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Hot Water

Hot water in your business 
Hot water case study 
Hot water tips

Hot water in your business

There are many cost-effective ways to improve the efficiency of your electric storage hot water system. In fact, you may only need to make minor changes to your system. To minimise costs, the demand for hot water in your business should be kept as low and consistent as possible. This concept is known as demand management.

There are basically three ways of reducing hot water expenses:

• Improve the efficiency of your current hot-water system
• Purchase a new high efficiency model
• Use less hot water

There are many ways to achieve these objectives:

• Don't oversize your unit
• Insulate the tank, pipe work and fittings
• Install flow restrictors wherever possible
• Don't overheat the water
• Use 'off peak' power if feasible
• Preheat feed water with waste heat from other processes
• Locate the system as close as possible to the point of use
• Maintain your system in efficient working order

Hot water case study

Reducing the temperature can reduce the costs

Most domestic/commercial storage hot water systems come with a thermostat, which has a variable temperature set-point (typically up to 70°C). These thermostats are typically set at 65°C. You can save a significant amount of energy by reducing the temperature of your hot water system.

The following figure shows the savings you might achieve by adjusting your hot water system temperature.

Note: To prevent the formation of ‘Legionella pneumophila’ bacteria (which cause Legionnaires' disease) the ‘WA Code of Practice - Legionnaires Disease’ recommends that hot water temperatures be set to at least 60 degrees centigrade

Figure 1: Approximate annual electricity savings from reducing water temperature (based on average cost of 13 cents per kilowatt hour)

Off-peak water generation

If you have an electric hot water storage system, it may be possible to save energy and reduce costs by generating your hot water during off-peak times.

The following figure shows the potential savings of adjusting your hot water system to only heat water in off-peak periods. The savings presume that the hot water storage is sufficient to allow the heater to be turned off during the whole peak period. Calculations are based on the R1 and S1 gazetted tariffs in the Electricity and Corporations (Charges) By-Laws 1996.

Figure 2: Approximate annual savings from operating hot water system at ‘off-peak’ times only (based on 1 kilowatt element for 100 litre, 2 kilowatt element for 200 litre and 3 kilowatt element for 300 litre systems)

The S1 Tariff shows higher savings due to the reduction in demand.

Note: Whilst care has been taken in the preparation of this material, it is intended to provide a general idea about what can be achieved in a particular situation. Quantitative indicators may vary with time and changing circumstances. Each situation is different, requiring its own evaluation; and therefore the results given above should not be taken as being directly transferable to other circumstances. Names and addresses have been withheld for privacy reasons.

Hot water tips

Choose the right size unit

Work out the maximum number of hot water outlets likely to be used simultaneously and choose a unit that can meet this requirement. That way you’re not wasting money and energy by producing superfluous hot water.

Insulate the tank, pipe work and fittings

If your business is in a cold region or the pipe work is exposed to prevailing winds then make sure all exposed pipes are well insulated, with insulation at least 10 millimetres thick. Also, make sure that storage systems are insulated and sheltered – this will reduce heat loss and protect pilot lights from draughts. With gas (or other combustion fuels) it’s important make sure you provide enough ventilation to allow efficient combustion.

Don't overheat the water

Naturally, you can further reduce your energy costs by lowering* the temperature of your system. Reducing the water temperature by as little as 5.6°C, can reduce water-heating energy consumption by 3% to 5%.

*Please note the Legionella warning in the case study above.

Locate the system as close as possible to the point of use

A simple way to save energy is to keep your hot water pipes as short as possible, by installing the water heater as close as you can to the main points of use. Long pipes mean higher temperatures are needed to keep the water hot as it travels. What’s more, the hot water leftover in the pipes eventually cools, wasting the energy used to heat it.

Further information

Find out how to reduce your energy costs, by contacting Synergy's Energy Consultants. Just email us at  energyreview@synergyenergy.com.au or call 1300 859 333.

For more information on energy efficiency in your business visit the Sustainable Energy Development Office at http://www1.sedo.energy.wa.gov.au