With the UK government legally committing to net zero targets, home refurbishment projects are increasingly gaining popularity. Homeowners are opting for energy-efficient heating solutions to enhance their control over energy supply, cut costs, ensure security and build resilience against global uncertainties.
As an installer, when fitting renewables such as heat pumps into home refurbishment projects, there’s a key consideration related to hot water delivery that you need to account for, especially if the property previously had a combi boiler as the primary heating source. That is, the need for additional thermal storage to provide hot water.
So, what are the popular thermal storage options in terms of benefits, challenges, and regulatory requirements, and what does this mean for installers regarding compliance, cost, and long-term performance?
Let’s break it down.
What is an unvented cylinder?
Unvented hot water cylinders have been popular over the past few decades primarily because they offer high pressure hot water directly to taps and showers without the need for a separate cold water storage tank. This makes them ideal for homes with multiple bathrooms or properties where space is limited, as there’s no need for the traditional cold-water tank, often found in lofts.
The ability to supply hot water at mains pressure means better performance and faster filling times for showers and baths, which is a major selling point for homeowners. Modern unvented cylinders can be quiet, compact and efficient, offering a streamlined solution for homes looking to upgrade hot water systems.
Unvented cylinders are also relatively efficient. With greater efficiency you get a more reliable supply of hot water with less energy consumption, lowering both energy costs and carbon footprint.
What is the problem with unvented hot water cylinders?
While unvented hot water cylinders are an excellent solution for many homes, they come with several challenges.
For instance, since they operate under significant pressure, these systems have some unique safety considerations. When the water inside the cylinder is heated, it expands. This pressure can be a concern if not properly managed. That’s why, unlike vented systems, which rely on gravity to maintain water pressure, unvented cylinders require additional mandatory components to ensure safe operation. These help prevent over-pressurisation, which could lead to leaks or even catastrophic failures if not installed properly. Also, because an unvented cylinder is supplied by the mains, if the mains is turned off for any reason, you will not have hot water.
Moreover, as these systems operate under mains pressure, installers need to ensure that house plumbing is compatible with this type of system, especially when it comes to pipework size and pressure capacity. Also, unvented cylinders aren’t always compatible with modern power showers and mixers.
G3 Building Regulations and Challenges for Installers
When it comes to the installation of unvented hot water systems, the UK’s G3 Building Regulations come into play. These regulations govern the safe installation and operation of unvented hot water cylinders, outlining the need for qualified installers to follow specific safety procedures.
What G3 covers: The G3 regulations are designed to ensure that unvented systems are safely installed and that the system can withstand the pressure of mains water. The regulations require installers to be qualified and competent to work with high-pressure systems, as unvented cylinders operate at pressures exceeding 3 bar. Installers must also ensure that safety devices are installed, including pressure relief valves and temperature controls.
How a G3 affects installers: Certification is essential for anyone who is installing or maintaining unvented hot water cylinders in the UK. The certification process can be time-consuming and may add additional costs to a project, particularly if tight schedules or budgets are a concern.
Additionally, unvented cylinders often require a considerable amount of space which can be a major challenge in space-constrained homes, or those hoping to only use the space previously taken up with a combi boiler, making installations more complex.
Installers also face issues with compliance and paperwork; another reason why having the proper training and certification is crucial. While this may seem like a significant hurdle, the G3 Building Regulations are there to protect both homeowners and installers, ensuring that these systems are safely integrated into a property.
You can check out the UK Government website on G3 Building Regulations for more information.
Introducing Thermino heat batteries - a competitive advantage for installers
Sunamp’s Thermino heat batteries are a modern alternative to traditional unvented hot water cylinders, providing installers with some major advantages in terms of compliance, efficiency and installation.
Thermino heat batteries store less than seven litres of water, meaning that G3 certification isn’t necessary for installation. In fact, according to G3 Building Regulations, systems that store less than 15 litres of water are exempt from certification requirement, significantly reducing installation complexity for installers while ensuring resident safety.
Darren Milkins, Regional Sales Manager, Sunamp
Here are some key competitive advantages that Thermino heat batteries offer:
- No G3 certification required
This saves installers time and money, making Thermino a great alternative, especially for new or smaller projects where time and budget are tight. - Space-savings
Thermino heat battery is small and compact, making it the perfect solution for installations in tight spaces like under the sink or stairs. Whether it’s a small flat, an apartment or a home with limited loft space, this compact design allows for a quick and easy installation, freeing up valuable storage space. This is crucial for homes transitioning to renewables as the primary energy sources, including heat pumps & solar PV, as well as those using electric storage heaters. - Low maintenance
Compared to unvented hot water cylinders, Thermino heat batteries require no regular servicing, saving on running costs over the years. A lifetime of hot water on demand. - Energy source compatibility
Thermino heat batteries can work with a variety of energy sources, including heat pumps and solar PV systems. The Optimino controller enables Thermino ePlus and xPlus range to work with different energy sources, meaning homeowners can add solar PV to the ePlus model, and a solar PV and heat pump to the xPlus model to suit their budget without the need to change the heat battery. As energy efficiency becomes an increasingly important factor in homes, Thermino’s compatibility with renewables makes it a foolproof option for customers interested in sustainable living. You can read all about our Optimino technology here.
