Prince William County, VA Noise from Specific Sources: HVAC & Mechanical Noise (2026)

County Code Sec. 14-4(a)(2) carves HVAC equipment serving a residential dwelling out of the county's nighttime noise ceiling. Table 1 in Sec. 14-4(a)(1) otherwise sets residential nighttime limits at 55 dBA, but subsection (a)(2) says heating and cooling systems, including but not limited to air conditioners and heat pumps, and radon systems serving a residential dwelling, shall not be subject to the nighttime levels enumerated in Table 1 or in subsection (b). cannot be cited for exceeding the 55 dBA residential nighttime cap purely on that basis.

The exemption does not swallow all HVAC-related noise complaints, however: Sec. 14-3 separately defines 'steady tonal sound,' the droning whine, hum, or rumble a compressor or heat pump can produce, and lists heating, ventilating, and air-conditioning units among its named examples. That definition is enforced through Sec. 14-4(b)'s residential limits of 73 dB(C) daytime and 68 dB(C) nighttime, measured at the receiving property line, with a narrower tolerance of plus or minus 3 dB (or 5 dB where multiple sources are audibly beating together). So while an HVAC unit's ordinary A-weighted decibel level is not measured against the nighttime Table 1 ceiling, a persistent low-frequency hum from the same unit can still be measured and cited under the separate C-weighted tonal-sound standard if it crosses that threshold at a neighbor's property line.