Viessmann Boiler Problems & How To Fix
Viessmann boilers are known and rated for top performance and reliable central heating systems.
This doesn’t mean to say a common problem, a strange noise or an error code won’t occur within your heating system.
Heating systems work long and hard for a long time, the guide below is to prepare you if any common faults occur which you may be able to solve yourself rather than wait for a boiler repair technician.
If any issues do occur with your heating or hot water and you do not feel confident yourself to have a look, always ensure to contact a Gas Safe engineer as soon as possible.
Below is a list of the most common Viessmann boiler problems and how to repair them:
No hot water:
Is your heating working with no problems but you have no hot water?
If the answer is yes, there could be multiple reasons why.
The problem could be a leak, an issue with the power or water supply, low pressure, or a faulty diverter valve.
- NEXT STEP: Firstly, test the power supply, try the lights. If the power supply is ok, check your gas and water supply. Go on to check the temperature on the boiler, is it at the right temperature at that time? Also, is the hot water switch on the control panel switched on?
- If the issue does not solve after the above steps, ensure to contact a Gas Safe registered boiler engineer.
Boiler Ignition Problem:
Does your boiler not turn on?
If the answer is yes, there could be a couple of fault findings why this is happening.
- There could be build up in the system. Dirt could be blocking the burner.
- The air pressure sensor could be causing a boiler fault.
- NEXT STEP: Viessmann boilers will display the fault code “F5” if build up in the system is causing the burner to be blocked. If this is the issue, ensure you call a Gas Safe engineer as soon as possible. They will come and flush the system until it is clear.
- If the boiler engineer finds that the burner is not the issue, they will inspect the system to see what the problem is.
Leaking Water from the Boiler:
Is water leaking from your Viessmann boiler?
If the answer is Yes, contact a Gas Safe engineer as soon as possible.
A leak is dangerous and can be expensive to solve if the issue is there for an extended period.
- NEXT STEP: Turn the boiler off.
- Contact the Gas Safe registered engineer.
- Boiler leaking water is often an internal issue, high water pressure, boiler casing could be cracked, or joints could be loose.
Boiler Pressure is Low:
Is your Viessmann boiler showing pressure is low (below 1 bar)?
If the answer is yes, this could be caused by a couple of reasons. Radiators need bleeding or a water leak.
- NEXT STEP: If you find a leak in the pipework, radiators or boiler contact a Gas Safe registered engineer as soon as possible.
- Firstly bleed your radiators – this can cause the pressure to lower.
- Secondly, if you feel confident enough to do so, you can re-pressurise your boiler by following a step by step guide.
If the above steps do not solve the low-pressure problem, contact a Gas Safe registered engineer who will check what the issue is, solve the problem, and ensure the boiler is safe for you.
Frozen Condensing Pipes:
Is your Viessmann gas boiler not working when the weather goes cold?
Is there no heating, hot water and a Gurgling noise?
If the answer is yes, this could be a simple issue for your to solve.
- NEXT STEP: In the freezing cold winter months the condensate pipe can freeze. Depending which boiler you have, the error code ‘F4’ may show on the display.
- The condensate pipe is the one and only plastic pipe connected to the boiler, so it is simple to find.
- Pour TEPID water over the frozen section of the pipe. If all the pipe is frozen, start at the top as it will allow any water that has been trapped elsewhere in the pipe to escape once it is able to. (Don’t use Boiling water)
- After this, pour hot water on any sections with are flat or elbows as these are known to freeze faster.
- If this does not melt the ice inside, you may try using a hot water bottle or hot towel. This will allow constant heat to the frozen area for a longer period of time.
- Hopefully, you will now see water leaving the pipe or hear a new sound, “trickling”.
- Next step is to reset the boiler, if you have succeeded the fault code will disappear.
- The condensing pipe stops wasted gas going out of the boiler by recycling it and turning it into heat.