Definition
A pressure below atmospheric pressure. A perfect vacuum is 30 inches of mercury (periodic symbol “Hg”)
Why it matters in the Wenatchee Valley
The Valley's 100° summers, single-digit winters, and orchard dust work HVAC equipment harder than most climates — so terms like this show up on real estimates here. Use it to ask sharper follow-up questions, and if a quote doesn't add up, our free second opinion reviews it line by line.