Heating system

Since beginning of winter 2021, Kanthaus is powered by an air heatpump heating system which is partly installed in the garden next to K20 garden door (actual heater), in K20 "water storage room" (some connections, valves, filters, meters) and the rest of the house (pipes, radiators).

User guidelines

What is special about a heatpump heating system is that to be efficient, the heating system's temperature has to be as low as possible (e.g. exactly fitting to the house). That is why the heating system has no reserves, so

  • You can not heat up a room quickly (turn on the radiator at least 4 hours before you want to notice some warmth, expect a room to becomme "warm" only 2 days after turning on the radiator)
  • The maximum reachable temperature in a room is given by the settings of the central heating systems, normally should be around 18 Degrees in Kanthaus
  • To keep the efficiency of the system high, we actively decided that "badly heatable rooms" (e.g. with too small radiators for the specific room) stay colder. An incomplete list (generally notice badly heatable rooms by looking at the 6 surfaces of the room: The more cold rooms are on the other sides, the worse heating works)
    • The Private (~13 degrees)
    • Freeshop Lounge (~13 degrees)
    • Cloud room (~14 degrees)
    • Hipster room (~13 degrees)

Additionally, a heatpump works very differently from a gas heating system and likes to run continously, as well as needs a minimum water flow through the radiators to work at all. This means

  • At least 7 Radiators need to be turned on all the time
  • Radiators should ideally not be turned on/off every some minutes (which provides no advantage anyways)

The heating system is normally running all day, heating power is slightly reduced during nighttime (~20pm until 6am). It is normal and wanted that the heatpump outside is working all the time.

When it is warm outside (> 5 degrees), we might turn off the heatpump during nighttime.

When it is very warm outside (> 10 degrees) depending on the number of rooms we heat the heating system might turn off for 90 minutes multiple times a day because it has a certain minimum power it needs to provide.


  • A radiator is not getting warm, although the heating system should be running?
    • Is it warm outside? Maybe the heating system turned off temporarily. Wait 90 minutes.
    • Try another radiator in another room, preferably on the other side of the house or in the other house
      • If successful, a part of the heating system might be turned off at the valves in K20-B-old-heating-room or K22-b-event-storage. Find people who might be working on the heating system before turning it back on.

If both are not successful, locate the heating system panel in K20-b-water-storage-room just on the right next to the two electricity meters.

  • It does not show anything?

    • Locate the heating systems fuse in the main electricity fuse box in the room on the other side on the bottom right
    • When you open the right panel of the heatpump outside (losen 4 screws, push it down, yes, push it down harder!) there is also 2 fuses at the top.
  • It shows an error?

    • H62: Too many radiators are turned off so the heatpump could not satisfy its minimum water flow. Turn on some more radiators and make sure that nobody can turn them off (e.g. by removing the thermostat to have it fully on)
    • H70: Check the fuse "heater" in the main electricity box on the bottom right
    • H74: Maybe the house bus node controlling the heating system had a problem? Press the "On" button and watch it for 5 minutes, if it reappears, disable "Optional PCB connectivity" in the installer menu to make it completely autonomous again.
  • I really want to heat a badly heatable/cold room/ I need to heat a room quickly because I forgot early enough.

    • Use an electric heater ("Heizlüfter"). We don't have any right now, but this means we should acquire one.
    • Isn't this very expensive?
      • Yes (60 cents per hour), but adjusting the heating system so this is possible without the electric heater is more expensive all the time and this scenario should not happen daily.
  • I would like to permanently use a badly heatable room. What do I need to do?

    • Install fans underneath the radiator for ~50 percent increased power output
    • Install a bigger radiator
    • If this need is really there for many rooms, we might want to increase the hole heating systems temperatures, this increases the heating cost about 2.5 percent per degree (+ the increased heating cost for the rooms getting warmer of 6% per degree of room temperature)
  • The heatpump is annoyingly loud, can we do something?

    • Depends. Is it a certain time or mode of operation? We can always have it operate on lower power for some hours, where it will then be more silent. Communicate your wish :-)

Advanced information

The heatpump is a Panasonic Aquarea T-Cap 12 kW WH-MXC12H9E8. Service Manual Planungs- und Installationsanleitung

We use the weekly timer to

  • quickly reheat the house in the morning (about +2-3 degrees)
  • use a bit of solar energy throughout the day (about +1 degree)
  • fade down in the evening before turning off for the night

In the K20 water storage room, there is two filters that should be cleaned regularly (e.g. at least once per heating season in the future, currently I do it weekly to get old dirt out of our system):

  • Spirotap MB3 (The "big" thing in the return line on the bottom)
    • Turn off the heatpump, so the pump is not running
    • Take off black magnetic cap to the bottom
    • Get a bucket, put it underneath the exhaust in the bottom and turn the knob using the cap fully on for a second
    • Careful water comes out with high pressure!
    • Put black magnetic cap back on, turn heatpump back on
  • Superfilter (The ball valve with the black handle on the bottem)

Housebus integration

Because of some shortcomings of the controller, it is additionally controlled via a HouseBus node. The housebus node is a new generation coming from our other nodes as it uses upgraded uavcan v1 and an arduino base stack.

It allows reading all status from the heatpump, the heatmeter and the electric counter. On top of that, it emulates the Optional PCB thus is able to set the SG ready signals and demand control.

Currently, it is used to make the heatpump stay off a bit longer when it turns off due to running below minimum power, also it uses demand control to make the heatpump start slowly over a timeframe of 90 minutes.

Unfortunately, the original controller does not allow setting a temperature for the night where it turns off (e.g. to only keep it running below -5 degrees) so this could also be implemented in the housebus node (turn it off in the night whenever flow target temperature is above X)

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