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Last Updated 1 year by Lukas

Table of contents

In this article I would like to cover ways to improve an existing recuperation, heating system installation. I’ll be doing this using a system installed in my own home. This means that I can give you tested and practical experience of tuning the system. You can then judge for yourself if it makes sense to try to replicate similar changes. The original description of Passive House systems was covered in: Introduction, Solar System description, Recuperation and heat pump system description and finally inside real consumption numbers posts.

What are we going to discuss?

  • What has been changed from default settings inside service menu
  • What has been changed against original installation of recuperation, heating delivered from developer
  • We will also evaluate these changes together and try to assess if it makes any sense

Changes inside Atrea system defaults

Please DO NOT change these settings without knowing what you are doing. Read the manual and consult with your service company before making such changes. It may invalidate your warranty if you damage your system without knowing what you are doing. Important values we are talking about would be highlighted in yellow.

  • Ventilation interval – How long unit will ventilate every hours if set into ‘Automate’ mode
  • Period for filters replacement – Number of days when your recuperation unit notify you about required change of filtering medium

  • Minimum voltage prim. heater – minimum voltage to switch on (output from the regulator). If the value is lower, the heater will stop. This helped me to prevent the system from trying to reach 0.1 – 0.2 degrees difference and heating for a few hours.

  • Temperature difference – cooling – helps to increase cooling capacity. Obviously, the system is not powerful enough to cool the house without outside curtains. With this setting, you allow the recuperator to maintain a 13 degree difference between the indoor air temperature and the cooled air provided by the heat pump.

  • Here you can generally set any temperature compensation you wish to use. For example, if you have thermo-meters on the ceiling. You want to compensate for it (because you are not Spiderman and live on the ground where the temperature is usually 1-2 degrees lower). In other words, you set the unit to add/subtract from the desired temperature for heating/cooling.

  • Here you can set corrections for specific inputs/outputs. You can use the ‘i’ icons to get details. But in general it works similar to the above description of Temp. corrections. You can also change the behaviour for inputs from external systems.
  • For example you can bring 220V onto input and it will trigger action. Please go through manual !

  • Hysteresis for heating – This sets the guard rail within which the system will operate. For example, with a set temperature of 20 degrees and a hysteresis of 3, this means the system will trigger at 17 and heat up to 23. It simply ensures that the heater does not switch on and off all the time.
  • Maximum Solar Heating Temperature – the maximum temperature inside the internal storage tank at which it will block any further heating. Please note that your exact setting will depend on the position of the service thermometer. The temperature inside the water tank is coolest at the bottom and hottest at the top. So if you are blocking at 75 degrees, but your thermo-meter probe is not in the top position. This can easily mean that you already have around 90 degrees of water at the top of the water tank. Keep this in mind!
  • IN2 setup – Setup on the picture means your solar heating won’t be blocked by HDO (device from the distributor that tells you if the current is high consumption tarif or the low one).

  • Temperature difference when the system uses electric cartridges together with the heat pump / or only electric cartridges to heat water. In other words, if your current temperature is 30 and you request 60. System will primarily use electric cartridges to heat water as they are faster compared to heat pump. Of course the system will try to use the heat pump if possible as it’s much more efficient. Please note that the heat pump can only work up to 52 degrees, above this value the system always uses electric cartriges.

  • 9.3.1 and 9.3.2 indicate whether the temperature is lower than bivalence 1 (using the heat pump and electric heater for heating) or bivalence 2 (using only the electric heater for heating). Please note that if you change these parameters without fine-tuning 9.3.8 and 9.3.9, you will force the compressor to work more -> it will reduce efficiency and wear the compressor more.
  • 9.3.3 – Is used to tell the system if it should stop ‘cooling’ and start heating with heat pump if there is a request for this. The Comfort option will ignore the request for heating if the heat pump is already cooling and will use the electric cartrige instead.
  • 9.3.5 – How much time the system waits before checking if the heat pump has reached the expected performance. This parameter must be fine-tuned if you want to change the control constants. Otherwise, your installation will give false alarms about the low performance of the heat pump.
  • 9.3.7 – It’s the minimum temperature for the heat pump to start. Because the 425 litre water tank works as a split unit for the heat pump outside the unit.
  • 9.3.8 – Maximum temperature at which the heat pump is allowed to work (heating water).
  • 9.3.9 – What is the temperature of the medium (R-32) used to heat the water.
    • 9.3.8 + 9.3.9 – are together number for which to regulate temperature of heating medium (R-32).
  • 9.3.10 to 9.3.12 – are constants used within the control equation (more on this in another post)
  • 9.3.21 – Is control voltage in case the outside unit reports that it is doing defrost. Note that if you send 0V, it will cancel the defrost. Make sure it is ideally 5V for Sinclair outdoor unit.

  • 9.4.1 and 9.4.10 – It’s used to tell the system when to let the solar heat into the water again after the maximum (75 degrees in my case) has been reached.

What has been changed against original installation of recuperation, heating delivered from developer

  • Installed extra 65 litre water heater to be able to set low temperature for 425 litre water tank and still have hot water. It was also installed so that I could fill the bath (without waiting two hours for the heat pump to heat the 425 litre water tank). By default, this system is only good for showers if you set the temperature above the heat pump’s limit. It works, of course, but you have literally created a large electric water heater. And you will notice this on your electricity bill.
  • I had to fine-tune the heat pump parameters to prevent the system from using a lot of energy on cold days.
  • I had to solve problems with defrosting for the outdoor unit (it is already built into the Atrea control system).

Is the system really worth buying?

Here I can definitely say yes. If I forget all the parameters I had to tweak and problems I had to solve (usually incorrect configuration). I’m very happy with the system. The automatic ventilation is amazing as you have fresh air inside all the time, the monitoring and debugging capabilities of the system are amazing (with access to the service menu). And it is a Czech product, so you are supporting the local company Atrea. Also, the heat pump, if properly configured, can give you heating/cooling with a high COP (coefficient of performance), which these days translates into saving a lot of money on electricity consumption. A 425 litre water tank is a cheap way to store energy. And in general, hot water is usually the biggest energy guzzler in many homes because it’s usually used for heating, showering, etc.

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By : Lukas Tags: