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

Page 19 / 19 Prev

Air Source Heat Pumps (ASHPs)

Last Post by cathodeRay 5 minutes ago

217 Posts

15 Users

32 Reactions

29.3 K Views

RSS

cathodeRay

(@cathoderay)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 2147

12/09/2025 8:50 am

Posted by: @pash44pump

↑

From experience what is the rate of flow change per turn of the lockshield valve as I've never done this before?

@jamespa is right, typically they are far from linear, with most of the change in flow rate happening near total closure. Do be careful not to over-close them, though, as I mentioned before this can unwittingly throttle the system. Once you have found what you think is the right position (by trial and error), make a mark to identify the position, then fully close and then open again to the marked position, to confirm that it isn't all but closed. If it is, then start the process again (yes, it can be tedious! But worth it).

Posted by: @pash44pump

↑

On a different note, @cathoderay I read somewhere that you had advised someone on how to schedule DHW on the Midea. If I do that I think you said that the DHW will not run at any other time other than that programmed and will only run to schedule if the DHW temp is 10C below what is set. Is that correct? Can the 10C tolerance be adjusted somewhere? I think last night there was no DHW cycle but then this morning I see DHW at 40C which is 2 degrees below my 52-10 setting so I have to adjust manually which is not what I want to be doing every day. Any advice?

Yes, you can put the DHW heating on a timer, and reading between the lines you have already done that, if not it is done via the Schedule > Timer menu and for once is reasonably intuitive: tick checkbox, set start and end time and set mode got DHW. Using my setup (timed to 1300-1400 daily to use what may be the warmer part of the day, DHW set temp 50°, drop to trigger reheat 10°) as an example, what this means is:

(1) left untouched, my DHW heating will only come on at 1300 when the tank is at less than 40°. In practice, it turns out it doesn't always happen at 39°, sometimes it needs to be a bit lower. When it does come on, the heat pump works flat out, LWT approaches 60°, and the reheat to 50° typically takes 30-40 minutes, during which time the space heating is off. If the tank is already above 40°, nothing happens.

(2) yes, you can adjust the drop from set temp to trigger a reheat value, via For Serviceman > DHW Mode Setting > Item 1. 6: dT5_ON. The default is 5°, mine is set to 10°. Don't forget that going into and out of the For Serviceman menu will usually turn any current heating off, just turn it on again on the Home page.

(3) if you want to trigger a reheat outside the timed period, you can do thins manually by turning on the DHW heating on the Home page. To trigger the DHW heating when you do this, the DHW tank actual temp must be below whatever the trigger temp is - it won't just go into DHW heating regardless. If you want a reheat when this condition isn't met, then the easiest way I have found to trigger a reheat is to increase the DHW set temp on the Home page. For example, if my DHW is currently 41°, I set the set DHW temp to 55° and because 55-41 > 10, the DHW heating comes on when I manually turn the DHW on. I then wait until the DHW reaches the temp I want, and then, on the Home page, turn off the DHW heating manually, and then finally set the DHW set temp back to 50°.

To avoid having to do manual adjustments all the time, try to find a combination of set DHW temp and drop to trigger reheat value that works most of the time for you. There will always be exceptions, but most of the time the system will look after itself.

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

ReplyQuote

Page 19 / 19 Prev