Troubleshooting
Combi Boiler No Hot Water (Heating Works)
When the radiators warm up but the taps run cold.
If your home is heating fine but the hot taps run cold, the fault is on the domestic hot water side of your combi boiler. Combis heat water on demand, so the issue usually involves the flow sensor, diverter valve, or the DHW heat exchanger.
These components sit inside the sealed appliance, so diagnosis and repair require a licensed technician.
Likely causes
- Faulty flow sensor not detecting tap demand
- Stuck diverter valve staying on heating
- Scaled or blocked DHW (plate) heat exchanger
- Low incoming water pressure
- Faulty DHW temperature sensor
This is not a DIY repair
Combi boilers are gas-fired appliances regulated under the BC Safety Standards Act. Opening the unit, touching the gas valve, or working on the flue without a valid BC gas-fitter licence is both unsafe and illegal. Diagnosing the fault is helpful — fixing it should always be left to a certified technician.
Call 778-909-5731Frequently Asked Questions
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