Posted by: @thylacine333

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Hello,

 

I have an airwell monobloc 12 kw ASHP - I understand it to be essentially a rebranded midea unit and certainly the instructions seem to be identical.

The installer set it up to run rads as well as new under floor in an extension. They have it linked to salus room thermostats and originally it was set up like a conventional boiler- turning on and off according to set temp on the thermostats. I followed advice and have been targetting flow temp with the thermostats set just above comfortable room temp to try to find a 'low flow temp/ on all the time' setting to maximise efficiency.

However, since adjusting the weather compensation (instructions from Graham Hendra's really helpful youtube video on the Midea unit) it does not seem any longer to be heating the hot water tank. The house heating is working very well and much better with flow temp adjusted way down from the default -2 and 15 degree settings but the hot water tank only heats for the weekly immersion 'anti legionella cycle'. The wavy lines used to come on next to the DHW icon and that also no longer happens.

I don't know whether I have inadvertently tweaked something I shouldn't have when adjusting the weather comp, or if somehow going from the room thermostat led initiation to leaving the heating on all the time at low flow water temp has affected something.

I've had a look at Graham's Midea set up video as well and the hot water settings seem to be as they should be (at least superficially).

The installer is I am afraid to say hard to track down.

I would be very grateful for any thoughts. I can't help thinking this must be something simple and silly (fingers crossed!).

 

many thanks!

I would suggest that you check to see if your system is set for CH priority rather than DHW priority. If so, set it to DHW priority and schedule it for times when you require less heating.

@thylacine333 - I got caught by this one, at least my guess is it's the same problem. It's another user unfriendly gotcha. Going into For Serviceman and setting the weather curve numbers turns off DHW heating. Your tank will cool, and then die. The solution is to manually turn it on again after exiting the tradesman's entrance. Do it on the main home/front page, right arrow to hot water and make sure you've got the squiggly lines by the tap symbol using the On/Off button, then OK. The squiggles just mean the hot water is 'on' in a general sense, and will call for heat when it needs to, with no squiggles it is 'off' and will never heat. It's like turning an immersion heater on and off at the mains.      

@cathoderay thank you so much I think this is the problem! Yes I thought the squiggly lines meant that the ashp was actually heating the tank at that moment rather than just it was ‘on’ in the usual sense.

I thought it had to be something silly and simple but you’ve saved me a lot of time and stress and trying to sort it out!

@derek-m thanks for the suggestion. I think it seems to be a quirk of the control system. Hopefully sorted now fingers crossed!