PTAC Frequently Asked Questions

Q: How do I size a PTAC unit?

A: Use our PTAC Cooling Calculator at:
www.ultimateptac.com/ptac-cooling-calculator/ to determine your maximum cooling load.
Take this value and use our PTAC Selection wizard at:
www.ultimateptac.com/ptac-selection-wizard/ to select the ultimate PTAC for your application.

 

Q: The next larger PTAC is only $50 more. I’d rather have more than enough capacity for those extremely hot, humid days. Should I go for it?

A: NO. It’s important to never oversize any air conditioning product. Those extremely hot days occur a couple times per year. It’s better to size your unit for typical operation. A byproduct of the cooling mode is dehumidification. The right balance of temperature and humidity creates the most comfortable environment. If you oversize your PTAC unit, it will quickly match your temperature set point, but will not run long enough to dehumidify. The result is a cool, damp environment, similar to a basement. Under sizing your PTAC will allow it to run longer and dehumidify more. This will result in a more comfortable environment.

 

Q: I am replacing a 30 year old GE PTAC unit. Do I need a new wall sleeve and exterior grille?

A: Assuming the dimensions are standard, probably not. If the existing wall sleeve and exterior grille are in good condition, there’s no need to replace them. Sometimes the exterior grille is weathered. Newer grilles look nicer and there are a lot of colors to choose from. A new grille is an inexpensive upgrade that can give your exterior a fresh new look. See the next question below for dimensional considerations.

 

Q: I have a 20 year old Amana PTAC unit. Will a new unit slide into the existing wall sleeve?

A: Most likely! Measure your existing wall sleeve. If it measures 42” Wide x 16” High x 16” deep, then a new unit should slide right in. The PTAC industry has been using these standard dimensions for 30-40 years. Occasionally you’ll find an odd size that an off brand manufacturer thought would be a good idea. It wasn’t a good idea, and that odd size is probably no longer around. If you have an odd size, search the web for “Retrofit PTAC”, there are a handful of companies that specialize in replacing old units that never made it very far.

 

Q: I am building a new addition on our home. The PTAC is the best solution because my existing system can’t reach the new room. Do I have to install a wall sleeve or can my contractor simply frame the opening?

A: New installations REQUIRE a wall sleeve and exterior grille. There are 3 main components to a new installation; the main A/C or heat pump unit (also called the “chassis”), the wall sleeve and the exterior grille. You must have these 3 components for a PTAC system to operate properly. The chassis is the heart of the system. The wall sleeve is nothing more than an insulated steel casing that acts as the outer shell. The grille serves 2 functions; it protects the coils on the back of the chassis, and it separates the 2 air paths in the back of the unit (fresh air coming in, hot discharge air going out) Here are a few pictures to help simplify the system:

PTAC Chassis shown without its front cover
 

Above: PTAC Chassis shown without its front cover. This is the heart of the system, but without the wall sleeve and exterior grille, it won’t function properly.

Complete PTAC system
 

Above: Complete PTAC system showing the front cover, inner chassis, metal wall sleeve and a basic exterior grille.

PTAC air path
 

Above: This shows the air paths during the cooling mode. Hot room air enters the front cover in the bottom, cool conditioned air is discharged out the top. On the backside, outdoor air enters the exterior grille on the right and left, hot discharge air from the room leaves through the middle.

 

Q: I am having a hard time finding an air conditioning contractor to install a new PTAC system in my office. Any ideas?

A: We hear this often. A PTAC unit is a self-contained air conditioner. The scope of work is too small for most air conditioning and heating contractors. They specialize in piping and metal ductwork. Try calling a general contractor or carpenter. They will cut the hole in your wall, install the sleeve and run a 220 Volt electrical outlet. With a little help from a friend, you can slide the PTAC unit into the sleeve and plug it in. Also, ultimateptac.com is set-up to accept advertisements from local installers. When you visit the home page, advertisements from local installers should appear. Check back often, these ads may change giving you multiple installers to choose from.

 

Q: My old PTAC stopped working and I can’t find anyone to service it. Help!

A: Chances are you won’t find anyone to service it unless it’s a friend of the family. PTAC units are like refrigerators; the time it takes for a technician to visit your location, identify the problem, order the part, make a 2nd trip to install the part, you just spent more on service then you would have on a brand new unit. Technicians have been down this road too many times and will often pass on the opportunity to quote you.

 

Q: There seems to be 4 major brands, all claiming to be the quietest. Who makes the quietest PTAC unit?

A: This is a question that should be easier to answer then it is. All manufacturers publish extremely confusing sound data, but they use different testing standards. With no industry standard testing procedure, each manufacturer has the flexability to test in the environment that suits their units best. It’s easy to get into a technical debate with no clear resolution, so here’s the best recommendation: Whichever brand you choose, make sure they use a 2 fan system. 2 fan systems are quieter than older 1 fan systems. The PTAC unit should have 1 fan that handles the condenser side and 1 fan that handles the evaporator side. The bottom line is if you placed 4 different brands side-by-side in the same exact room, it would be difficult to determine which unit was the quietest.

 

Q: I am replacing a 26 year old Amana PTAC unit. How do I make sure the new unit will plug into my existing electrical outlet? I don’t want to hire and electrician to change my electrical service.

A: Matching the electrical outlet is equally as important as making sure the new unit will slide into an existing wall sleeve. There are 3 power cords available, 15 Amp, 20 Amp, 30 Amp. Each cord has a different plug that will only fit into a matching wall outlet. Your existing PTAC unit chassis should have a data plate with electrical information. It will give the actual Amp draw, and the recommended electrical circuit size. Don’t stop there. If your existing unit says it recommends a 20 amp circuit, look in your circuit breaker box to see what size breaker actually serves the unit. Don’t stop there either. Triple check the circuit size by using the chart below to find your existing electrical outlet size.

PTAC electrical outlets
 

 

Q: What is the difference between a PTAC air conditioner and PTHP heat pump?

A: From the outside of the unit, you wouldn’t know if it was an air conditioner with primary electric heat, or a heat pump air conditioner with secondary electric heat. A heat pump air conditioner describes a unit that offers the heat pump mode of heating. The heat pump mode simply reverses the refrigeration cycle so that warm air enters the room, and cool air exits to the outdoors. The heat pump mode of heating is the most efficient source of heat. Both PTAC and PTHP units have electric strip heaters. The electric heater is the only source of heat on a PTAC unit, it’s a back-up source of heat on a PTHP. A heat pump can’t generate heat easily when it’s really cold outside. The back-up electric heat will be energized when the PTHP unit can no longer keep up in the heat pump mode.

 

Q: How do I decide if I need a PTAC air conditioner or a PTHP heat pump?

A: Heat pump air conditioners have become the norm. Improvements in technology allow heat pump air conditioners to operate longer in colder climates, they are as reliable as air conditioner units and the additional cost can be justified. Even though electric heat strips are 100% efficient, heat pumps can be up to 300% efficient! This means that for every 1 BTU of energy you put into a heat pump unit, you receive 3 BTU’s in the form of heat. There are limitations to the heat pump mode. When outdoor temperatures drop below 35F, the heat pump mode can no longer generate sufficient heat, and electric strip heaters are energized. The heat pump vs. non-heat pump debate can be endless and it usually involves critics that experienced the pitfalls of early heat pump unit designs from 40 years ago. Here’s a simple way to decide: The additional cost of a heat pump unit is about $60. If you won’t use your PTAC unit for heating, don’t spend the extra money on a heat pump unit. If you will use your PTAC unit for heating, it will take about 240 hours of operation in the heat pump mode (when it’s 35F-60F outdoors) to pay for the $60 premium. In the Northeast, a heat pump would pay for itself in 1-2 years. The cooling mode is identical with both types of units.

 

Q: What are EER and SEER ratings?

A: Both are energy efficiency ratings that quickly allow you to compare different models. EER is an acronym for Energy Efficiency Ratio, SEER is an acronym for Seasonal Energy Efficiency Ratio. EER’s are used to rate efficiency levels of packaged air conditioners, SEER’s are used to rate efficiency levels of split systems (indoor unit piped to outdoor unit). The higher the value, the higher the efficiency. Do NOT compare an EER value against a SEER value. These 2 ratings use different testing procedures.

 

Q: I see a lot of options for exterior grilles. How do I decide which one is best?

A: The PTAC doesn’t care which grille you choose, but your neighbors may. Grille choice is strictly about aesthetics. If you want it to look nice, choose an architectural style, if you don’t care, go with the stamped aluminum. Here are basic pictures of a stamped aluminum grille and architectural grille.

PTAC typical stamped aluminum grille

Above: This is a typical stamped aluminum grille. They are cheap, can be painted, and they work fine.

PTAC typical architectural grille

Above: This is a typical architectural grille. They look nice, and are usually offered in extruded aluminum or plastic. On large projects, custom colors are available to match the exterior of a building.

 

Q: Is a remote thermostat required?

A: No. PTAC units have built in thermostats with digital keypads that allow you to select your temperature setting. Wall mounted thermostats are available if you would like something higher up, closer to the entrance to the room. Be sure to plan for this additional wiring before your walls are enclosed. If you are installing a PTAC into an existing room, many manufacturers offer a wireless wall mounted thermostat that doesn’t require interconnecting wiring.

 

Q: Do I need to install the PTAC on the floor or can it be raised above the floor?

A: Most PTACs are mounted on the floor. Occasionally outdoor restrictions require the unit to be mounted higher (rooms that are partially below grade). This is fine, just make sure your wall sleeve is installed so that it can handle the cantilever weight of a raised unit. Keep in mind the control panel is on top. If you go too high, you will need a ladder to turn the unit on and off.

 

Q: I see many distributors offer a drain kit. Is this required?

A: No. A drain kit is simply a metal flange and spout that attaches to the bottom pan of the PTAC. Most condensate is slung back onto the coil inside the PTAC unit to increase efficiency levels. Excess condensate occasionally runs out of the back of the unit, through the exterior grille, onto the ground below. If you have a patio outside under the PTAC unit, the drain kit will allow you to add a flexible hose to re-direct the condensate. The most common use for drain kits are on large hotel or condo projects. Each PTAC unit is drained into a common drain system that runs through the inside of the walls, down to the basement.

 

Q: How far into my space does the wall sleeve need to go?

A: Check the manufacturer's wall sleeve installation guide to be sure. They should publish a table that indicates minimum and maximum clearances for the wall sleeve. The sleeve can usually be mounted flush with the interior side of the wall, or a ¼” from the exterior side of the wall. A small lip may be required on either side to allow enough room for the front panel and exterior grille to fasten tightly. Check your manufacturer’s literature. Wall sleeves are usually several inches deeper than the wall thickness. This means you have the choice of pushing the entire sleeve out towards the exterior, or pushing it in towards the interior. Usually more floor space inside is desirable, but if the unit is mounted on the 1st or 2nd story, you may want to push more unit inside so people don’t bump into it outside.