526 HVAC contractors ranked by CR ScoreUpdated 0 paid placements in this rankingHow we rank →
Best overall in Merrimack: Heritage Home Service, CR Score 93/100; 4.8★ from 7,956 Google reviews; open 24/7.
Best for emergencies (open 24/7): High Ground Service Pros - Plumbers Electricians & HVAC Technicians, posts 24/7 hours; ranked #2 of 526.
Most-reviewed: Papalia Home Services, 3,978 Google reviews at 4.9★, the most of 526 ranked after Heritage Home Service; ranked #13.
Rankings can't be bought. Contractors can't pay to change their rank or score. How we rank
526 Merrimack HVAC contractors are ranked here by CR Score, from 8 published factors. 147 are open 24/7, 251 open Saturdays and 180 open Sundays, based on posted hours. The median Google rating is 4.9★ across 526 rated businesses.
| Rank | Business | CR Score | Google rating | Based in | Hours | Best for |
|---|---|---|---|---|---|---|
| 1 | Heritage Home Service | 93 | 4.8★ (7,956) | Auburn, 10 mi away | 24/7 | Overall |
| 2 | High Ground Service Pros - Plumbers Electricians & HVAC Technicians | 92 | 4.9★ (2,303) | Manchester, 9 mi away | 24/7 | Emergencies |
| 3 | Sanford Temperature Control | 91 | 4.9★ (1,832) | Milford, 11 mi away | 24/7 | — |
| 4 | Walley's Heating & Air | 91 | 4.9★ (793) | Nashua, 8 mi away | 24/7 | — |
| 5 | A. Fagundes Plumbing & Heating Inc. | 90 | 4.9★ (348) | Nashua, 6 mi away | 24/7 | — |
| 6 | A.J. LeBlanc Heating, A/C, Plumbing & Electrical | 90 | 4.8★ (683) | Bedford, 7 mi away | 24/7 | — |
| 7 | Wilson Brothers Heating & Air Conditioning, Inc. | 90 | 4.9★ (1,275) | Fitchburg, 14 mi away | 24/7 | — |
| 8 | Ferris Plumbing, Heating & Air | 90 | 4.9★ (320) | Litchfield, 6 mi away | 24/7 | — |
| 9 | LHR Plumbing Heating Cooling and Electric | 90 | 4.9★ (454) | Manchester, 8 mi away | 24/7 | — |
| 10 | A. Fagundes Plumbing & Heating Inc. | 89 | 4.8★ (1,626) | Billerica, 15 mi away | 24/7 | — |
Ordered by CR Score, a 0–100 score from 8 published factors. Paid placement never changes the order.
Scores below: based on 6 of 8 factors; credentials and recency not yet collected. Hatched segments mark factors we don't have yet.
Ranked #1 because of its Google rating and review volume: 4.8★ from 7,956 Google reviews, the most Google reviews on this list (7,956).
Based in Manchester, 9 mi away
Ranked #2 because of its Google rating and availability: 4.9★ from 2,303 Google reviews, open 24/7.
Based in Milford, 11 mi away
Ranked #3 because of its Google rating and availability: 4.9★ from 1,832 Google reviews, open 24/7.
Based in Nashua, 8 mi away
Ranked #4 because of its Google rating and availability: 4.9★ from 793 Google reviews, open 24/7.
Based in Nashua, 6 mi away
Ranked #5 because of its Google rating and availability: 4.9★ from 348 Google reviews, open 24/7.
Based in Bedford, 7 mi away
Ranked #6 because of its Google rating and availability: 4.8★ from 683 Google reviews, open 24/7.
Based in Fitchburg, 14 mi away
Ranked #7 because of its Google rating and availability: 4.9★ from 1,275 Google reviews, open 24/7.
Based in Litchfield, 6 mi away
Ranked #8 because of its Google rating and availability: 4.9★ from 320 Google reviews, open 24/7.
Based in Manchester, 8 mi away
Ranked #9 because of its Google rating and availability: 4.9★ from 454 Google reviews, open 24/7.
Based in Billerica, 15 mi away
Ranked #10 because of its Google rating and availability: 4.8★ from 1,626 Google reviews, open 24/7.
Based in Londonderry, 8 mi away
Ranked #11 because of its Google rating and availability: 4.8★ from 433 Google reviews, open 24/7.
Based in Chelmsford, 18 mi away
Ranked #12 because of its Google rating and availability: 4.8★ from 2,927 Google reviews, open 24/7.
Based in Acton, 25 mi away
Ranked #13 because of its Google rating and availability: 4.9★ from 3,978 Google reviews, open 24/7.
Based in Manchester, 8 mi away
Ranked #14 because of its Google rating and availability: 4.7★ from 598 Google reviews, open 24/7.
Based in Chester, 14 mi away
Ranked #15 because of its Google rating and availability: 5.0★ from 263 Google reviews, open 24/7.
Based in Manchester, 9 mi away
Ranked #16 because of its Google rating and availability: 4.9★ from 167 Google reviews, open 24/7.
Based in Haverhill, 20 mi away
Ranked #17 because of its Google rating and availability: 5.0★ from 449 Google reviews, open 24/7.
Based in Chelmsford, 21 mi away
Ranked #18 because of its Google rating and availability: 5.0★ from 443 Google reviews, open 24/7.
Based in Derry, 9 mi away
Ranked #19 because of its Google rating and availability: 4.8★ from 176 Google reviews, open 24/7.
Based in Billerica, 21 mi away
Ranked #20 because of its Google rating and availability: 5.0★ from 476 Google reviews, open 24/7.
Based in Concord, 19 mi away
Ranked #21 because of its Google rating and availability: 4.9★ from 539 Google reviews, open 24/7.
Based in North Andover, 23 mi away
Ranked #22 because of its Google rating and availability: 5.0★ from 562 Google reviews, open 24/7.
Based in Manchester, 8 mi away
Ranked #23 because of its Google rating and availability: 5.0★ from 54 Google reviews, open 24/7.
Based in Nashua, 10 mi away
Ranked #24 because of its Google rating and availability: 4.9★ from 77 Google reviews, open 24/7.
Based in Manchester, 8 mi away
Ranked #25 because of its Google rating and availability: 5.0★ from 46 Google reviews, open 24/7.
#1 to #25 are shown in full above. Here are #26 to #50, in CR Score order; each links to its profile. We publish the top 50 of 526 ranked HVAC contractors here; the rest are on their profiles.
20 more HVAC contractors within 25 mi that we can't rank yet: too few reviews, or a trade we couldn't confirm. Listed A to Z.
| Business | Google rating | Distance |
|---|---|---|
| Advanced Refrigeration & AC | 3.0★ (2) | 12 mi |
| Allied plumbing and heating | 5.0★ (2) | 6 mi |
| Borelli Plumbing & Heating | 5.0★ (2) | 8 mi |
| Complete Home Services | 4.8★ (20) | 11 mi |
| Denommee Plumbing, HVAC & Electric | 4.9★ (51) | 10 mi |
| Diversified Site Services | 5.0★ (1) | In Merrimack |
| Fusion Mechanical Services | 3.0★ (2) | 7 mi |
| Harley Weymouth Plumbing & Heating | 5.0★ (2) | 15 mi |
| Homeworks Heating and Air Conditioning | 3.0★ (2) | 12 mi |
| HVAC Unlimited LLC | 5.0★ (2) | 13 mi |
| James Gardner Plumbing & Heating LLC | 5.0★ (2) | 14 mi |
| JLEMOS HVAC | 5.0★ (2) | 10 mi |
| Kaizen Controls, LLC | In Merrimack | |
| Mikey Pipes Plumbing & Heating LLC | 5.0★ (2) | 15 mi |
| Nick’s Heating and Cooling | 5.0★ (2) | 11 mi |
| Patriot Heating & Cooling, LLC | 4.8★ (174) | 17 mi |
| Paul Mechanical LLC. | 5.0★ (4) | In Merrimack |
| Purple HVAC | 5.0★ (2) | 8 mi |
| Spencer Deal Heating Services LLC | 4.0★ (2) | 15 mi |
| Tyngsboro Plumbing & Heating | 5.0★ (2) | 16 mi |
National price ranges in USD, not adjusted for Merrimack. Each row names its basis and the month we checked it.
| Job | Low | Typical | High | Basis | Checked |
|---|---|---|---|---|---|
| AC replacement | $3,887 | $5,978 | $8,073 | Per system, installed (unit plus labor); typical range of customer-reported jobs. US national range | October 2026 |
| Furnace replacement | $2,823 | $4,814 | $6,896 | Per system, installed; typical range of customer-reported jobs. US national range | October 2026 |
In New Hampshire, furnace and heat pump calls peak in the coldest winter weeks and AC calls in summer heat waves. Spring and fall are the easiest times to book maintenance or a replacement.
We scored 526 Merrimack HVAC contractors on 8 factors, weighted as shown. A business is ranked when its trade is confirmed and it has 3 or more Google reviews or a claimed profile. Unknown factors are left out of the score, not counted as zero. Scores last refreshed October 22, 2026.
Paid placement never changes a rank or score. Featured businesses are paid, labelled, limited to 3 and shown above the ranking, outside it.
| Factor | Weight | Computed from | In Merrimack data |
|---|---|---|---|
| Reputation | 35% | Bayesian-adjusted Google star rating | Measured |
| Credentials | 15% | Active state license 0.6, bond 0.2, workers’ comp 0.2 | Not yet collected |
| Review volume | 10% | log10(reviews + 1) against the list maximum | Measured |
| Recency | 10% | Share of reviews from the last 12 months | Not yet collected |
| Availability | 10% | Weekly open hours, Saturday, Sunday, 24/7 or same-day | Measured |
| Trade focus | 10% | Google main category 1.0, business name 0.7, additional category 0.5 | Measured |
| Proximity | 5% | 1.0 when based in the city, falling to 0 at the trade’s radius | Measured |
| Completeness | 5% | Website, photos, description, hours, claimed profile (0.2 each) | Measured |