Whether you have lost heating, hot water, or both tells an engineer a lot before the boiler casing comes off. It is worth noting exactly what still works when you call.
Start with the simple things
- Check the programmer is on and not sitting in a holiday or off schedule
- Turn the room thermostat well above the current room temperature
- Check boiler pressure is around 1.0 to 1.5 bar when cold
- Check the electrical supply to the boiler and any trip switches
- Note any fault code shown on the display
Hot water but no heating
This usually points to the heating side of the system rather than the boiler burning. Common causes are a stuck diverter valve, a seized or failed circulation pump, a faulty motorised valve on a system boiler, or a failed room thermostat or wiring centre.
Heating but no hot water
On a combi this is often the diverter valve, the flow sensor, or a scaled plate heat exchanger. On a system or regular boiler with a cylinder it is more likely to be the cylinder thermostat, the hot water motorised valve or the immersion and coil.
Neither heating nor hot water
If nothing runs, the boiler is usually locked out or not firing at all. Low pressure, a frozen condensate pipe in winter, a tripped supply or an internal ignition fault are the usual culprits.
Never bypass a safety device or open the boiler casing. Anything inside a gas appliance must be handled by a Gas Safe registered engineer.
When to call us
If the controls, pressure and power are all correct and you are still without heating or hot water, call us. Same day visits are often possible Monday to Saturday.
Written by the engineering team at Newcastle Boiler Maintenance Ltd, Gas Safe registered heating engineers in Newcastle upon Tyne.