The heating of water in the home, in an industrial business or even just in commercial premises, is a huge cost annually, and it is estimated that around 80-90% of this energy is then wasted. Certainly in a domestic environment, the heated water that goes to drain from showers, baths, sinks, washing-up, washing machines and dishwashers takes a lot of energy to heat, and because we have so many systems in the home that have heated water demand, it makes perfect sense to recover heat from water we have already used and adapt it to help heat cold water we are using for other purposes.
Extracting this heat from waste water is the principal behind waste water heat recovery, and relatively simple systems are growing in popularity, particularly in new-build homes, as they reduce the work a boiler needs to do to get water up to a desired temperature. This subsequently cuts energy costs and extends the efficiency and lifespan of your boiler, while at the same time reducing maintenance costs.
Two types of waste water heat recovery
There are typically two types of waste water heat recovery system; storage and non-storage. A non-storage system is usually a long copper pipe, which can run vertically or horizontally, depending on the item it is servicing and its location, and this feeds in the cold mains water. A spiral tube will then run around this pipe which takes the waste water away, a heat exchange then takes place and the cold water is heated. It is estimated that this system is roughly 60% efficient, ie. 60% of the potential energy is converted into heat for the incoming water. This is a fairly simple and durable device with no electrical components, pumps or controllers and very little maintenance. Storage waste water heat recovery systems store recovered heated water for later use through the use of insulated tanks, but of course you need space and storage capacity for this.
The benefits of waste water heat recovery
Initial installation costs of a waste water heat recovery system can be relatively expensive and it is not a simple process to retro-fit a system in an existing home, because the recovery device is not compatible with many baths, showers and sinks etc, and hence, they are far more popular with new-build homes. This therefore affects the payback period on a domestic level. It is believed that a waste water heat recovery system will reduce energy consumption by between 5-10% annually, which is not insignificant, and as with many green projects currently being developed, with costs likely to reduce as technology improves the payback period will become more attractive.
Certainly property developers are keen on the system as waste water heat recovery scores well in the Government’s Standard Assessment Procedure (SAP), ie. for the energy rating of a new-build dwelling. Of course each house differs in design, but waste water heat recovery is becoming popular because more than one waste water unit can be fed into a single system.
How we can help you
Waste Water heat recovery technology works well with all types of water heaters, but particularly demand and solar water heaters, and certainly when combined with a more efficient use of showers, washing machines and washing-up water – a more established way to reduce energy bills and save water – waste water heat recovery is sure to become a very popular method for domestic homes to contribute to Green initiatives and reduce the UK’s carbon footprint.