one radiator on two zones

[NZMike001]

I am about to undertake an installation of radiator central heating into an existing house which is two levels. As part of the install I am going to have 5 zones (controlled via zone valves) as the house is quite large and a large part isn't used during the day and will be closed off and not heated

Part of the design I wish to have a radiator located near the bottom of the stairwell that is linked to two separate zones. The reason behind this is when the upstairs zone is on I want the radiator at the bottom of the stairs on to warm any air coming in from an external door, that might go upstairs. However I also need that radiator on when the zone for the down stairs part of the house is active as my wife works downstairs.

Any ideas or help would be great. Central heating isn't very common down here in NZ?

Thanks
Mike

 

[stem]

I did something similar here in the UK. The premises had a shop downstairs and a firm of architects upstairs, but they shared a common hallway & kitchen. Because the architects were closed at the weekend, and the shop was open at the weekend but closed one day in the week the landlord wanted individual control of the heating, but both companies needed to have the hallway and kitchen heated when they were in.

So I wired a relay across the motorised valves for the shop and architects office and used their contacts to switch a third motorised valve solely for the hallway and kitchen. That way if either the upstairs or downstairs heating was on the shared rooms came on also. It did mean that the shared radiators had to be plumbed as a separate zone as below.

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• stem
• 22 Apr 2015
• 1

The relays provided the isolation so that the downstairs heating didn't turn on the upstairs heating and vice versa. A separate wired thermostat also controlled the hallway.

If you are happy to dispense with a wired thermostat for the hallway and just have a thermostatic radiator valve, then the micro switches inside the the upstairs and downstairs motorised valves could be used to operate the hallway motorised valve, and the micro switch in that could control the boiler.

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• stem
• 22 Apr 2015
• 1

I've just noticed an error in my drawing above. The live supply to the upstairs and downstairs motorised valve micro-switch should be from the permanent live, not the switched live from the thermostats as shown. If wired as above, the live would be fed back from the one valve and keep the other valve motor energised even when the thermostat had opened.

 

[NZMike001]

Thanks for your reply. How do i get on with only rad on the circuit, can i then have a trv on it or not?

Cheers
Mike

 

[Dan Robinson]

Why not plumb that rad so that it works as a general system bypass? Simples.

 

[NZMike001]

Dan

I did think of thsat but then I loose the ability to control that rad using a trv.

was hoping there was a method where I could keep control due to asking one rad to do two jobs, need more heat when on the upstairs circuit than when on lower circuit

????

MIke

 

[stem]

How do i get on with only rad on the circuit, can i then have a trv on it or not?

Yes you can, a TRV won't be a problem because in reality it will never really be 'on' on its own, because at least either the upstairs or downstairs radiators will be 'on' as well.

Why not plumb that rad so that it works as a general system bypass? Simples.

I wondered about that, but it has disadvantages

1.The OP said there would be 5 zones, so it it were a by-pass then it would come on with any of them, not just the two mentioned.

2. It would not be possible to have any thermostatic control for the stairwell radiator.

3. If there is a hot water cylinder connected to the same boiler, then the stairwell radiator would also heat up in the summer when the hot water was on.

need more heat when on the upstairs circuit than when on lower circuit

Then the radiator could be sized for the worst case and adopt the relay solution and then you can have a separate programmable thermostat for the stairwell motorised valve which will let you set different temperatures at different times.

 

[Agile]

If you really badly want to have this rad on with either or both of the other zones then you will need a valve for it and two relays.

Depending on exactly what you want to do then it might be possible to use other tactics but the simple one is as described.

Tony

 

[gigz]

As dan says, when its not required turn it off manually.

 

[Dan Robinson]

Or use a programmable trv.