1) AC – alternating current
2) ACH – air changes per hour
3) AHU – air handling unit
4) AMP – ampere
5) BDD – back draft damper
6) BH – British thermal units per hour (BTU/ hr)
7) BHP – brake horsepower
8) BTU – British thermal units
9) CFM – cubic feet per minute
10) CAV – constant air volume
11) CHWR – chilled water return
12) CHWS – chilled water supply
13) CV – constant volume
14) CW – chilled water
15) DB – dry bulb
16) DBT – dry bulb temperature
17) DC – direct current
18) DP – dew point, differential pressure
19) DPT – dew point temperature
20) DX coil – direct expansion coil
21) EAT – entering air temperature
22) EF – exhaust fan
23) ERU – energy recovery unit
24) ERV – energy recovery ventilator
25) EWT – entering water temperature
26) EXH – exhaust
27) FCU – fan coil unit
28) FLA – full load amps
29) FPM – feet per minute
30) FPS – feet per second
31) GPM – gallons per minute
32) HEPA – high efficiency particulate air
33) HP – horsepower
34) HRU – heat recovery unit
35) HVAC – heating, ventilation, and air conditioning
36) HW – hot water
37) HZ – hertz
38) I - current
39) IAQ – indoor air quality
40) LAT – leaving air temperature
41) LWT – leaving water temperature
42) MAT – mixed air temperature
43) MAU – make-up air unit
44) MBH – thousands BTUs per hour
45) MERV – minimum efficiency reporting value
46) NC – normally closed
47) NO – normally open
48) NTS – not to scale
49) OA – outside air
50) OAT – outside air temperature
51) PD – pressure drop
52) PH – phase, pre-heat
53) PSI – pounds per square inch
54) RA – return air
55) RAT – return air temperature
56) RF – return fan
57) RH – re-heat, relative humidity
58) RTU – roof top unit
59) SA – supply air
60) SAT – supply air temperature
61) SF – service factor, supply fan
62) SP – set point, static pressure
63) SPEC – specification
64) TEAO – totally enclosed air over
65) TEFC – total enclosed fan cooled
66) TON – 12,000 Btu/hr
67) TSP – total static pressure
68) TXV – thermal expansion valve
69) UH – unit heater
70) ULPA – ultra low particulate air
71) UV – ultra violet
72) V – voltage, velocity
73) VAV – variable air volume
74) VFD – variable frequency drive
75) VSD – variable speed drive
76) W - watt
77) WB – wet bulb
78) WC – water column
79) WG – water gauge