Top 5 HVAC companies in Nassau, New York

Nassau County sits in a heating-dominant climate zone that drives winter service demand and requires equipment sized for 15 °F design conditions. Public records supply the installed-cost ranges, licensing structure, and incentive rules that follow. The shortlist ranks firms by Bayesian-adjusted rating drawn from listed review volume and star scores.

Installed system costs

Typical full-system installation appears at $12,450, with published low and high bounds of $11,200 and $13,700. A separate 2025 invoice set reports an average of $15,721 and upper-quartile jobs reaching $22,000. Labor is stated at $160 per hour. Permit fees range from $200 to $700. The two sources differ on central tendency, so both figures remain visible for budgeting.

The shortlist

24/7 HVAC OF LONG ISLAND INC

151 reviews produce a raw 5 rating that the Bayesian adjustment lifts to 5.021 after tie-breaker credit for a public website and published 24/7 availability. The national mean sits at 4.764, and the modest upward movement reflects the volume already present. The firm operates from 700 Rockaway Tpke #400, Lawrence, NY 11559 as a general contractor and can be reached at (516) 717-7515. These numbers cannot reveal whether the same crew handles both residential and light-commercial work.

Home+ Air and Heat

79 reviews at a raw 5 yield an adjusted score of 4.995 once the mean of 4.764 and the two tie-breaker signals are applied. The adjustment is smaller than for the leader because fewer reviews anchor the score. The company lists 55 Jericho Tpke Ste 203, Jericho, NY 11753, operates as a general contractor, and answers at (516) 276-1911. The figures say nothing about average job duration or callback rates.

GallettAir Inc. Heating & Air Conditioning

431 reviews at 4.9 produce an adjusted 4.951. The raw score sits above the national mean, so the Bayesian step pulls it downward while 24/7 and website signals add slight upward movement. Address is 860 Little East Neck Rd North, West Babylon, NY 11704. The listing shows no phone number. The count of reviews limits what can be inferred about consistency across different system types.

Universe Home Services

7609 reviews at a raw 4.8 produce an adjusted 4.86 after the mean of 4.764 is applied and the two tie-breaker signals are added. Large volume keeps the adjusted figure close to the raw rating. Address is 260 Smith St, Farmingdale, NY 11735. Reach them at (516) 951-0506. The review depth cannot disclose how many of those jobs occurred inside Nassau County versus adjacent counties.

One Hour Heating & Air Conditioning of Nassau County

12 reviews at 4.8 produce an adjusted 4.834. The small sample allows the Bayesian adjustment to move the score farther from the raw value toward 4.764 before tie-breakers raise it again. Address is 3525 Lawson Blvd, Oceanside, NY 11572. The firm answers at (516) 862-4994. Limited reviews leave open questions about performance on complex retrofits.

Licensing and permits

New York maintains no statewide HVAC contractor license board. Authority rests with individual cities and counties; New York City’s Department of Buildings, for example, issues Oil Burner Equipment Installer (Class A or B) credentials for oil-fired equipment and may require High-Pressure Boiler Operating Engineer or Special Rigger licenses depending on system type. Electric-only central air or heat-pump work falls under general contractor and permit rules without a dedicated trade license. Insurance requirements vary by jurisdiction; New York City lists General Liability, Workers’ Compensation and Disability coverage for oil-burner licensees, but no uniform statewide minimum applies. Permits themselves are issued locally rather than at the state level.

Local climate demands

Nassau County falls mainly in IECC zone 5A with a moist regime. Heating degree days total 5,700 against 900 cooling degree days, confirming a heating-leaning mixed load. Winter design temperature is 15 °F and summer design reaches 91 °F with humid summers and drier winters. Primary heating fuel is natural gas or fuel oil. Heat-pump suitability is rated good with cold-climate backup. The engineering note highlights a large steam and hydronic retrofit market. Equipment must therefore be selected and sized for dominant heating loads and for compatibility with existing hydronic or steam distribution.

Available incentives

NYSERDA’s EmPower+ and NY Home Energy Rebates remain limited. Heat-pump rebates reach $8,000 under HEAR or up to $10,000 for income-eligible households via EmPower+. The state solar tax credit does not extend to heat pumps. Utility-administered NYS Clean Heat rebates range from $1,000 to $5,000, yet payment flows through a participating contractor; non-network installers forfeit the incentive. Federal 25C and 25D credits expired after 2025; only the commercial 48E ITC survives under strict timing rules. Homeowners must therefore confirm contractor network status before accepting any quote that includes rebate math.

How to choose

Verify the firm appears on the current NYS Clean Heat participating-contractor list when incentives are expected. Cross-check recent local permit records through the town building department. Compare both raw star rating and Bayesian-adjusted score against review count. Confirm the listed 24/7 availability matches actual service area coverage inside Nassau County. Request references from recent jobs that match the planned equipment type.