Sunday, May 20, 2012

PTAC Energy Saving Tips

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 Design
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 statements.
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.
Heat PumpsLastly, 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 Powerful Tool
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 satisfaction.

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

For more information on helpful tips and PTAC energy solutions please contact Brad Schneider, National Sales Manager a RoomAire via email brads@roomaire.com or visit www.roomaire.com

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