Viessmann Vitodens 100W Losing Pressure

Hi Everyone,

I have a Viessmann Vitodens 100W boiler installed last year. The boiler is continuously losing its pressure, especially at night. I have top up its pressure to 1.5 bar in the morning & heating runs well without losing pressure until the heating goes off late in evening. After 1-hour pressure of the boiler dropped below 1 bar & in two hours it is 0 bar. There are no signs of leaks. How can I fix it?

Thanking you in Anticipation


Hi Susan,

As you said that there are no signs of leaks then, the main problem can be within the boiler itself. Do check the pressure release valve because if this valve is leaking or even if there are few strains around your boiler then, this can be the problem. However, you cannot resolve this issue without the assistance of the specialist.

Viessmann Vitoplex 200 Boiler Leaking


I have purchased a Viessmann gas boiler model Vitoplex 200 four years ago. I am quite happy with its performance and overall efficiency. However, early this morning I am suspecting leaks from my boiler. Please help me to find out the reason for leaking.



Hi Rebeca,

Firstly, I would like to say that if your gas boiler is leaking constantly, then you should not try to fix this issue yourself, as leaks in the gas boiler is a serious matter & indicate that some internal components for example valve or seal is broken. This leakage can lead to rust and corrosion. If water is leaking from the boiler’s pipefittings, then I guess your boiler is not installed properly. You should call a Viessmann Vitoplex engineer to sort out the problem wisely

Viessmann Vitodens 200 Boiler Short Cycling

Hello All,

My seven years old Viessmann Vitodens 200 boiler has started short cycling. It fires up for approximately 10-20 seconds & then suddenly cuts out. Radiators are hardly getting Luke warm and it does the same for hot water. What should I do? Your suggestions are highly appreciated.

Thanks in advance


Hi Jim,

When your boiler’s minimum boiling & firing surpasses the existing system load, it can cause boiler short cycling because it can force the boiler to fire up for shorter periods. In other words, boiler short cycling occurs when the boiler is over lockout as compared to its heating demand. In case, you have various heating zones & just one or few zones are calling for heat then, boiler fires & gets to temperature quickly. It happens over & over causing useless firings. In order to prevent the boiler short cycling you have to check the following things:

  • Check for the correct grounding of your boiler
  • Check for the right flow of water in the system
  • Check for the air in your boiler
  • Check for congested air inlet on concentric venting system

Viessmann Vitodens 200W Creaking Sounds

Hi Guys,

I have a Viessmann Vitodens 200W boiler. It is about five years old. A few days ago, I heard a tinkling sound coming from my boiler, which lasted for few seconds & then suddenly went away. However, from last two days, the boiler is constantly making some weird sounds just like a creaking noise. What is the matter?



Hello, if you hear some creaking sounds coming from the walls or floor when the heating system is running then, this could indicate issues with the pipes within the walls or under the floorboards. Hot water always expands the pipes while traveling from the boiler through the walls. Once it cools down, pipes will then contract back to the normal size automatically. If the stretched out pipes fit extremely tight to the floor then, you will hear these creaking sounds as they contract & expand. I would advise you to find out the cause of the noise & check water pipes in that particular area for better fit. Moreover, if the water pipes are very tight try to cut a notch in the surface to make extra space for the water pipes to stretch out.

Viessmann 200 Boiler Fault Code Eb

Hi All,

I bought my Viessmann 200 boiler three years ago. I am extremely happy with my boiler’s performance but from the last two days, it is showing a Fault Eb. If I keep resetting the boiler, it starts up quite well & then runs all right for some time before showing the same error. I guess the main burner is not lighting. While trying to fix the issue, it makes fan noises & several ticking noises as if the boiler is trying hard to light a burner but giving up repeatedly. Someone, please help on this matter.



Hello John, I guess there is a blockage in the pipework. Because when flow pipes are blocked, this leads to the flow temperature sensor react very slowly once the boiler fired up thus, as a result, you have an insufficient heat generated by your boiler. You should call an expert boiler engineer in order to power flushed the boiler & replace the pump which is rattling.

Viessmann Vitodens 100 E8 on Display


I am constantly getting an E8 message on my Viessmann Vitodens boiler, which the user manual says “Burner Lockout”. It happened many times but I have managed to get my boiler going but today I have not been able to run it. Any suggestions?

Thanks for your help


Hi John,

One of the common problem, which will not give any indication of what is wrong with the boiler, is a burner lockout. Usually, boiler can face burner lockout due to severe blockage. You can follow these steps in order to resolve the issue:

  • Firstly, verify your gas supply along with gas train & connecting a lead
  • Secondly, verify sharing out of gas type, check ionization electrode
  • Do check the distance to the burner gauze & impurity of electrode
  • Lastly, press ‘reset’

Viessmann Vitodens 100 Boiler Hot Water But no Heating

Hi Everybody,

I have installed Viessmann boiler model Vitodens 100 five years ago. I have not faced any problem in terms of its performance until now but today I have observed that after turning on the tap I am not getting the required hot water. What should I do? Need help on urgent basis.



Hi Richard, if you turn on the tap & find you are not getting the required hot water, it might be due to the blockage of the diverter valve. In case of getting the hot water but no heating then, you should check all time clocks & controls. If everything else is okay then, it is almost definitely the case that the diverter valve is blocked open in the heating mode. After diagnosing the problem, it is advisable to call out a registered engineer in order to replace the boiler’s diverter valve.  

Viessmann Vitodens 200 Boiler Not Working

Hello Folks,

I am here to share my problem regarding Viessmann Vitodens 200, which I bought 3 years ago. Everything was working up to the mark. However, last night I have noticed that my boiler is not working. Any suggestions please as I am unable to figure out the problem.



Hello Jess, your boiler can stop working due to various reasons. In some cases, your boiler stops working due to minor electrical problems. It is advisable to check the following things:

  • The electrical supply to your boiler might have turned off. In case, this has happened you just have to switch on the electrical supply again & reset the boiler
  • If the electrical supply cut out a moment ago then, you have to reset the boiler like by correcting the timer
  • At times, a soft reset will resolve various electrical failures in the boilers. Here, soft reset means requires turning off the boiler & then turning it on again.

I hope that this information will help you in resolving your problem.

Viessmann Vitodens 100 Losing Pressure

Hi Everyone,

I have a Viessmann Vitodens 100 Boiler that provides heat and hot water. Well, currently I am getting neither, the reset light is flashing red on & off & the pressure is displaying at 0.5. Can I fix it at home or should I call a specialist?



Hi Tom,

You can use a filling loop for increasing the pressure of the boiler 1-1.5 bar. There should be the braided pipe under your boiler somewhere with the small tap on it. This braided pipe should have an isolation valve at it’s both ends, one from the rising cold water main & another one into your pressurized system. Firstly, find all these things. Moreover, sometimes valves have little flexible levers, which are at 90 degrees directly to the pipe once closed & in-line with a pipe when open. You have to open a valve at pressurized system end in a case; it is not open already. Afterward, while watching a pressure meter, gradually open an isolation valve. Allow some water in then, slowly close the isolation valve to order to stabilize the gauge. Repeat this process, until you will get the required pressure for your boiler that it 1-1.5 bar.


Viessmann Vitodens 200 Fault F4


I have a Viessmann Vitodens 100 boiler, which I bought two years ago. Yesterday I got fault F4 on it. When the fault F4 occurs, boiler makes a louder ignition as if the spark is not catching the gas properly initially, but then a fame does not stay on. It repeats constantly before locking out. I would like to share that that there is a signal electrode on it for flame rectification and sparking. Looking for expert advice



Hi Jonny, fault F4 on Viessmann Vitodens 100 indicates faulty burner. The possible reason behind it that flame signal is not present on the boiler. I would advise you to check the ionization electrode & leads. Apart from this, do measure the ionization current, check the gas combination valve, gas pressure, ignition module, ignition & condensate drain. After checking and verification, press reset.