat-starter-kit/701kg

And will that work with a combi boiler?

 

[Mister Banks]

Personally I would take it on the chin and buy the correct version of Hive, its only £58 and will give you a spare thermostat. The dual channel Hive can be sold on eBay.

Hive Mini Wireless Heating Smart Thermostat - Hubless White/Grey - Screwfix

Order online at Screwfix.com. For use with combi boilers. Designed for new building installations. Temperature adjustment and mode control via thermostat touch screen. Automatic frost protection. Can be installed on gas or LPG systems, oil boilers and certain electric boilers. Hub not included...

www.screwfix.com