Midea Heat Pump expensive to run

benson1980

@painter123 furthermore not sure if you use ChatGBT, but it is pretty good with this sort of thing. You can ask it to take you through setting it up step by step, for a good weather compensation curve. It will ask you the exact make/model and you can upload a photo of your wired controller. One thing it will probably miss is just making sure you select it to run on the custom curve (9) so you can 'remind' chatGBT to talk through how to do that as well.

I'd be arming yourself with a bit of info prior to AirsourceUK coming out and at least knowing what the settings are. You can enter the serviceman and have a look, without changing anything if you don't feel comfortable doing that yet. Even with the best will in the world an engineer isn't going to be able to get these settings right from one visit, and you'll need to tweak them over a period of time. This is why a lot of installers will just do what they have done with your inherited system to run a bit more like a traditional boiler, as well as probably not really understanding how to fully optimise perhaps.

Painter23

Can confirm no one has been using the electricity to charge anything they shouldn't! The only other usage has been occasional boiling of a kettle, ceiling lights and a broadband router, so almost all consumption is from the heat pump.

I've been submitting meter readings weekly rather than estimated. But it's a very old dial meter being replaced by a smart meter the week after next.

QrizB

Glad you've been keeping an eye on things!

By 'dial meter' do you mean one with rotating pointers, rather than digits? People sometimes make mistakes reading those, resulting in inflated bills. Have you got photos of your weekly readings and could you share them here?

It will be interesting to see if the recorded energy use falls once the smart meter is fitted.

Painter23

Here are my first (6th Dec) and most recent (today) readings

QrizB

Paging @SAC2334 who used to be a professional leter reader

I think the first is 52090.16 and the second is 53289.82

That's a difference of 1199.66 kWh, which is rather a lot for six weeks. 200kWh a week.

On the national average Ofgem-capped single-rate tariff of 27.69p/kWh and 54.75p/day, that would be £59.21 a week, £254 a month.

This is however somewhat less than the £350 that your first month cost.

Netexporter

I make it 10 units different but it is one of those ambiguous hard to decide readings.

I happened to get a bill, yesterday, and I used an average of 23 kWh/day compared to the 28kWh/day for the OP. I have a similar age detached bungalow, which is probably a similar footprint to this house, so the extra heat loss would be for the 1st floor walls and windows.

Without heating my daily consumption is usually around 4kWh, so this is around 8kWh/day more. My heat pump is rated at 5kW and used just over 30kWh on the days the temperature was at almost minus 10 degrees.

I'd say there was room for improvement but the usage is not out of the ballpark.

I suppose the meter being 35 years since it was last calibrated might be a factor.

Painter23

Morning all, I'm back at the property to have a play with the settings.

AI told me the following which corroborates some of the advice from you guys:

The ideal Hive strategy for a 4‑bed radiator home

You want Hive to act like a gentle demand switch, not a temperature booster.

Recommended Hive settings:

• Daytime: 19–20°C

• Night: 18–19°C

• Avoid big drops (never drop to 14–15°C overnight)

• Avoid big jumps (don’t go from 16°C → 21°C suddenly)

This keeps the heat pump running smoothly and avoids recovery spikes.

I've just made this adjustment to Hive:

I've gone into My Serviceman on the Midea panel and it's baffled me. 

The AI instructions use different terminology:

Use weather compensation on the heat pump

This is the magic ingredient.

For your 4‑bed radiator home:

• Curve slope: 0.8

• Offset: +3

• Min LWT: 35°C

• Max LWT: 55°C

This lets the heat pump automatically adjust flow temperature based on outdoor conditions.

Result:

• Mild days → 35–40°C flow

• Cold days → 50–55°C flow

• Much lower electricity use

However, this is what I get within the various menus. Any advice on what to adjust would be very welcome (apologies it insists on putting the photos in reverse order for heating and DHW!!)

benson1980

The AI suggestions are probably a bit too high.

 The important curve settings are in your first photo. Here’s mine (I can adjust them on my phone/laptop via home assistant so this is what the screen capture is)

T1setH1 is the flow temperature at outdoor temp T4H1. So…mine runs at 49C at -4 outside. 

Likewise T1setH2 is the flow temperature at outdoor temp T4H2.

This is for a bog standard 70s house with insulation that is not great in places btw.

These values are the custom curve settings. You then have to make sure the controller is set to run this curve. I cannot remember off the top of my head how to select this specifically but you want to look for weather temp set in the menu somewhere. This is the page in the manual:

Your values indicate to me that this custom curve has never been set up. What your installers might have done is used one of the pre programmed curves, but one that is too high for your house- then used the hive to prevent overshooting. If this is what they have done, this is a concern regarding their competency. 

The midea terminology is bizarre. It is difficult/impossible to remember without googling or checking the manual. I do have a handy crib sheet somewhere explaining what they all are. 

Painter23

Thank you.
I've made the changes to mirror yours to see what happens. Immediately it's dropped the flow rate to somewhere between the curve as expected. I didn't instruct it specifically to use this curve - I just adjusted then and 'saved changes' but it seems to have taken effect immediately.

benson1980

Yep....37C at OAT of 7C is spot on, with those WCC settings.

Even more odd what they've done then, to have set the custom curve, but have both values at 55C. It should then in theory at least have been operating at 55C all of the time.