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ASHP in Hampshire

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cathodeRay
(@cathoderay)
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Posted by: @batalto

it's a lot of rads - 22.

Wow, that is a lot. I have nine which at full whack can theoretically deliver 12.4kW. 

If the primary pump in your 12kW (which is very likely the same pump as in the 14kW unit I have and the 16kW unit, based GH's previous remarks) can get heating water to 22 rads, then it should have no trouble with nine rads. I take it your pipework is standard ie 28/22/15mm flow and return as appropriate, and the runs aren't unusually short or long, just a 'typical' installation?

 

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


   
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(@batalto)
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@cathoderay it's fairly typical. The water tank is in the loft, so it's a bit of a push for the pump up 7m (ish). But it was doing that run before anyway as that's where the LLH was. Upstairs is microbore as it's super insulated. Downstairs is just normal household rads and pipework. Honestly it's not the best, but it's what we had and I wasn't swapping when it's fine. In a few years we'll do the kitchen and get underfloor heating, but until then, it's rads all round.

I just need to work out my new heat curve

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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(@batalto)
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House is still feeling very hot. I've lowered the flow to 47° at -2 and 31° at 17. That's down from 52°/37° previously. 

I'll try to experiment over the next couple of days and not tell my wife - see if she notices lol. I've started logging COP now we are post change and adding it to the sheet in my signature in a separate colour. No where near enough data yet, but over time I should be able to see the trends 

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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cathodeRay
(@cathoderay)
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Posted by: @batalto

House is still feeling very hot.

Interesting. I take it the most likely reason for the increase is the removal of the LLH. It will be interesting to see how flow temps and COPs are affected.

I'm planning to do a trial 24 hour run of monitoring starting at noon tomorrow to see how the Midea app data compares to the ambient/inside delta T and external kWh meter data. I won't be getting up every hour during the night to see what the external kWh meter shows, but all the other data will be hourly. Once all that data is in, I will calculate the various COPs and see how they compare.  

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


   
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(@batalto)
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@cathoderay I assume the LLH removal means more heat is making it through to the house, rather than being diverted back to the return. It means I've been able to drop the flow temps and the house is still warm. I'm tracking the COP data from the app (as I was before) so inputting it into the sheet in my signature. It will be a while before I can give a judgement on how much the improvement is, but lower flow temps mean less energy consumed - its just a matter of if that really makes any difference to the long term COP. 

Without underfloor heating I think I have reached the limit of what I can optimise around the heating system.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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cathodeRay
(@cathoderay)
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@batalto - I've also put this on the Samsung buffer thread, but am adding it here as it is also relevant here:

I've just had a look at Freedom's latest Midea installation manual, available here, only to find the kiss your warranty goodbye message is there, albeit with slightly different wording:

"Every system must have hydraulic separation between the primary (heat pump) and secondary (heating circuit) pipe work. This can be via a buffer tank, low loss header or plate heat exchanger. If you install the unit without hydraulic separation, you will void the warranty."

Arrgghh...  

 

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


   
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(@batalto)
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@cathoderay well they told me I could take it out. So hey ho. If I ever had a big problem it's got ball valves in place, I can just pop the whole thing back in. No one would ever know

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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cathodeRay
(@cathoderay)
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Hey ho indeed. Glad my Stilson is still in the toolbox.

I think you once mentioned a Freedom Midea app, as opposed to the Midea app. It seems @grahamh may have written this app, and apparently it records and displays flow rates and LWT/RWT:

Freedom Midea app

which means it might well make it possible to use the flow rate formula to calculate output if the app has historical data. Did you manage to download and use the app?

Freedom also now have something called the FHP Cloud, launched last month. It has installer and home owner browser based dashboards and the former looks very interesting, potentially all sorts of data, see here. I've managed to login to the installer dashboard, but haven't figured out a way to get it to display data, probably because I haven't got the "incredibly simple to install piece of hardware".

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


   
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(@batalto)
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Nov 21 - Dec 21st bill is in and the damage is... £450. I averaged 22.94p/kWh using a mix of solar and batteries. Interesting is was basically a 50/50 split between off peak and on peak power. The latter costing me 5x the off peak cost.

image

Without the batteries it would have been £617 - so saved a few hundred in the last month during the cold snap.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
Oswiu reacted
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(@bob77)
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Posts: 36
 

Posted by: @batalto

Nov 21 - Dec 21st bill is in and the damage is... £450. I averaged 22.94p/kWh using a mix of solar and batteries. Interesting is was basically a 50/50 split between off peak and on peak power. The latter costing me 5x the off peak cost.

-- Attachment is not available --

Without the batteries it would have been £617 - so saved a few hundred in the last month during the cold snap.

I have just had my bill for the same period and it was £405. However my electricity usage was around 30% lower than last year, despite the weather being much colder and the ASHP being set too high for much of the time as I optimised the settings. The next month will be the real test as I think I have the WC curve dialled in now.

 


   
Derek M reacted
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(@batalto)
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Topic starter  

@bob77 I used 1.8MW which is my highest use - ever. But that includes all the power in the house too. The ASHP has never been so cold. Last year I was already on weather comp so benefits this year stem from the LLH removal mostly (and some more radiator balance). My second battery also came into its own this month

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
Derek M reacted
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(@derek-m)
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Hi Batalto,

Could you please remind me of the password to access the Midea manual that you provided quite some time ago.


   
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