SAVING ENERGY WITH PTACS
Tips from Amana on making the most of your PTAC units.
by Tom Guffey
PTACs represent 50 to 70 percent of the energy usage
in a typical limited-service hotel or motel. This energy usage
represents a huge opportunity to take control of and reduce operating
expenses. Here are some ways to take control of this major component of
energy consumption at your properties:
Energy Efficiency Rating and
PTACs with the highest Energy Efficiency Rating (EER) are not always the
best option. In general, a PTAC with a higher EER will consume less
energy during cooling operations. But, how do the PTACs achieve these
higher EERs and how are they rated? As coils become
“tighter” (deeper fin pack and higher fins per inch), it
becomes easier for dirt to get trapped in the coil, resulting in loss of
airflow through the coil and a drastic drop in capacity and efficiency.
This means that to keep the PTAC operating at higher efficiencies, both
the evaporator and the condenser coils will need to be cleaned more
often to maintain the EER rating and capacity of the PTAC.
You should also check to see who is rating the
unit’s capacity and EER. Most PTAC manufacturers are members of
American Refrigerant Institute (ARI), which oversees manufacturer
efficiency ratings. ARI also randomly audits units and independently
tests them to make sure that the units perform as advertised by the
manufacturer. If a manufacturer is not an ARI member, then you are on
your own and ARI cannot verify the accuracy of the manufacturer’s
Size of PTAC
Ensure that your PTACs are properly sized. For example, oversized PTACs
will not dehumidify well. Also, in general, PTACs with higher
British Thermal Units per Hour (BTUH) capacities are less efficient than
units with lower capacity. Larger units use compressors and fan motors
that use more watts of electricity to produce the cooling BTUH. The same
is also true for an electric heater. Larger heaters will spike your
Kilowatt (KW) demand to the power company and could result in a much
higher demand portion on your power bill.
Lastly, when buying PTACs, consider purchasing heat pumps. Heat
pumps work very well in 95 percent of the United States and will save
you money when heating as compared to electric heat units. Reverse cycle
heat pump operation only consumes about one-third the watts as an
electric heater. Additionally, some power companies offer rebates
for purchasing heat pumps.
Operate PTACs Efficiently - Information is a
Regardless of EER, you can minimize energy consumption by efficiently
operating the unit. With the incorporation of microprocessors into the
PTAC control, today’s models have many capabilities that were not
possible just a few years ago. These capabilities include:
• On-Board Energy Management System (EMS)
Functions - Many manufacturers offer an array of different displays
and software programs that can save you money. Digital displays
allow the guest to view the temperature of the room, thus saving money
because the guest will not over-cool or over-heat the room as much.
Temperature Limiting enables the owner to set a maximum cooling
limit (the lowest temperature that the guest can cool the room) and a
minimum-heating limit (the maximum allowable temperature that the guest
is allowed to heat the room).
• In-Room EMS Functionality - Several
PTAC manufacturers as well as some EMS companies offer occupancy
controls for PTACs, which allow you to set the room temperature back
from what the guest had set. This can save a significant amount of
energy from being wasted. There are various types of occupancy
connectivity: wired devices (both line-voltage and low voltage), IR
wireless and RF wireless options. Each has advantages and disadvantages,
such as final installed cost, system operation and savings of energy
dollars for you.
You certainly want a system that works well and does
not interfere with guest comfort, but the operation and maintenance of
the system is also important. If you cannot keep the unit running in the
field without costly support, then it will not get used.
• Property EMS - Some EMS systems can
also connect directly to your property management system (PMS) software,
so you can integrate the information concerning room occupancy into how
you operate your setbacks. When the room is vacant, you can achieve
deeper setbacks, saving additional energy dollars from being wasted.
Several manufacturers also offer software programs that will increase
room dehumidification when the room is vacant.
A few systems also enable you to connect and
communicate with your power provider, allowing you the interoperability
of Demand Reduction and Capacity Curtailment programs. Most power
companies are looking for commercial customers that can partner with
them to shed consumption in the afternoons when most hotel rooms are
vacant. You can even have the electric meter read via the Internet and
verify that your power bill is 100 percent accurate. You can also
analyze your rate structure and negotiate with your power provider to
make sure you have the best rate for your consumption patterns.
• Enterprise Integration EMS - Once
you have access to your energy data and single-room connectivity, you
can then use an EMS throughout your entire network of properties. This
allows for even more potential energy savings through Bill and Demand
Aggregation from your power company. This level of energy management
connectivity sophistication can save a lot of energy dollars.
Maintain PTAC Efficiency
You can buy efficient PTACs and you can operate them efficiently;
however, if you do not monitor the operation and regularly clean and
maintain the PTACs, you still waste a lot of energy dollars. Here are a
few tips that can save you money.
• Clean PTAC Filters Regularly –
Clean the filters at least once a month or more if the PTAC operates in
a dusty environment. A dirty filter reduces the airflow through the
evaporator coil, which causes the BTUH capacity to drop and the wattage
usage to rise, wasting energy and money. Dirty filters also put guest
comfort and satisfaction at risk because it makes it harder for the
guest to get his or her desired temperature.
• Dirty Evaporator Coils - A dirty
room coil has the same consequences as a dirty filter. Unfortunately, it
is not as noticeable and harder to clean properly.
• Dirty Condenser Coils – A
clean outside coil, the condenser coil, is just as important or more
important in order to maintain proper airflow through the coil. The
outside coil does not have a filter to help keep it clean like the room
coil does. This causes the condenser to easily become impacted with
dirt, bugs and debris. Condenser coils should be cleaned at least once a
year and it would be best if they were checked twice a year.
Dirty coils waste energy dollars and overheat the
compressor, thus shortening the life of the system.
Some PTAC systems have the option of monitoring the
operational properties and will notify you when the unit needs cleaning
and maintenance or if some operational parameter is out of the norm.
• Remove Air Flow Restrictions and
Blockages – There are several types of restrictions and
blockages that can waste a lot of energy:
1. Exterior Air Restrictions – Make sure
that the entire exterior grille is not being blocked by vegetation. If
this happens, the discharge air from the unit is, in all likelihood,
hitting the plant and getting drawn back into the unit. The closest
plant leaf should be at least 3 feet away from the exterior PTAC grille
to allow for proper operation. The same is true for walls or awnings or
anything else that could cause the discharge air to be drawn back into
the unit. You should contact your PTAC manufacturer for details on
clearance measurements to ensure that energy is not being wasted.
2. Improper Exterior Grilles - Each PTAC manufacturer
has similar but very different condenser discharge patterns. You should
always check with the manufacturer to make sure that the grille you are
using does not cause discharge air recirculation. The best grille is one
purchased from the manufacturer of the PTAC because it has been designed
to maximize heat exchange and minimize energy consumption. If you change
out PTAC units, you should verify that the existing grille works
properly with the new PTAC units that you are purchasing.
3. PTAC Air Leakage - The PTAC sleeve should be
caulked on both the outside and inside of the room to prevent air
leakage around the unit. Air that you have just paid to be conditioned
can leak away and raise your energy bills. Also check and make sure that
the PTAC is securely fastened with four or ideally six screws to the
wall sleeve. This allows for the gasketing between the unit and the
sleeve to seal properly and minimize air infiltration. Also,
unless you have a need for outside air, you should keep the vent door
closed and if possible, securely and permanently shut with a screw. Any
air leakage wastes energy and allows exterior sounds to come through and
around the PTAC into the room. The added benefit of reducing air leakage
is a guest that is not bothered by exterior sounds.
4. Interior Air Restrictions - Furniture that is too
close to the PTAC can cause air restrictions or air recirculation with
either the intake air trying to come into the unit or discharge air
trying to exit the unit. Both waste energy. The unit needs unrestricted
air movement to operate at peak energy-saving performance. If discharge
air is blocked, it will fall to the floor and recirculate back into the
unit, wasting energy and causing the guest to set the unit to a lower
temperature in an effort to cool the guestroom. The same is true for
blowing draperies. If the discharge air from the PTAC is blowing up the
drapes, you are wasting massive amounts of energy. The air gets pulled
back into the unit and cannot get into the room to satisfy the
guest’s cooling or heating needs. The guest compensates by setting
the thermostat even lower and the unit basically runs 100 percent of the
time and the room may never be conditioned to the guest’s
• Too Much Ventilation - Some properties use the PTAC for
what is called “make-up air,” running the ventilation fans
24-hours-a-day and seven-days-a-week. This brings in unconditioned air
and forces the PTAC to run much longer to condition the air and remove
the humidity. In many instances, the PTAC is not able to remove the
humidity that gets introduced into the room, and instead of helping, it
actually causes potential mold and mildew issues. This ventilation air
also uses more energy in trying to condition not only the air that is in
the room, but also the outside air that is now entering.
All of the above suggestions can save massive amounts
of energy and dramatically reduce your power bill. You will also get the
added benefit of a PTAC that will operate at peak efficiencies for a
longer period of time and be less prone to premature failure.
Tom Guffey is the vice
president of the Amana PTAC Division. For more information, please
call 931-438-3521, via e-mail at email@example.com or visit www.amana-ptac.com.