TYPES OF HOT WATER SYSTEM
- There are two basic types of water heaters - storage systems and continuous systems. Each system can use a variety of energy sources to heat water.
- Instantaneous systems cannot run out of hot water and can be mounted internally or externally.
- Standard units can only deliver adequate hot water to one or two points at the same time but high performance gas units can supply several points at once. They also have sophisticated temperature controls.
STORAGE WATER HEATERS
- Water is heated and stored in an insulated tank for use when it is required. These systems can operate on mains pressure or from a gravity feed (constant pressure) tank.
- Mains Pressure: Hot water is delivered at a similar pressure and flow rate to cold water so more than one outlet can usually be turned on without greatly affecting pressure. The storage tank is usually located at ground level inside or outside the house.
- Constant Pressure or gravity feed: Hot water is delivered at lower than mains pressure from a tank located in the roof of the house. Pressure depends on the height difference between the tank and the point of use. Gravity feed systems are most common for properties not connected to mains water. They are often cheaper to purchase and last longer than mains pressure systems.
ENERGY SOURCES FOR HEATING WATER
SOLAR ENERGY
In warmer climates or areas where access to the sun is not a problem solar systems can provide virtually all of your hot water. In cooler climates or small households it is not the best choise. Even is climates where it is desirabel to use solar power, a backup system powered by other means is needed for times when the sun is not sufficient to meet the demands for hot water.
NATURAL GAS
Natural gas water heaters generate far fewer greenhouse gas emissions than standard electric storage systems. They also use smaller tanks and recover more quickly. Instantaneous systems usually use natural gas.
ELECTRICITY
Electricity can be used for standard storage heaters, for heat pump systems or for boosting solar systems. Expensive three-phase electricity supply is needed for instantaneous systems.
Electric Heat Pumps:
- Electric heat pumps extract heat from the environment to heat water. They pay back the extra initial investment more quickly in larger households.
- There are different types of heat pumps. Some use air as a heat source. Others use water or earth. Rather than using electricity to create the heat, is only used to move the heat from one place to another.
- Geothermal heat pumps can produce more than 4 units of heat energy for every unit of electrical energy used.
- Heat pumps can be located and designed to utilise waste heat from air conditioners and refrigerators.
Electric Storage Water Heaters:
- Standard electric storage water heaters use a heating element inside the tank to heat the water, just like an electric kettle, but because they are responsible for the most greenhouse gases of any water heater they are not recommended.
- An electric storage water heater can indirectly produce as much carbon dioxide each year as the average family car.
CHOOSING A HOT WATER SYSTEM
- Of the many different types of water heaters on the market, the best hot water system for your home will depend on your situation. Consider the following.
- Use patterns for your household such as the number of people and time of day useage for various activities that will place demand on the system will be a deciding factor on the choice of system.
- Initial cost should be weighed against efficiency, long term operating cost and the time it will take to recoup any extra purchase cost for a more efficient system.
- Available Energy Sources. Your choice may also be limited by the available energy sources. Natural gas is not available in some areas and solar energy may not be ideal in cooler climates or shaded areas.
THE BEST SYSTEM FOR YOU
- The following suggests the best systems for various situations in terms of cost-effectiveness and environmental protection.
- For a small, water-efficient household choose an instantaneous gas hot water system or a small, high-efficiency gas storage system.
- For a medium-sized household select a high-efficiency gas or electric heat pump system. If you get enough sunshine, a solar water heater may also be a good option.
- If you get plenty of sunshine and have a large household, the best option might be a solar hot water system. However, a high-efficiency gas storage system or a solar-boosted electric heat pump may also be suitable.
DESIGN AND INSTALLATION
Heat loss in your hot water system accounts for as much as 60 percent of your hot water bill . Plan an efficient layout and for the optimum size system to keep long term operating costs down. Locate pipes and heaters close to areas of use and insulate pipes and tanks. Do not install a larger or smaller system than necessary. If suitable install timers and switches so the heating of water only occurs at times of day that it is needed.
HOT WATER TIPS