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Our Service Area

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 409 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

Replaced expansion tank and relief valve.Boiler has bad aqua stat and should be tuned up.Will call to set up estimate
Replaced expansion tank and relief valve.Boiler has bad aqua stat and should be tuned up.Will call to set up estimate
Mark D.
Mark D. Checked in
Replaced expansion tank and relief valve.Boiler has bad aqua stat and should be tuned up.Will call to set up estimate
Manchester, NH 03104
Jack D.
Jack D. Checked in
Filter + belt on Carrier RTU. Filters on other 3 RTU's. Wash all evap + condenser coils for all 4 RTU's.
Manchester, NH 03102
While we can certainly replace just the problematic heat pump and tie it into your existing furnace, I also wanted to provide you with this option to proactively replace the entire HVAC system.

By replacing both the heat pump and the aging furnace simultaneously, we create a perfectly matched, fully communicating Lennox Dual-Fuel system. This eliminates the need for any third-party interface modules. The new Lennox furnace and heat pump will communicate natively with the S40 Smart Thermostat, seamlessly balancing your heating and cooling loads for the absolute highest efficiency and quietest operation possible.

Scope of Work

1. Outdoor Heat Pump Installation

Equipment: We will supply and install a new, high-efficiency Lennox Heat Pump condenser in the exact same location as your existing unit.

Site Prep & Winterization: We will lay a fresh gravel base and set a new equipment pad. Because this unit will be running in heating mode during the winter, we will securely mount it on an e
While we can certainly replace just the problematic heat pump and tie it into your existing furnace, I also wanted to provide you with this option to proactively replace the entire HVAC system.

By replacing both the heat pump and the aging furnace simultaneously, we create a perfectly matched, fully communicating Lennox Dual-Fuel system. This eliminates the need for any third-party interface modules. The new Lennox furnace and heat pump will communicate natively with the S40 Smart Thermostat, seamlessly balancing your heating and cooling loads for the absolute highest efficiency and quietest operation possible.

Scope of Work

1. Outdoor Heat Pump Installation

Equipment: We will supply and install a new, high-efficiency Lennox Heat Pump condenser in the exact same location as your existing unit.

Site Prep & Winterization: We will lay a fresh gravel base and set a new equipment pad. Because this unit will be running in heating mode during the winter, we will securely mount it on an e
Adam P.
Adam P. Checked in
While we can certainly replace just the problematic heat pump and tie it into your existing furnace, I also wanted to provide you with this option to proactively replace the entire HVAC system. By replacing both the heat pump and the aging furnace simultaneously, we create a perfectly matched, fully communicating Lennox Dual-Fuel system. This eliminates the need for any third-party interface modules. The new Lennox furnace and heat pump will communicate natively with the S40 Smart Thermostat, seamlessly balancing your heating and cooling loads for the absolute highest efficiency and quietest operation possible. Scope of Work 1. Outdoor Heat Pump Installation Equipment: We will supply and install a new, high-efficiency Lennox Heat Pump condenser in the exact same location as your existing unit. Site Prep & Winterization: We will lay a fresh gravel base and set a new equipment pad. Because this unit will be running in heating mode during the winter, we will securely mount it on an e
Auburn, NH 03032
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance today. Everything went great! Please see the attached form.
Bedford, NH 03110
Mark D.
Mark D. Checked in
Pm on a/c system everything was good.Use electric snake t I clean shower drain.Removed quite a bit of hair
Merrimack, NH 03054
Jack D.
Jack D. Checked in
Replace Belts + grease bearings on all 3 exhaust fans.
Manchester, NH 03102
Replace Filters + belts for all 3 make up air units. I cleaned the old insulation off of the covers. One of the motors needs to be replaced. The restaurant owner mentioned that they could hear the failing motor in the kitchen.
Replace Filters + belts for all 3 make up air units. I cleaned the old insulation off of the covers. One of the motors needs to be replaced. The restaurant owner mentioned that they could hear the failing motor in the kitchen.
Jack D.
Jack D. Checked in
Replace Filters + belts for all 3 make up air units. I cleaned the old insulation off of the covers. One of the motors needs to be replaced. The restaurant owner mentioned that they could hear the failing motor in the kitchen.
Manchester, NH 03102
Jack D.
Jack D. Checked in
Replace RTU Belt + Filters. Wash Evap + Condenser coils. Replace broken condensate trap. Check refrigant operation for both cooling circuits.
Manchester, NH 03102
Completed the electric water heater maintenance today. Everything went great! Please see the attached form.
Completed the electric water heater maintenance today. Everything went great! Please see the attached form.
Qwentin G.
Qwentin G. Checked in
Completed the electric water heater maintenance today. Everything went great! Please see the attached form.
Merrimack, NH 03054
Exeter, NH - Installed hot and cold outside faucet.Reset toilet and installed valve
Mark D.
Mark D. Checked in
Installed hot and cold outside faucet.Reset toilet and installed valve
Exeter, NH 03833
Review
The work was completed on schedule. One small surprise was quickly dealt with by the installers. The “ceiling cassette” option for this AC has made for a system that is aesthetically low-impact, and was worth the extra cost.
Klaatu - Nashua, NH 03062
Review
Arrived in a timely manner with a cheerful attitude. He went straight to work and completed the job quickly/efficiently. Thank you Jack.
Kathleen - Merrimack, NH 03054
Review
Quentin was great! Very thorough pleasant and neat
Susan - Bedford, NH 03110
Review
Friendly, thorough and efficient!
Bob - Sandown, NH 03873
Review
Qwentin was super communicative about what the AC service check entailed - accommodating/ polite/professional. Thank you Qwentin!
Susan - Hooksett, NH 03106
Review
Customer service great, technician knowledgeable & explained what was going on.
Michelle - Manchester, NH 03104
Review
Very good.
Phil - Hooksett, NH 03106
Review
I’ve used GSMS for years now. They have always provided top notch services and workmanship. Shout out to Jack specifically for today help 🙌🏻
Sam - Concord, NH 03301
Review
Prompt and attentive young man. Excellent job
Sandra - Bedford, NH 03110
Review
As always, Excellent work!
Jenn - Hudson, NH 03051
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
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
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.

Trusted Quality & Service