Installing Hive Mini Wiring help
- Thread starter DaleW
- Start date
As you still haven't confirmed the type of system you have, (i.e. Y-Plan / S-Plan / Gravity hot water with pumped central heating / something else?) but you don't mention any motorised valve/s, I suspect that you may have an old system whereby the hot water is heated by natural gravity circulation (warm water rises, cooler water falls) so that whenever the boiler is 'on' hot water from it circulates around the hot water cylinder. Then, when the heating is required, the pump is turned 'on' by the room thermostat and circulates water from the boiler around the radiators. Something like this:
Based on that, if you do have this sort of system, I think that you may have a problem in the summer. If the boiler was controlled by the TimeGuard so that whenever it was 'on' you got hot water, and the heating could be turned off by the room thermostat. [at least that's how it should have been wired for this type of system] The situation is now different. Hive takes over the functions of both the TimeGuard and the room thermostat in the same unit, providing only one output, so you may find that in the summer it will be necessary to have the radiators actually hot, in order to get the hot water cylinder heated as well. The pump doesn't seem to feature in your wiring diagrams so without knowing where it's connected into the circuit, it's impossible to tell, but to avoid this scenario the pump should not just be wired to the same LN&E as the boiler.*
The usual arrangement for the wiring of a gravity hot water pumped heating system to a dual channel Hive is:
Here, when the hot water only is 'on' the boiler fires up and the hot water circulates around the hot water cylinder. [The pump doesn't run so the radiators remain cold] This allows the hot water only to be heated in the summer.
When heating is required the pump is started and circulates water around the radiators. However the boiler obviously also has to be on, so the hot water would still need to operate. Hive has a function that allows this to happen automatically. But the wiring would need to conform to my diagram above for it to work.
*The final fly in the ointment, is that if your boiler requires a pump overrun, (i.e. it's controlled by dedicated pump terminals from the boiler) then it can't be done, and your boiler is not suitable for this type of system. This would then of course explain the lash up of the existing wiring to try and get around it and as it originally was you wouldn't have been able to heat just the hot water cylinder without having the radiators on as well.
Based on that, if you do have this sort of system, I think that you may have a problem in the summer. If the boiler was controlled by the TimeGuard so that whenever it was 'on' you got hot water, and the heating could be turned off by the room thermostat. [at least that's how it should have been wired for this type of system] The situation is now different. Hive takes over the functions of both the TimeGuard and the room thermostat in the same unit, providing only one output, so you may find that in the summer it will be necessary to have the radiators actually hot, in order to get the hot water cylinder heated as well. The pump doesn't seem to feature in your wiring diagrams so without knowing where it's connected into the circuit, it's impossible to tell, but to avoid this scenario the pump should not just be wired to the same LN&E as the boiler.*
The usual arrangement for the wiring of a gravity hot water pumped heating system to a dual channel Hive is:
Here, when the hot water only is 'on' the boiler fires up and the hot water circulates around the hot water cylinder. [The pump doesn't run so the radiators remain cold] This allows the hot water only to be heated in the summer.
When heating is required the pump is started and circulates water around the radiators. However the boiler obviously also has to be on, so the hot water would still need to operate. Hive has a function that allows this to happen automatically. But the wiring would need to conform to my diagram above for it to work.
*The final fly in the ointment, is that if your boiler requires a pump overrun, (i.e. it's controlled by dedicated pump terminals from the boiler) then it can't be done, and your boiler is not suitable for this type of system. This would then of course explain the lash up of the existing wiring to try and get around it and as it originally was you wouldn't have been able to heat just the hot water cylinder without having the radiators on as well.
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Thanks for this stem. I am going to wait until the summer and take a look at getting this sorted as you are correct, we could only have hot water if either the heating has been on or the immersion was switched on. This is a pain as you can imagine but for now, all we require is the heating to be controlled via the hive so that we have more control based on temp instead of time and in turn we will have hot water alongside this.
The system as-was had the programmer and room stat wired directly in series, so nothing has changed in that respect with the introduction of the Hive. The boiler is definitely a pump overrun type, I had a look in the manual online and the wiring diagram makes that clear; connecting the pump to the boiler is also a condition of the guarantee. Anyway, if it's a gravity fed system then what is the yellow wire at block 2 doing? The only thing that makes sense with the system behaviour as described is for it to be connected to the cylinder stat and the stat output connected to the brown wire of a 2-port valve controlling flow to the coil, with the grey and orange wires of that valve left blank. That would at least be a sensible design decision to avoid overheating the tank if the central heating is run for a long time.
Just another thought... have you looked for another timer unit or programmer in the cylinder cupboard? It would in theory be possible to take a separate live source through a programmer, cylinder stat and zone valve to send a call for hot water (only) through that yellow wire. Bad electrical practice for sure (as you'd have to isolate two circuits to make the heating controls safe) but as you've been throwing the master switch you'll not have noticed!
Just another thought... have you looked for another timer unit or programmer in the cylinder cupboard? It would in theory be possible to take a separate live source through a programmer, cylinder stat and zone valve to send a call for hot water (only) through that yellow wire. Bad electrical practice for sure (as you'd have to isolate two circuits to make the heating controls safe) but as you've been throwing the master switch you'll not have noticed!
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Yes that's what I suspected. Sometimes the programmer is connected to the boiler and the pump fed by the thermostat. So looks like I was right about the lash up
As @DaleW confirmed he can only have hot water when the radiators are on as well.
My guess (as still no mention of motorised valves, or their inclusion in the diagrams) it is an old gravity circulation / pumped heating system and an old back boiler that didn't need a pump overrun has been taken out and one that does installed in it's place which has prevented the pump being controlled by the programmer and allowing the hot water to be on independently of the heating. What a bodge.
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