It doesn’t take long for a hotel PTAC to ruin itself. Take it from Douglas Mackemer, national director of parts, supplies and specialized equipment for HVAC and PTAC distributor Carrier Enterprise, who has seen equipment get so clogged up in less than a year’s use that it voided the machine's warranty.
And where did the hotel operators go so wrong? The unsexy and sometimes painful answer is: routine maintenance. According to Mackemer, pouring a little water in PTAC drain cans and cleaning filters (and letting them dry) on a regular basis can stave off extensive cleaning procedures and prolong, even save, the life of some equipment.
“Basic maintenance is critical with any system,” Mackemer said. “It is the same level that would be performed on an automobile to change its oil. You will always shorten the life of machinery by not working on it.”
Don Wojcik, national manager of LG’s PTAC division, suggests a monthly, quarterly and annual cleaning schedule so hotels can be sure their devices will stay running as long as possible. Wojcik said that modern PTACs, while capable of greater energy savings and effectiveness, need to be cleaned more diligently because of the closer grouping of fins on their heat-transferring interior coils. These fins, which lie on copper tubing, are found in groups of 13-14, whereas 15 years ago there may have only been six or seven to a group. Because these are responsible for moving heat from one place to another, they must be kept clean.
➔ “Basic maintenance is critical with any system.”
Douglas Mackemer, national director of parts, supplies and specialized equipment, Carrier Enterprise
“Monthly, housekeeping should rinse air filters and wipe down unit covers,” Wojcik said. “This keeps dust and dirt out as a first line of defense.” On a quarterly basis, Wojcik said to clean the blower wheel and vacuum the PTAC’s interior evaporator coil.
But Wojcik added that annual deep cleaning, where PTACs are removed from their wall sleeves and a professional washes the interior and exterior, should also take place.
This deep cleaning is imperative due to the strain dirty coils place on the refrigerants used in the machines. PTACs found in rooms six to 10 stories high or higher could malfunction if their coils are not properly cleaned, as unclean coils work harder and add pressure to internally stored refrigerant.
The ebb and flow of equipment replacements
Mitsubishi Electric Cooling & Heating is installing a variable refrigerant flow system into hotel properties that allows one outdoor rooftop unit to manage the cooling of up to 50 rooms, all through the use of new or existing ductwork or piping. Kevin Miskewicz, senior manager, commercial marketing, with Mitsubishi, said the system allows for simultaneous cooling and heating independent of room configurations by redirecting refrigerant.
“By taking rejected heat and re-circulating it, there is an efficiency gain,” Miskewicz said. “No one is messing with the individual units.”
Systems like this are designed with new builds and renovations in mind, but can also be installed in existing properties through added piping. These systems are also attractive due to their low maintenance, which can be contrasted against the maintenance required in many modern PTACs.
According to Don Wojcik, national manager of LG’s PTAC division, hotels often wait for their existing PTAC units to burn out before replacing them. There is good news for hotels that have been holding on to their 15-year-old antique air conditioners: Wall sleeves have remained a standardized size, meaning the only thing a hotel will be buying is the machine itself.
“Typically, once a wall sleeve is installed, most units fit into the 16-by-42-inch opening,” Wojcik said. “The only time hotels will replace the wall sleeve is in the event that it becomes damaged, much like the PTAC.”
The process behind choosing the right PTAC
Some hotels have been holding on to their outdated PTAC equipment for some time and may be surprised with what is now on the market. In terms of modern advances, Douglas Mackemer, national director of parts, supplies and specialized equipment for Carrier Enterprise, said the biggest advances have been made in energy savings and sound levels.
“Accessories, such as insulated sleeves, can drop equipment sound even lower than the machine on its own, and also stop the transfer of outside noise,” Mackemer said, adding that the construction of PTAC sleeves has also improved.
“We’ve made the covers [for our machines] a little sleeker, more attractive, but the new units are much quieter and more efficient,” said Don Wojcik, national manager of LG’s PTAC division.
The sound levels of modern PTACs are in the low 40-decibel range, which can positively impact the guest comfort level of the room. “If you check guest complaints across the industry, the number one or two by far is a noisy air conditioner,” Wojcik said.
But a sophisticated machine can still be a detriment if used improperly, as many PTACs are. Equipment must be chosen based on the size of the room, and many hotels are guilty of incorrectly “sizing” machines with rooms. According to Wojcik, 30 cubic feet per minute per square feet of floor space is the right measurement, but if it’s impossible to ascertain the correct size, he recommends under-sizing slightly. “Ideally you want to right-size, but err on under-sizing to help de-humidify the rooms,” Wojcik said.
Mackemer said the reason for this is that a PTAC that is too strong for a room will begin a process called short cycling, wherein it never allows the room to dry out and creates a damp atmosphere conducive to mold or mildew growth. He conceded that sizing equipment for a room is a delicate balancing act that depends not only on room size, but also construction.“Is the exterior wall wood or brick? Is it well insulated? What is the quality of glass? What direction does the room face?” Mackemer asked.