Shower Water Heat Recovery

Shower Water Heat Recovery

We all like to have warm/hot showers, but water consumes a large amount of energy when raising its temperature from the environmental ambient temperature to something that we would consider ‘nice to show in’ (approximately 43 degrees centigrade).

The majority of that energy then runs out of the waste pipe of our showers. Heating up the environment whilst incoming cold water is required to be heated again for the next shower.

Introducing the UFL Shower Water Heat Recovery System

We at UFL have designed a stainless steel heat exchanger specifically for the task of recovering heat from waste shower water to feed back into the hot water tank or combi-boiler supply.

shower water heat recovery

UFL Shower Water Heat Exchanger

The pipe sizes and anticipated flow rates of both the cold water refill and waste water drainage have been designed for maximum recovery efficiency and zero maintenance. The internal pipe sizes and structure ensure that there is minimal/no air gaps within the waste water flow to allow the efficiency to be optimal whilst the overall size being compact.

shower water heat recovery

Internal Structure

The internal structure of the heat exchanger is a collection of small corrugated pipes producing high surface area contact of the water flows and turbulence within the flows to maximise heat transfer.

The UFL Waste Water Heat Recovery heat exchanger is made from 100% 316L stainless steel and is tested to 20 bars. They are 350mm long (including end fittings) and have a diameter of 60mm, making them easy to install in even the smallest of places.

The end connections, which are used for the waste water flow, have 1.25″ BSP female fittings. This fitting gives an outside dimension suitable for straight coupling to standard waste water push-fit couplings.
The side fittings, which are used for the supply water flow, are 1″ BSP female fittings allowing either 15mm compression couplings to be used or 22mm couplings.

How much can you save?

Let’s assume you have 2 showers per day and these consume 50L of water during each shower. A short (5 minute) shower consumes 35L of water and a short power shower uses nearly twice this amount. This equates to 36,500L of heated water going out the grey-water waste of your house. The annual average incoming water temperature is 9 degrees centigrade. If you have your shower at 43 degrees centigrade then in a year 36,500L of water need to be heated from 9 to 43 degrees, which is 34 degrees.
It takes 1.163 Whrs to raise one Litre of water one degree centigrade. This means nearly 1500kWhrs (1.163 x 34 x 36500) of energy goes out the shower tray each year.
At a cost of gas at 3.5p/kWhr, kerosene/LPG at 7p/kWhr, and grid electricity at 12p/kWhr the price to heat this water is (assuming a boiler efficiency of 70%):-

  • Grid natural gas cost is nearly £75 per year
  • Kerosene or LPG cost is nearly £150 per year
  • Grid electricity cost is nearly £175 per year

At the stated temperature difference (9 and 43 degrees), the UFL shower water heat recovery heat exchanger is rated at 8kW. This means that it is very capable of recovering over half the heat going through it.

Service and maintenance

The UFL shower water heat recovery heat exchanger requires no servicing or maintenance beyond that which you’d do to the shower trap. It is made from stainless steel so is perfectly capable of handling most drain cleaning fluids.


Installation is very simple. The exchanger needs to be fitted into the waste water flow pipe beneath or somewhere close to your shower using the end fittings. The supply water pipe returning to your hot water tank or combi-boiler needs to be re-plumbed in order to direct the flow through the heat exchanger.

shower water heat recovery

Please note: the two water flows should be plumbed in so that they flow in opposite directions, as shown above.


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