Why does my boiler fire up and then turn off?
If you are sitting in your kitchen enjoying a cup of tea and hear your homes boiler start up then almost as quickly shut down, do not worry, it is not a problem (or is not necessarily a problem).
This is a feature of many brands of Combi Boiler where it fires up then turns off. It is most likely a Preheating setting to make sure that there is always some hot water ready for when you turn your hot tap on.
We say it is not necessarily a problem because it your boiler keeps firing up and then turning itself off – then you may indeed have a problem (called Short Cycling) that requires further investigation and potentially a boiler repair job.
What is Short Cycling?
Short Cycling is where the internal thermostat in your boiler detects the temperature of the water in your heat exchanger to have dropped while the boiler is off. It then powers up (fires up) to heat that water back to the correct temperature. This doesn’t take very long hence it turns off quite quickly. But if there is an issue with the internal thermostat, it will make the boiler fire up frequently and therefore use more gas to heat your home. This can also damage the heat exchanger.
Another cause of Short Cycling is if you have the wrong size of boiler for your home. If you have an oversized boiler that is too powerful for your homes heating requirements, it will fire up a lot more for internal water heating that it needs to. Modern combi boilers are incredibly efficient so you only need to get the size of boiler that suits your home.
Another potential issue could be that the water pump on your boiler is having issues. Your heating system relies on hot water being pumped through the home and that needs a healthy water pump. If the water in your central heating system is not being pumped around the home efficiently then it will start to overheat and cause Short Cycling.
Don’t ignore Short Cycling
Whatever the potential cause of Short Cycling, it needs to be looked at to make sure your boiler is safe and working properly. If you do not do something about your boiler Short Cycling, it can lead to increased heating bills, damage to internal parts and as a worst case scenario, require a completely new boiler to be fitted.
Find out more
If you think your boiler is having Short Cycle issues where it turns on then off a lot then call your local gas engineer Wright Gas. We are Gas Safe Registered, a Baxi Approved Boiler Engineer and are a Which Trusted Trader.
Call today to book an appointment to get your boiler looked at and avoid costly repair bills.