General information on sealed combustion water heaters

Closed-circuit water heaters are safe because they draw in the air from outside for the fuel-burning (combustion) and also discharge the combustion gases to the outside. The gas burning process is sealed and isolated from the indoor air of your home. So you do not use air from the room itself and there are no combustion gases in the room where the water heater is located. This makes the water heater ideal for rooms with limited ventilation or for indoor use in general. You therefore need a flue pipe that consists of 2 pipes (concentric), an inner pipe for the combustion gases and an outer pipe for the fresh air. Because the exhaust gases are discharged through the inner pipe, the outer pipe also remains a lot cooler for your safety. Please note that the inner pipe is not plastic but metal, otherwise it might deform/melt and cause problems. Pay extra attention to the rubbers that connect different drain pipes, as this can be the cause of malfunctions.

It is annoying if your (new) device does not work after installation. Of course we will do our best to help you solve this problem. That is why this page contains the most frequently asked questions. There are a number of important points that we would like to mention:

  1. We recommend hiring a qualified installer for all our water heaters. Make sure that the water heater is installed as prescribed in the enclosed manual. It is therefore important to read the manual carefully before contacting us.
  2. Check the gas type and pressure.
  3. NEVER use the water heater without a flue gas outlet.
  4. In the event of malfunctions, check the message in the manual and remove the cause before restarting the water heater.
  5. Before going through the questions below, it is important that you take a good look and listen to what the water heater does and does not do. This information can be important in diagnosing the problem. Our service team can also ask about this.
  6. In the case of the TTulpe C-Meister 11 & 14, check which flange you should use for your drain before installation (see page 7 in the manual).
  7. Also pay close attention to the connections. Red = hot, Blue = cold and Yellow is gas.
  8. The TTulpe C-Meister 13 is equipped with a water reducing tap (white with the text “hot” and “cold”).

Closed water heaters have various error codes if something is wrong. Below are several common faults and how to fix them.

TTulpe C-Meister 11 & 14

  • AL01; There is something wrong with your drain, check that you have used a concentric drain, that all rubbers seal the connections properly and that you have used the correct flange. Once you have made sure that everything is correct, reset the device according to the instructions in the manual and try again. If the problem recurs, contact technical service.

    NB! Failure to rectify the cause of the AL01 will result in a permanent AL62 malfunction, which means that the water heater must be returned, which is not covered by the warranty!

  • AL02; The outgoing water is too hot, check whether there is enough water flowing through the geyser, a pipe may be pinched, or the pipes have a diameter that is too small.
  • AL28; Check the connections. First disconnect the geyser from the mains before removing the cover. After checking, replace the cover and restore the drain if necessary before switching the water heater back on.
  • AL62; If this error code appears, several error codes have been ignored (reset button pressed). The water heater has been reset, but the cause of the malfunction has not been remedied. The water heater is now in permanent malfunction and will have to be sent back to be recalibrated. The costs that this entails are not covered by the warranty!

TTulpe C-Meister 13

  • E0 & E4; Temperature sensor hot ( E0 ) and cold (E4 ) a white wire that goes into the copper pipe by means of a brass nut, check whether it is correctly placed and the connector is properly connected. Reconnect the water heater and the pipes and start the water heater. If the problem persists, please contact info@kiip.de
  • E1; The most common of all occurring error codes. The solution can be before the water heater or after the water heater:
    • Before the water heater; there is something wrong with the gas supply, this could be wrong gas pressure, too little gas, too thin and/or too long pipes. The gas pressure regulator does not work. We recommend using gas pipes of at least 10mm, larger if significantly longer. Is the gas bottle still full, is the pipe not clogged or is a shut-off valve turned on? Do you have the right gas pressure regulator for your geyser and the P30 geyser needs a pressure regulator of 30mbar and a P50 one of 50mbar. Never use an N25 (natural gas) with butane, propane or LPG and vice versa. If you have a gas pressure regulator with rupture protection, it can operate when a gas bottle is changed or if it is incorrectly installed (position). Gas pressure regulators can break. Replace it as a precaution, if the above is in order.
    • After the water heater; there is something wrong with the flue gas outlet. Drains are essential not only for your health but also for the proper functioning of the water heater. In order to be able to comply with the current (stricter) regulations, in particular the NOx emissions, modern geysers have been adjusted more precisely. Your current drain may not be sufficient for the new water heater. Make sure that drains never become narrower than the diameter they start with, they can be wider. The geyser detects if something is wrong and the combustion gases are not properly discharged. Possible causes may include:
      • You have installed a single outlet instead of a concentric one.
      • The gaskets between the various connections are not properly placed, the water heater sucks oxygen-poor air
      • Flexible pipes definitely inhibit the airflow if they run in a bend, replace them with fixed bends if possible
      • Concentric drains with a plastic inner pipe are unsuitable for flue gases, as they melt/deform. Replace these for concentric drains with a metal inner pipe suitable for temperatures up to 200 degrees
      • Check that your drain is not clogged with a bird's nest or other foreign objects that do not belong there
      • The minimum length of the flue gas outlet must be 70 cm. long and may not exceed 10 metres. For more information, see the manual on pages 14 & 15, points 6.6 and 6.7
  • E5; Check that the inner pipe at the top of the water heater is not loose.
  • E8; If your exhaust is very long or winding, this can cause problems with the discharge of the combustion gases. Other causes can also cause this error:
    • Check whether the water heater is getting the right pressure and the right amount of gas. For a 30 mbar water heater, a 30 mbar gas pressure regulator must be mounted; for a 50 mbar water heater, a 50 mbar gas pressure regulator. The gas pressure regulator must also allow at least 1.5 KG/h to pass through, 2 kg is even better.
    • Check whether the gas discharge pipe is connected correctly; there should be no blockages or leaks.
    • We recommend a gas pipe with an average thickness of 10 mm or even 12 mm or 15 mm, depending on the length of the pipe.

If you have checked everything and the water heater still gives error E8, you can request our E8 procedure via info@kiip.de

Resonance of the water heater, the vibration and abnormal noise of the water heater

The cause of resonance is as yet unclear. Contact us via info@kiip.de and send a video along (possibly via We-Transfer), in the meantime do not use the water heater. Resonance can be harmful to your installation. If you have a resonating water heater, we have a procedure for you that will enable you to remedy the resonance.


It is important to protect your water heater against frost. In particular, geysers that hang in unheated rooms can freeze through the drain due to cold. This is not covered by the warranty. So protect your device well, especially if you do not use it for a longer period of time, then let it drain by means of the drain valve (This is only on the C-Meister 13, see the manual page 7. For the C-Meister 11&14 see the manual page 9). For example, use a bicycle pump for the last bits of water.. Store in a heated room is our advice. This way you can fully enjoy your water heater again the following year. If something has frozen to pieces, you can find the right part on our parts page.


Before you uninstall and return your device, we would like to ask you to send us an email ( info@kiip.de ) with the following information:

      1. A photo of the entire installation, showing the water and gas connections and drain pipe;
      2. A photo of the water and gas connections (supplemented with a gas pressure regulator if possible)
      3. Pictures of what is shown on the display
      4. Any detail photos
      5. Order or invoice number
      6. Clear description of the problem and what you have already tried to solve it

Although it is sometimes necessary for the device to be checked or repaired by our technical department, in many cases the problem can be solved remotely by means of the photos and description so that you can quickly enjoy hot water. This is how you prevent that; transport costs will be at your own expence, research costs may be charged, but more importantly, that you are not without hot water for longer than necessary. If, in our opinion, a return is necessary, we will send you a return label so that you can send the device free of charge


In the event that the device has to be returned to us, please be aware the following:

      • Pack the device properly! (preferably in the original packaging including outer box) so that no transport damage occurs
      • If possible, include the used gas pressure regulator and hose
      • Make sure there is no more water in it.