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Two heating zones to one zone

 
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Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by Profzarkov 2 weeks ago
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Profzarkov
 Profzarkov
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Topic starter 05/05/2026 11:30 am   [#2981]

Hi

Just a quick one...

I have a two zone system - daft really as we're in a bungalow & the second zone is just the two bedrooms. I've replaced the stupid neomitis thermostat in zone one with an old Hive one - mainly so I can control & monitor things. What's the easiest way to make it just one zone? I have motorised valves for both zones. 

I had thought of just connecting the two "demand"s together?

Steve

IMG 20260505 112333

 


This topic was modified 5 months ago by Mars

   
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JamesPa
 JamesPa
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05/05/2026 12:31 pm  

What do the thermostats connect to?

 

Generally the easiest way to make something single zone is simply to turn all thermostats to max so they are effectively disabled, and run on weather compensation alone.  Is there a reason not to do that?


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Profzarkov
 Profzarkov
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Topic starter 05/05/2026 2:19 pm  

Well, as per previous posts, I'm working towards that...

I think my weather compensation needs tweaking:

"

I've adjusted a few parameters 

 

201 is now 16°. -4°

 

202 is now 27°. 43°

 

If that makes sense.

 

See what happens next winter."



   
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JamesPa
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05/05/2026 2:57 pm  

I would just do this and turn up the stats.  Otherwise you will need to work out what both are controlling and how to rewire.  You also need to check if it’s 240V logic or 5V logic.  All very doable, but easier just to turn the stats up, at least initially until you have proven what you want.


This post was modified 5 months ago by Mars

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Profzarkov
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Topic starter 05/05/2026 4:16 pm  

@jamespa are those temperatures ok?



   
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JamesPa
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05/05/2026 4:19 pm  

@profzarkov 

They arent obviously wrong, but the only way to determine the right temperatures is to adjust it (with all zones open, thermostats to max, operated 24x7) until the house temperature is right.  They are house dependent and there is now way around that!  I would leave 27/16 and if necessary adjust 43 if necessary next season.  It needs to be cold to make these adjustments!


This post was modified 5 months ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 sarahstrachan
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09/07/2026 6:35 am  

In your case, converting it to a single zone sounds like a reasonable approach. If you're keeping both motorised valves, the goal is for them to operate together whenever there's a call for heat. I wouldn't recommend simply linking the demand wires without first checking the wiring centre, as the valve end switches and boiler interlock still need to operate correctly. A quick photo of the wiring centre and the make of the zone valves would make it much easier to suggest the best approach.



   
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Profzarkov
 Profzarkov
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Topic starter 10/09/2026 12:07 pm  
IMG 20260909 175946
IMG20260909175816
IMG20260909175806

@sarahstrachan 

Hello & apologies for the delay...

Autumn's here & I'm still think of ditching the second zone. Joining the two demands together - they are both simple 240V lines.

You asked for more detail - the valves are simple Honeywell ones. I suppose I could lock zone two open🤔.

 

Cheers

Steve

IMG20260909175759


   
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JamesPa
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10/09/2026 1:45 pm  

Posted by: @profzarkov
↑

You asked for more detail - the valves are simple Honeywell ones. I suppose I could lock zone two open🤔.

Or lock them both open by turning up the stats, then adjust the weather compensation curve and if  necessary balance to get the house temperature right at the lowest flow temp.  No wiring needed.

 


This post was modified 2 weeks ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Profzarkov
 Profzarkov
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Topic starter 10/09/2026 1:47 pm  

@jamespa 

Yes 

Everyone keeps saying this but I'm not keen on doing that. I have many reasons - one is keeping it cooler overnight & also I don't want the pump running 24/7.



   
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Transparent
 Transparent
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10/09/2026 2:20 pm  

@profzarkov - where is that Tempest water cylinder situated?
Is it within the heated envelope of the house?
... or in a porch, garage, basement?

Am I allowed to comment on the insulation which isn't covering all those nice, shiny brass bits? 😉 


Save energy... recycle electrons!


   
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Profzarkov
 Profzarkov
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Topic starter 10/09/2026 2:22 pm  

@transparent 

Anyone can comment - as long as they're kind!

Troy is in the garage & yes I could cover more of it up!



   
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