There are two categories of gas hot water systems for commercial hot water installations and domestic installations. They are gas continuous flow/instantaneous (instant) and gas storage systems. Below is an explanation of how a continuous flow gas hot water heater works. You can also learn about How gas storage systems work.
1. All hot taps are closed. There is no flow. The 3 litres of cold water in the heat exchanger is stone cold. The gas burner is off.
2. A hot tap is turned on and cold water begins to flow through the heat exchanger. The gas valve opens and the gas is ignited. The gas flame begins heating the heat exchanger. 300ml of the original cold water in the heat exchanger comes through the hot water outlet of the system. This water is not hot enough for use.
3. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger is moving through the system and is taking on heat. Although not as cold, another 300ml of the original cold water in the heat exchanger comes through the hot water outlet of the system. The water at the outlet of the system is still not hot enough for use.
4. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger is moving through the system and is taking on more heat. Although slightly warmer, another 300ml of the original water in the heat exchanger comes through the hot water outlet of the system. The water at the outlet of the system is still not hot enough for use.
5. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger is moving through the system and is taking on more heat. Although slightly warmer again, another 300ml of the original water in the heat exchanger comes through the hot water outlet of the system. The water at the outlet of the system is still not hot enough for use.
6. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger is moving through the system. Now much warmer, another 300ml of the original water in the heat exchanger comes through the hot water outlet of the system. The water at the outlet of the system is still not hot enough for use.
7. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger is moving through the system. The water is about 45 degrees and another 300ml of the original water in the heat exchanger comes through the hot water outlet of the system. Although very warm, the water at the outlet of the system is still not hot enough for use.
8. A hot tap is on and cold water continues to flow into the heat exchanger. The cold water originally in the heat exchanger has completely moved through the system. The water is about 50 degrees and another 300ml of the original water in the heat exchanger was lost through the hot water outlet of the system. The water at the outlet of the system is now hot enough for use. Now the hot water must travel from the outlet of the system to the tap. The hot tap is typically 2 -20m from the hot water system.
ADVANTAGES AND DISADVANTAGES of gas continuous Flow/Instant/instantaneous hot water systems
As a plumber I am often asked if I would choose a gas storage system or a continuous flow hot water system. These are the Pros and cons of the gas continuous flow.PROS
- They produce an unlimited amount of hot water.
- Take up minimal space.
- They can be installed in roof spaces and under floors.
- Are available in indoor and outdoor models.
- Are available in a range of sizes for different uses.
- Models are available for commercial hot water installations.
- Suitable for inconsistent and extremely high hot water demand such as canteens, hotels and sporting fields.
- Rheem and Rinnai make very reliable models.
- Better for the environment than electric hot water systems.
- Are not very well insulated so the water inside the system looses heat very quickly.
- Not very water efficient. Owners have to wait longer for hot water than they would for hot water from a gas storage system.
- Most require a 240 volt power supply for the electronics.
- They require 80% more gas than a gas storage system when heating- this means larger gas pipes. Sometime they require a full upgrade to the gas meter and the gas piping from the meter.
- They are more computer than plumbing. Therefore, they are not easy to repair and can be expensive to repair.
- Some brands are not very reliable.
- Inconsistent hot water temperature.
- They are restricted to minimum and maximum flow rates.
- Most will only lift the temperature 25 -35°C above the incoming water temperature.
- You will not have hot water during blackouts.
- Because of the cost of water in Canberra, they are more expensive to run than high efficiency gas storage systems.
- They are more expensive to install.
- Because of the electricity they use and the energy involved in treating potable water, it is likely they are not as beneficial to the environment as people expect.
We hope this review of hot water systems and the pros & cons of instant/continuous flow systems helps you to compare them with gas storage hot water heaters.
If you would like to know more or get help with your Continuous flow gas hot water in Canberra or Queanbeyan you can contact us on 61619417
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