Replacing a gas furnace or hot water heater could be an opportunity to simplify your home's appliances while lowering your energy costs. Homeowners who
are dreading the prospect of replacing an aging furnace or water heater may want to investigate a new integrated system developed by Rheem, a leader in U.S. water heating and HVAC (heating, ventilation,
and air conditioning) technology.
This innovative solution heats both the home and the hot water supply with just one heat source – the company's tankless water heater – while
using just one vent and one gas supply line. It would replace your conventional warm air furnace with an air handler (blower) that would house a
hydronic water-to-air heat exchanger as well as accommodate a cooling unit from your central air conditioner if you have one. The company asserts that
its integrated system is the first one that incorporates heating, air conditioning, water heating, and air handling components all designed by the same
manufacturer and all designed to work together.
If you're not familiar with tankless water heating systems, they are known for saving on energy by eliminating the between-use activation of a
conventional storage tank's burner to compensate for heat loss. Instead, a tankless water heater is activated when a hot tap is opened, and a computer
regulates the system's operation so the temperature of the water leaving the unit is controlled within two degrees of a target temperature. It is a
rectangular appliance that is mounted on a wall with a (cold) supply water line input and a heated water line output. Rheem explains how it works on the company web site. One additional
advantage to tankless systems is that just-in-time water heating means household members can use an endless amount of hot water in multiple showers and
in the kitchen or laundry. The number of bathrooms and other hot water appliances comprise the home's "domestic demand," and it is one key factor that
determines the output size of the system that would be installed.
With respect to the new integrated home heating system innovation, the tankless water heater essentially serves as an "engine" for the system,
says Tim Shellenberger, vice president of engineering for Rheem and overseer of the company's air conditioning and tankless hot water technologies. He
points out that in about 50 percent of homes, gas hot water tanks are already in close proximity to the warm air furnaces, as they often use the same
vent access to the outdoors.
To use a tankless water heater for home heating, a hot water line would run to the air handler, which Mr. Shellenberger points out has about the
same footprint as a warm air furnace. The heated water would circulate through a configuration of pipes that would create an exchange of heat from the
water to the air that would then be blown into the home's ductwork. When the water would circulate back to the tankless heater, it would be cooler, and
the computerized controls for the system would enable the heater to use just enough energy to raise the water temperature to the target output
temperature. An added benefit to the water-to-air exchange, according to Mr. Shellenberger, is that the warmed air would not be heated to the high
temperatures typically reached by conventional furnaces, so the air in the home would not be as dry.
While the installation of this combination system would reduce two gas vents to one, it may require an upsizing of the natural gas line. Also, the
electrical power needed for the air handler is comparable to a warm air furnace, and since the power needed to operate the tankless heater's controls
is low amperage, drawing about 75 watts (about the power needed for a light bulb), it could most likely use the same circuit as the air handler.
In practice, the domestic load on a tankless system (showers, etc.) is greater that the need for hot water for home heating, according to Mr.
Shellenberger. Moreover, the need for hot water to run to the air handler never overrides the domestic demand. In other words, if all of a home's
showers were in use and the hot water supply was at its maximum output, the tankless water heater would automatically maintain the hot water supply to
those bathroom and kitchen taps rather than supply heated water to the home heating air handler.
Homeowners typically rely on their plumbers or HVAC professionals to determine the correct size of the home heating or water heating appliance to
install, and this would still be true with the new combo system. However, Rheem lets consumers access the same proprietary EZ Spec software on its web site that is
used by the professionals installing the systems. There are three sizes of tankless water heaters, with the largest accommodating a home with three
full bathrooms. In settings in which more capacity is required, including commercial buildings, multiple tankless water heaters can be installed to
accommodate a high demand.
In an age when homeowners are looking to reduce energy bills as well as take advantage of the Energy Star federal tax credits that are in effect
until the end of 2010 (at least), the new Energy Star-qualified Rheem combination system components may be an innovation that is introduced at an
opportune time. Don't forget, the required energy guides make it easy to compare operating costs of home heating and water heating appliances.
