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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 206 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
Install new outside faucets. 12" frost free. Isolation valve inside.
Nashua, NH 03062
Adam P.
Adam P. Checked in
Replacement of the existing air conditioning system while retaining the current furnace. A new high-efficiency Lennox outdoor condensing unit will be installed along with a new indoor A/C coil, properly matched to the existing furnace to ensure reliable performance and efficiency. New refrigerant lines will be installed to meet current standards and maximize system longevity. The existing service outlet has been verified to meet code and does not require updates. All work will be completed with careful attention to integrating the new A/C components with the existing heating system for seamless operation. The return drop will be adapted to accommodate our AirBear media filtration system, enhancing indoor air quality.
Epping, NH 03042
Review
The friendly team at Granite State Mechanical always do great work at a reasonable price
Barry - Manchester, NH 03109
Jack D.
Jack D. Checked in
GSMS HomeClub AC maintenace today. Everything went great. I replaced the air filter. I emailed you an estimate for the new nest thermostat replacement. Please see the maintenance form for detailed results!
Manchester, NH 03109
Jack D.
Jack D. Checked in
Everything went great with your GSMS HomeClub AC maintenances performed on both central air systems. New air filters in upstairs and basement system. Thank you!
Windham, NH 03087
Jack D.
Jack D. Checked in
GSMS HomeClub maintenance performed. Everything went great. Please see attached maintenance form for detailed results!
Windham, NH 03087
Jack D.
Jack D. Checked in
Everything went great on the maintenance visit for both ductless systems. We will provide a quote to replace the louver down stairs. Thank you! Please see the attached maintenance form.
Barrington, NH 03825
Review
Great service
Michael - Newbury, NH 03255
Jack D.
Jack D. Checked in
All set ac maintenance! See fork for results. Thank you!
Newbury, NH 03255
Review
Let a vmail message to make sure Jack feels appreciation. He's thorough, explains what he's doing/fixing. Its nice to know I can count on him. Thank you!
Sandra - Nashua, NH 03064
Jack D.
Jack D. Checked in
AC planned Maintenance went great today. I also replaced the washer in the outside hose bib because it was dripping. New air fliter, indoor blower motor capacitor, and dual capacitor in outdoor unit. Thank you!
Nashua, NH 03064
Adam P.
Adam P. Checked in
We will replace the existing Lennox system with a new high-efficiency heating and cooling system to provide ultimate comfort and improved performance. The existing supply and return plenums will be adapted to fit the new system. The return will be modified to incorporate our AirBear whole-home filtration system, helping to deliver cleaner, healthier indoor air. To meet our safety standards, the existing CSST gas piping will be replaced with black iron piping for the connection to the furnace. The PVC venting will also be replaced to comply with the latest installation requirements for the new furnace. A new bypass humidifier will be installed, and we will replace the existing piercing saddle valve with a proper shut-off valve to ensure reliable, worry-free water control. Outside, the new A/C unit will be installed on the existing poured concrete pad, with a new composite plastic pad placed on top to provide a durable and level base. The electrical disconnect and whip will also be r
Manchester, NH 03109
Review
It is always nice to see Jack! Super friendly, polite and explains what needs to be done.
Karen - Nashua, NH 03063
Jack D.
Jack D. Checked in
Mini split maintenance. Central AC maintenance. Replace two outside faucets. Please see maintenance form for AC results. Everything looked good thank you!
Nashua, NH 03063
Review
Excellent service
Alison - Londonderry, NH 03053
Review
Great service. Very knowledgeable. Great price.
Dean - Deerfield, NH 03037
Review
Excellent service and depth of knowledge makes working with GSMS so comforting. Jack, Thanks for your help today!
Michele - Milford, NH 03055
Review
As usual, GSMS (Mark) did a great job.
Bob - Sandown, NH 03873
Review
As always, nothing but the best customer service from Mark and GSMS. Timely arrival, methodical and thorough review of issues, and great communication with me about the work or home systems.
Jenn - Hudson, NH 03051
Review
Service Excellent
Paul - Nashua, NH 03062
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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