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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 227 customer reviews

Customers say: The reviews exhibit a positive sentiment, with a majority of customers expressing satisfaction with the services provided by GSMS. The recurring themes include praise for the quality of work, professionalism, responsiveness, and excellent customer service. Customers also appreciate the technicians' expertise, friendliness, and the overall positive experience they had with GSMS. Negative reviews are minimal and focus on specific issues or misunderstandings, which were promptly addressed by GSMS. Overall, the reviews suggest that GSMS is a reliable and trustworthy company that delivers high-quality services to its customers.

Job Locations and Reviews

Jack D.
Jack D. Checked in
GSMS AC HomeClub maintenance. Everything looks great thank you!
Stratham, NH 03885
Mark D.
Mark D. Checked in
Estimate for plumbing work
Epping, NH 03042
Jack D.
Jack D. Checked in
Replace water control valve that is leaking.
Merrimack, NH 03054
Mark D.
Mark D. Checked in
Install hot and cold silcock with vacuum breakers also add vacuum breakers on existing hot and cold faucet
Manchester, NH 03109
Jack D.
Jack D. Checked in
Mini split maintenance today on both systems. Everything went great. The master bedroom indoor unit needs a deep clean performed. The blower wheel is clogged and that is the cause of poor cooling performance. We have sent an estimate to complete that service. Thank you!
Windham, NH 03087
Adam P.
Adam P. Checked in
Put more insulation around supply vent
Greenland, NH 03840
Review
Thank you Mark
Diane - Nashua, NH 03064
Adam P.
Adam P. Checked in
Replacement of failed cast iron boiler with a new standard cast iron boiler. A new power vent assembly will be installed since there is no chimney for exhaust. The existing fresh air intake will be modified to accommodate the new burner. The existing zone valves will be replaced with new dedicated zone circulators, and the return piping will be re-piped for improved maintenance and purging. The existing indirect tank will be replaced with a new 40-gallon indirect tank to provide reliable domestic hot water. The oil line will be replaced with a new, above-ground coated oil line, and a new oil filter will be installed on the existing oil tank.
Barrington, NH 03825
Review
A pleasure to deal with
Alison - Amherst, NH 03031
Jack D.
Jack D. Checked in
AC Maintenance as part of GSMS Homeclub membership. We also replaced your Lennox pure air carbon filter and UV bulb. We cleaned your HRV core and filters. Thank you!
Manchester, NH 03104
Review
First of all I would like to thank Mark for taking care of this plumbing issue. My 2nd floor toilet was leaking down to the ceiling on the first floor. He arrived on time, diagnosed the problem and fixed it in a timely manner for a fair price. I would highly recommend GSMS for their professionalism and excellent service.
Deb - Hooksett, NH 03106
Jack D.
Jack D. Checked in
Evap coil in attic leaking. We checked refrigerant to make sure it is still all set for the summer. We will get back to you with an estimate for the repair.
Manchester, NH 03102
Mark D.
Mark D. Checked in
Snaked toilet,reset toilet and cleaned intake screen
Bedford, NH 03110
Review
I needed a new fan motor for my air conditioner. Jack replaced the motor and it ran for about 30 minutes and stoped. I called the company and explained what I had observed and they sent Mark out the next day to replace the motor and the same thing happened. They ordered a replacement motor from the air conditioner company, Mark installed it and problem was solved. This was all done very professionally and within a reasonable time period.Great company to deal with.
Ronald - Bedford, NH 03110
Review
Jack is always polite and friendly and willing to answer any questions we might have.
Fran - Amherst, NH 03031
Review
Five Stars
Ellen - Merrimack, NH 03054
Review
We were without hot water when a very old heater stopped working. Mark installed a new hot water heater and brought the old plumbing up to current code.
Oakwood Properties - Nashua, NH 03064
Review
Waiting for completion of project
Edie - Nashua, NH 03062
Review
Jack is the best of the best
NH - Amherst, NH 03031
Review
Couldn’t have asked for a better installation of dishwasher/toilets. Mark was very personable and professional. Arrived on time and finished on time. Excellent experience
Wayne - Merrimack, NH 03054
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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