Traditional Tank Type Water Heaters
Traditional tank type water heaters heats water on a continual basis, whether you are using hot water or not. When you draw off hot water, cold water enters the tank to replace the hot water drawn out. When the thermostat senses the water temperature has dropped below the hold level, it initiates the heating element(s) in an electric water heater or the burner in a gas model.
Traditional tank type water heaters heats water on a continual basis, whether you are using hot water or not. Even if you don’t use hot water, the temperature in the tank will fall and so the water will be periodically reheated to bring it back up to the desired temperature. Because of this wasted energy, 911 Plumbing Services recommends switching to Tank-Less water heater system, where you can save energy, space and at the same time have hot water as needed.
How a Tank-Style Water Heater Works
Water heaters are not really all that mysterious. A water heater heats water on a continual basis, whether you are using hot water or not. When you draw off hot water, cold water enters the tank to replace the hot water drawn out. When the thermostat senses the water temperature has dropped below the hold level, it initiates the heating element(s) in an electric water heater or the burner in a gas model.
The cold water supply line connects to the water heater, typically on top of the appliance. Instead of dumping the water on top of the hot water in the tank, a dip tube carries the cold water down to the bottom of the tank. The outbound hot water line takes the water off the top of the tank. That way, when hot water is drawn out, it is at full temperature. Only after most of the hot water has been used do you start to get the hot and cold water mix.
When you open a hot water tap, the water pressure from the cold water supply line pushes the water out of the water heater and refills the tank with cold water. As cold water enters the tank, the thermostat(s) senses the lower temperature and triggers the heating mechanism.
Water heaters have a temperature and pressure relief valve to allow water to escape if the water pressure or temperature exceeds the limits of the tank. Tanks normally operate up to 150 psi. The T & P valve is designed to release water from the tank when the pressure exceeds 150 psi. The valve will also open if the water temperature reaches 210 degrees (F). The T & P valve should have pipes connected to safely carry away the water without flooding or exposing people or pets to scalding hot water.
Details Unique to an Electric Water Heater
On an electric heater the thermostats are in contact with the tank, and operate mechanically. The thermostat is like a switch. The switch is on by default, but when the temperature of the tank rises to a certain point, it expands and pushes a small metal rod against a dimpled piece of metal. That movement breaks the contact in the thermostat and stops current from flowing to the heating elements. The upper thermostat also functions as a reset switch and is sometimes referred to as the ECO (Energy Cut Off). Pressing the ECO restores to power to the water heater.
Full size electric water heaters typically have two heating elements, the upper and the lower. Most models are designed for the elements to operate independently, but in some models they may only operate in tandem. When the thermostats are closed current flows to the immersion heating elements inside the tank.
Details Unique to a Gas Water Heater
The thermostat on a gas heater is an integral part of the gas control valve and is immersed inside the tank. When the temperature drops, the thermostat signals the gas control valve to supply gas to the burner. However, before it allows gas to flow, the thermocouple must signal that the pilot light is lit, otherwise a dangerous gas leak would occur.
The thermocouple is situated in or near the pilot flame. The heat of the flame creates millivolt current which engages a magnet in the gas valve. The gas valve releases gas in a burner adjacent to the pilot flame and is ignited. If the pilot goes out, the current stops and the magnet disengages, preventing the gas valve from opening.
Gas water heaters must be vented to the outdoors. The combustion of natural gas results in toxic carbon monoxide. In the center of the tank is a flew to carry the gases away to the vent mounted on top of the tank. The vent is critical to your safety because it carries the carbon monoxide outside your home.
911 Plumbing Services highly trained plumbers will repair or replace your water heater professionally as needed.