The existing standards and test procedures for the three Heating Products are described below.

Residential Water Heaters

Energy consumed by residential water heaters accounts for 11% of the electricity and 24% of the natural gas consumed in the residential sector in the United States. However, residential hot water use and the associated energy consumption are not well characterized. Most analyses done to date use a single average daily value for hot water use, regardless of the number of people in the household, the type of appliances, or the climate in which the house is located. It is known from other studies that these and other factors influence the amount of hot water used and the amount of energy needed to generate that hot water.

NAECA's energy conservation standards for residential water heaters require that each gas, oil, and electric water heater manufactured on or after January 1, 1990, meet a minimum energy factor based on the water heater's rated storage volume in gallons. On January 17, 2001, the Department published a final rule in which it increased the mandatory minimum efficiency levels for gas and electric storage water heaters (except for tabletop models). The Department did not amend the energy conservation standards for oil storage water heaters. The Department also established separate product classes for tabletop water heaters, instantaneous gas-fired water heaters, and instantaneous electric water heaters, but left the existing EPCA levels in place for these types of equipment. The January 2001 final rule amended the DOE regulations to specify a minimum energy factor (EF) for each of the six product classes based on rated storage volume, as follows. These standards became effective on January 20, 2004.

• Gas-fired Storage-type EF: 0.67 - (0.0019 x Rated Storage Volume in gallons)
• Oil-fired Storage-type EF: 0.59 - (0.0019 x Rated Storage Volume in gallons)
• Electric Storage-type EF: 0.97 - (0.00132 x Rated Storage Volume in gallons)
• Tabletop EF: 0.93 - (0.00132 x Rated Storage Volume in gallons)
• Instantaneous Gas-fired EF: 0.62 - (0.0019 x Rated Storage Volume in gallons)
• Instantaneous Electric EF: 0.93 - (0.0013 x Rated Storage Volume in gallons.

In 1998, DOE revised its test procedure for residential water heaters, which included: (1) revisions to make the water heater test procedure applicable to electric and oil-fired instantaneous water heaters, (2) coverage for testing storage-type water heaters with rated storage capacities less than 20 gallons (76 liters), (3) revision of the first-hour rating for storage-type water heaters, (4) amendment to the current definition for heat-pump water heater, and (5) the addition of new definitions for heat-pump water heater storage tank, add-on heat-pump water heater, integral heat-pump water heater, and solar water heater. For more information, see DOE's residential water heaters website.

Direct Heating Equipment

All types of direct heating equipment have two characteristics in common: 1) heat is conveyed without ducts from the point of generation to the room that is being heated and 2) the flue products (products of combustion) are vented outside. Direct heating equipment comes in a wide variety of styles and models that can be categorized into four main groups:

• room heaters
• gravity wall furnaces
• fan wall furnaces
• floor furnaces.

each of these four main categories, heat is generated and conveyed much in the same way. Fuel gas is ignited at the burner and converted to heat by transferring the heat from the flue gases to a heat exchanger surface. This is accomplished without mixing the flue gases and the circulated heated room air.

Room heaters are free-standing and are installed directly within the space they are heating. They are not recessed in the wall or floor. All currently manufactured models of room heaters are gravity-vented (without fan-assisted combustion) and draw their combustion air from the room. Some room heaters are also equipped with high-temperature glass panels and radiating surfaces to increase radiant heat transfer.

Wall furnaces are either installed on the wall as a free-standing unit or recessed within the wall. All currently manufactured models of wall furnaces are gravity-vented (without fan-assisted combustion). Heated air can be furnished either by gravity or fan circulation. Gravity units operate in the same manner as gravity room heaters. Like room heaters, gravity units can be shipped with optional counterflow fans. Fan wall furnaces are equipped with factory-installed air circulation fans. The efficiencies of fan wall units are relatively high, since they are designed to take full advantage of the counterflow air circulation. Both gravity and fan wall furnaces are available in either conventional-vent or direct-vent models.

Floor furnaces are suspended from the floor of the heated space. They are typically installed within an unconditioned crawl space, such that they are directly exposed to the outside air. All currently manufactured models of floor furnaces are gravity-vented (without fan-assisted combustion) and draw their combustion air from the outside. In all models, heated air is provided without the assistance of an air circulation fan.

EPCA's energy conservation standards specify a minimum annual fuel utilization efficiency (AFUE) for sixteen product classes of direct heating equipment, as follows:

• Gas wall fan type (up to 42,000): 73 AFUE
• Gas wall fan type (over 42,000): 74 AFUE
• Gas wall gravity type (up to 10,000): 59 AFUE
• Gas wall gravity type (over 10,000 up to 12,000): 60 AFUE
• Gas wall gravity type (over 15,000 up to 19,000): 62 AFUE
• Gas wall gravity type (over 19,000 up to 27,000): 63 AFUE
• Gas wall gravity type (over 27,000 up to 46,000): 64 AFUE
• Gas wall gravity type (over 46,000): 65 AFUE
• Gas floor (up to 37,000): 56 AFUE
• Gas floor (over 37,000): 57 AFUE
• Gas room (up to 18,000): 57 AFUE
• Gas room (over 18,000 up to 20,000): 58 AFUE
• Gas room (over 20,000 up to 27,000): 63 AFUE
• Gas room (over 27,000 up to 46,000): 64 AFUE
• Gas room (over 46,000): 65 AFUE

These energy conservation standards for direct heating equipment became effective on January 1, 1990. The Department initially considered amending the energy conservation standards for direct heating equipment as part of an eight-product standards rulemaking. It issued a notice of proposed rulemaking (NOPR) on March 4, 1994, proposing to amend the energy conservation standards for direct heating equipment as well as other consumer products. The Interior and Related Agencies Appropriations for Fiscal Year 1996 included a moratorium on appliance standards rulemakings, which caused DOE to suspend action on the 1994 proposed standards. Currently, the EPCA efficiency levels for direct heating equipment and pool heaters remain in place. DOE published test procedures for direct heating equipment in 1997.

Pool Heaters

A pool heater is defined by NAECA as "an appliance designed for heating non-potable water contained at atmospheric pressure, including heating water in swimming pools, spas, hot tubs, and similar applications." This definition is limited to residential pools and spas by the general application of NAECA to consumer products only.

Pool heaters are used for residential swimming pools and spas. Spas are much smaller than swimming pools, but the temperatures are usually higher. To keep the warm-up time short, the heater for a spa is often as large, or almost as large, as a heater used for a swimming pool. In addition, 18% of spas use the same water and equipment as an adjacent swimming pool.

Water is heated as it passes through a pool heater. The pool heater does not store heated water. The heaters are installed on the water line that circulates pool water through the filter. This plumbing arrangement avoids the necessity for an additional pump for the heater. When the circulating pool water temperature is too low, a thermostat turns on the heater. After the pool water reaches the desired temperature, the heater is turned off.

EPCA requires gas pool heaters manufactured on or after January 1, 1990, to meet a thermal efficiency standard of no less than 78 percent. The Department initially considered amending the energy conservation standards for pool heaters as part of the eight-product standards rulemaking mentioned above. Currently, the EPCA efficiency levels for pool heaters remain in place. DOE published test procedures for pool heaters in 1997.

Analyses: Under contract to DOE, LBNL's EES Group is conducting analyses for all three products, including:

• Markups from manufacturer price to consumer price
• Energy use
• Energy prices
• Life-cycle cost and payback period analysis
• Shipments analysis
• National impact analysis (national energy savings and net present value)