Vaillant Anti-Cycling Mode Explained

Vaillant boilers are famed for their efficiency, reliability, and intriguing designs. As such, it is one of the leading boiler brands in the UK market, and seeing you on this page, chances are high that you own one too. Vaillant has invested a lot in intelligent energy-saving technologies, such as anti-cycling mode, which homeowners are having a hard time figuring out.

In an ideal boiler operation, the boiler will run until the hot water in the central heating or domestic water system achieve the desired temperature, then it will shut off. This is a good thing as it will help you minimize energy wastage. However, the problem kicks in when the boiler is in central heating mode only. This is because when the radiator nearest to the boiler achieves the desired temperature, the temperature sensor will instruct the boiler to switch off even if the other radiators are not hot enough.

And in the short period that the boiler is off, the temperatures in the hot radiators will drop, prompting the boiler to fire up again. This results in the boiler cycling on and off until the furthest radiator is heated to the desired temperature. This may mean your boiler will be switching on and off up to three times in a minute. The repeated cycling of the boiler will not only result in fuel wastage but also irritate you, especially if you have a noisy boiler.

Anti-cycling mode

Anti-cycling mode is a setting in Vaillant boilers that allow you to set a time delay between the boiler switching off and firing on when there is a demand for central heating. As this is a programmable electronic function, once it is activated, the boiler will not fire up again until the set time has elapsed.

Once the set time has elapsed, the boiler will resume firing as usual and wait for the next cycle. During the wait duration, the boiler pump will continue pumping the hot water into the CH system, thus ensuring the furthest radiator from the boiler is effectively warmed up.

To ensure your radiators won’t become cold when the boiler is in anti-cycling mode, ensure you set your room thermostats to a higher temperature. For instance, if your desired flow temperature is 60 degrees Celsius, you can set the boiler thermostat at 65 degrees. This way, when the anti-cycling mode is on, the radiator temperatures will drop to around 60 degrees before the boiler fires up again.

How long should I set my boiler’s anti-cycling mode to last?

The ideal anti-cycle time varies from one boiler to another, depending on the boiler output and the target radiator temperatures. Normally, when purchasing your boiler, this time is usually set at 20 minutes, and for most properties, this works fine. However, if you want to change this time, you can set it to any value between 2 minutes and 60 minutes.

To determine the ideal waiting cycle for your radiator, consult your boiler manual. The manual usually contains a table of effective anti-cycle times depending on your desired flow temperatures. However, it is worth noting that the boiler can sometimes fire up earlier or later than the set time.

To better understand this, consider a simple set-up where the anti-cycle time is set at 20 minutes while the flow temperature is set at 40 degrees. Once the desired flow temperature is achieved, the boiler will shut off for twenty minutes. But during this waiting time, room temperatures will drop, and the controller will change the flow temperature from 40 degrees to 60 degrees. This means that the waiting time for the next cycle will be 17 minutes, as that is the recommended cycle time for 60 degrees.