5 CombiBoiler Problems and How to Troubleshoot Them. Troubleshooting your combiboiler - Premier Gas_11zon. These compact units provide both central heating and hot water on demand, without needing a separate hot water cylinder or cold water tank. In this comprehensive guide, we’ll delve into the reasons behind a combiboiler losing pressure but no leaks, and provide effective troubleshooting solutions to address issues such as combiboiler losing pressure overnight or when heating is off. Understanding CombiBoilers A Guide To Home Heating Boiler Repair. With our boilertroubleshootingguide, you can fix it yourself and save a lot of money. The average repair call will cost well over $100. Mid-Atlantic homes that use radiant heat rely on a continuous supply of hot water to provide comfort and safety when weather turns frigid. A common complaint among homeowners with Worcester Bosch combiboilers is the hot water turning cold, disrupting normal daily routines. Identifying the cause of this fluctuation is essential as it is often symptomatic of underlying issues within the boiler system. Boilers are an essential part of our lives, especially during the colder months. However, they can cause unexpected problems that leave us without heat or hot water. Before calling a professional, there are some DIY solutions to troubleshoot your boiler at home. CombiBoiler Installation: Step-by-Step Guide. How to install a combiboiler involves careful planning and execution.