If your boiler is running but your taps only produce cold water, the issue could be low boiler pressure, a faulty diverter valve, thermostat settings or an internal boiler fault. Check the pressure gauge and look for any error codes on the display. If the problem continues after these basic checks, it's best to arrange an inspection with a Gas Safe engineer.
This is a common sign of a faulty diverter valve in a combi boiler. The valve controls whether hot water is sent to your radiators or your taps. If it becomes stuck or fails, your heating may continue to work while your hot water stops. A qualified engineer can diagnose and replace the faulty component if required.
Yes. If your boiler pressure falls below the recommended level, your boiler may stop producing hot water or fail to operate correctly. Most boilers work best between 1 and 1.5 bar when cold. If you're unsure how to repressurise your system, consult your boiler manual or contact a Gas Safe engineer.
Resetting your boiler can sometimes clear a temporary fault and restore your hot water. However, if the problem returns or the boiler continues displaying an error code, avoid repeatedly resetting it. Persistent faults should be professionally diagnosed to prevent further damage.
Fluctuating water temperatures can be caused by a faulty thermostat, a blocked plate heat exchanger, low water pressure or a failing diverter valve. If the problem occurs regularly, your boiler should be inspected to identify the underlying cause.
In most cases, a boiler that isn't producing hot water isn't immediately dangerous, but you shouldn't ignore the problem. If you notice water leaks, unusual noises, a smell of gas or repeated fault codes, switch the boiler off and contact a Gas Safe engineer immediately.
The cost depends on what's causing the problem. Simple issues, such as repressurising the system, may take only a short visit, while replacing components like a diverter valve or pump will cost more. After diagnosing the fault, a qualified engineer can provide an accurate quotation before carrying out any repairs.
If you've checked your boiler pressure, thermostat settings and power supply but still have no hot water, it's time to call a Gas Safe engineer. You should also seek professional help if your boiler is leaking, displaying repeated fault codes, making unusual noises or repeatedly losing pressure.
Yes. Keystone's Gas Safe engineers diagnose and repair a wide range of boiler faults, including no hot water, low pressure, diverter valve failures, faulty thermostats and boiler error codes. We provide fast, reliable boiler repairs across London to help restore your heating and hot water as quickly as possible.
Many boiler problems can be prevented through regular servicing and routine maintenance. An annual boiler service helps identify worn components, pressure issues and developing faults before they lead to a complete loss of hot water. Keeping your heating system well maintained can also improve efficiency and extend the lifespan of your boiler.
Before booking a repair, check that your boiler has power, the pressure gauge reads between 1 and 1.5 bar, the thermostat is set correctly, your stop valve is open and there are no obvious fault codes displayed. If these checks don't restore your hot water, professional diagnosis is recommended. This can help identify the fault quickly and avoid unnecessary downtime.