Sizing Guide for PTACs

   SQ. FT.

  BTU

Factors that affect heating and cooling include: 

Room Size:  Sq. Ft. x 30 = Rough Estimate of BTU Output needed

Usage:  Number of people that typically occupy the room

Room Design:  The ceiling height and insulation factors

Room Location:  The direction the room faces; amount of sunlight and whether it receives afternoon or morning sun.

Should you not find a PTAC unit with a BTU Output to meet your heating and cooling needs, you will need to decide whether to use an undersized or oversized unit for the area.

Slightly undersized PTACs operate continuously to provide more comfort and savings in a smaller room than oversized units operating intermittently.  In larger rooms, two smaller units will cool more efficiently than one large unit, and in milder weather you can run a single unit to save money.

Significantly undersized PTACs cannot cool the room down, nor remove moisture from the air.  As a result, the room will feel warm and possibly humid.

Oversized PTACs will cool the space quickly, but not remove moisture to lower the humidity.  As a result, the room will feel cool and humid.

100–150

5000

150–250

6000

250–300

7000

300–350

8000

350–400

9000

400–450

10000

450–550

12000

550–700

15000

700–1000

18000

1000–1200

21000

1200–1400

23000

1400–1600

25000

1600–1900

28000

1900–2700

36000