What is a Boiler Interlock? – Explained!

Boilers are crucial to maintaining a cosy home environment and providing us with hot water. They operate tirelessly and efficiently, utilising both electricity and fuel. However, it is essential to implement specific protective measures to ensure the safe operation of your boiler. One such safety measure is known as a boiler interlock.

In this article, we will delve into the concept of boiler interlock, explore the reasons behind its necessity, and outline the tools required for its implementation. By the end, you will have a comprehensive understanding of this vital safety feature for your boiler.

What is a boiler interlock?

The boiler interlock function is a crucial safety measure that prevents your boiler from operating unnecessarily. It is not a physical device that is installed internally or externally.

Instead, a boiler interlock combines controls and wiring with your thermostat. This interlock system effectively prevents your boiler from firing up when it is not required, conserving energy and avoiding potential damage.

Incorporating an interlock mechanism safeguards your boiler against excessive temperature and pressure. When parameters increase beyond the desired levels pre-set by you, the interlock mechanism is triggered, immediately shutting down the boiler. This prevents unnecessary energy consumption and protects your boiler from potential harm.

Why is a boiler interlock necessary?

Implementing a boiler interlock system is essential for maintaining the efficiency and longevity of your heating system. It ensures that your boiler operates only when necessary, reducing energy waste and potential damage to your family and the boiler.

Also, according to the building regulations for 2022, it is essential to incorporate a boiler interlock system with thermostats into your boiler controls. This measure is crucial to minimising energy waste.

For more information, read this detailed guide.

Problems that boiler interlocks potentially prevent

The interlock prevents your boiler from firing up unnecessarily and indicates problems with your central heating system. The issues that make interlocking necessary are the following:

1. Inadequate Water pressure

Proper water pressure is crucial for your boiler’s safe and efficient operation. When the pressure is too low, it can result in inadequate heating and potential damage to the system. Conversely, excessively high pressure can strain the boiler, causing it to malfunction or, in extreme cases, explode.

Boiler interlock systems act as a protective mechanism to safeguard you from these hazards. When the pressure falls below the required threshold, the interlock system triggers an automatic shutdown, preventing the boiler from accessing fuel. This immediate response ensures the boiler is not operated under unsafe conditions, minimising the risk of damage or catastrophic failure.

2. Faulty forced draught fans

The boiler interlock also helps you depict issues with your forced-draught fans. These fans play a critical role in supplying pressurised air and creating a vacuum of negative air pressure that aids in removing flue gases.

If the fans become defective due to damage or wear and fail to start up due to insufficient energy flow, the interlock system will promptly activate an alarm. This alerts you to a fault with your fan and prompts you to arrange repairs or replacements.

Tools and controls that are used to achieve boiler interlock

1. TRV (Thermostatic Radiator Valve)

Thermostatic Radiator Valves, also known as TRVs, are water-regulating valves installed on radiators to control water flow into them. It is important to note that a thermostat must be installed alongside the TRV for the boiler interlock.

Although installing your thermostat and TRV in the same room is unnecessary, it is important to ensure that your TRV is not located in warm and humid rooms, e.g., bathrooms and kitchens, and to place them in open spaces. If you put them in warm and humid rooms, your TRV will switch on or turn off the water flow to your radiators when there is no need. This is because the room temperature confuses the TRV.

Also, you can find electronic TRVs that provide the control needed to set different temperatures for different rooms.

2. Hot Water Cylinder Thermostats

Another crucial component of your boiler interlock system is the hot water thermostat. This device accurately detects the temperature and pressure of the water stored in your cylinder, subsequently sending signals to your boiler to activate or deactivate based on the optimised temperature.

If the temperature, pressure, and gas controls specified for the cylinder are not met, the thermostat will promptly instruct your boiler to switch on. Conversely, if the temperature, pressure, and gas settings are met, the hot water thermostat will signal your boiler to turn off.

It is highly recommended to avoid excessively high temperatures on the thermostatic valves to expedite the heating process. Instead, it is advisable to pre-set the timer for the cylinder, ensuring that you won’t have to wait for heating at your desired time.

3. A Room Thermostat

To properly interlock your combi boilers, it is essential to install a room thermostat. The first step is to set your desired room temperature. Once this temperature is set, the room thermostat will detect it and send signals to the boiler, prompting it to cease the flow of hot water and gas energy when the desired temperature is achieved. This crucial function of the room thermostat prevents rooms from overheating, ensuring optimal comfort.

The room thermostat plays a pivotal role in correctly functioning your boiler interlock. Installing it in open spaces is imperative, avoiding warm and humid areas. By doing so, you guarantee its effectiveness and longevity.

What are Boiler Interlock Switches?

Boiler interlock switches are not the same as boiler interlocks, although they function similarly. Interlock switches serve as heat protection devices by interrupting the electrical circuit. It is important to note that interlock switches should not be mistaken for safety switches.

How do interlock switches save energy?

Interlock switches offer a practical solution to help you save a sufficient amount of money. You can achieve substantial savings by reducing your thermostat’s temperature rating by one degree. Once your desired temperature is reached, the interlock switch will prevent your boiler from firing unnecessarily.

For instance, if you lower the temperature ratings from 22°C to 21°C, your boiler will not need to remain on for an extended period as it will reach the lower temperature more rapidly. This efficient adjustment can lead to considerable cost savings.

By implementing this small change, you can save up to £85–90 per year.

Additionally, there are other measures you can take to further reduce your expenses. One such measure is to ensure that your digital thermostats are positioned in open spaces, away from direct sunlight and external pressure. This precautionary step prevents false readings of the actual room temperature, which could cause your boiler to shut down unnecessarily.

These cost-effective strategies can save money and enhance your heating system’s efficiency.

Conclusion

After reading this article, I hope you know why a boiler interlock is necessary and the tools required to achieve a boiler interlock. Still, if you have any queries or are facing any difficulties regarding your boiler, don’t hesitate to contact us at 0345 3192 247, and one of our representatives will assist you with your problem.