Case study 1 Case study 2 This was a system for a typical, small, pre- This was a system for a shower block in a fabricated fast food restaurant. It is assumed holiday camp, with six showers and four the system only serves the hot water demand. basin taps. The life cycle analysis includes the initial For the continuous flow option, the analysis single continuous flow water heater would
capital costs, projected annual fuel costs, and is based on a configuration of 4 continuous equate to an efficiency of 95% based on
estimated annual servicing costs which are flow water heaters that each have a nominal the performance curve. As the hot water
assumed to increase by 2% each year. output of 48 kW, which, for this particular demand increases, the modular nature of this
Each shower would typically have a flow rate
of around 9 litres per minute, which if mixed
to 40ºC would equate to an instantaneous
load of around 19 kW each, so even if there
was only one shower running, the load on a
application, because there is a very short particular configuration would allow the 95%
The annual fuel cost assumes the same daily run of pipe work between the water heaters efficiency to be maintained for the bulk of the
fuel consumption over the whole year. and the fixtures, it is possible for the water demand.
The servicing cost is based on £130/year
per boiler, and £160/year for a boiler and
cylinder. The resulting net present values of
heaters to generate water at 40°C. The risk
of legionella is overcome by the regular
turnover of the system.
The difference in daily fuel costs between
the three systems is around 7%. The usage
profile for this case study is particularly
the three showed that the continuous flow For the energy required to deal with the suited to continuous flow systems (i.e.
system is 6 - 7% lower than the two storage instantaneous hot water demand the analysis high but infrequent demand over the day),
systems based on that 20-year analysis assumes that the bulk of the hot water which is why there is an advantage in fuel
period. demand would be due to the showers. consumption over the storage systems.
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