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
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:
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.