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fe31nz
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  #3019360 10-Jan-2023 00:25
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The reason is simple - the heat pump only reads the air temperature at its intake.  In high wall units, that intake is on the top of the heat pump, so it is reading the air temperature quite high up in the room.  Hot air rises, so the temperature at the top of the room is always significantly hotter than lower down.  The humans in the room, unfortunately, are normally rather lower down than the intake air temperature sensor.  So the heat pump never has an actual room temperature to work from.  What most manufacturers do is to subtract an arbitrary number from the intake temperature reading and use that as the guessed real room temperature at human level.  There is no way to adjust that arbitrary number for the room which the heat pump is installed in, or its position in the room.  There is no option to do calibration.  So you just have to set the heat pump setpoint temperatures to whatever works to produce the desired temperature at human level.  For example, our big Panasonic heat pump in the kitchen needs to be set to 19 if we want about 22 on heating, and to 23 if we want 24 on cooling.  Things are further complicated by the flow of heat in and out of the room.  For example, if we are heating in winter before the sun starts to shine in through the windows, we may need to set it to 20 to get 22, but when the sun is shining, 19 works.  This seems to be a result of how the airflow works in the room to distribute the heat, and what the heat gradient is from ceiling down to the floor.  If you really want the setpoint to mean what it says, you need to use a temperature sensor away from the heat pump at human level and unaffected by the airflow.  And it will need to be calibrated for the room.  And recalibrate it if you rearrange the room in a way that affects the airflow.  I do wish that heat pump manuals actually mentioned this problem!

 

So to emphasise the basic point here, the setpoint numbers on a heat pump are not calibrated - they do not match real temperatures.  You just use whatever setting works.




timmmay

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  #3019371 10-Jan-2023 07:15
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fe31nz:

 

The reason is simple - the heat pump only reads the air temperature at its intake.  In high wall units, that intake is on the top of the heat pump, so it is reading the air temperature quite high up in the room.  Hot air rises, so the temperature at the top of the room is always significantly hotter than lower down.  The humans in the room, unfortunately, are normally rather lower down than the intake air temperature sensor.  So the heat pump never has an actual room temperature to work from.  What most manufacturers do is to subtract an arbitrary number from the intake temperature reading and use that as the guessed real room temperature at human level.  There is no way to adjust that arbitrary number for the room which the heat pump is installed in, or its position in the room.  There is no option to do calibration.  So you just have to set the heat pump setpoint temperatures to whatever works to produce the desired temperature at human level.  For example, our big Panasonic heat pump in the kitchen needs to be set to 19 if we want about 22 on heating, and to 23 if we want 24 on cooling.  Things are further complicated by the flow of heat in and out of the room.  For example, if we are heating in winter before the sun starts to shine in through the windows, we may need to set it to 20 to get 22, but when the sun is shining, 19 works.  This seems to be a result of how the airflow works in the room to distribute the heat, and what the heat gradient is from ceiling down to the floor.  If you really want the setpoint to mean what it says, you need to use a temperature sensor away from the heat pump at human level and unaffected by the airflow.  And it will need to be calibrated for the room.  And recalibrate it if you rearrange the room in a way that affects the airflow.  I do wish that heat pump manuals actually mentioned this problem!

 

So to emphasise the basic point here, the setpoint numbers on a heat pump are not calibrated - they do not match real temperatures.  You just use whatever setting works.

 

 

That makes sense. I can see the temperature inside the Daikin and in the room, the Daikin is usually 2-3 degrees warmer, for the reason you said which is heat effectively rises. The manufacturer differential makes sense as well, as this is a smaller room, ceiling not quite as high and is sloped. Setting to what works is probably the only practical option. Thanks for the interesting analysis :)


timmmay

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  #3019372 10-Jan-2023 07:18
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Here's why I don't use auto mode.

 

  • I initially had the unit in heat mode 21 degrees started by automation, it was idle. The room temperature was 21.5 degrees, the heat pump temperature was 23 degrees.
  • I thought I'd try auto mode as suggested.
  • As soon as I hit auto, for some reason the unit decided it needed to cool the room, and went into cooling mode. When it did that it changed to the last preset temperature for auto, which was 20 degrees.
  • I then noticed it was getting colder and changed it back to heat mode

It might work better if I started it out in auto mode. I'll change my automation and see what happens tomorrow.

 

 

 

 

 




insane
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  #3019419 10-Jan-2023 09:21
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Does Daikin not have a service menu like this Panasonic?

Offers some temp offset settings and some limits too.



There's another section that shows what the expected resistance output of the temperature sensors is at various temperatures. Presumably you could 'tweak' it by physically adding another resistor if you're off by a little.


timmmay

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  #3019428 10-Jan-2023 09:47
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insane: Does Daikin not have a service menu like this Panasonic?

Offers some temp offset settings and some limits too.

 

I'm not aware of that being available, but if it is I'd like to have a look.


tweake
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  #3019681 10-Jan-2023 16:37
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timmmay:

 

 

 

It's not overshooting. The fan can be completely off, set to heat mode 22, the room is 24 degrees, and it will start off and heat the room. It's not just blowing air about. It's not overshooting if it starts up explicitly. The unit is sized about right for the room. Thanks for the thought though.

 

 

if its heating above the setpoint, thats overshoot. like wise with cooling, if it cools down past set point that over shoot. regardless of if it starts higher or not.

 

 


tweake
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  #3019684 10-Jan-2023 16:44
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fe31nz:

 

The reason is simple - the heat pump only reads the air temperature at its intake.  In high wall units, that intake is on the top of the heat pump, so it is reading the air temperature quite high up in the room.  Hot air rises, so the temperature at the top of the room is always significantly hotter than lower down.  The humans in the room, unfortunately, are normally rather lower down than the intake air temperature sensor.  So the heat pump never has an actual room temperature to work from.  What most manufacturers do is to subtract an arbitrary number from the intake temperature reading and use that as the guessed real room temperature at human level.  There is no way to adjust that arbitrary number for the room which the heat pump is installed in, or its position in the room.  There is no option to do calibration.  So you just have to set the heat pump setpoint temperatures to whatever works to produce the desired temperature at human level.  For example, our big Panasonic heat pump in the kitchen needs to be set to 19 if we want about 22 on heating, and to 23 if we want 24 on cooling.  Things are further complicated by the flow of heat in and out of the room.  For example, if we are heating in winter before the sun starts to shine in through the windows, we may need to set it to 20 to get 22, but when the sun is shining, 19 works.  This seems to be a result of how the airflow works in the room to distribute the heat, and what the heat gradient is from ceiling down to the floor.  If you really want the setpoint to mean what it says, you need to use a temperature sensor away from the heat pump at human level and unaffected by the airflow.  And it will need to be calibrated for the room.  And recalibrate it if you rearrange the room in a way that affects the airflow.  I do wish that heat pump manuals actually mentioned this problem!

 

So to emphasise the basic point here, the setpoint numbers on a heat pump are not calibrated - they do not match real temperatures.  You just use whatever setting works.

 

 

back to what i mentioned before, high walls are meant to be installed at a certain height no doubt thats the height the sensor is calibrated for. what i noticed with mine that in the instructions that came with it, the required height is higher than what the wall is. that may trick the unit into making the room hotter.

 

odds are our heat pumps are designed for a different market.

 

i was originally looking at getting a wall controller. i wonder if that would fix the issue because the wall controller has its own temp sensor and they are required to be installed at a certain height.


 
 
 

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Stu1
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  #3019853 11-Jan-2023 09:26
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fe31nz:

 

The reason is simple - the heat pump only reads the air temperature at its intake.  In high wall units, that intake is on the top of the heat pump, so it is reading the air temperature quite high up in the room.  Hot air rises, so the temperature at the top of the room is always significantly hotter than lower down.  The humans in the room, unfortunately, are normally rather lower down than the intake air temperature sensor.  So the heat pump never has an actual room temperature to work from.  What most manufacturers do is to subtract an arbitrary number from the intake temperature reading and use that as the guessed real room temperature at human level.  There is no way to adjust that arbitrary number for the room which the heat pump is installed in, or its position in the room.  There is no option to do calibration.  So you just have to set the heat pump setpoint temperatures to whatever works to produce the desired temperature at human level.  For example, our big Panasonic heat pump in the kitchen needs to be set to 19 if we want about 22 on heating, and to 23 if we want 24 on cooling.  Things are further complicated by the flow of heat in and out of the room.  For example, if we are heating in winter before the sun starts to shine in through the windows, we may need to set it to 20 to get 22, but when the sun is shining, 19 works.  This seems to be a result of how the airflow works in the room to distribute the heat, and what the heat gradient is from ceiling down to the floor.  If you really want the setpoint to mean what it says, you need to use a temperature sensor away from the heat pump at human level and unaffected by the airflow.  And it will need to be calibrated for the room.  And recalibrate it if you rearrange the room in a way that affects the airflow.  I do wish that heat pump manuals actually mentioned this problem!

 

 

 

So to emphasise the basic point here, the setpoint numbers on a heat pump are not calibrated - they do not match real temperatures.  You just use whatever setting works.

 



Dumb question If I set my daiken on heat at 21degrees will the fan slow down and stop at that temp? I did a test gave up after 90 minutes it was still going and hadn’t reached the temp. The daiken techs seemed to think that’s normal . My central heating stops when it reach’s 21 but my heat pump won’t?


  #3019856 11-Jan-2023 09:33
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is the fan on auto too?

 

i would have thought if it was on a fixed speed then the fan would keep going, the unit would just ramp down its heating/cooling output till it turned off at the set temp. The fan would keep running.

 

In auto (Fan speed) the fan would slow down to its slowest speed. as it still needs to be bringing air into the unit to be monitoring the temp.


timmmay

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  #3019862 11-Jan-2023 09:45
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Jase2985:

 

is the fan on auto too?

 

i would have thought if it was on a fixed speed then the fan would keep going, the unit would just ramp down its heating/cooling output till it turned off at the set temp. The fan would keep running.

 

In auto (Fan speed) the fan would slow down to its slowest speed. as it still needs to be bringing air into the unit to be monitoring the temp.

 

 

The fan behavior changes depending on mode:

 

  • Cool: fan runs all the time
  • Heat: fan runs until up to heat, then it occasionally spins up on a very low speed to check the temperature in the room
  • Auto: fan seems to only run when required, including on cool

I tend to use a fixed fan speed in both modes, as the unit on auto selects a very low fan speed. I want the fan speed higher to push the air out through the room, and to mix the air up a bit so the heat gets down to the floor level.


insane
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  #3019875 11-Jan-2023 10:18
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timmmay:

 

....

 

I tend to use a fixed fan speed in both modes, as the unit on auto selects a very low fan speed. I want the fan speed higher to push the air out through the room, and to mix the air up a bit so the heat gets down to the floor level.

 

 


Well that explains a lot, you need to leave the fan on auto or it's going to keep pulling residual heat from the coil/heat exchanger.

 


Do you have a "powerful" option that you can use in conjunction with the auto fan speed? 

 

 


  #3019881 11-Jan-2023 10:24
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even on the lowest fan speed it will still mix the air in the room, all be it a little slower.


timmmay

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  #3019892 11-Jan-2023 10:34
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insane:

 

Well that explains a lot, you need to leave the fan on auto or it's going to keep pulling residual heat from the coil/heat exchanger.

 

Do you have a "powerful" option that you can use in conjunction with the auto fan speed? 

 

 

I don't understand how you came to that conclusion. My understand of fan speed is simply that when the system is in heat / cool mode that's the fan speed to use. The fan turns off when the unit is up to heat, just like auto mode.

 

I use a higher fan speed because I often see the temperature at the Daikin is say 24 degrees, but the temperature at my desk is 22 - 23 degrees. The higher fan speed pushes the air harder and reduces stratification.


insane
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  #3019894 11-Jan-2023 10:45
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@Timmmay - My Panasonic and Mitsubishi units fans seem to keep running if I manually set a fan speed. As best I understand the compressor then throttles / stops / starts to regulate temperature. That removes one of the units tools to regulate room temperature.

 

Granted I may be mistaken, and your Daikin could behave differently


timmmay

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  #3019943 11-Jan-2023 10:52
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Daikin behaves differently from Panasonic / Mitsubishi then. The fans only run when required to achieve the setpoint.


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