Look at the top of a tank-type water heater. If there is a flue (round metal tubing) rising out of the center of the top of the water heater, then it is a gas water heater. Also, an older (pre-2002) gas water heater has an access panel to the burner at the bottom of the tank to light the pilot light, and all have a dial to adjust the temperature in the same area.
An electric water heater does not have a flue and, instead, has electric cable or conduit connected to it—typically at the top surface. The only exception to this way of determining what fuel source a water heater uses is a tankless (also called “on demand”) gas water heater installed at an exterior wall. It will have louvers around the top area to exhaust combustion gases instead of a flue, whereas an electric tankless water heater will not have the louvered vents—although we have never seen an on-demand electric water heater installed at an exposed exterior location.
Also, see our blog post What's that powdery crust on the pipe connections at the water heater?
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Here’s links to a collection of more blog posts about WATER HEATERS:
• What is a "tabletop" water heater?
• Are water heaters required to be raised off the floor?
• Can a Temperature and Pressure Relief (TPR or T&P) valve be mounted to discharge horizontally?
• Where are gas water heaters not allowed to be installed?
• Is the minimum size water heater inlet pipe 1/2" or 3/4" according to the building code?
• Can you use a light switch for a water heater disconnect?
• How can I tell if a water heater is HUD-approved for mobile/manufactured homes?
• Can you wire a 240-volt water heater with 120 volts?
• Is it alright to have a shut-off valve on both the hot and cold water pipes at a water heater?
• What is the minimum clearance to doors and windows for an outdoor tankless gas water heater?
• What is required clearance for access and working space in front of an electric water heater?
• Why is the water heater older than the house?
• Does a water heater need a shut-off valve?
• Why should a tankless water heater have an isolator/service valve kit installed?
• When was a gas water heater first required to be elevated 18 inches above a garage floor?
• Can the temperature and pressure relief (TPR) valve discharge pipe for a mobile/manufactured home water heater terminate under the home?
• What is the purpose of a thermostatic mixing valve above a water heater?
• Does a tankless gas water heater still work with no electricity during a power outage?
• Why do water heaters have a sacrificial anode?
• What is the difference between a manufactured/mobile home water heater and a regular water heater?
• Does a tankless water heater require a pressure relief valve?
• When is a water heater drain pan required?
• Why is there water in my water heater drain pan?
• What does it mean when a water heater Temperature/Pressure Relief (TPR) discharge pipe is "trapped"?
• Can I leave a gas water heater in place when remodeling a garage into a family room or bedroom?
• Where do I find the water heater in a mobile home?
• Does a tankless water heater in an attic require a drain pan?
• Does an electric water heater require a disconnect?
• Is a catch pan and drain piping required for a replacement water heater?
• What is the difference between a single element and dual element electric water heater?
• What is an FVIR water heater?
• What is a heat pump water heater?
• What is a dielectric union?
• What are the most common installation mistakes with water heater replacement?
• Why is my water heater making strange (rumbling, gurgling, knocking or banging) noises?
• What can I do to make my water heater last longer?
• How can I determine the age of a water heater if the serial number is missing or decoding it is impossible?
• How does a hydronic heating system work?
• What is the difference between a regular water heater and a direct vent water heater?
• What is the difference berween a regular water heater and a power vent water heater?
• What is backdrafting at a gas water heater?
• What does it mean when a gas appliance (water heater, furnace, or range) has been "red tagged"?
• What's the valve with the flip-up handle on the water heater for?
• Why is an older water heater an insurance problem?
Visit our WATER HEATERS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.
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