Most hot water cylinders heat water through coils or an immersion heater at the bottom of the cylinder. The heat rises until all the water in the cylinder has reached the set temperature. 

Mixergy cylinders are different. Their patented volumetric heating method heats the water from the top down, in 10% increments, using thermal stratification. And smart technology means you only heat the water you need – saving energy. In fact, when installed with a gas boiler, the Mixergy cylinder reduces gas consumption by as much as 21% compared to a conventional cylinder. 

Another benefit is that, because you aren’t heating the whole cylinder, usable hot water can be generated 10 times faster than in a conventional cylinder.

So, what is thermal stratification? Simply put, thermal stratification is the result of heat rising; hot water floats on top of cooler water. The area between the hot and cold sections of water is known as the thermocline. 

The Mixergy cylinder starts by heating a small volume of water at the top of the cylinder and then grows that volume downwards. A sensor in the cylinder lets the user know exactly how much hot water is available and because it is ‘smart’, the cylinder will start to learn when the user wants hot water, and make sure it is available. For example, it will learn what time showers are taken every morning and ensure enough is hot water available.   

The Mixergy app

The Mixergy app has lots of useful features to help the household make the best and most efficient use of their hot water cylinder. Once the Mixergy cylinder has been connected to the internet, the app downloaded, and an account set up and verified, the manufacturer’s 25 year warranty is activated. 

It can also be integrated into existing home automation systems. For example, it can be controlled using Amazon Alexa, Google Home and Hive from British Gas.

The app will tell you how much hot water is in the cylinder, what the temperature is, what it is costing, and how much space is left. If there is suddenly a need for a lot of hot water, the app can be used to boost to 100% hot water capacity and it can also change the temperature if required. A daily schedule can be set and there’s also a holiday mode, so departure and return dates can be set, along with the temperature required while away.

For installers, the benefit of the Mixergy app over a programmable heating and hot water control is that you don’t need a dual twin channel programmer, you just need a single channel programmer for the heating, and the hot water is controlled via the Mixergy app.    

The cylinders have built-in frost protection, especially important during the winter if installed in an unheated loft or garage. The internal temperature is continually monitored, and if the water at the bottom of the cylinder drops below 5oC, it will automatically heat up to prevent freezing. This gives peace of mind for the end-user, knowing that their hot water and heating system is protected from freezing, even when they are away from home.

Smart tariffs and renewable technologies

As more flexible electricity tariffs become available, the cylinder can be programmed to only work when the electricity is at its cheapest. Thermal stratification means there’s more space in the cylinder to take advantage of this economical hot water.   

For homes with solar PV, Mixergy’s PV Switch can be retrofitted to the cylinder to connect with an existing solar PV battery, or connected directly to the solar PV using their embedded diverter. The embedded diverter is able to store the excess energy from the solar PV, effectively heating the water for free when the sun is shining.

All Mixergy cylinders are heat pump-ready. An external plate heat exchanger can be fitted to the heat pump flow and return. Energy is always transferred from the coldest part of the cylinder and forced convection occurs on both sides of the heat transfer surface, achieving a low thermal resistance and the best possible co-efficient of performance (COP).

In conclusion, talking to their customers about Mixergy cylinders gives heating engineers the opportunity to open up the conversation about being renewable-ready, whether that’s for solar PV or heat pumps, and also to talk about flexible tariffs. The advice they give their customers today will be crucial in helping them make the right decisions about their future heating systems and could also contribute to significant cost savings by getting the best from their gas boilers right now.