Water heaters are among the most ignored component, of a typical homes basic systems, – until they break. Since the average lifespan of a water heater is 15 years, when replacing one, it is worth spending some time familiarizing yourself with the different types of water heaters available to you.
Water heaters come in two basic forms: tanks and tank-less.
Conventional Tank Water Heaters
The most common type of water heaters are the cylindrical tanks that keep a supply of heated water in your home at all times. These tanks will run on natural gas, propane, electric (220 volts), and there are even models that have been designed to run on solar or geothermal power. Typical sizes range from 20 to 100 gallons. Compared to tankless heaters, conventional or storage water heaters have the advantage of using energy at a relatively slow rate, and then storing the heat for later use. The disadvantage is that over time, the water inside the tank will cool down and waste the stored heat. Additionally, there is a significant delay before hot water is available again once the supply has been exhausted. Larger tanks will tend to provide hot water with less temperature fluctuation at moderate flow rates.
A tankless water heater, or an instant water heater, only provides hot water as needed and saves energy. These high-power water heaters instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil. They are designed to run on natural gas or propane and heat water directly without the use of a tank. The absence of a tank saves energy as conventional water heaters have to reheat the water in the tank as it cools off, this is called standby loss. At Benjamin Franklin Plumbing® we offer our own brand of tank-less water heater, goHot TM that delivers an endless supply of hot water through a piece of equipment the size of a briefcase.
Solar Water Heaters
Increasingly, solar powered water heaters are being used in some areas with ample sunlight. Solar collectors are installed outside the home, on the roof, or nearby in a sunny location. Nearly all models consist of flat panels in which water circulates. Other types may use dish or trough mirrors to concentrate sunlight on a collector tube filled with water, brine or other heat transfer fluid. These models are indirect or closed-loop systems that do not allow potable water through the panels, but rather pump a heat transfer fluid (either water or a water/antifreeze mix) through the panels. After collecting heat in the panels, the heat transfer fluid flows through a heat exchanger, transferring its heat to the potable hot water.
A storage tank is used to collect the heated water. Circulation is caused by natural convection or by a small electric pump. At night, or when there is insufficient sunlight present, circulation through the panel can be stopped by closing a valve and/or stopping the circulating pump, to keep hot water in the storage tank from cooling.