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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 448 customer reviews

Customers say: The overall sentiment across these reviews is overwhelmingly positive, reflecting high levels of customer satisfaction and appreciation. Customers consistently express enthusiasm about the quality of service they received, with recurring praise for professionalism, expertise, and efficiency. A dominant theme throughout is the technical skill and knowledge demonstrated by the service team, with many reviewers highlighting how thoroughly problems were diagnosed and resolved. The interpersonal qualities of the technicians emerge as another strong positive trend, with customers frequently describing them as friendly, personable, pleasant, and respectful. Communication stands out as a particularly valued aspect, with reviewers appreciating clear explanations, patience in answering questions, and being kept informed throughout the service process. Timeliness and punctuality are consistently mentioned as strengths, alongside respect for customers' property and maintaining clean, orderly work practices. Many customers express strong loyalty and trust in the company, with several indicating they are repeat customers or plan to continue using the service. The tone is enthusiastic and grateful, with multiple reviewers offering strong recommendations and expressing genuine happiness with the results. Overall, these reviews paint a picture of a service provider that excels in both technical competence and customer care, creating consistently positive experiences that foster long-term customer relationships.

Job Locations and Reviews

Blocked vent. Disassembled and cleaned obstruction. Tested operation multiple times. All set, thank you.
Blocked vent. Disassembled and cleaned obstruction. Tested operation multiple times. All set, thank you.
Jack D.
Jack D. Checked in
Blocked vent. Disassembled and cleaned obstruction. Tested operation multiple times. All set, thank you.
Pembroke, NH 03275
Review
Qwenten contacted us before his arrival to let us know he was on his way and arrived promptly. He was very knowledgeable and answered all our many questions. He provided different possible solutions for at this time and went with our decision with no pressure. Very friendly and easy to discuss options with.
Peter - Merrimack, NH 03054
Qwentin G.
Qwentin G. Checked in
Found that the compressor capacitor failed. The outdoor condenser coil was very dirty as well so I washed it with water and coil cleaner. I tested the operations and the unit was running decent. We will schedule Zak to come out to give you an estimate on a system replacement.
Pelham, NH 03076
Jack D.
Jack D. Checked in
Dirty condenser coil causing pressure switch to trip. I recommend routine maintenance/ signing up for our HomeClub. Thank you!
Bedford, NH 03110
Mark D.
Mark D. Checked in
Repaired leak in garage,installed outside faucet,replaced water filter,removed rain head from second floor bath rm and installed temperaily shower head
Londonderry, NH 03053
Jack D.
Jack D. Checked in
Replace drain tubing in Avards bathroom and clear out debris from pop-up arm. Replace drain tubing in 3rd floor men's bathroom.
Nashua, NH 03060
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance today. Everything went great. I cleaned the drain pan and the drain line with a bunch of drain cleaner. Please see the attached form.
Merrimack, NH 03054
Review
We have been very pleased with GSMS services from replacing our central AC & furnace 2 years ago plus a few plumbing issues we have had repaired and regular maintenance services. Jack, Qwentin, Mark and the rest of the team have been very professional and friendly and do a great job the first time and always cleaned up after themselves. They definitely go above and beyond and we highly recommend GSMS and we do. Fair prices as well!
Pamela - Manchester, NH 03109
Qwentin G.
Qwentin G. Checked in
Completed the oil furnace maintenance and the AC maintenance. Everything went great today! Please see the attached form.
Candia, NH 03034
Install check valves on hot and cold outside faucet
Install check valves on hot and cold outside faucet
Mark D.
Mark D. Checked in
Install check valves on hot and cold outside faucet
Amherst, NH 03031
Review
Extremely professional and on time, great work! Highly recommend their services.
Georgine - Bedford, NH 03110
Qwentin G.
Qwentin G. Checked in
Replaced the condensate pump for the mini split. Tested operations and everything was working as it should.
Bow, NH 03304
This proposal outlines the comprehensive modernization of both your second and third-floor HVAC systems. By electing to complete both of these installations simultaneously, our team is able to consolidate our labor, particularly when running the new refrigerant line sets for both systems at the exact same time. This streamlined, single-visit efficiency allows us to pass significant labor savings directly back to you! For the Second Floor, we will replace the aging equipment with a modern, high-efficiency gas furnace and AC system that seamlessly ties into your existing ductwork. For the Third Floor, we will upgrade the failing system to a premium, 100% electric Mitsubishi Heat Pump. Because of the square footage of this space, this is a much more cost-effective investment that guarantees robust heating even in sub-zero temperatures, allowing us to safely cap off the gas line for this zone. Scope of Work Phase 1: Second Floor Gas & AC System Upgrade Indoor Equipment (Attic): We wil
This proposal outlines the comprehensive modernization of both your second and third-floor HVAC systems. By electing to complete both of these installations simultaneously, our team is able to consolidate our labor, particularly when running the new refrigerant line sets for both systems at the exact same time. This streamlined, single-visit efficiency allows us to pass significant labor savings directly back to you! For the Second Floor, we will replace the aging equipment with a modern, high-efficiency gas furnace and AC system that seamlessly ties into your existing ductwork. For the Third Floor, we will upgrade the failing system to a premium, 100% electric Mitsubishi Heat Pump. Because of the square footage of this space, this is a much more cost-effective investment that guarantees robust heating even in sub-zero temperatures, allowing us to safely cap off the gas line for this zone. Scope of Work Phase 1: Second Floor Gas & AC System Upgrade Indoor Equipment (Attic): We wil
Adam P.
Adam P. Checked in
This proposal outlines the comprehensive modernization of both your second and third-floor HVAC systems. By electing to complete both of these installations simultaneously, our team is able to consolidate our labor, particularly when running the new refrigerant line sets for both systems at the exact same time. This streamlined, single-visit efficiency allows us to pass significant labor savings directly back to you! For the Second Floor, we will replace the aging equipment with a modern, high-efficiency gas furnace and AC system that seamlessly ties into your existing ductwork. For the Third Floor, we will upgrade the failing system to a premium, 100% electric Mitsubishi Heat Pump. Because of the square footage of this space, this is a much more cost-effective investment that guarantees robust heating even in sub-zero temperatures, allowing us to safely cap off the gas line for this zone. Scope of Work Phase 1: Second Floor Gas & AC System Upgrade Indoor Equipment (Attic): We wil
Nashua, NH 03064
Review
Excellent, professional, friendly service
Ginger - Hollis, NH 03049
Review
Always willing to help and does an excellent job.
Darlene - Manchester, NH 03109
Review
AC Service
Dean - Bedford, NH 03110
Review
Quen was great! Professional and knowledgeable!
Mike - Weare, NH 03281
Review
Great job. Very courteous and friendly.
Aaron - Manchester, NH 03103
Review
Excellent service!
Barb - Merrimack, NH 03054
Review
As always very professional
Steve - Nashua, NH 03064
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 service again. On time and professional. I 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
Prompt, profession and knowledgeable. Always a great experience
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
I needed to have shut off valves under my kitchen sink and a new hose attachment on my sprayer since the cheap plastic tubing was cracked. Mark was punctual, professional and extremely knowledgeable regarding the job. I am always impressed with GSM and how they run their family business. Mark completed the job quickly and efficiently. I can trust GSM and will continue to seek their help in the help in the future. GSM has installed a mini split, oil boiler, hot water heater in my home and I would highly recommend them to family and friends.
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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