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Air Source Heat Pumps (ASHPs)
Last Post by TechnoGeek 8 months ago
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 Pie_Eater
(@pie_eater)
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Topic starter 26/06/2025 8:56 am  

Hi all

Given the high temperatures of late plus my abundant solar generation I was thinking of figuring out how to enable cooling on the daikon altherma. This is disabled at the machine (i believe as a condition under the UK subsidy scheme)  , but surely someone has figured out how to bypass?

Is it worth having it and what’s involved?

 



   
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Majordennisbloodnok
 Majordennisbloodnok
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26/06/2025 1:49 pm  

I would be wary, @pie_eater. Using liquid to cool means you will get condensation on any uninsulated surfaces, including the pipework itself. That includes inaccessible places, and I doubt persistent moisture under floorboards, through joists and in wall cavities is going to do your home any good. That’s why most air to water systems try not to allow the functionality. Don’t get me wrong; it can be made to work, but it’s much more involved than it first appears.


105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"


   
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JamesPa
 JamesPa
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Posts: 4391
26/06/2025 2:13 pm  

Posted by: @pie_eater
↑

Given the high temperatures of late plus my abundant solar generation I was thinking of figuring out how to enable cooling on the daikon altherma. This is disabled at the machine (i believe as a condition under the UK subsidy scheme)  , but surely someone has figured out how to bypass?

I don't know how to enable cooling on Daikin and @majordennisbloodnok is correct to sound a note of caution re condensation, although some heat pumps will measure and run above the dew point in an attempt to circumvent.  Also you will only get material cooling with fancoils or UFH, ordinary rads don't cut it.  

Its not a condition of the BUS scheme that cooling is disabled (I dont know about ECO4).  It was a condition of permitted development rights (England and Wales) that the system is 'used only for cooling'  which again didn't require colling to be disabled, just not used.  The recent amendment to pd rights has further relaxed this and now only requires that is 'not used solely for the purpose of cooling.'   


This post was modified 8 months ago 2 times 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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downfield
 downfield
(@downfield)
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28/06/2025 3:41 pm  

As I have reported elsewhere we turned on the cooling option on our Mitsubishi Zubadan unit after installation.  It was just a case of flipping a dip switch and restarting.

But - we have invested in Jaga Strada fancoils which are designed for light cooling and this works fine so long as you keep the chilled water above 16C.

Any condensation is a minor inconvenience in the scheme of things when you can get a decent reduction in room temps of 5 - 7C.  Powered by solar so zero running cost (after the considerable capital outlay).

 


Mitsubishi Zubadan 14kW with Mixergy 210l DHW in 220m2 barn property. 24 solar panels = 9kWp with GivEnergy 5.0kW Hybrid inverter and 19kWh GivE batteries. Jaga Strada fan-assisted rads throughout. Landvac vacuum glazing/triple glazed windows.


   
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 comfortablehomeseeker
(@comfortablehomeseeker)
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12/07/2025 12:09 pm  

@downfield 

may I ask whether the pipework in your barn [you shared this, including pictures, in another post] is insulated?

I am trying to understand whether 'light cooling' - https://jaga.com/uk/light-cooling-heating/ needs insulated pipework.

if it does need insulated pipework, then it's impractical ASHP retrofit; it would need changes to pipework in walls and floors, that are impractical.



   
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downfield
 downfield
(@downfield)
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Posts: 118
12/07/2025 2:49 pm  

@comfortablehomeseeker I have the usual combination of insulation under the suspended ground floor and no insulation where pipes are in the heated space i.e. under the first floor.

The whole purpose of light cooling is that you don't need insulation if you keep the water temp above the dew point.  Jaga recommend using 16C but obviously on a humid day that might be a bit low.  But it's not a problem in normal UK conditions on a hot day which is when you need the cooling.  If you feel the pipes as they go into the radiator at worst they might be slightly damp.


Mitsubishi Zubadan 14kW with Mixergy 210l DHW in 220m2 barn property. 24 solar panels = 9kWp with GivEnergy 5.0kW Hybrid inverter and 19kWh GivE batteries. Jaga Strada fan-assisted rads throughout. Landvac vacuum glazing/triple glazed windows.


   
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 Pie_Eater
(@pie_eater)
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Posts: 38
Topic starter 13/07/2025 7:34 am  

I’m sort of keen to try it , seems like a good solution provided condensation is kept under control. 
no idea how to change the daikin for it to cool though. Found some very limited info that you may have to change the pcb from edla to ebla or so. 



   
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downfield
 downfield
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13/07/2025 9:18 am  

@pie_eater Try asking the Perplexity AI engine how to turn on cooling on your specific model.  It's available through your web browser or as a free iOS app.  Or just ask Daikin.

We changed three rads in our bedrooms first to see how well it worked.  If you buy through a supplier like GoGeothermal they seem to give a decent discount on the list prices.


Mitsubishi Zubadan 14kW with Mixergy 210l DHW in 220m2 barn property. 24 solar panels = 9kWp with GivEnergy 5.0kW Hybrid inverter and 19kWh GivE batteries. Jaga Strada fan-assisted rads throughout. Landvac vacuum glazing/triple glazed windows.


   
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TechnoGeek
 TechnoGeek
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Posts: 167
14/07/2025 12:54 pm  

@pie_eater I have been thinking of adding cooling to my system over the last 12 months+. I am not too keen on the condensation issue as I have had to fix a lot of condensation issues in the house in the past due to old building design and lack of ventilation.

To avoid condensation issues I am going to see if it is feasible to have a separate insulated pipe system going from the heat pump to the loft space with suitable fan coil units installed and a divert valve fitted at the heat pump to direct the hot or cold flow accordingly. I can then run it during the cheap power hours so we can sleep better at night 🙂

All subject to me finding someone who can do the appropriate cooling calculations and approval from "the boss!" 😀


5 Bedroom House in Cambridgeshire, double glazing, 300mm loft insulation and cavity wall insulation
Design temperature 21C @ OAT -2C = 10.2Kw heat loss, deltaT = 8 degrees
Bivalent system containing:
12Kw Samsung High Temperature Quiet (Gen 6) heat pump
26Kw Grant Blue Flame Oil Boiler
4.1Kw Solar Panel Array
34Kwh GivEnergy Stackable Battery System


   
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