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Auto adapt and the Ecodan curve

 
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Air Source Heat Pumps (ASHPs)
Last Post by SUNandAIR 1 year ago
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 Westkent
(@westkent)
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Joined: 3 years ago
Posts: 67
Topic starter 03/03/2025 9:30 am   [#2163]

Iv read often on here that while your on auto adapt the ecodan system will still to a good degree use the set curve you’ve set.

But…Recently iv had the it set at 38 high end @ -3.

The MELCloud app shows on cold mornings though the flow temperature reaching as high as 45c.

At the weekend just to see what happens I lowered my high end to 30c.

This morning MELCloud showed my flow rate at one point reaching 50c.

Is this going to show that while on auto adapt that actual set flow rate has no real affect??

IMG 9520


   
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SUNandAIR
 SUNandAIR
(@sunandair)
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Joined: 3 years ago
Posts: 569
03/03/2025 10:21 am  

Was this chart taken when the house was cold? 
I think it would help others to interpret this if you can give OAT outside ambient temperature and  inside thermostat temperature. And third piece of info is what was the target room temperature at this point. Also how long the HP has been on.

Problem is the chart shows a steep cool-down during the off time of 4 or 5 minutes. Not only that it’s cooling is accelerating towards the end of the off period.
As much info as you know is always handy but appreciate you may not know what’s needed. EG rads or UFH. Size of HP, how big is the load (size of total emitter capacity at T50 rating)

in principle if your room temp is close to your target room temp Auto Adapt will reduce its output but only as it gets close to room temp. But I have often seen Auto Adapt rising above my weather curve so I often stop using it.

So I’m not entirely sure if it uses my  weather curve at all or if it has its own notional weather curve built in. That’s not to say it doesn’t use your curve I’m just not 100% convinced.

but regarding the curve you’ve posted it shows it wants to heat at a high output because the heat loss at that point in time is very high.

here is a chart of ours when the room temp is almost reached and you can see the drop in return temp is not steep.

I’ve also just noticed your curve might be doing a defrost???

6461923D 28FE 4CF7 BB4D C8DB35C30B6E

 



   
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 Westkent
(@westkent)
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Joined: 3 years ago
Posts: 67
Topic starter 03/03/2025 11:36 am  

Below are charts showing the hour before and hour after. Also a chart showing set temp/ room temp/ outside temperatures.

iv no underfloor heating.

size of pump is 8.5kw

no understanding tbh of t rating.

3 bed semi approximately 

100sq meters 

I have to state I’m not at all unhappy with performance as my house is well able to heat to a nice comfortable temperature seemingly quite easy. All rads fully open other than one in bedroom turned down to 2 tvr.

IMG 9525
IMG 9522
IMG 9523
IMG 9524


   
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SUNandAIR
 SUNandAIR
(@sunandair)
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Joined: 3 years ago
Posts: 569
03/03/2025 3:14 pm  

@westkent hi

i can see now that at zero OAT these charts are showing defrosting. There seems to be a consistent deltaT. Does you house get up to the desired temperature in WCURVE mode? 



   
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 Westkent
(@westkent)
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Joined: 3 years ago
Posts: 67
Topic starter 03/03/2025 3:28 pm  

At 38c top end yes but as I said atm it’s down to 30c.

how do you know when it’s defrosting??



   
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SUNandAIR
 SUNandAIR
(@sunandair)
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Posts: 569
03/03/2025 4:02 pm  

@westkent it’s defrosting when the flow temp line (in blue) drops below the return temp line. (In black) 

The flow temp rapidly drops because the defrost system works in reverse so the flow water is chilled as its relative heat is used to warm up the refrigerant to melt the frosting.

depending on how many radiators you have your HP may struggle to operate as low as 30c without shutting down a lot. That’s why I asked about the T50 rating. That’s a measure of a radiator output at a given room temperature.

as an example my 8.5 ecodan works well at 35c and cannot go below 32c without rapid cycling.

we have 15 radiators 



   
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 Westkent
(@westkent)
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Joined: 3 years ago
Posts: 67
Topic starter 03/03/2025 5:09 pm  

So as I have glycol in the system am I able to some way or other deter the H/P from defrosting???



   
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Toodles
 Toodles
(@toodles)
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Joined: 4 years ago
Posts: 2733
03/03/2025 5:16 pm  

@westkent The glycol is there to stop the water from freezing and causing damage to any of the pipework (in or outside the heatpump). The defrosting will still be a necessary stage in the heat pump’s cycle - when the fins ice up due to moisture freezing on them, they need to be defrosted or cleared with some heat. Regards, Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
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 Westkent
(@westkent)
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Joined: 3 years ago
Posts: 67
Topic starter 03/03/2025 5:54 pm  

Thanks for the replies. Very helpful in understanding how things to a degree work.

Im going to keep the upper temp at 30c at -3 and see if it continues to heat the house comfortably.

My heating went back on near on a couple of hrs ago at 3pm and the flow atm is at 34c with an OAT of 9c.

My wireless remote thermostat is set to 20c and showing a room temperature of 20.5c and still heating.



   
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Toodles
 Toodles
(@toodles)
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Joined: 4 years ago
Posts: 2733
03/03/2025 6:04 pm  

@westkent A thermostat has a ‘Hysteresis’; this may well be ~1 degree or possibly a little more - thus preventing a system from being turned on and then off at short intervals. Some controllers allow adjustment of this ‘tolerance’, others are fixed by the manufacturer. Regards, Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
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 Westkent
(@westkent)
Trusted Member Member
Joined: 3 years ago
Posts: 67
Topic starter 04/03/2025 6:44 am  

 

IMG 9535

So just to reaffirm..

Considering my top end weather curve is set to a low 30 @ -3 while on Auto Adapt, the curve seems not to be effecting the flow rate or certainly not to the effect I would of thought.

outside temperature at 5am was -3.

This morning’s data below 

IMG 9533
IMG 9531
IMG 9530

 



   
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 Gary
(@gary)
Reputable Member Member
Joined: 3 years ago
Posts: 350
04/03/2025 7:41 am  

What does the front display of your main controller show you can offset the weather comp curve from there.

No one other than Mitsubishi really knows what auto adapt is allowed to do but all the info says it starts with the weather curve but then learns how you house heats up and adjusts from there.

if you have been running it for a while maybe it’s now doing it own thing  

 



   
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