Junkers HydroPower boiler won’t turn on



The Junkers HydroPower boiler is well-known for its energy efficiency. It is therefore not surprising that it is often the first choice for domestic hot water (DHW) in homes. Installation is inexpensive and the unit helps to save on energy, reduce your electricity bill and reduce polluting gas emissions. But what do you do when your Junkers HydroPower boiler won’t turn on? After reading this article, you will be aware of all the possible causes of this problem, and also some solutions. We will also discuss, in a general sense, how to correctly install a Junkers butane gas boiler to avoid future problems.

Why won’t my Junkers HydroPower boiler turn on?

Even the most efficient boilers from the top brands sometimes experience malfunctions or breakdowns. The Junkers HydroPower is no exception. Despite its battery-free design (because of the hydro-generator it only needs water flow and gas to start and operate), it can sometimes experience problems, like any other hard-working household appliance. Let’s take a look at some of the reasons why your Junkers HydroPower boiler might not be igniting (not “sparking”) or working properly:

  • Installation problem: water supply failure
  • Installation problem: gas supply failure
  • Installation problem: gas outlet incorrectly installed
  • Low water flow rate
  • Unsuitable accessories in the home’s water system
  • Dirty or congested gas outlet
  • Hydro-generator stuck or out of calibration
  • Dirty turbine filter
  • Dirty burner
  • Faulty protection relay
  • Malfunctioning solenoid valve
  • Malfunctioning ionization electrode
  • Faulty switchboard
  • Faulty ignition microswitch

Possible Solutions When a Junkers HydroPower Boiler Won’t Turn On

If your Junkers boiler doesn’t turn on due to any of the above-mentioned causes, try some of the following solutions and you will have probably resolved the problem. We cannot advise what exactly is wrong with your specific unit as we haven’t physically seen it. However, you can try and implement each of these solutions until you find the correct one:

  • Water supply failure. The water flow may not be adequate for the boiler to work properly, either due to problems with the boiler’s installation or due to problems with the household water supply. As mentioned, Junkers HydroPower boilers start without batteries, meaning they only need a flow of water and gas to start. If either of these two fails, the ignition will also fail.
  • Insufficient water flow. Your Junkers HydroPower boiler has been designed to operate at a minimum flow rate of 3.2 to 4 liters of water per minute. This means that the unit needs a flow at this level in order to function optimally. Anything outside of these parameters or this water flow rate, means that it won’t work properly.
  • Unsuitable accessories in the home’s water system. Some accessories are not suitable to work with the Junkers HydroPower boiler, whether for design or water flow reasons. Such items will prevent the boiler from starting or working stably. For instance, some showers need a water flow rate above that which the boiler can generate (this is the case with showers requiring a flow rate of 9 liters per minute). If you need to start your boiler and one of these showers is operating, the unit may not be able to start, or it may turn off if the shower is turned on when it’s already running. A simple test to check if the problem is related to this is to remove the shower head and open it with the boiler running. If the problem is the shower (or another item), as soon as you remove it, the boiler will begin working normally.
  • Gas supply failure. The gas flow from the butane cylinder to the boiler might not be sufficient or may have been interrupted for some reason. The pipe may be perforated, congested or twisted, the gas regulator may not be working correctly, or it may even be that the cylinder valve is closed or the cylinder has been emptied and you haven’t noticed. Gas boilers raise the temperature of the water within minutes, but in order to do so, they need the fuel to flow well.
  • Hydro generator stuck or miscalibrated. As mentioned a few times, the Junkers HydroPower boiler starts without a battery and uses the water and gas flow in the same way as river mills or dynamos. This is possible due to the fact that a water-driven grinder inside the hydro-generator produces the current (about 1.2 volts) that starts the boiler. If, for any reason, the grinder locks up or becomes miscalibrated (bear in mind that the minerals present in the water can always catalyze and form stones, especially when the temperature rises), then the hydro-generator is not producing enough energy to start the unit up.

You should therefore check the grinder to ensure that nothing is blocking it, and it is not miscalibrated. If so, you should take it to a qualified technician to have it recalibrated. Some people believe that a hydro-generator can’t be recalibrated and that it can only be replaced by a new part. It is up to your technician to decide. However, in order to avoid mineral particles from blocking the hydro-generator, you should place a filter just in front of the boiler. You should note that the filter shouldn’t be too fine as this may reduce the water flow.

  • The turbine filter is dirty. If you have already established that there are no problems with the gas or water flow, and the problem is that the boiler simply does not turn on, check the turbine filter as it may contain impurities. A way to check if your turbine filter is dirty is to disassemble it, blow through the water inlet and see if it moves or not.
  • Lack of maintenance: Your boiler will not work well if it has dirty parts, either due to a lack of maintenance or if there is another reason for the dirt. Burners are especially prone to attracting dirt, but so are the jets and the other parts. In these cases, of course, the solution is to do some general boiler maintenance and meticulously clean the dirty parts.
  • Broken protection relay: If your boiler’s pilot flame is able to light up a few times, but then goes off again, this is a sign that the protection relay has failed and needs to be replaced with a new part.
  • Problems with the solenoid valve or ionization electrode. One of the reasons your boiler tries to ignite but fails could be a problem with the solenoid valve or the ionization electrode. To establish which of these two parts is the problem, you should measure the voltage with a multimeter. Open the gas cock and measure the solenoid valve’s voltage. If there is no current in the solenoid valve, it could be that the control unit is not sending current as it is, in turn, not receiving the necessary information from the electrode. In this case, the electrode could be faulty. However, if the solenoid valve is receiving current and still does not work, then the solenoid is faulty. In either case, replace the faulty part with a new one. Bear in mind that the cables may be damaged and not the parts, so be sure to check these too.
  • Faulty control unit. The control unit functions as a kind of central nervous system for your water heater (and the same is true for boilers). There are many functions that completely depend on the switchboard or control center. If, for any reason, the control unit fails (because of a malfunction or breakdown), the unit won’t work. In these cases, you would need to repair or replace it with a new part.
  • Faulty ignition microswitch. Sometimes, for various reasons, water enters the boiler’s electronic system and some of these parts can get damaged. This can happen to the ignition microswitch. If it accidentally comes into contact with water, it oxidizes, breaks down, and prevents the unit from starting.

A preventative measure:

Ensure you install your boiler correctly. As you may have already noticed, many breakdowns in Junkers HydroPower boilers can be caused by installation errors. This is why we are going to give you some general tips below on how to install a Junkers butane gas boiler correctly:

  • You should think twice about installing the unit yourself. There are many details to get right and you may miss some of them. A qualified technician, on the other hand, can do the installation without any problems as they have all the necessary experience and tools. Initially, it may appear that installing the boiler yourself can save you money, but it could mean spending more money in the future to correct what you did wrong.
  • When you are fixing the boilerplate to the wall, be careful where you drill. Sometimes, when drilling, the water pipe can get partially perforated, and although you may not notice the problem immediately, in the medium or long term, it will be problematic. As we have already seen, insufficient water flow is one of the causes of ignition problems in a boiler.
  • Ensure that the electrical system to which you connect your boiler is working properly and has no false contacts or short circuits. Boiler problems or breakdowns are often due to external reasons. For instance, sudden voltage changes or momentary and random power outages.
  • When connecting the butane cylinder to the heater, always remember to install the gas outlet pipe and ensure that the thread is vertical and connects seamlessly. Any gas leaks will cause the boiler to malfunction, plus this is also dangerous.
  • Be very careful when installing the vent in your new boiler. Any problems with the gas expulsion system or in the chimney can result in a malfunction or breakdown later on.

(For more details on Junkers boiler installations, read our article entitled “How to Install a Junkers Butane Gas Heater in 10 Easy Steps”)

Get all the spare parts you need from Suner

Whenever you need to source spare parts for a boiler, remember that Suner always has your back. Browse our store and see for yourself how simple and intuitive the buying process is. You will always find the parts you are looking for (original parts that are high quality and durable) as our website is user-friendly and logical, and our spare parts search engine is highly specialized. Visit our store and see for yourself.

Don’t think twice about using us when you need spare parts for your furnace or boiler. All our parts are 100% original, meaning we guarantee that the quality is the best and they are long-lasting. Although generic parts are cheaper, using original brand name replacements is more efficient and gives you better peace of mind.

Our company has over 40 years of experience in supplying spare parts for boilers, furnaces and water heaters. We have proudly satisfied over 14,000 customers in over 30 countries. Suner has all the spare parts that your boiler needs. Buy the spare part you need with us.


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