You are smart, I've used trial and error, and discovered the same thing. I set heat pump at 30c at 10c and use home assistant to monitor it and switch it off over 10c outside say for half and hour and vice versa. The heat pump is happiest us 35c, and I use rads only and is fine at lower LT. - 5 it is set at 45c. Good video and analysis. ❤
This is excellent information. Thank you! I don't have a heat pump yet - probably next year (awaiting planning permission) - and while I wait, I am collecting temperature data from various rooms inside the house and the outside temperature and noticing how the house responds. I'll keep a close eye on the heat pump efficiency when I get it; the one they have proposed for me is a Daikin 4kW unit and given that my bills are fairly low, I'm confident that that's the right size of unit.
Thank you for creating this video! I have also been trying to figure out why my heat pump's COP is so low and why it can't achieve a delta T of 5K. But thanks to your video, everything's clear now. My LWT is only 28°C (at 1°C ambient temperature) and my return water temperature is 26˚C (this keeps my floor surface temperature at 25°C, which keeps my room temperature at 22°C). After watching your video, it's now obvious why these conditions can never produce a delta T of 5K. Also, I have noticed an interesting thing when I lowered the desired delta T in the heat pump's settings from 5K to 3K. With a delta T of 5, the inverter cycled between 15 and 22 Hz. The COP was constantly cycling between 2.5 and 4.5, but the average COP seemed to be around 3.5. The 5K delta T also caused the LWT to overshoot by 3K on startup, causing short cycling (but I solved this by increasing the max overshoot setting from 1K to 3K). As an experiment, I tried lowering the desired delta T to 3. This made the heat pump run the inverter at a constant 19 Hz and it no longer overshot the LWT by more than 1K. However, this reduced the COP even further (to only 3). I wonder if it makes sense to turn off some of my underfloor heating loops (e.g. in the two halls). This would then allow me to bump the LWT above 30°C, but the room temperature would stay the same, since the other underfloor loops would have to provide the heat for the halls. Did you try turning off some radiators when you increased the LWT to 30°C? I'm also considering running the pump every other hour (i.e. on 1 hour, off 1 hour). This would allow the screed to cool down by 1 or 2K, and would also require increasing the LWT. This should help the pump reach the 5K delta T and run more efficiently.
@@markoluksa Tomorrow I’ll run another test at 35k and see how the system responds. General advice has been to open up every radiator loop as this encourages a greater delta T. Your circulation pump is already likely on the minimum flow rate already. I can’t configure a DeltaT of 3K on my system - it’s either 5k or 10k. I still hope to find those wonderful CoP figures for mild temperatures in a reliable way, and I think I’m getting close!
COP is not everything. We may have a high COP and have consumed more energy. If you increase Delta T you will have more compressor work, therefore, within certain limits of the equipment, you may have a higher COP, you may have reached the setpoint in more time and therefore you may have consumed more energy. I think the important thing is to tune the Delta T and the climate-dependent curve in such a way that the equipment does not stop unless it has reached ambient temperature and therefore will not start successively. Allowing an excess of a few degrees in the water temperature to maintain the delta t is also important, as is allowing modulation so that the heat pump can change the leaving water temperature according to the distance or approach to the setpoint.
@@anthonydyer3939 Yup, circulation pump is at its minimum (around 6.6l/min). My heat pump is massively oversized (8kW, whereas my heat loss is only around 1.5kW most of winter). BTW I think if you set the emitter type in the settings to underfloor instead of radiator, the you can then configure the delta T in 1K increments.
@@profilatic Yeah, my heat pump is running at its absolute minimum, because it's massively oversized (8kW, but the heat loss is only 1.5kW or even slightly less). The inverter runs below 20Hz (with 15Hz being the minimum). The circulation pump is also at minimum flow rate. The low COP isn't really a problem, since my yearly energy bill for space heating is less than 250€, and the house is very cozy (I don't even use a thermostat, as the weather-dependent curve is set perfectly), but the engineer in me wants to squeeze as much as possible from the heat pump. I think switching the heat pump off for periods of time (even though this goes against what is usually the best way to run a heat pump), might actually increase the COP and reduce the energy consumption. Especially, since the ambient temperature here is always around 1°C, and humidity is high, causing the heat pump to defrost often (and this of course reduces the COP further - from 3 to 2.5).
@@markoluksaI understand what you're saying, but I think you can improve the settings of the heat pump, a greater delta t and a curve with a higher minimum temperature, as well as the floor, adjusting the flow meters to guarantee balance in all spaces. I even believe that you should apply a brand's own thermostat and choose wisely where to place it so that it serves essentially as a modulator of the output temperature by moving away from or approaching the setpoint and also as a temperature limiter, if exceed the setpoint, the heat pump stops, but remains stopped until the temperature drops so there is no cycling. I don't see any major problems with heat pumps that are a little more powerful than necessary, a Daikin of this generation really allows for a lot of fine tuning...
Interesting to see your results, I have the Daikin 6kW Altherma monoblock, over past few months I've been running it on flow temperature control. My unit has run very stable most of the time, I believe compressor and pump are more or less running continuously at low demand. Today at 8.6C it's drawing 525W, LWT 35C, and outputting @ 2kW of heat to 70m^2 two bed semi, which is a COP of 3.8 estimated, and showing a dT of 5.1K I'm using the open energy monitor Pi2 package (no MID flowmeter as yet), so COP is based on simulated Carnot COP, I believe this is a good representation based on the SCOP data from Daikin control panel over longer periods. There is a 'Holiday' mode in Daikin Onecta App' which I see under 'schedule' at top right of screen. I used this last February when away and heat pump sat asleep consuming @ 10W, as far as I remember as soon as outside temperature dipped to 5C the system woke up and maintained a flow of 12C until external temperatures rose again. Unfortunately this was before I'd started monitoring details so working off memory. Antifreeze valves would trigger at 3C. when coldest at -3.9C last week or so the indicated simulated COP was 2.8.
Hard to tell from the angles but it doesn't look like you have much if any vibration isolation/dampening on your heat pump, so if you did want to reduce or potentially eliminate the noise of the unit in the lounge/kitchen then some cheap rubber isolators might do the job - we had a similar issue as ours is wall mounted and the rubber rings supplied with the unit were inadequate, but £8 for 4 mounts on Amazon sorted it completely and was quick to install, just raised it by about an inch. Also, you might to look into getting a condenser comb/brush that works with the spacing of the fins on the Daikin and helps deal with the larch needles!
Hello antonhy. I'm Marcos from Portugal. Go to the climate control settings with the installer password, parameter 9-04 (excess) there you can define how many degrees the pump can raise the water temperature before stopping the compressor. you can by up to 4 degrees. If the pump is unable to maintain the delta T of 5 degrees, before stopping the compressor it increases the water temperature, avoiding stopping and working at very low compressor speeds, as in order to be able to return the oil to the compressor it will have to be keep the rotation a little higher. keep up the good work.
Im experiencing the same behaviour of Altherma 3R in mild conditions. Using weather depended control WITHOUT thermostat gives much higher COPs and more predicable behaviour of HP especially during sunny days. It is very significant difference. You can move the weather curve up and down by temp offset, I use it to adopt to different weather situation. Interesting fact about the poor COP regime is that that refrigerant pressure (also captured by ESP Altherma) goes up and actually you can hear squeaking sound from refrigerant pipes. Unfortunately, we don't know if it is something to be addressed in the control logic.
Really cool analysis. Thanks for digging into the numbers. Do you know if this also happens for other heat pumps? It really sounds like a bit of a crappy design of the control loop if the outdoor unit just falls into an inefficient mode. I would not have expected this from a premium brand.
@@michaelgilch3645 It’s more the design of the heating medium temperature. If it’s run at too low a temperature, then it just hits the minimum flow rate and compressor speeds. I’m guessing that the efficient mode that I saw, utilising the accumulator, was just a fluke, rather than a design feature of the heatpump, though I’d like to be convinced otherwise.
Watch out when just burning kindling alone... I managed to overheat my stove doing something similar when getting rid of some old dry furniture from the previous owners and crazed the glass! It was a basic rectangular shape so only came to about £50 to replace but I dread to think about how much a curved piece would be!
That was one option presented, but the heatpump would be set low down. That's not good considering we sometimes have over 40cm of snow from time to time.
The approximate theoretical power maximizing COP is COP_theo = T_ambient / (2*(T_LWT - T_ambient)), where T_ambient is the external temperature in Kelvin, and T_LWT is the leaving water temperature in the heat pump. Note that this is different to the Carnot COP (which maximizes output energy but takes an infinite amount of time to do so, i.e. has an output power of zero), and is much closer to what heat pumps actually do. If the minimum power input is P_in_min, then the minimum heat power output at maximum efficiency is P_out_min = P_in_min * COP_theo. As T_ambient goes up, P_out_min only increases. On the other hand, the heat power required to keep your house warm is P_req = K*(T_desired - T_extra - T_ambient) where T_desired is the temperature you want in your house (eg 20 degrees C), T_extra is the heat you get from people and devices inside your house (typically 2 to 3 degrees C) and K characterizes the heat loss of your house (eg 300 watts per degree). As T_ambient goes up, P_req only goes down. Above some ambient temperature P_out_min > P_req, and something has to give if you don't want your house to get too hot. If you exclude silly actions like opening a window (= increase K) or moving out (= decrease T_extra), then you either have to turn off the heat pump (= cycle), or it has to run at less than maximum efficiency. It might be interesting to see where the cross-over point is for your house, and what P_out_min vs P_req is like when your heat pump moves into the inefficient regime.
You can set an offset to the LWT using the Altherma integration in HomeAssitant I have not tried using this so not sure if this would work for you or not. Also I'm not sure it would be a good idea unless you house is vacant for a longer period. On my Daikin Monobloc you can also override the minimum set point on the heating curve of 25 degrees in the installer settings. No idea if this is a good idea or not.
Nice explanation! I set the overshoot to 5oC in space heating setup to achieve a similar result. Are your defrosts noisier/noisy/audible? Your data indicates they consume significant power. Daikin support is horrid, the heat pump performance is opaque and they are horribly complex to configure. It's all marketing and little substance. If I could go back in time and choose again I would not purchase a Daikin system. I should have chosen a Vaillant Arotherm Plus. It would have been cheaper, quieter and simpler. That one will have to go down to experience.
Defrosts are noisy, and I only recently discovered this. It's a rumbling sound that I hear for a few seconds when the refrigerant is forced the other direction. Most of the time, I'm in bed during a defrost cycle, but recently they've been making themselves heard during the day. I like the Daikin hardware, but the literature on their website is all over the place. They have glossy brochure literature for homeowners, but there's no reference to datasheets or manuals from that literature. They don't even have the exact model names in that literature. That operating temperature chart I showed in the video took a good hour of searching the internet to find. It's not in the datasheet, or the manual. The complexity of configuration is OK (for me anyway). But the advice out there for configuring a weather comp curve assumes that the heatpump can operate well below it's minimum output. As we've seen it can operate beautifully below the minimum output ...... but only sometimes, for reasons beyond our control.
I've yet to be convinced of the virtues of heat pump's. Reliability issues are a common complaint and because of the varying loads on the rotary compressor motor the three phase VFD that power them are prone to burn out. It may be that lack of steady line voltage down under is a significant factor. Lightning storm surges are another VFD killer.
Regarding reliability. This is what my installer has said: " We have installed about circa 600 systems to date ......... off the top of my head I have changed 3 compressors in that time. These were due to faulty accumulators which leaked refrigerant which was the cause (about 12-15 years ago and Daikin covered this even out of warranty) I wouldn’t worry about reliability"
@anthonydyer3939 Being sealed units the compressors should last a reasonable time. But a friend who is a refrigerator engineer keeps very busy replacing fried units. Bad installation can be a factor. By and large Daikin has a good reputation though. Others not so much. Aussie tradies don't have the best reputation for proper installation..
Is it possible your ASHP is oversized with respect to operation during milder conditions and the operation regime changes could be explained by slight ‘shoulder’ conditions which you are not recording?
Sizing a heatpump. Ideally you'd have two compressors - one for low loads and one for high loads. Indeed you often find this for the 12kW+ models. But this 8kW example does work well at low loads - but only sometimes. But the operation regime change has to be determined from the sensor inputs, there aren't many of those on this system, and I'm recording all of them. I've not found the magic combination that brings the pump down below the minimum continuous operating regime.
Is that Hot Water Temp Correct? 58.9'C seems very high! The Daikin unit I think you had installed (Low Temp) will only heat water to 50'C when the outside temperature is 0'C or lower and can only manage 55'C when positive using only the heat pump . Anything above that will require the use of the immersion heater which kills your efficiency. Worryingly it seems that the data provided by the Daikin is not very accurate. Tests carried out by other youtubers have shown wild differences in the accuracy. Daikin showed 22kw and a Shelly Energy Monitor showed 18.5kw . The larger concern is whether the Energy out is also that inaccurate.....
Yes it's correct, but it only does this once a week as part of its disinfection cycle. The rest of the time it's set to 47 degrees. And yes it does need the immersion heater for that disinfection cycle. Thankfully though the disinfection cycle is set to run in the cheap overnight period. In terms of accuracy. Output: I've only got the flow rate and leaving /return water temperatures to go by. I do the calculations of heat output from those measures. Input: I've only got the compressor primary current as a measure. I don't have any measure of power. I have to measure power factors for different loads, and apply a best fit curve. Voltage I've retrieved from my SolarEdge Inverter, but recently I've just assumed 238 Volts because the modbus comms keep dropping out causing my program to crash. I'm minded to explore the pulse output on the Eastron meter and wire that up to my Pi so I can measure energy flux and derive power from that.
I have the Daikin 6kW Altherma 3 'low temperature' monobloc, I believe it can heat hot water to 60C with no additional resistive heating, it has a small 'booster heater' in HP which can be used to push that to 65C if required (I have booster disabled, and control panel shows no increase in booster hours run). Other than that I normally heat mixergy HWC to 43C which I find sufficient for hot bath or shower. Next time it goes below 0C I'll do a 60C run (usually just done when half price tariff available)
@@_Dougaldog Just out of interest what do you think the booster is? You should be able to see it installed into the bottom of the volumiser or buffer tank (depends which you have).
@@MagicianMan Nothing fitted to volumiser, I'd assumed it resides within monoblock unit and was there perhaps to meet some EU requirement to be able to heat to over 60C, as far as I remember when enabled in installer settings and HW pushed to 65C the control panel showed increase in hours of booster usage (Daikins own terminology). Heating to 60C shows no increase in usage, it has not moved since just after commissioning back in February. Daikin control panel 'Information/Actuators' section clearly shows whether booster off or on. The Mixergy cylinder has it's own immersion unit, which is not called upon at all. Edit :- Daikins use of term 'booster' refers to immersion in HWC (it assumes a Daikin HWC as default) info' from schematic. The EDLA can have an integrated 3kW backup heater for extreme low temperatures, or larger fitted externally.
@@anthonydyer3939 We have just installed a Homely controller which connects through the Daikin MMU. When they install it they change the control to Leaving Water Temperature and the Hot Water to Reheat. The algorithm then uses outside temp, inside temp, weather forecast, learned solar/heat gain and customer set point for Heating. We have set it to 07.30-21:30 @ 19'C and it will work out a setback for itself. For Hot Water there are two options both use reheat for control but offer slightly different operations: 1) Hot Water to reach the set temperature by your desired time. 2) Hot Water to reach the set temperature but ONLY operate between your set times. We run 48'C and 13:00-14:00 time slot. Anti-legionella is still controlled by the Daikin MMU, ours is 60'C 14:00-14:30 It is going to be interesting to see what impact it has on efficiency whilst it "learns" over the next couple of weeks and going forward. We took weekly & monthly readings from the Daikin MMU but will now take daily readings as well to see what impact it makes.
Hello antonhy, I have watched and listened to your assessment of this particular Diakin. A couple of questions I have may point me in another direction for my forth comming heat pump install via Octopus energy. They only supply Diakin or their cosy brand. After having a survey from Octopus, My 1960 bungalow was assesed at 10500 watts of loss with a recomended 14 kw unit. I am not a heating engineer, but a retired electronics man with a life interest of reducing my energy bills and this size of unit really made me baulk. I am sure this might be twice the size I need. But, watching your video has made me realise Daikin might not be my best option. Octopus cosy, although not quite as efficient have a lot more sensors in the AHU and I think ( not 100%) more weather compensation options. Just to give you a better idea of my set up, when the FIT scheme started , I had 3.2 kw Solar array fitted to my roof and this has given me a fantastic income over the years. I reckon my FIT generation earnings are just on £.80 per kilowatt of generated. On top of this, I can use all my generation for whatever use I want and still receive the 80p/kw. So a few years ago I constructed what I, at that time called a skimming unit, or harvesting unit and used my power to heat a preheat tank for all my hot water. It has been my most successful action giving us free hot water . Any way, my question to you is..... Would you have used Diakin given your testing and observations, or changed to another type of unit. Secondly, would you say your install is much more efficient than gas. Thanks for a very interesting video.
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Good on Merv
You are smart, I've used trial and error, and discovered the same thing. I set heat pump at 30c at 10c and use home assistant to monitor it and switch it off over 10c outside say for half and hour and vice versa. The heat pump is happiest us 35c, and I use rads only and is fine at lower LT. - 5 it is set at 45c. Good video and analysis. ❤
This is excellent information. Thank you! I don't have a heat pump yet - probably next year (awaiting planning permission) - and while I wait, I am collecting temperature data from various rooms inside the house and the outside temperature and noticing how the house responds. I'll keep a close eye on the heat pump efficiency when I get it; the one they have proposed for me is a Daikin 4kW unit and given that my bills are fairly low, I'm confident that that's the right size of unit.
Thank you for creating this video! I have also been trying to figure out why my heat pump's COP is so low and why it can't achieve a delta T of 5K.
But thanks to your video, everything's clear now. My LWT is only 28°C (at 1°C ambient temperature) and my return water temperature is 26˚C (this keeps my floor surface temperature at 25°C, which keeps my room temperature at 22°C). After watching your video, it's now obvious why these conditions can never produce a delta T of 5K.
Also, I have noticed an interesting thing when I lowered the desired delta T in the heat pump's settings from 5K to 3K. With a delta T of 5, the inverter cycled between 15 and 22 Hz. The COP was constantly cycling between 2.5 and 4.5, but the average COP seemed to be around 3.5. The 5K delta T also caused the LWT to overshoot by 3K on startup, causing short cycling (but I solved this by increasing the max overshoot setting from 1K to 3K).
As an experiment, I tried lowering the desired delta T to 3. This made the heat pump run the inverter at a constant 19 Hz and it no longer overshot the LWT by more than 1K. However, this reduced the COP even further (to only 3).
I wonder if it makes sense to turn off some of my underfloor heating loops (e.g. in the two halls). This would then allow me to bump the LWT above 30°C, but the room temperature would stay the same, since the other underfloor loops would have to provide the heat for the halls. Did you try turning off some radiators when you increased the LWT to 30°C?
I'm also considering running the pump every other hour (i.e. on 1 hour, off 1 hour). This would allow the screed to cool down by 1 or 2K, and would also require increasing the LWT. This should help the pump reach the 5K delta T and run more efficiently.
@@markoluksa Tomorrow I’ll run another test at 35k and see how the system responds. General advice has been to open up every radiator loop as this encourages a greater delta T. Your circulation pump is already likely on the minimum flow rate already. I can’t configure a DeltaT of 3K on my system - it’s either 5k or 10k.
I still hope to find those wonderful CoP figures for mild temperatures in a reliable way, and I think I’m getting close!
COP is not everything. We may have a high COP and have consumed more energy. If you increase Delta T you will have more compressor work, therefore, within certain limits of the equipment, you may have a higher COP, you may have reached the setpoint in more time and therefore you may have consumed more energy. I think the important thing is to tune the Delta T and the climate-dependent curve in such a way that the equipment does not stop unless it has reached ambient temperature and therefore will not start successively. Allowing an excess of a few degrees in the water temperature to maintain the delta t is also important, as is allowing modulation so that the heat pump can change the leaving water temperature according to the distance or approach to the setpoint.
@@anthonydyer3939 Yup, circulation pump is at its minimum (around 6.6l/min). My heat pump is massively oversized (8kW, whereas my heat loss is only around 1.5kW most of winter).
BTW I think if you set the emitter type in the settings to underfloor instead of radiator, the you can then configure the delta T in 1K increments.
@@profilatic Yeah, my heat pump is running at its absolute minimum, because it's massively oversized (8kW, but the heat loss is only 1.5kW or even slightly less). The inverter runs below 20Hz (with 15Hz being the minimum). The circulation pump is also at minimum flow rate. The low COP isn't really a problem, since my yearly energy bill for space heating is less than 250€, and the house is very cozy (I don't even use a thermostat, as the weather-dependent curve is set perfectly), but the engineer in me wants to squeeze as much as possible from the heat pump.
I think switching the heat pump off for periods of time (even though this goes against what is usually the best way to run a heat pump), might actually increase the COP and reduce the energy consumption. Especially, since the ambient temperature here is always around 1°C, and humidity is high, causing the heat pump to defrost often (and this of course reduces the COP further - from 3 to 2.5).
@@markoluksaI understand what you're saying, but I think you can improve the settings of the heat pump, a greater delta t and a curve with a higher minimum temperature, as well as the floor, adjusting the flow meters to guarantee balance in all spaces. I even believe that you should apply a brand's own thermostat and choose wisely where to place it so that it serves essentially as a modulator of the output temperature by moving away from or approaching the setpoint and also as a temperature limiter, if exceed the setpoint, the heat pump stops, but remains stopped until the temperature drops so there is no cycling. I don't see any major problems with heat pumps that are a little more powerful than necessary, a Daikin of this generation really allows for a lot of fine tuning...
Interesting to see your results, I have the Daikin 6kW Altherma monoblock, over past few months I've been running it on flow temperature control.
My unit has run very stable most of the time, I believe compressor and pump are more or less running continuously at low demand.
Today at 8.6C it's drawing 525W, LWT 35C, and outputting @ 2kW of heat to 70m^2 two bed semi, which is a COP of 3.8 estimated, and showing a dT of 5.1K
I'm using the open energy monitor Pi2 package (no MID flowmeter as yet), so COP is based on simulated Carnot COP, I believe this is a good representation based on the SCOP data from Daikin control panel over longer periods.
There is a 'Holiday' mode in Daikin Onecta App' which I see under 'schedule' at top right of screen. I used this last February when away and heat pump sat asleep consuming @ 10W, as far as I remember as soon as outside temperature dipped to 5C the system woke up and maintained a flow of 12C until external temperatures rose again. Unfortunately this was before I'd started monitoring details so working off memory. Antifreeze valves would trigger at 3C.
when coldest at -3.9C last week or so the indicated simulated COP was 2.8.
Hard to tell from the angles but it doesn't look like you have much if any vibration isolation/dampening on your heat pump, so if you did want to reduce or potentially eliminate the noise of the unit in the lounge/kitchen then some cheap rubber isolators might do the job - we had a similar issue as ours is wall mounted and the rubber rings supplied with the unit were inadequate, but £8 for 4 mounts on Amazon sorted it completely and was quick to install, just raised it by about an inch.
Also, you might to look into getting a condenser comb/brush that works with the spacing of the fins on the Daikin and helps deal with the larch needles!
Hello antonhy. I'm Marcos from Portugal. Go to the climate control settings with the installer password, parameter 9-04 (excess) there you can define how many degrees the pump can raise the water temperature before stopping the compressor. you can by up to 4 degrees. If the pump is unable to maintain the delta T of 5 degrees, before stopping the compressor it increases the water temperature, avoiding stopping and working at very low compressor speeds, as in order to be able to return the oil to the compressor it will have to be keep the rotation a little higher. keep up the good work.
❤Great content Anthony! Keep up the good work - Merv
Im experiencing the same behaviour of Altherma 3R in mild conditions. Using weather depended control WITHOUT thermostat gives much higher COPs and more predicable behaviour of HP especially during sunny days. It is very significant difference. You can move the weather curve up and down by temp offset, I use it to adopt to different weather situation.
Interesting fact about the poor COP regime is that that refrigerant pressure (also captured by ESP Altherma) goes up and actually you can hear squeaking sound from refrigerant pipes. Unfortunately, we don't know if it is something to be addressed in the control logic.
Really cool analysis. Thanks for digging into the numbers. Do you know if this also happens for other heat pumps? It really sounds like a bit of a crappy design of the control loop if the outdoor unit just falls into an inefficient mode. I would not have expected this from a premium brand.
@@michaelgilch3645 It’s more the design of the heating medium temperature. If it’s run at too low a temperature, then it just hits the minimum flow rate and compressor speeds. I’m guessing that the efficient mode that I saw, utilising the accumulator, was just a fluke, rather than a design feature of the heatpump, though I’d like to be convinced otherwise.
Watch out when just burning kindling alone... I managed to overheat my stove doing something similar when getting rid of some old dry furniture from the previous owners and crazed the glass! It was a basic rectangular shape so only came to about £50 to replace but I dread to think about how much a curved piece would be!
If you rubber mount the heat pump stand you can reduce that noise transmission.
That was one option presented, but the heatpump would be set low down. That's not good considering we sometimes have over 40cm of snow from time to time.
The approximate theoretical power maximizing COP is COP_theo = T_ambient / (2*(T_LWT - T_ambient)), where T_ambient is the external temperature in Kelvin, and T_LWT is the leaving water temperature in the heat pump. Note that this is different to the Carnot COP (which maximizes output energy but takes an infinite amount of time to do so, i.e. has an output power of zero), and is much closer to what heat pumps actually do. If the minimum power input is P_in_min, then the minimum heat power output at maximum efficiency is P_out_min = P_in_min * COP_theo. As T_ambient goes up, P_out_min only increases. On the other hand, the heat power required to keep your house warm is P_req = K*(T_desired - T_extra - T_ambient) where T_desired is the temperature you want in your house (eg 20 degrees C), T_extra is the heat you get from people and devices inside your house (typically 2 to 3 degrees C) and K characterizes the heat loss of your house (eg 300 watts per degree). As T_ambient goes up, P_req only goes down. Above some ambient temperature P_out_min > P_req, and something has to give if you don't want your house to get too hot. If you exclude silly actions like opening a window (= increase K) or moving out (= decrease T_extra), then you either have to turn off the heat pump (= cycle), or it has to run at less than maximum efficiency. It might be interesting to see where the cross-over point is for your house, and what P_out_min vs P_req is like when your heat pump moves into the inefficient regime.
You can set an offset to the LWT using the Altherma integration in HomeAssitant I have not tried using this so not sure if this would work for you or not.
Also I'm not sure it would be a good idea unless you house is vacant for a longer period.
On my Daikin Monobloc you can also override the minimum set point on the heating curve of 25 degrees in the installer settings. No idea if this is a good idea or not.
Nice explanation! I set the overshoot to 5oC in space heating setup to achieve a similar result.
Are your defrosts noisier/noisy/audible? Your data indicates they consume significant power.
Daikin support is horrid, the heat pump performance is opaque and they are horribly complex to configure. It's all marketing and little substance. If I could go back in time and choose again I would not purchase a Daikin system. I should have chosen a Vaillant Arotherm Plus. It would have been cheaper, quieter and simpler. That one will have to go down to experience.
Defrosts are noisy, and I only recently discovered this. It's a rumbling sound that I hear for a few seconds when the refrigerant is forced the other direction. Most of the time, I'm in bed during a defrost cycle, but recently they've been making themselves heard during the day.
I like the Daikin hardware, but the literature on their website is all over the place. They have glossy brochure literature for homeowners, but there's no reference to datasheets or manuals from that literature. They don't even have the exact model names in that literature. That operating temperature chart I showed in the video took a good hour of searching the internet to find. It's not in the datasheet, or the manual.
The complexity of configuration is OK (for me anyway). But the advice out there for configuring a weather comp curve assumes that the heatpump can operate well below it's minimum output. As we've seen it can operate beautifully below the minimum output ...... but only sometimes, for reasons beyond our control.
I've yet to be convinced of the virtues of heat pump's. Reliability issues are a common complaint and because of the varying loads on the rotary compressor motor the three phase VFD that power them are prone to burn out. It may be that lack of steady line voltage down under is a significant factor. Lightning storm surges are another VFD killer.
Regarding reliability. This is what my installer has said: " We have installed about circa 600 systems to date ......... off the top of my head I have changed 3 compressors in that time. These were due to faulty accumulators which leaked refrigerant which was the cause (about 12-15 years ago and Daikin covered this even out of warranty) I wouldn’t worry about reliability"
@anthonydyer3939
Being sealed units the compressors should last a reasonable time. But a friend who is a refrigerator engineer keeps very busy replacing fried units.
Bad installation can be a factor.
By and large Daikin has a good reputation though. Others not so much.
Aussie tradies don't have the best reputation for proper installation..
Is it possible your ASHP is oversized with respect to operation during milder conditions and the operation regime changes could be explained by slight ‘shoulder’ conditions which you are not recording?
Sizing a heatpump. Ideally you'd have two compressors - one for low loads and one for high loads. Indeed you often find this for the 12kW+ models. But this 8kW example does work well at low loads - but only sometimes.
But the operation regime change has to be determined from the sensor inputs, there aren't many of those on this system, and I'm recording all of them. I've not found the magic combination that brings the pump down below the minimum continuous operating regime.
Is that Hot Water Temp Correct? 58.9'C seems very high! The Daikin unit I think you had installed (Low Temp) will only heat water to 50'C when the outside temperature is 0'C or lower and can only manage 55'C when positive using only the heat pump . Anything above that will require the use of the immersion heater which kills your efficiency.
Worryingly it seems that the data provided by the Daikin is not very accurate. Tests carried out by other youtubers have shown wild differences in the accuracy. Daikin showed 22kw and a Shelly Energy Monitor showed 18.5kw
.
The larger concern is whether the Energy out is also that inaccurate.....
Yes it's correct, but it only does this once a week as part of its disinfection cycle. The rest of the time it's set to 47 degrees. And yes it does need the immersion heater for that disinfection cycle. Thankfully though the disinfection cycle is set to run in the cheap overnight period.
In terms of accuracy.
Output: I've only got the flow rate and leaving /return water temperatures to go by. I do the calculations of heat output from those measures.
Input: I've only got the compressor primary current as a measure. I don't have any measure of power. I have to measure power factors for different loads, and apply a best fit curve. Voltage I've retrieved from my SolarEdge Inverter, but recently I've just assumed 238 Volts because the modbus comms keep dropping out causing my program to crash.
I'm minded to explore the pulse output on the Eastron meter and wire that up to my Pi so I can measure energy flux and derive power from that.
I have the Daikin 6kW Altherma 3 'low temperature' monobloc, I believe it can heat hot water to 60C with no additional resistive heating, it has a small 'booster heater' in HP which can be used to push that to 65C if required (I have booster disabled, and control panel shows no increase in booster hours run).
Other than that I normally heat mixergy HWC to 43C which I find sufficient for hot bath or shower.
Next time it goes below 0C I'll do a 60C run (usually just done when half price tariff available)
@@_Dougaldog Just out of interest what do you think the booster is?
You should be able to see it installed into the bottom of the volumiser or buffer tank (depends which you have).
@@MagicianMan
Nothing fitted to volumiser, I'd assumed it resides within monoblock unit and was there perhaps to meet some EU requirement to be able to heat to over 60C, as far as I remember when enabled in installer settings and HW pushed to 65C the control panel showed increase in hours of booster usage (Daikins own terminology). Heating to 60C shows no increase in usage, it has not moved since just after commissioning back in February. Daikin control panel 'Information/Actuators' section clearly shows whether booster off or on.
The Mixergy cylinder has it's own immersion unit, which is not called upon at all.
Edit :- Daikins use of term 'booster' refers to immersion in HWC (it assumes a Daikin HWC as default) info' from schematic. The EDLA can have an integrated 3kW backup heater for extreme low temperatures, or larger fitted externally.
@@anthonydyer3939 We have just installed a Homely controller which connects through the Daikin MMU.
When they install it they change the control to Leaving Water Temperature and the Hot Water to Reheat.
The algorithm then uses outside temp, inside temp, weather forecast, learned solar/heat gain and customer set point for Heating.
We have set it to 07.30-21:30 @ 19'C and it will work out a setback for itself.
For Hot Water there are two options both use reheat for control but offer slightly different operations:
1) Hot Water to reach the set temperature by your desired time.
2) Hot Water to reach the set temperature but ONLY operate between your set times.
We run 48'C and 13:00-14:00 time slot.
Anti-legionella is still controlled by the Daikin MMU, ours is 60'C 14:00-14:30
It is going to be interesting to see what impact it has on efficiency whilst it "learns" over the next couple of weeks and going forward.
We took weekly & monthly readings from the Daikin MMU but will now take daily readings as well to see what impact it makes.
Hello antonhy, I have watched and listened to your assessment of this particular Diakin. A couple of questions I have may point me in another direction for my forth comming heat pump install via Octopus energy. They only supply Diakin or their cosy brand. After having a survey from Octopus, My 1960 bungalow was assesed at 10500 watts of loss with a recomended 14 kw unit. I am not a heating engineer, but a retired electronics man with a life interest of reducing my energy bills and this size of unit really made me baulk. I am sure this might be twice the size I need. But, watching your video has made me realise Daikin might not be my best option. Octopus cosy, although not quite as efficient have a lot more sensors in the AHU and I think ( not 100%) more weather compensation options.
Just to give you a better idea of my set up, when the FIT scheme started , I had 3.2 kw Solar array fitted to my roof and this has given me a fantastic income over the years. I reckon my FIT generation earnings are just on £.80 per kilowatt of generated. On top of this, I can use all my generation for whatever use I want and still receive the 80p/kw. So a few years ago I constructed what I, at that time called a skimming unit, or harvesting unit and used my power to heat a preheat tank for all my hot water. It has been my most successful action giving us free hot water .
Any way, my question to you is..... Would you have used Diakin given your testing and observations, or changed to another type
of unit. Secondly, would you say your install is much more efficient than gas.
Thanks for a very interesting video.