Understanding Boiler Short Cycling
Boiler short cycling occurs when your boiler turns on and off more frequently than it should. Normally, a boiler should run in longer cycles, with a break in between, to heat your home efficiently.
However, if it’s short cycling, it means the system is struggling to maintain a consistent temperature, causing it to fire up and shut down in rapid succession.
While this issue may seem minor, over time, it can reduce the lifespan of your boiler and increase the need for repairs, not to mention those rising energy bills.
Common Causes of Boiler Short Cycling
Oversized Boiler
One of the most common causes of short cycling is having a boiler that’s too large for your home. If the boiler produces more heat than your home needs, it quickly reaches the desired temperature and shuts off.
This cycle then repeats itself, leading to short cycling. It’s important that your boiler is correctly sized to match your home’s heating demands.
Faulty Thermostat
If your thermostat is faulty or positioned in a poor location, it can send incorrect signals to your boiler, causing it to fire up unnecessarily.
For example, if the thermostat is located in a draughty area or near a heat source, it may falsely detect that your home is colder or warmer than it actually is, leading to short cycling.
Low Water Pressure
Your boiler relies on the correct water pressure to function properly. If the pressure drops too low, it can cause the boiler to shut off prematurely, leading to short cycling.
A common reason for low pressure is a leak somewhere in the system, so it’s crucial to check for any signs of leaks around the boiler or radiators.
Blocked Heat Exchanger
The heat exchanger is responsible for transferring heat from the boiler to your water. If the heat exchanger becomes blocked or covered in limescale, it can prevent the boiler from heating water properly, leading to short cycling.
How to Fix Boiler Short Cycling
Get the Right Boiler Size
If you suspect your boiler is oversized, it might be time to consult with a heating professional about replacing it with a properly sized model. Having the right-sized boiler ensures it runs efficiently without constantly switching on and off.
Check and Reposition Your Thermostat
Ensure your thermostat is in an appropriate location — not near drafts, direct sunlight, or heat sources. If it’s faulty, replacing it with a more modern, programmable thermostat could resolve the issue and give you greater control over your home’s temperature.
Increase Water Pressure
If your boiler’s pressure gauge shows a reading below 1 bar, it’s likely too low. You can increase the pressure yourself by following the manufacturer’s instructions, but if the pressure continually drops, it’s best to call in a professional.
Schedule Regular Boiler Servicing
One of the best ways to prevent short cycling is through regular boiler servicing. A professional service from a reputable company like iHeat will ensure your system is running at peak efficiency and extend the lifespan of your boiler.Â
Servicing can also involve descaling the heat exchanger and flushing out any trapped air, preventing short cycling.
Final Thoughts
Boiler short cycling is a frustrating and potentially costly problem, but it’s usually fixable with the right approach.
Whether it’s adjusting the thermostat, bleeding radiators, or scheduling a boiler service, tackling the issue early on will save you money and extend the life of your heating system.
