Midea ASHP – how to set weather compensation

Curlykatie · 2023-01-20T17:15:11Z

After lots of help from @derek-m around balancing the system I am now looking for some advice on how best to set weather compensation. We have moved into a 4 bed new build with a Midea ASHP and underfloor heating throughout and individual thermostats in each room. I have looked at the manual and on YouTube but still rather confused as to the best way to set weather compensation. On the main panel I have found the option to select the weather compensation curves- when I click through it says ‘zone 1 high temp mode’ and ‘zone 2 low temp mode’- I have found the high and low temp curves in the manual but unsure which I should be selecting? I also came across a video on YouTube about setting for weather compensation within the serviceman settings? Thank for everyone’s kind help, Katie

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cathodeRay

(@cathoderay)

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28/08/2025 8:13 pm

Posted by: @pash44pump

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plus the compressor pic appearing on the heat pump controller

That is a fairly good indication it is running! As a further check, when the compressor appears to be operating, go to Menu > Operation Parameter and scroll down through the screens. Screens 3 and 6 will give you more useful info. Note that on screen 3 'Power Consum' is lifetime energy in (used) in (k)kWh, the one above (Heat Pump Capacity) is the current power out (in kW). Screen 6 has compressor info, current (draw) and frequency, both will be zero when it is off and non-zero when it is on.

Posted by: @pash44pump

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What do you mean by primary pipework?

The pipes that run from the heat pump into your property. If you know where they end up inside the property, that is the best place to determine whether they get warm or not.

Posted by: @pash44pump

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I don't have design details so I don't know if heat loss and emitters match but I think I can get these from the installer.

This should have happened at design/quote stage, bit of a red flag if that didn't happen. Get what you can from the installer now. Forget the EPC, it's a comedy exercise at best, a damn nuisance at worst. Mine had errors as well.

Initially I thought you had weather compensation on (where you say "turn it on, leave it on" which is how you run weather compensation, plus this thread is about weather compensation) but it ("turn it on, leave it on") could also apply I think to fixed flow temp running, ie no weather compensation (which is simply adjusting the flow temp based on the outside air temp, higher flow temp when it is colder outside and vice versa). Do you know what your system is using?

Midea 14kW (for now...) ASHP heating both building and DHW

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JamesPa

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28/08/2025 8:19 pm

@pash44pump

I'm going to leave this mostly to @cathoderay as he has a midea and I don't. However...

Just a guess but one quite likely reason for the nighttime firing up is that it's cold outside so the WC curve instructs the heat pump to fire (we don't yet know how it's set up by your installer so it may instruct it to fire even if the outdoor temperature is quite high). It depends on how the thermostats (which ideally you shouldn't have, or if you do should be set a couple of degrees above the desired temperature) are set up and what they are set to, as well as whether the heat pump has been configured to take any notice of them. Fwiw my heat pump, which works very well, would be firing up now at night if I hadn't told it to stop heating altogether (just as I did with my boiler in summer!).

Alternatively many heat pumps and boilers fire up their water pump daily to stop it seizing, although this wouldn't account for 1.5kWh.

Do either of these make any sense in relation to what you observe? If not please can you tell us a bit more about the 'call for heat'. How do you know that there is none?

Can I also suggest you read this introduction to help a bit with the terminology and how heat pumps differ from boilers in the best way to operate them.

This post was modified 44 minutes ago by JamesPa

This post was modified 43 minutes 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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