Although heating water falls under the H in HVAC, you are not likely to find water heaters there. By the way, if you’re looking for information on hot water heaters, I have the e-mail addresses of about 100 grizzled veterans who would love to bestow upon you the difference between hot water heaters and water heaters. Although nearly every dwelling in America has a water heater, they tend to be overlooked in our profession — from textbooks right to the technician who walks past the water heater to tune up the furnace.
By obtaining a good working knowledge of water heaters, you are preparing yourself to fulfill a customer need and at the same time create opportunities for your company.
Today we will examine the basics of gas and electric water heaters. The following are components common to both gas and electric water heaters.
Dip tubes — Cold water enters the tank and travels down the dip tube to the bottom to be heated. As the water heats up, it becomes less dense and rises towards the top of the tank for discharge. Most dip tubes are plastic, and some are curved near the bottom. Curved tubes swirl the water, preventing a buildup of sediment on the bottom.
Anodes — Water heaters consist of a steel tank lined by glass. Over time, the glass dissolves or wears away and exposes the steel. To prevent the steel from rusting, an anode is inserted into the top of the tank. Made from an alloy of aluminum, zinc, or magnesium surrounding a steel wire, the alloy dissolves by way of an electrochemical reaction. As long as alloy remains on the rod, the steel tank will not rust.
Temperature and pressure relief valve — A safety valve that senses both temperature and pressure. If temperature exceeds 210 degrees F, the valve opens and releases hot water, allowing cold water to enter and prevent overheating. If pressure exceeds 150 pounds per square inch, the valve opens and relieves excess pressure. This valve is sometimes referred to as a pop-off valve.
Electric water heaters — Heating elements are inserted at the high and low points of the tank (some use only one element). A separate thermostat located on the outside of the tank controls each element. High limit controls keep water temperature from exceeding a predetermined limit. Elements may be each wired into a separate high limit control or wired into one limit.
We have touched on some very basic points about water heaters here today. For additional information on maintenance, troubleshooting, application, and general knowledge, visit www.waterheaterrescue.com. Another excellent resource is The Water Heater Book, by Larry and Suzanne Weingarten. This information-packed book can be purchased at www.heatinghelp.com.
Rothacker is a member of the National Comfort Institute’s Advisory Board and a National Comfort Team Founding Member. For questions or comments on the Tech Basics, contact Rothacker at email@example.com.
Publication date: 03/31/2003