Hive and Combi with a Megaflow (unvented hot water tank)

[NP62]

I have a Greenstar 42CDi combi that also feeds a Megaflow with motorised valves, controlled by a Honeywell heating/water programmer and a basic Honeywell roomstat. I would like to replace this with a Hive system. Can someone please point me to any previous threads that have covered this situation or help with what Hive to buy and how I should connect the Hive? Thanks!

 

[CBW]

As it’s unvented, I don’t think it’s a diy job (I have been told previously), happy to be corrected though.

 

[Madrab]

I don’t think it’s a diy job

If it's needed to re-wire the 2 port controlled throughthe HL and cylinder stats (basic S plan) then yes it really should be an UV qualifed bod doing it as it's playing with a safety system. If it's a Y plan with unvented then it would probably only be the feed to the 3 port that would need tied into from the Hive so maybe not in that case.

@NP62 - What type of system doo you have - S plan or Y plan? You will need a dual channel Hive as they are the only ones that would give you HW and CH control and it throughputs a 240V switched live (SL) internally. Your boiler will probably already be using a SL @ ST10, so shouldn't be an issue. Wiring wouldn't be much different that it is already, there may be a bridged 240v @ the programmer which wouldn't needed but wouldn't see much else having to change.

 

[NP62]

If it's needed to re-wire the 2 port controlled throughthe HL and cylinder stats (basic S plan) then yes it really should be an UV qualifed bod doing it as it's playing with a safety system. If it's a Y plan with unvented then it would probably only be the feed to the 3 port that would need tied into from the Hive so maybe not in that case.

@NP62 - What type of system doo you have - S plan or Y plan? You will need a dual channel Hive as they are the only ones that would give you HW and CH control and it throughputs a 240V switched live (SL) internally. Your boiler will probably already be using a SL @ ST10, so shouldn't be an issue. Wiring wouldn't be much different that it is already, there may be a bridged 240v @ the programmer which wouldn't needed but wouldn't see much else having to change.

Need some help here what is S and Y plan? Also, what is HL?

 

[CBW]

S plan and Y plan denoted the number of motorised valves you have. I think HL is High Limit.

 

[NP62]

Ok - there are 2 Honeywell motorised valves and what looks to be a Honeywell junction box (all near the Megaflow)

 

[Madrab]

S plan and Y plan denoted the number of motorised valves you have

Maybe .... It could be a Y plan with a 2 port on the UV to protect the cylinder through the High Limit (HL) and the cylinder stat, so would still have 2 valves .....

@NP62 can you post pics of the motorised valves?

 

[NP62]

Here are the photos

 

[ianmcd]

you have an S plan and you require a dual channel hive

 

[NP62]

Thanks - so that needs a qualified person to work on it?

 

[Madrab]

Yup

 

[NP62]

Thanks for all of the help - does anybody have the diagrams of how to connect the new parts (dual channel Hive) and exactly what I need to buy? Not that I will connect myself, just curious as to what it looks like.

 

[Madrab]

You only need the dual channel hive - there are only 2 - single is used for CH only on a combi, dual which is used to control CH & HW

Wiring is the standard dual programmer wiring used for an S Plan ( loads available online) with a little extra understanding for the requirement of the Unvented.

 

[NP62]

Thank you - this is great. Does anyone have a simple schematic diagram showing how the Hive system (thermostat, hub, receiver) fits with the S-plan? I assume I need all of these?

 

[Madrab]

If you want it connected through the app on your phone to the system then yes all is needed, hub connects to the net and talks to the receiver and then the stat.
The receiver wires in similar to the programmer in the S-Plan but whoever the pro is that's fitting it will know all of that ...