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Our Service Area

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Proudly Serving New Hampshire Homeowners

At GSMS, we are proud to serve New Hampshire with our comprehensive range of HVAC and plumbing services.

As a family-owned business with 35+ years of experience, we have built a reputation for excellence, reliability, and outstanding customer care. Our skilled technicians are dedicated to providing top-quality repairs, installations, and maintenance tailored to meet the unique needs of New Hampshire homeowners.

Explore our service area below, read reviews in your city, and see why homeowners across New Hampshire trust GSMS for their HVAC and plumbing needs.

Contact us online today or call 603-424-8258 to schedule your service and experience the GSMS difference.

Recent Jobs and Reviews

Rated 5.0 out of 5 stars based on 270 customer reviews

Customers say: The recent reviews exhibit a predominantly positive sentiment, with recurring themes of satisfaction, professionalism, and expertise. Customers express gratitude, recommend the company, and acknowledge the quality of the work performed. Positive reviews frequently mention friendly and knowledgeable technicians, timely responses, and efficient service. Negative reviews are minimal and do not represent a clear, recurring trend. Overall, the reviews suggest a positive experience with the company, with many customers expressing satisfaction with their HVAC and plumbing needs.

Job Locations and Reviews

Jack D.
Jack D. Checked in
Replace S30 with S40. Configure new control. Troubleshoot zone stat with communication error. Thank you!
Merrimack, NH 03054
Review
Excellent service and communication from scheduling to job completion!
David - Hampstead, NH 03841
Mark D.
Mark D. Checked in
11/4x11/4x3/4 blk tee,2=11/4 close nip,installed new out faucet and shut off valve
Hampstead, NH 03841
Review
I'm appreciative this company is standing by the products they sell. Tech is professional, friendly and knowledgeable.
JD - Barrington, NH 03825
Jack D.
Jack D. Checked in
Perform tests as RQ'd by Lennox technical representative. We will reach out to you when we hear back. Thank you for your patience!
Barrington, NH 03825
Qwentin G.
Qwentin G. Checked in
Replaced broken louver on the living room mini split.
Weare, NH 03281
Adam P.
Adam P. Checked in
Installed new evaporator coil on second floor air handler. Evacuated system. Charged.
Manchester, NH 03102
Jack D.
Jack D. Checked in
Replaced water filter o-ring.
New Boston, NH 03070
Review
The team at GSM has been my go to for years now. They do an amazing job and are always there when needed!
Harold - Hudson, NH 03051
Jack D.
Jack D. Checked in
Found that the cold water pipe for the outside shower had completely disconnected from the pipe going to the shower. We reconnected the pipes together and added hangers to support the pipe.
Seabrook, NH 03874
Review
Excellent Service
Mark - Nashua, NH 03062
Review
Excellent in all areas of service. Punctual, courteous, kept us well informed of service progress. Upon completion of the furnace installation Adam explained all features of the new system , and addressed questions . The above statement can be said of all GSMS employees as we have used them over the years for several different systems installation. Excellent in all areas.
Bob M - Merrimack, NH 03054
Jack D.
Jack D. Checked in
Furnace maintenance went great!
Manchester, NH 03104
Adam P.
Adam P. Checked in
Replacement of the existing failed gas furnace with a new Lennox high-efficiency gas furnace. The existing Trion air filtration system, Reme Halo UV light, and bypass humidifier will remain in place and be reconnected to the new furnace. The existing A/C coil will be held in place, and the new furnace will slide into position. All necessary supply and return plenum modifications will be made to allow for a seamless installation of the new system. Due to the height limitations of the new furnace, furnace "footies" (elevating risers) most likely will not be able to be installed; while not a code requirement, these are a beneficial feature we typically prefer for basement installations. Gas and electrical connections will be re-made. System venting will remain in place and be modified to follow manufacturer standards. The existing neutralizing condensate pump will remain in place; however, the drain at the PVC will be changed to meet current code requirements, including proper trapping
Merrimack, NH 03054
Jack D.
Jack D. Checked in
Today we went through the entire new home and recorded all of the information. We put together a GSMS Homeclub for both the main home and the guest home. The water down stairs is from the suction pipe of the Attic AC. It freezes over because it is low on refrigerant, then it melts and creates the puddle in the basement. The HRV is running to introduce fresh air into the home and exhaust the stale air from the home. We reccomend having Zak come out to look at replacing the system in the attic. The upstairs toilet and the master bath, we reccomend replacing the internals of the toilet. We reccomend replacing the supply valve for the master toilet and the main area toilet, as well. We sent an estimate for that as well.
Bedford, NH 03110
Review
Excellent service
Sylvie - Merrimack, NH 03054
Review
Service people were very courteous.
Bruce - Nashua, NH 03062
Review
Excellent
Michelle - Bedford, NH 03110
Review
Very professional, knowledgeable, and the issues were repaired. Jack went beyond to make certain our system was at its max performance!
Ray & Di - Manchester, NH 03102
Review
Qwentin has always been incredibly sweet, kind and professional when fixing our mini splits.
Stephen - Barrington, NH 03825
Review
Love dealing with this company. Their techs are always prompt, efficient and courteous. We've been happy to be their customer since 2010.
Skip Sagris - Bow, NH 03304
Response from GSMS Air•Heating•Plumbing:

Thank you so much for the kind words and for being part of the GSMS family since 2010! It means the world to us to have earned your trust over the years. I’m proud of our team for continuing to deliver the kind of service that keeps clients like you coming back. We truly appreciate your loyalty and support. – Zak D., Second-Generation Owner

Review
Qwentin was on time, very friendly and professional. He was able to identify the issue, communicate it effectively, and then fix it. Highly recommend.
Phil Cutler - Bedford, NH 03110
Response from GSMS Air•Heating•Plumbing:

Thank you so much for the kind words and for trusting GSMS to take care of your home. Qwentin is a rising star on our team, and it means a lot to hear that his professionalism and communication made a strong impression. As a local, family-run business, we’re grateful for your recommendation and honored to have earned your trust. – Zak D., Second-Generation Owner

Review
Great water heater service. On time and professional l He gave me some helpful tips on other water related issues. Highly recommend GSMS.
Katherine Turner - Exeter, NH 03833
Response from GSMS Air•Heating•Plumbing:

Thank you for the great review! I’m glad to hear our Specialist was able to get your water heater squared away and offer some extra tips while he was there. We always aim to go beyond just the repair, and I really appreciate you taking the time to share your experience. Thanks for choosing GSMS — it means a lot to our family and our team. – Zak D., Second-Generation Owner

Review
David DiNardo - Bedford, NH 03110
Response from GSMS Air•Heating•Plumbing:

Thank you for the 5 stars, David! We really appreciate you choosing GSMS and supporting our family-run team. If there’s ever anything more we can do for you, don’t hesitate to reach out. – Zak D., Second-Generation Owner

Review
claire lafond - Merrimack, NH 03054
Response from GSMS Air•Heating•Plumbing:

Thank you so much for the 5 stars, Claire! We’re grateful for your support and truly appreciate you choosing GSMS. It means a lot to our family and our entire team. – Zak D., Second-Generation Owner

Review
Great work, fair prices.
Tom Grasse - Manchester, NH 03104
Response from GSMS Air•Heating•Plumbing:

We thank you for sharing your positive experience. It made our day.

Review
top notch service, always professional. would recommend to anyone needing HVAC service, repair or install.
Ben Bouchard - Nashua, NH 03062
Response from GSMS Air•Heating•Plumbing:

It was a pleasure serving you and your family. Thank you for sharing your kind words with us. It means the world to us and to our entire team!

Review
Had an issue with our heat pump. Reached out for assistance and they had someone on site that afternoon. Problem was resolved quickly. Super friendly service. The tech was exceptionally friendly and an excellent communicator. Highly recommend
Mark Cooke - Greenland, NH 03840
Response from GSMS Air•Heating•Plumbing:

It was a pleasure serving you and your family. Thank you for sharing your kind words with us. It means the world to us and to our entire team!

Review
Jack was on time and professional upon his arrival to my home. He quickly diagnosed the problem with my hot water heater and had it fixed on the same day. Granite State Mechanical offers unsurpassed customer service and expertise in the area of heating plumbing and cooling. I tell all my neighbors how great they have treated me, and I am so glad I chose GSM to install and service my home HWH and Mini split.
Kimberly Cichon - Newmarket, NH 03857
Response from GSMS Air•Heating•Plumbing:

We thank you for sharing your positive experience. It made our day.

Review
As usual, Jack's work is stellar.
Bob Bedrosian - Merrimack, NH 03054
Response from GSMS Air•Heating•Plumbing:

We are so glad to hear that you had a good experience.

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