Daikin 9kW ASHP application discussion

Hardware Heatpump
42

This has been quite a roller-coaster :joy:

It would be interesting to know what the maximum output is of the 8kW model, it looks like it’s a different model / range from the ebla 9-16 kW range. If it’s about 30% below rated capacity that would be ~5.6kW which should meet your 4.5kW requirement assuming on consistently over 24h period? But then if you want more uplift / faster recovery time from periods of having the heat pump off that will throw these calculations out of the window and it becomes a question of how fast you want that recovery and how many off hours you want to design for?

2 Likes
43

Hi Trystan,

It’s a steep learning curve with a heat pump, not everything is as I expected in the way it all behaves, how it was designed and how/where to compromise to get the best out of it.

I suspect most retrofits have to compromise a lot and there will always be problems to overcome.

My biggest issue was how limited the range of operation of this heat pump is, first at the low end and then the defrosting.

It’s too big when warmer and coupled with radiators that were way too small it was difficult to run efficiently, I was genuinely scared for the cold weather and if I had to run at 50c as designed it would have cost a fortune as I would have been on a BUH I suspect.

The heat pump has done OK though, the house was cold having been off for hours in -3c weather and it recovered from it quite well, just not the same overpowering that I have when it is warmer.

The new radiators are working well and heating the house at a decent COP at a flow of 35c or less, but more importantly, consuming the lowest amount of electricity it can.

I think it is about the best I can do with it.

But I think I would have done just as well with the 16kW in the same circumstances so I stand by my view that the other three in the range are pointless.

I don’t think there is much to gain with the 8kW, I might get a better COP for much of the time but I fear it won’t be enough when really needed and it has no BUH in the UK.

I am not changing, there are other factors that are influencing my decision and one big thing is the appearance of it, none of them are the most beautiful things in the world but at least this one looks a bit more modern with the silver and black, the 8kW in white isn’t so great because the heat pump is at the front of our house, a `cheapo looking air conditioning unit’ won’t look great.

I am now looking at how to make the most of this heat pump, I am happy to just run it continuously or at least for as long as possible as that is what works best.

I want to try just a fixed flow and remove Madoka influence now, I don’t really know exactly what it does and how it interacts with the heat pump to influence flow rates and temperatures.

So later today I will just go back to straight fixed flow with no room influence. I will just manage it manually from the app for now and maybe set up a WD curve or go back to room influence in it doesn’t work.

I am also looking for plumbing advice, or more accurately design advice for adding a room to my heat system, I started a separate thread.

4 Likes
44

I’m struggling to understand what is going on with my heat pump. My radiators are now big enough to cope with the heat output but I have a more fundamental question when I compare my system to the 11kW Daikin in Cambridge.

Same flow temperature and same outside temperature but my heat pump uses far more electricity at the same flow rate and flow temperature. I want to find out what the problem is.

My heat pump, 1,348w flowing at 35.4c

image
image1115×1125 133 KB

11kW in Cambridge only using 970w to flow at 36.1c

image
image1136×1197 153 KB

I am using 50% more electricity for the same result, I just don’t get it?

My heat output is what I would expect at the flow rate and temperature, it’s just the electricity consumption that is required to achieve it. Looking at other pumps n the range it seems like I just consume more electricity.

At times it is fine but it is inconsistent.

Madoka influence?

Pipework problems, but then I would expect that to be a problem all of the time?

Lack of refrigerant?

I feel that electricity consumption has always been my biggest issue rather than heat output.

45

Have you tried popping it into Leaving Water Temperature and turning off all other influence. easy to change back if needed and will allow you to dial in the WDC to exactly where it needs to be (for this time of year at least).

1 Like
46

Hi Zak,

Yes, that is exactly what I have done.

COP is all over the place and flow temperature is not steady like the one in Cambridge.

I have always thought there is something wrong with this heat pump, I don’t know what but I have never felt that I can get a grip of it and get consistent results that I can work with.

One day it’s great at times, then terrible and I really cannot work out why.

I have understood radiator limitations and I can see that sub optimal pipework could be an issue but they are all constants.

The radiator issues are gone yet I am still having problems.

It feels like something that is suffering from intermittent fuel starvation, that is the only way I can describe it.

I don’t know what is wrong but right now the weather is perfect, the flow temperature should be good but I just cannot get any consistency.

I am out of my depth with it if I am honest.

I feel like it is fighting me every step of the way, I am really trying to make it work.

1 Like
47

Hi Matt

Yeah, very interesting. I have compared my recent numbers to yours (Heatpumpmonitor.org, top right/ graph symbol/ compare function, Reading Altherma vs Ipswich Altherma, dates 27/11-7/12), and yours seems maybe less consistent than mine. Even Electric Input vs Outside Temp shows mine with much lower numbers, which is a surprise to me, sitting in my plasterboard tent! There is one outlier on mine which is the dratted booster heater for legionella.

Reading vs Ipswich E_Input vs Outside T
Reading vs Ipswich E_Input vs Outside T1524×1228 48.9 KB

Do you think it’s worth doing a direct comparison of your MMI settings with mine, via an export to a USB stick, just to see if there’s any unspotted parameter?

48

Hi John,

Is yours the Cambridge one?

Look at this, my flow set at fixed 35c with no other influence I am aware of

image
image1115×1099 75.8 KB

Compared to this, I just don’t understand what would cause the different behaviour? Mine is currently flowing at 34.2c even though it is set at 35.0c

image
image1128×1162 75.5 KB

I am going to try and download the settings now.

I think I have sent them to you.

49

Now it is doing this.

I think it is heating DHW, it is scheduled for 13.00 tomorrow to heat to 50c and the tank is currently 47c.

I have seen strange DHW times with the schedule ignored and random unrequested reheats

image
image1154×1039 67.2 KB

50

@matt-drummer
Here’s the diff between your MMI settings and mine. Points of interest seem to be:

  • LWT_Spmode_main - you 2; me 3; can’t see any documentation for 3?!
  • Quiet level - you 2 (Auto); me 0 (0ff)
  • Flow/Return delta you 8; me 5; also Radiators vs. FanCoil (as set by Octopus)
  • Disinfect - you Off; Me On
  • Building Equilibrium temp - you 0; me -5
  • [6-00] Tank Hysteresis - you 20; me - 10
  • DHW Schedules: yours don’t have a “off” setting! I found that I had to enter an explicit OFF session to stop it being on all the time; this could be why yours works “randomly”, although it’s on a schedule, the schedule is effectively open??

26c26
< LWT_shift_heating_main=-2

LWT_shift_heating_main=0
81c81
Room Temp Setpoint??
< RT_SP_heating=22.000

RT_SP_heating=19.000
83c83
LWT Setpoint
< LWT_SP_heating_main=35.000

LWT_SP_heating_main=50.000
87c87
< DHW_SP=50.000

DHW_SP=44.000
112c112
Not sure what this is doing? 2.4 MZ Setpoint Mode, but manual says 0/1/2, my MMI set to 3!
< LWT_Spmode_main=2

LWT_Spmode_main=3
136c136
< WD_curve_type_main=1

WD_curve_type_main=0
138c138
QUiet level!!
< quiet_level_limit=2 - Auto (!)

quiet_level_limit=0 - Off
189,192c189,192
WD Curve settings
< 1-00=-40
< 1-01=25
< 1-02=60
< 1-03=40

1-00=-10
1-01=15
1-02=50
1-03=26
197,198c197,198
< 1-08=22
< 1-09=18

1-08=15
1-09=7
200c200
< 1-0B=8 dT Flow/Return

1-0B=5
205,206c205,206
< 2-01=0 Disinfect - none
< 2-02=4

2-01=1 Disinfect - yes
2-02=2
209c209
< 2-05=8 Room antifrost temp

2-05=12
214c214
< 2-0C=2 Emitter type radiator

2-0C=1 Emitter type fancoil
223,224c223,224
< 3-06=30.0 Max/min room temp heating
< 3-07=12.0

3-06=26.0
3-07=16.0
229,230c229,230
< 4-02=25 Outdoor temp to start heating
< 4-03=3 Booster heater permission - Compressor off

4-02=14 Outdoor temp to start heating
4-03=4 Booster heater - legionella only
242c242
< 5-01=0 Building equilibrium temp

5-01=-5 Building equilibrium temp
256c256
< 6-00=20 Temp diff determining heat pump ON

6-00=10 Temp diff determining heat pump ON
264c264
< 6-08=8 Reheat mode hysteresis

6-08=10 Reheat mode hysteresis
266,268c266,268
< 6-0A=50 DHW Comfort
< 6-0B=45 DHW Eco
< 6-0C=43 DHW Reheat

6-0A=48 DHW Comfort
6-0B=44 DHW Eco
6-0C=44 DHW Reheat (!)
280,281c280,281
< 8-01=30 DHW max run time
< 8-02=3.0 Anti recycling time

8-01=45 DHW max run time
8-02=1.0 Anti recycling time
285c285
< 8-06=1 LWT max modulation

8-06=5 LWT max modulation
288,289c288,289
< 8-09=42 Main Zone Comfort LWT
< 8-0A=42 Main Zone Eco LWT

8-09=45 Main Zone Comfort LWT
8-0A=43 Main Zone Eco LWT
293c293
< 9-00=60 Main Zone max LWT

9-00=50 Main Zone max LWT
297c297
< 9-04=2 LWT Overshoot temp

9-04=4 LWT Overshoot temp
306c306
< 9-0D=8 Pump Limitation 80-50% during sampling

9-0D=6 Pump Limitation 80-50% during sampling
*** Snipped Heating schedules ***
426,432c454,467
DHW Schedule
< monday=12:30 1
< tuesday=13:00 1
< wednesday=14:50 1
< thursday=13:00 1
< friday=13:00 1
< saturday=13:00 1
< sunday=13:00 1

monday=13:00 0
monday=14:00 2
tuesday=13:00 0
tuesday=14:00 2
wednesday=13:00 0
wednesday=14:00 2
thursday=13:00 0
thursday=14:00 2
friday=13:00 0
friday=14:00 2
saturday=13:00 0
saturday=14:00 2
sunday=13:00 0
sunday=14:00 2
434a470,471
Legionella Schedule
friday=1:50 1
friday=4:10 0
440a478

51

Thanks for your efforts John.

The DHW 44 is an eco setting that was first set by Octopus but now I heat to 50c on the schedule that doesn’t go off! I can correct that.

I tried fan coils again a couple of days ago but it was worse, it was on fan coils at installation.

But the problem may be the quiet mode!

I tried it about a month ago after talking to a Daikin `engineer’, he assured me it would cut the power and the electricity consumption as I was having big problems running at a high flow temperature to get a reasonable COP, the house was a furnace.

I have encountered this before thinking something was changed and not actually saved, probably entirely my fault.

I will change that shortly and see what happens.

I don’t know what building equilibrium is, I don’t recall ever having seen that.

I just looked at quiet mode, on the MMI settings it is off. When it is on it shows on the home screen, it was showing nothing but I have made sure again that it is off.

Maybe I can do a reset as I have played with it so much?

52

@matt-drummer

From Reference Manual:

[9.3.6] [5-00] Equilibrium: Is backup heater operation allowed above equilibrium temperature during space heating operation? :black_small_square: 1: NOT allowed :black_small_square: 0: Allowed

[9.3.7] [5-01] Equilibrium temperature: Outdoor temperature below which operation of the backup heater is allowed. Range: –15°C~35°C

[5-00] is 1 on both HPs, you’ll be pleased to hear!

1 Like
53

I think this might be LWT setpoint mode. 0=Fixed, 1=Weather Dep, 2=Fixed+Schedule, 3=Weather Dep+Schedule. But this is from my older Altherma EDLQ manual.

I’m watching this thread. I’ve been running fixed LWT (at 38C) for the last couple of weeks which has improved things, but thinking of going back to weather dependent with a very shallow curve.

2 Likes
54

Hi John,

Thanks.

My quiet mode was definitely off and is off now.

I have switched to fancoils for the last heating run and the delta t is 5c My flow rate is fixed at 35c, in theory obviously! It won’t do it for some reason. It has been on fixed flow of 35c since 16.00, I don’t understand. The flow temperature is not measured at the heat pump of course, maybe that makes a difference? But you would expect it to be constant at a constant flow rate?

image
image1139×1082 131 KB

55

Do you have your Tank Temp available? Use the Graphs to select more items, App view is a bit limited. I reckon your DHW topped up about 18.00. You could also display the Flow Rate l/min, rather than just Flow Temp

56

Hi John,

The tank did reheat at 18.00 ish but I have sorted that now thanks to you, I have set it to off between 15.00 and 13.00 the next day.

The flow rates are added, I don’t think I have a problem here.

I think I might have an issue with radiator balancing that I need to address. I have turned up the flow to 42c to see if I have any obvious problems with that. I have noticed the radiators go much cooler from time to time.

I have fitted Ultraheat K3 radiators downstairs. The are like a K2 with a K1 on the front with what appear complex connections between them. There are also two blanking plugs on a connector at the underside of each radiator on one end.

I notice that the back panel gets much warmer than the foremost panel, I can’t get to the centre panel without removing the covers but I will check when I get a moment.

Maybe I don’t get the full output of the radiator? Maybe I have done something wrong?

image
image1148×1085 134 KB

57

@matt-drummer Hi Matt, this one is mine.

I use Leaving Water Control (aka pure weather compensation).

I have dT set to 5C target

Set to Sample and also Pump limitation for sampling at 60%

I have very narrow curve (32C @ 15 & 38C @ -3C) as it seems happiest in this range.

I have disabled the boost it does around 0C

I have disabled all backup and booster heaters

Auto bypass valve fully closed

Open system.

In fact I have tried reinstating the Honeywell controls to load shift using the UFH, and can see that it save no input electrical power, just outputs less heat!!! So UFH is now back to fully open, no valves, no pumps, no controls. Just old fashioned balancing.

Importantly, I have overshoot at its max of 4C - today a perfect example as most of the day it has run just over the target flow temp by a degree or two, and if I hadn’t got the 4C overshoot enabled, it would cycle like mad.

This unit appears to be most efficient running at minimum output (with the caveat that it needs the emitter output to be able to take the heat and dissipate it)

I think the madoka + its modulation may be your issue at this point as I use neither and you have significantly upgraded the heat output/load now

2 Likes
58

Bizarre as that’s where I’ve got to as well. Very interesting we’ve come to the same conclusion.

I just have to turn mine off in milder weather for a period of time.

2 Likes
59

@matt-drummer do note that as I’m running ESPAltherma, I have been able to add the “target flow temp” value.

Note that the flow temp is in the “overshoot” window (I have set it at 4C). This implies it is running at minimum output, can’t drop lower, but the overshoot parameter prevents short cycles.

Madoka + modulation probably does the exact opposite to this.

1 Like
60

Hi Stephen,

I now have 40kW of radiators at a delta of 50c and will add another 6kW soon and increase the heat loss.

This should be enough to accommodate the full minimum output of this heat pump at a COP of 5, electrical input of 900w and a flow temperature of 35c at 7c outside.

I am sure my overshoot is at 4c but I need to check again.

I am now on fixed flow, no Madoka, fan coils and a delta t of 5c with overshoot of 4c.

I have no trvs on my radiators, normal fully open lockshields on one end and Danfoss RLV-D lockshields on the other end.

The radiators I have now are what I worked out I needed to produce my heat loss at a mean flow temperature of 32.5c and 21c indoors, about 4.5kW.

I should be getting that now but for some reason I am not, I get close at times, I can only think I have flow issues, but I have a thermal imaging camera so should be able to find the issue(s).

I am going to go over it all again at the weekend and remove any variables I can, I just need a decent day where I can set a flow temperature and maintain it with no defrosts.

I think the Madoka messes things up but I may revert to it in the end, I just want to get it functioning properly first.

1 Like
61

How have Octopus/Daikin responded to this same question?

There should not be such a discrepancy in steady state conditions.