Natural Gas Water Heaters - Product Overview
Natural gas water heaters offer two distinct choices in style (storage tank and tankless) and three choices for venting (conventional, direct vent, power vent). Additionally, you may be able to combine your water heating with home heating.
Storage Tank Water Heaters
A storage tank water heater is the most common type of water heater in Canada. It consists of a gas burner and a steel cylinder storage tank with capacities ranging from 30 to 100 gallons (113 to 378 Litres).
How storage tank water heaters work:
Cold water is drawn into the bottom of the tank where it is quickly heated by a gas burner. Hot water rises to the top of the tank. As the hot water is used, it is replaced at the bottom with cold water.
The tank thermostat controls the water temperature in the tank both when it is leaving the tank to your taps and when it is on “stand by”, waiting in the tank to be used. The more efficient a water heater is the less heat is lost when the unit is on “stand by”.
Tankless Water Heater (also called On-Demand or Instantaneous
A tankless water heater has no tank and stores no hot water. When hot water is needed, the water is heated on demand. When the hot water tap is turned on it triggers a flow switch that activates the burner which heats the cold water entering the tankless water heater. The water is rapidly heated to the desired temperature. This continues for as long as the hot water tap remains in the ‘on’ position. When the tap is turned ‘off’ the system shuts down resulting in substantial energy savings over units that have hot water stored in the tank on ‘stand-by’.
A tankless water heater can save space and offer flexibility being able to be installed close to the point of use.
Combination Water and Space Heating Systems
While many people have one appliance for space heating and another for water heating, you can have one natural gas appliance that heats both your water and provides heat to your home. This is called a combination system. These systems have one heat source that is shared between conventional pieces of equipment such as a tank water heater and an air handler to accomplish dual heating purposes.
Water Heating Venting 101
A natural gas water heater requires air for combustion and igniting. The air required can either come from outside or from the home itself. There are three types of venting for natural gas water heaters, each offering benefits depending on your installation limitations and requirements:
A direct vent does not require a chimney, but vents through an outside wall and also brings air for combustion in from the outside. Some types of direct vent water heaters must be located close to an outside wall, while others may be located further away. Replacing
This style of venting is most often convenient when:
Replacing an electric water heater and a chimney is not available
You do not have an electrical source close to the water heater to power the vent
FACT - Neither a direct vented nor a conventional vent water heater requires electricity. If there is a power outage you will still have hot water.
A power vent water heater does not need a chimney, but uses an electrically powered fan to move combustion products outside.
This style of venting is used when:
Replacing an electric water heater and you do not have ready access to a chimney
You have access to a dedicated electrical receptacle within six feet of the unit
A conventional vent is required on most standard natural gas water heaters. Conventional vents can be either type B, double-wall metal vents or a tile-lined brick chimney. The conventional vent can be shared with most standard mid-efficiency furnaces or boilers. This type of vent draws the air it needs from inside your home. In airtight homes it is important that there is an adequate air supply from outside.