Master Plumbers Council of the City of New York, Inc. e Voice of the Licensed Master Plumber
6
KEY POINTS
• e increasing popularity of gas for home heating has
led to improved e ciencies.
• Energy factors of natural gas water heaters range
from 0.67 (storage) to 0.96 (tankless).
• ENERGY STAR Most E cient 2014 furnaces have
annual fuel utilization e ciencies of 97 to 98 percent.
M
ore than half of all US homes have natural gas
service and residential consumption is expect-
ed to reach 7.4 quads by 2020, according to the
U.S. Department of Energy. Part of this growth is being
driven by the increasing popularity of gas home heating.
Gas technologies, whether for space or water heating,
continue to improve in e ciency and features, providing
builders with a variety of options from which to choose.
COMBINATION SPACE AND WATER HEATERS
ese systems combine high-e ciency, storage water
heaters or boilers with hydronic air handlers. When
space heating is needed, the thermostat activates a small
pump, which circulates hot water (from the water heater)
through an air handler coil. en, a fan blows air through
these coils and into the duct system. Advantages include
less maintenance and space. Installation requires a
contractor who has the training and experience to handle
the integrated plumbing and HVAC installation.
CONDENSING STORAGE WATER HEATERS
Gas condensing water heaters recover heat from
combustion gases through a submerged helical coil
or multiple pass ba ed ues. is increases thermal
e ciencies as much as 96 percent. Products typically
have ring rates ranging from 76,000 to 120,000 Btu/
hour with power or direct venting. While these systems
cost more upfront, they reduce water heating bills nearly
30 percent. Su cient space is required to accommodate
a condensate drain and special venting. National Grid
now o ers incentives of up to $200 for NYC & LI
customers.
CONDENSING TANKLESS WATER HEATERS
Tankless product manufacturers introduced condensing
products with energy factors (EF) of up to 0.96 starting
in 2009. Like condensing storage types, additional
heat is extracted from the exhaust gases, reducing the
temperature to around 100°F. At this temperature, a less
expensive venting material, like PVC, can be used.
One design features ultra-low NOx condensing
technology, which provides a 0.95 E F. e primary heat
exchanger is constructed of erosion-resistant copper. e
secondary heat exchanger is made of stainless steel to
protect against corrosion. Units with maximum ow rates
of up to 10 gallons per minute are available.
ENERGY STAR STORAGE WATER HEATERS
E ciency levels have increased from 0.62 to 0.67
EF; some power-vented units are higher at 0.7 E F.
Several strategies are used: pressurized combustion or
atmospheric combustion with motorized vent damper or
power or direct vents with plastic pipe venting. Common
features include electronic ignition and advanced
electronic control/diagnostics. National Grid now o ers
incentives of up to $100 for NYC customers.
E ciency is increased by incorporating better insulation,
heat traps, and more e cient burners. Water heating bills
are reduced by about 7 percent; no special installation or
maintenance is required.
HYBRID (TANK/TANKLESS) WATER HEATERS
Traditional storage water heaters and tankless water
heaters are integrated with matched hydronic air
handlers. ese water heaters address the shortcomings
of both tank (center ue losses) and tankless (cold water
on low/intermittent draws) systems. E ciency factors
range from 0.70 to 0.80.
Firing rates and storage-only volumes typically range
from under 100,000 to up to 200,000 Btu/hour and
4 to 40 gallons, respectively. One design features a
patented heat transfer process that utilizes a secondary
heat exchanger to capture the heated ue gas from the
tankless unit and route it through a bu er tank to extract
additional heat.
MOST EFFICIENT ENERGY STAR FURNACES
Furnaces with the ENERGY STAR Most E cient 2014
designation have annual fuel utilization e ciencies
(AFUEs) of 97 to 98 percent, resulting in a 20 to 23
ADVANCED GAS HEATING TECHNOLOGIES LEAD TO
ENERGY SAVINGS