Waste Water Heat Recovery (WWHR)
Frequently Asked Questions

Here is a list of our most commonly asked questions about WWHR.

How does a Power-Pipe WWHRS work?

A Power-Pipe works by recycling the heat from outgoing warm waste water- such as shower water- and uses this to pre-heat incoming cold fresh water. This helps to save energy, reduce CO2 emissions and keep heating bills down.

Where does the pre-heated water go?

In residential applications, the pre-heated water is fed into the cold water inlet of the shower mixer and the cold water inlet into the water heating system (combination boiler or hot water cylinder). That’s why it is sometimes referred to as Shower Heat Recovery.

Why is it important to install WWHR?

Wasted hot water is a huge untapped resource in the UK which is why it is important to have a good understanding of the technologies that can make showering and other hot water processes more energy efficient.

Typically, up to ninety percent of heat produced during showering is lost down the drain but the majority of this energy is recoverable through installing a Power-Pipe which is up to seventy percent efficient.

What are the benefits of Power-Pipe for home owners?

Installing a Power-Pipe can allow a home-owner to reduce their annual energy bills by ten percent or 500Kwh per person per year.

This could be a cost saving of £80 to £100 and the more people using the shower, the greater the energy saving returns.

These systems also reduce carbon emissions in a home by between 300kg to 1000kg a year dependent on how often the occupants shower and what fuel they use to heat their water with.

Power-Pipes have no electrical components, filters or controls so require no user interaction or maintenance. If they are made from 100 percent copper, they are also expected to last the life span of a building.

What are the benefits of a Power-Pipe for developers?

Waste Water Heat Recovery is now recognised by The National House Building Council (NHBC) as one of the methods that can be used to pass Building Regulations Part L and is the most cost-effective way of increasing a Standard Assessment Procedure (SAP) score.

Dependant on the model or size, a Power-Pipe costs between £250 to £750 (including installation) but will offer a generous SAP uplift in the region of two to eleven percent which could be the difference between a pass or a fail on a property. This is an equivalent energy saving to triple glazing or solar thermal, but at a fraction of the cost.
Power-Pipe has the most cost-effective units and highest WWHR SAP rating units in the UK which come with a ten-year manufacturer’s warranty.

Power-Pipe also offers developers greater flexibility as it’s the only system that comes in two diameters (50mm and 100mm) and multiple lengths (from 610mm to 2130mm) which gives you the choice to find a unit that best meets your budget and energy efficiency requirements.

What are the benefits of a Power-Pipe for installers?

Installation is much more straightforward with a Power-Pipe WWHRS. This is because all our systems come with 22 mm connections as standard and we are the only systems that do. This means the person who is fitting it won’t have to reduce the size of the incoming mains water feed (also 22mm) which would restrict the flow of the water passing through it.

Unlike other WWHR systems, these 22 mm connections, along with our patented multi-coil design, ensures virtually no pressure loss to the pre-heated water system. This means multiple showers can be run off one unit, making it even more cost-effective.

What is the minimum cavity size for a Power-Pipe?

A 110mm Power-Pipe (R4 series) requires a recommended minimum cavity of 125mm by 180mm. NOTE: This size unit replaces part of the SVP so, it is only slightly larger than the cavity size that would already be required for the SVP.

A 50mm Power-Pipe (E2 & X2 series) requires a recommended minimum cavity of 75mm by 130mm. Please note that this is in addition to the SVP that it is usually installed alongside.

What maintenance does a Power-Pipe WWHRS require?

As the Power-Pipe WWHRS has a self- cleaning design and is made from 100% copper, it is completely maintenance free. It comes with a 10-year manufacturer’s warranty but it is expected to last the lifetime of the building without any maintenance.

Where should a Power-Pipe WWHRS positioned/installed?

A Power-Pipe replaces a section of the waste water pipe from the shower. The 110mm diameter version can be used for all waste from the bathroom.

Are all Power-Pipes SAP listed?

Yes, there are 64 Power-Pipes listed in SAP which all have certified SAP efficiency ratings. They can be found in the SAP database and also on our website, on the pricing and sizing page

Are all Power-Pipes WRAS approved?

Yes, all 64 Power-Pipes are WRAS approved. They come in two diameters (50mm and 100mm) and multiple lengths (from 610mm to 2130mm).

Can a Power-Pipe be installed horizontally?

No a Power-Pipe must be installed vertically and on the first floor so it can’t be used in a bungalow or ground floor flat. An exception to this rule maybe in commercial or industrial application where very high flow rates are involved. Contact us to discuss this further.

Which hot water systems are compatible with Power-Pipe?

A Power-Pipe is compatible with all water heaters but will not provide any savings if used with electric showers.

Does a Power-Pipe work with baths and showers?

They are designed to work with showers only. If the shower and the bath water is connected through the same soil stack, the bath water will drain through the Power-Pipe but will not provide any energy savings.

Why can’t a Power-Pipe be used with an electric shower?

Electric showers cannot regulate both temperature and flow rate. If a Power-Pipe was connected to an electric shower, the primary benefit would be an increased flow rate and not energy savings so it would not have any SAP benefits.

Does a Power-Pipe have a vented twin wall?

Yes, but not all WWHRS systems do. This wall creates a barrier and helps to avoid any possible cross contamination between the waste and potable water supplies, as well as detect a leak if one occurs.

Can a Power-Pipe be retrofitted?

Power-Pipes are ideal for new build properties but can’t be easily retrofitted because it is normally difficult to access the pipework of a building.

What is a Power-Pipe made from?

Unlike some competitors which use plastic components, the Power-Pipe WWHRS is made of 100% Part L copper and is tested to over 1000 bars. This ensures quality and the best possible performance for the transfer of heat.

How big is a Power-Pipe WWHRS?

Power-Pipes WWHRS come in a range of different lengths and diameters. This means that you can find a Power-Pipe WWHRS to meet any situation or budget. A guide to choosing the right Power-Pipe WWHRS for you can be found here.

Do you offer any training or installation guidance?

Yes. Our technical team offers free training for plumbers to become approved Power-Pipe installers to ensure they can fit all systems to ensure maximum efficiencies and to comply with SAP. We also offer expert advice and SAP modelling guidance to specifiers for their specific projects and requirements.

What are the risks with Legionella?

The Power-Pipe WWHR unit is constructed from copper. Copper suppresses the colonization and growth of micro-organisms such as Legionella Pneumophila and is deemed low-risk.
Even so, a Power-Pipe should not be installed in an environment where the ambient temperature is naturally above 25C to minimise the risk of legionella growth.
The Health and Safety Executive has issued guidance for dutyholders on the control of legionella bacteria in hot and cold water systems in HSG374 Part 2. The areas of particular relevance to a system where a Power-Pipe is installed are Sections 2.36 and Sections 2.37.

Questions? Get In Touch

Call us:

0207 887 2270