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Mitsubishi Ecodan FTC6, Evohome & Economy 7. Getting Two Zones to Work Together

Air Source Heat Pumps (ASHPs)

Last Post by Abernyte 5 months ago

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Davispj3

(@davispj3)

New Member Member

Joined: 5 months ago

Posts: 1

Topic starter 07/05/2026 9:01 am [#2986]

My system set up is a mitsubishi ashp and — Ecodan FTC6, two zones, evohome with 2 x BDR91, and Economy 7 tariff. To work efficiently.
1. Which zone should be Zone 1 (UFH or radiators)?
2. How does the BDR91 evohome signal interact with their MELCloud commands — do they conflict?
3. How should I set evohome zone 2 (whichever they don't control) given the same flow temp limitation?

This topic was modified 5 months ago by Mars

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 5481

07/05/2026 9:23 am

Posted by: @davispj3

↑

My system set up is a mitsubishi ashp and — Ecodan FTC6, two zones, evohome with 2 x BDR91, and Economy 7 tariff. To work efficiently.
1. Which zone should be Zone 1 (UFH or radiators)?
2. How does the BDR91 evohome signal interact with their MELCloud commands — do they conflict?
3. How should I set evohome zone 2 (whichever they don't control) given the same flow temp limitation?

Lets step back. Why do you need/want 2 zones? The heat pump, just like a boiler, can only supply water at a single flow temperature at any one time and its generally best to operate 'low and slow' so that as much emitter area is active as possible thus allowing the minimum flow temperature for any given energy output (ie heat loss).

If you could explain the rationale for two zones and say a bit about your house (floor area, any notable layout features - eg a house split into two etc) I or others will be able to give a more focussed response.

In answer to the question - do the external controls conflict with the Mitsubishi controller, yes very likely unless the control strategy has been well thought through. Its generally best to avid external controls altogether unless they are specifically designed to control the flow temperature of the heat pump.

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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Batpred

(@batpred)

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Joined: 2 years ago

Posts: 1167

09/05/2026 3:33 pm

Posted by: @jamespa

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In answer to the question - do the external controls conflict with the Mitsubishi controller, yes very likely unless the control strategy has been well thought through. Its generally best to avid external controls altogether unless they are specifically designed to control the flow temperature of the heat pump.

This is what we are trying to avoid if we go Ecodan, multiple controls. We would have a single zone and Ecodan FTC Wireless Thermostat PAR-WT60R-E .

Hopefully it can work without internet.

8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kW export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; Vaillant Arotherm Pro 7kW; 100Amp head, HA lab on mini PC

👍

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F1p

(@f1p)

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Joined: 11 months ago

Posts: 126

11/05/2026 10:59 am

Posted by: @jamespa

↑

The heat pump, just like a boiler, can only supply water at a single flow temperature at any one time

Just a caveat to this, while we are mostly located in the UK - if people are browsing from mainland Europe, Ecodan systems with 2zones are commonly fitted with a mixing tank to allow different flow temperatures in different zones. Where Zone2 is usually the lower temperature UFH.

However, in this case, @jamespa is almost certainly correct

Posted by: @davispj3

↑

BDR91 evohome signal interact with their MELCloud

The BDR91 will control the demand from the heat pump, basic on/off when setpoint > actual
The "MELCloud" part is confusing, because MELCloud is supplementary

Posted by: @batpred

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We would have a single zone and Ecodan FTC Wireless Thermostat PAR-WT60R-E .

Hopefully it can work without internet.

Indeed this is the way to go, if your main controller screen is not located within the house in a sensible location for taking a room temperature measurement

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