Heating and cooling # What is an ERV? ERV stands for energy recovery ventilator. An ERV brings in outdoor air and exhausts indoor air through a shared core that transfers both heat and moisture between the two streams, so ventilation costs less conditioning than opening a window would. ## What does the acronym stand for? **ERV** — energy recovery ventilator. ## Is it something you have at home? **Residential equipment.** This term describes equipment that can genuinely be in a US single-family home. ## Why it matters to you This equipment matters more the tighter the house. A well-sealed modern home does not exchange enough air on its own, and mechanical ventilation is how it gets fresh air without simply throwing away the energy already spent conditioning the old air. ## What should you know about refrigerant? Refrigerant circulates in a sealed loop. It is not consumed the way fuel or oil is, so a system that is low on charge **has a leak**. Adding refrigerant without finding and repairing that leak treats the symptom, vents the new charge over the following weeks, and costs you the same money again next season. It is also regulated. Only Section 608 certified technicians may purchase refrigerants intended for use with stationary refrigeration and air-conditioning equipment. The restriction covers ozone-depleting substances and non-ozone-depleting substitutes — including HFCs — in cylinders, cans or drums. Wholesalers must record the purchaser's name, the date of sale and the quantity. There is one exception that confuses people: small cans of refrigerant for *vehicle* air conditioning are still sold without certification. That exception is for cars and does not extend to the equipment in your house. For new equipment, the 700 GWP limit in force since January 1, 2025 is why current systems ship with R-454B (GWP 465) or R-32 (GWP 675) rather than R-410A (GWP 2088). R-410A inventory built before 2025 can still be legally installed — EPA removed the installation deadline on May 21, 2026. [The full timeline](https://hvacbuddy.shop/refrigerants/). ## How is the right equipment size decided? Nearly every persistent comfort problem traces back to equipment size, and size is decided before the first box arrives. The standard is the ACCA **Manual J** load calculation (ANSI/ACCA 2 Manual J - 2016), which totals the heat gain and loss of your specific house: orientation, window area and type, insulation levels, air infiltration, internal gains, and your local design temperature. What a Manual J is *not*: square feet per ton, and not the old unit's tonnage. The first ignores everything that makes one house different from another. The second assumes whoever sized the old equipment got it right, and propagates their error for another fifteen years. Oversized equipment reaches the setpoint and shuts off before it has dehumidified, so the house ends up cold and clammy at the same time. Every start is also the hardest moment in a compressor's life, so wear accelerates. And you pay for the surplus capacity twice — once to buy it and again to run it. Ask for the completed Manual J in writing, not the claim that one was done. [What it contains and how to read it](https://hvacbuddy.shop/sizing/manual-j/). ## What actually drives the cost? We publish no national average price, and the reason matters: an average across every house, region and system type is not a number you can act on. A replacement that includes duct modification, an electrical upgrade and a permit is a different job from a straight swap, and both read as "system replacement" on a one-page proposal. What actually drives your number: - **Equipment capacity and tier**, which should come from the Manual J rather than the old nameplate. - **The ducts** — whether they can move the air the new equipment needs, and what it costs if they cannot. - **Electrical work**, if a circuit or panel change is required. - **Permit and inspection**, usually required. - **Refrigerant** — current equipment uses R-454B or R-32; remaining pre-2025 R-410A stock may price differently. [What a bid should itemise](https://hvacbuddy.shop/costs/) · [operating cost calculator](https://hvacbuddy.shop/calculators/). Sources (1) - U.S. Environmental Protection Agency — [Introduction to Indoor Air Quality](https://www.epa.gov/indoor-air-quality-iaq/introduction-indoor-air-quality) (accessed 2026-08-20) By [HVACBuddy Editorial Team](https://hvacbuddy.shop/authors/editorial-team/). Last reviewed: 2026-08-20. HVACBuddy publishes independent information. We do not install or service equipment, we do not dispatch contractors, and we do not sell leads. Nothing here is engineering, tax, or legal advice.