Equipment Basics
Many
advancements have been made in the design of heating and cooling
equipment that make them more energy efficient, reliable, quieter and
provide more even temperatures. Following is a description of
key
available features and some basic terminology.
Gas Furnaces
AFUE
– The Annualized Fuel Utilization Efficiency is a standardized measure
of the heating efficiency of a gas furnace. It is expressed
as a
percentage. The higher the percentage, the more efficient the
furnace.
Energy
Efficiency - Gas furnaces burn natural gas or propane
(LP).
If your
furnace has a pilot light that burns all the time it is no better than
a 65% AFUE. If it has electronic ignition (no pilot light)
and a metal
flue it is 80% AFUE. If it has electronic ignition and a
plastic PVC
flue it is 90% AFUE or better.
A 90% AFUE furnace transfers 90%
of the heating value of the gas that is burned into your home for
heating. The other 10% is the heat that is lost up the
chimney.
Two
Stage Gas Valves - Traditional furnaces have one capacity,
full
blast.
They are single stage furnaces. We size furnaces to be able
to warm
your home to 70 degrees when it is 20 below outside. Since
most of the
year is much milder than this, it doesn’t take the furnace long to
reach the set-point on the thermostat in milder weather.
Two
Stage furnaces have two heating capacities, first stage and second
stage. Second stage is full blast; first stage is about 60%
of that.
The furnace initially fires in first stage and only goes to second if
it can’t satisfy the thermostat. This provides longer run
times at a
lower firing rate. This in turn provides for more even
temperatures
and more efficient operation.
Fully Modulating Gas Valves -
The new Lennox SLP98 furnace features fully modulating
heating. This
will vary the heating output in 1% increments from 40% of its capacity
to 100% based on the temperatures outside. This does a better
job than
a two-stage unit of providing even longer run times at a lower firing
rate. Again, this provides for more even temperatures and
more
efficient operation.
Variable Speed Blowers - Traditionally
furnaces have included multispeed blowers. One speed is set
by the
technician for heating operation, usually medium and high is typically
set for cooling operation.
Variable speed blowers use advanced
motors that work in conjunction with a control board to vary the
speed. You will notice three differences in their operation.
1. When the furnace starts-up they are
much quieter as they ramp up the speed gradually.
2.
They use less electricity to operate and are ideal for improving indoor
air quality by running the fan continuously.
3.
The Lennox variable speed blowers are programmed to deliver specific
amounts of air movement. These motors will work harder over
time as
the filter loads-up so they continue to deliver the air required.
Finally,
they are a great choice for zoning applications. When teamed
with a
Lennox Harmony zone control, the variable speed blower will deliver the
proper amount of air depending on which zone or zones are calling.
Silicon
Nitrate Igniters - A bugaboo of many early high efficiency
furnaces was
that the igniter would fail every year or two. Lennox began
using
silicon nitrate igniters back in 2000 with tremendous
success. These
igniters just haven’t failed.
Combustion Air – Combustion air is
the air used by the furnace to burn the gas, it will go out the
flue.
Adequate combustion air is required for proper venting of the gas to
the outdoors.
Return Air – This is the room air
returned by the
ductwork to the furnace to be heated or cooled so it can be
redistributed out the supply ducts into the home.
Inadequately sized
return air is a common problem, it hurts cooling performance and can
shorten the life of a furnace.
Heat Exchanger – This is the
chamber where the fuel is burned and the heat is transferred to the
air. A cracked heat exchanger can allow carbon monoxide to
enter the
home, which is a serious health risk and can cause death.
Electric
Furnaces
Electric
furnaces do not have a flue and transfer 100% of the heating value into
the home. Although they are 100% efficient, the cost of the
energy is
greater than natural gas, but less than propane. See our
Heating Cost
Comparison to compare different fuels and heating equipment.
Air
Conditioning
SEER
– Seasonal Energy Efficiency Ratio is a standardized measure of the
cooling efficiency of an air conditioner. The higher the SEER
number
the more efficiently the air conditioner will cool your home.
Energy
Efficiency - Several years ago the government implemented a
higher
minimum efficiency of 13 SEER for manufacturers. While
systems are
available that achieve over 20 SEER, our cooling season is so short
that these systems won’t cost justify themselves on energy saving alone.
Heat Pumps
Air
source heat pumps work just like air conditioners with one big
exception; they can cool and heat the home. To heat the home
they run
in reverse of air conditioning and transfer heat from the air outside
into the home. In our region, air source heat pumps typically
can heat
the home until the outdoor temperature falls below freezing.
Traditionally, air source heat pumps have been teamed with electric
heating elements to kick in more heat as needed. The heat
pump and
electric heat elements will run at the same time in cold temperatures.
HSPF
– The Heating Seasonal Performance Factor is a standardized measure of
the heating efficiency of a heat pump. The higher the HSPF
number the
more efficiently the heat pump will heat your home.
Hybrid
Heating Systems
Hybrid
heating systems team a heat pump, which operates on electricity with a
gas furnace. By using the best of both, operating costs are
reduced.
New thermostats have been developed that incorporate an outdoor
temperature sensor and will automatically switch between the heat pump
and the gas furnace. The heat pump and gas furnace will not
both heat
at the same time, it’s one or the other.
Air
Conditioning & Heat Pumps
Environmentally
Friendly Refrigerants - Beginning in 2010 all residential air
conditioners and heat pumps manufactured use environmentally friendly
refrigerant. We have been installing these models for several
years.
This is good for the future of our environment, but it poses challenges
for repairing old systems.
The old refrigerant R22 cannot be
mixed with the new refrigerant. The new refrigerant operates
at much
higher pressures and uses different metering devices for the
refrigerant. So when old R22 systems fail, most of the time
it will
make the most sense to replace the indoor evaporator, metering devise
and the outdoor condenser.
Hail Protection - In our country,
hail happens. Louvered doors that wrap around the unit will
protect
the delicate copper fins from damage.
Noise Suppression - If
your outdoor condenser sits on your back patio or outside your bedroom
window you might be interested in units that feature noise reduction.
•
Compressors are made quieter by wrapping them in blankets or better yet
enclosing them in insulated compartments.
• Air noise is reduced with “stealth” fan
blades and aerodynamic grillwork on top of the unit.
Two
Stage Compressors - Similar to two stage gas valves, these
compressors
will run at two different capacities to provide longer run times, more
even temperatures and more efficient operation.
|
|
