8 Common Combi Boiler Problems

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A combi boiler system that uses gas as a heating medium is often preferred by the property owners. All of its components are hidden within the boiler itself, that’s why the system is compact and looks very neat. Yet, there is a downside, too. As all moving parts are hidden within the unit, there is a whole array of combi boiler problems that can arise.

Combi boiler problems

Below you can find 8 most common issues:

#1: Water leak

Leaking or dripping water is by far the most common problem of the combi gas installations. There are several possible causes for this issue, so a DIY repair is usually very problematic. Contract a licensed serviceman to do the check and solve the issue.

#2: Pressure loss

The most common cause of the pressure loss is water leak (discussed above). However, there is a possibility the issue is caused by a faulty vessel, which needs replacement.

#3: No hot water

The sole purpose of a combi boiler is to produce hot water to heat up your living spaces as well as for your daily needs. When it stops executing its prime function, look for several common issues:

  • Broken diaphragm;
  • Broken airlock;
  • Faulty motorized valves;
  • Faulty thermostat.

Usually replacement of the broken or faulty item is necessary. Such procedures are best performed by a professional.

#4: Kettling

In the areas where water supply comes with hard additives, boilers can suffer from kettling. Heat exchanger is the component where limescale builds up. If the size of the deposits grows too big, rumbling and steam bubbles can appear.

#5: Vibration and noise

The source of the banging noise can be kittling discussed above, with other causes being low water pressure in the system. There are other types of noises combi boilers can produce, and such should be inspected by a specialist.

#6: No pilot light

Common reasons are:

  • The flame is blown out by a draught;

  • Thermocouple is broken and needs a replacement;

  • Limescale buildup on the pilot light, which needs to be cleaned

#7: Thermostat Error

This combi boiler problem is most common in older units. Thermostats often produce various issues towards the end of their lifecycle. Possible signs to pay attention to are:

  • The unit can switch itself on and off spontaneously;
  • Temperature misreading.

These issues should be checked and solved by a professional serviceman. If your system has grown old, sometimes even a better idea is to upgrade it with a new, more efficient boiler. In fact, such investment is well justified by reduced utility bills.

#8: Condensate pipe freezing

This issue is not common for older units simply because they have no condensate pipe. However, modern systems utilize the pipe to remove waste water. At cold temperatures water inside the tube freezes creating blockages. These pipes can be very expensive to replace, so the best possible issue is to hire a professional to melt the ice and remove the blockages safely.

So, these are the combi boiler problems you may encounter. If you have little knowledge in the boiler systems, you’d better not attempt DIY repair even for the tiniest problems. Correcting any mistakes can get much more expensive than contracting a professional serviceman in the first place.