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Hot and Cold Water

Managing the hot and cold water systems effectively is a key aspect of any new build home, directly impacting its energy efficiency, sustainability, and the overall comfort of its occupants.

This page delves into various critical elements of water management, including pipework insulation, rainwater harvesting, waste water heat recovery, unvented hot water cylinders, and solar thermal systems.

Each part of the water system, from the pipes that carry hot and cold water to the innovative technologies for harvesting and recycling water, plays a vital role in creating a home that is not only comfortable to live in but also environmentally responsible and cost-effective to maintain.

Understanding these components and their best practices is crucial for homeowners to ensure their new build home is both efficient in its water use and aligned with modern sustainability standards.



Effective insulation and installation of pipework are crucial aspects in new build homes, directly impacting energy efficiency, water conservation, and overall comfort. The Zero Carbon Hub’s guide provides valuable insights into avoiding common pipework problems. Here’s a focused overview for homeowners:

Insulating Domestic Hot Water Pipes

A common issue in new homes is uninsulated domestic hot water pipes, leading to significant heat loss and potential overheating. This not only wastes energy but also increases heating costs. Properly insulating all hot water pipes is essential to maintain energy efficiency and reduce heat loss.

Minimum Insulation Requirements

The guide recommends a minimum of 25mm thick insulation around pipes, conforming to BS 5422 standards. This thickness is considered a rule of thumb to ensure adequate insulation. Additionally, when installing pipes, there should be enough space to accommodate this thickness of lagging around the pipe’s diameter.

Using Correct Stand Off Brackets

The installation should include the use of correct stand off brackets. These brackets ensure that pipes are securely and appropriately positioned, reducing the risk of damage and maintaining the integrity of the insulation.

Timing of Insulation

A key recommendation is not to cover up or dryline before the pipework is insulated. This ensures that the insulation is properly applied and effective. Insulating pipework after walls are finished can be challenging and may lead to inadequate insulation.

Insulating Cold Water Pipes

Cold water pipes should also be insulated, but in this case, against heat gain. This is important to maintain the desired temperature of the water and to prevent any unnecessary energy expenditure in cooling systems.

In summary, for new home buyers, ensuring that all pipework in your home is correctly insulated and installed is vital. It improves the energy efficiency of your home, reduces heating costs, and contributes to a comfortable and sustainable living environment.


Rainwater Harvesting

Rainwater harvesting is an eco-friendly feature increasingly being integrated into new build homes in the UK, offering a sustainable way to use water for various non-potable purposes. However, to ensure its effectiveness and compliance with regulations, certain precautions and best practices must be followed. Here’s what homeowners need to know:

Separation of Drain Systems

Ensure that site drawings distinctly separate all foul water drains and surface water drains. It’s crucial that ground workers adhere to these plans strictly to prevent cross-connection, which can lead to contamination of the stored rainwater.

Direct Connection to Surface Water Drain

All rainwater pipework should connect directly to the surface water drain, avoiding any back inlet gullies. This direct routing prevents potential contamination and ensures that the rainwater harvesting system functions correctly.

Treatment of Collected Rainwater

If you’re collecting rainwater from paved areas, it’s important to treat the water before storage. This step is necessary to remove contaminants and ensure the quality of the stored water.

Compliance with Water Regulations

Connections to mains water must be made via a type AA or AB air gap, compliant with Water Regulations. It’s recommended to use proprietary rainwater harvesting systems that include these air gaps or provide the necessary parts and instructions for correct installation.

Marking and Understanding of Pipework

Pipework carrying rainwater should be clearly marked, and both first and second fix plumbers must understand which appliances can be fed by rainwater. This knowledge is crucial to prevent any incorrect connections.

Labelling Appliances and Taps

Label appliances and taps that are connected to the rainwater harvesting system. This helps in identifying which sources are suitable for tasks like watering gardens or flushing toilets.

Accessibility of Filters

Ensure that the rainwater harvesting system’s filter can be easily accessed for maintenance after other works, including landscaping, are completed.

Electrical Connection Compliance

Check that electrical connections related to the rainwater harvesting system are IP66 or IP67 rated as required by BS 7671 to ensure safety and compliance.

By adhering to these guidelines, homeowners can effectively and safely incorporate rainwater harvesting into their new homes, contributing to water conservation and sustainability.


Waste Water Heat Recovery

Waste Water Heat Recovery (WWHR) systems are an innovative technology increasingly used in new build homes in the UK, aiming to improve energy efficiency by recovering heat from waste water. However, for optimal performance, there are specific installation considerations and potential issues to avoid. Here’s a concise guide for homeowners:

Checking Mains Water Pressure

Before fitting a WWHR unit, ensure that the site’s incoming mains water pressure is suitable. Inadequate water pressure can impede the efficiency of the WWHR system, making it less effective in recovering heat.

Vertical Installation of WWHR Pipe

The WWHR pipe should be installed vertically, within 1° of vertical, to ensure maximum performance. Proper orientation is crucial as it affects the distribution and flow of waste water inside the unit, which in turn impacts the efficiency of heat recovery.

Manufacturer’s Installation Guidelines

Always refer to the manufacturer’s installation manual for specific guidance. This includes adhering to recommendations regarding the installation of components like the top connector and ensuring that the waste water circulates effectively down the inside face of the inner pipe.

Orientation of Top Connectors

The top connectors of the WWHR unit should be correctly orientated. This orientation is vital for achieving the maximum distribution of waste water, which enhances the heat recovery process.

Plumbing in Accordance with System Specifications

The WWHR unit must be plumbed in accordance with the specific system type (either A, B, or C) as defined in the dwelling’s SAP (Standard Assessment Procedure). This ensures that the installation aligns with the energy efficiency assessment and contributes to the overall performance of the home.

Avoiding Installation Errors

Common installation errors like a single 90° bend or poor fixing should be avoided. Such mistakes can lead to suboptimal performance of the WWHR system and may compromise the system’s ability to recover heat effectively.

By following these guidelines, homeowners can ensure their Waste Water Heat Recovery system is installed correctly, contributing to the energy efficiency and sustainability of their new home.


Unvented Hot Water Cylinders

Unvented hot water cylinders are a key component of many modern heating systems in new build homes, providing efficient hot water storage. However, correct installation and maintenance are crucial for their optimal performance. Here’s what homeowners need to know:

Proper Installation and Accessibility

One of the main issues with unvented hot water cylinders is improper installation, leading to difficulties in accessing controls and performing maintenance. It’s essential to ensure that the cylinder is installed correctly, with easy access for any future maintenance or control adjustments. This accessibility is crucial for both safety and functionality.

Commissioning and Labelling

Another common problem is cylinders not being commissioned correctly or labelled for future maintenance. After installation, the cylinder should be thoroughly commissioned, following the benchmark checklist as stated in the Domestic Building Services Compliance Guide (DBSCG). Proper labelling of valves and controls is also important for ease of maintenance and to ensure that future servicing can be carried out correctly.

Efficiency in Pipework

Long pipework runs and dead legs can cause wasted water and heat. When planning the installation of the cylinder, consider the layout of the pipework to minimise these issues. Shorter, more direct pipework can significantly reduce heat loss and water waste.

Choosing Quality Cylinders

Opting for better performing and better insulated cylinders can improve the overall efficiency of your hot water system. A well-insulated cylinder keeps the water hot for longer, reducing the need for constant reheating and thus saving energy.

By addressing these key factors, homeowners can ensure that their unvented hot water cylinder functions efficiently and effectively, providing a reliable source of hot water in their new home.


Solar Thermal

Solar thermal systems are an excellent sustainable energy solution for new build homes, providing an eco-friendly way to heat water. However, their efficiency heavily depends on correct installation and maintenance. Here’s a guide for homeowners on what to consider for solar thermal systems:

Quality of Installation and Commissioning

One of the primary concerns with solar thermal systems is poor installation and commissioning, which can lead to inefficient usage and reduced energy savings. It’s essential to ensure that the system is installed and commissioned by experienced professionals. This includes correct positioning of panels and proper integration with your home’s hot water system.

Use of Pre-Insulated Pipework

To prevent heat loss, install pre-insulated flexible solar thermal pipework. This type of pipework is designed to maintain the temperature of the water as it moves from the solar collectors to the storage cylinder.

Connection to the Cylinder

The solar thermal system should be connected to the bottom of the hot water cylinder. This ensures optimal heat transfer and efficient heating of the water in the cylinder.

Accessibility and Functionality of Controls

Check that the controls of the solar thermal system are working correctly. They should be easily accessible for monitoring and adjusting the system’s operation. Ask the installer or site manager to demonstrate how the controls work.

Installer Certification and Experience

Ensure that the installers of the solar thermal system have MCS (Microgeneration Certification Scheme) certification. This certification is a guarantee of their expertise and experience in installing solar thermal systems correctly.

Regular Maintenance Checks

As part of installation and ongoing maintenance, check the glycol mix in the system. The glycol mix is crucial for the system’s operation, especially in preventing the fluid from freezing during colder months.

Sizing the Solar Thermal System

A general rule of thumb for sizing solar thermal panels is 1m² of panel per 50 litres of water cylinder capacity. For example, a 3-bedroom house with a 200l cylinder would require approximately 4m² of flat plate collector.

Optimal Placement of Solar Collectors

The solar collectors should ideally be placed with a southerly aspect and in a position that is not overshadowed, to maximise sun exposure and efficiency.

By following these guidelines, homeowners can ensure their solar thermal system is well-integrated, efficient, and effective, providing a sustainable source of hot water.