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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 361 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

Qwentin G.
Qwentin G. Checked in
Replaced the inducer motor assembly and gasket. Tested operation after and was running extremely quiet.
Sandown, NH 03873
Review
Very knowledgeable & very helpful
Steve - Nashua, NH 03064
Jack D.
Jack D. Checked in
Replaced hot water outlet valvebody & thermistor. Also replaced the inlet screen. Brought 3 air filters as well.
Windham, NH 03087
Replaced flapper in seco d floor toilet
Replaced flapper in seco d floor toilet
Mark D.
Mark D. Checked in
Replaced flapper in seco d floor toilet
Manchester, NH 03104
Qwentin G.
Qwentin G. Checked in
Completed the plumbing inspection today all of the fixtures and drains looked good. The air lines looked good as well. The water heater is 15 years old so I did not perform a flush on it due to the age. Other than that the inspection went good today.
Nashua, NH 03064
Merrimack, NH - Completed the Rinnai tankless water heater maintenance today. I ran cleaner through it for 40 minutes. Next I flushed 10 gallons of water through it. I cleaned the water inlet screen. I vacuumed out the inside of the unit and vacuumed the filter. I checked incoming gas pressure and that was according to manufacturer specifications. I also checked all the drains and fixtures and everything looked great!
Qwentin G.
Qwentin G. Checked in
Completed the Rinnai tankless water heater maintenance today. I ran cleaner through it for 40 minutes. Next I flushed 10 gallons of water through it. I cleaned the water inlet screen. I vacuumed out the inside of the unit and vacuumed the filter. I checked incoming gas pressure and that was according to manufacturer specifications. I also checked all the drains and fixtures and everything looked great!
Merrimack, NH 03054
Deerfield, NH - We will replace the one-piece fiberglass shower unit in the basement bathroom due to mold growth. We will demo and remove the existing tub unit and cap off the water and waste lines. A new Sterling Accord 48" shower unit will replace the one-piece unit. This unit will be installed with new connections and drain and a new Moen polished chrome shower valve with a standard shower head. The client will be responsible for the carpentry work. This work will be done, understanding that mold remediation will be completed between the project.Install customers toilet.lav faucet and install clean out in kitchen drain line.
Mark D.
Mark D. Checked in
We will replace the one-piece fiberglass shower unit in the basement bathroom due to mold growth. We will demo and remove the existing tub unit and cap off the water and waste lines. A new Sterling Accord 48" shower unit will replace the one-piece unit. This unit will be installed with new connections and drain and a new Moen polished chrome shower valve with a standard shower head. The client will be responsible for the carpentry work. This work will be done, understanding that mold remediation will be completed between the project.Install customers toilet.lav faucet and install clean out in kitchen drain line.
Deerfield, NH 03037
Installation of a multi-zone mini-split system to provide the main house with priority cooling. Note on Heating: This system is sized and designed primarily for the cooling load. While it will provide supplemental heating during shoulder seasons, it is not designed to provide the total heating load for the home during winter. System Overview A multi-zone outdoor unit will be placed in a central location on the back side of the home. This system is sized to handle the current load with enough remaining capacity to add an additional 6,000 BTU head for the second bedroom in the future (a great selling feature). Indoor Unit Locations & Routing TV Room / Kitchen: The indoor unit will be installed to the left of the slider. The lineset will run down through the deck into the unfinished basement, run across, and penetrate out to the outdoor unit. This ensures a clean finish and allows a future contractor to easily refinish the deck around the lineset. Great Room / Living Area: The unit wi
Installation of a multi-zone mini-split system to provide the main house with priority cooling. Note on Heating: This system is sized and designed primarily for the cooling load. While it will provide supplemental heating during shoulder seasons, it is not designed to provide the total heating load for the home during winter. System Overview A multi-zone outdoor unit will be placed in a central location on the back side of the home. This system is sized to handle the current load with enough remaining capacity to add an additional 6,000 BTU head for the second bedroom in the future (a great selling feature). Indoor Unit Locations & Routing TV Room / Kitchen: The indoor unit will be installed to the left of the slider. The lineset will run down through the deck into the unfinished basement, run across, and penetrate out to the outdoor unit. This ensures a clean finish and allows a future contractor to easily refinish the deck around the lineset. Great Room / Living Area: The unit wi
Adam P.
Adam P. Checked in
Installation of a multi-zone mini-split system to provide the main house with priority cooling. Note on Heating: This system is sized and designed primarily for the cooling load. While it will provide supplemental heating during shoulder seasons, it is not designed to provide the total heating load for the home during winter. System Overview A multi-zone outdoor unit will be placed in a central location on the back side of the home. This system is sized to handle the current load with enough remaining capacity to add an additional 6,000 BTU head for the second bedroom in the future (a great selling feature). Indoor Unit Locations & Routing TV Room / Kitchen: The indoor unit will be installed to the left of the slider. The lineset will run down through the deck into the unfinished basement, run across, and penetrate out to the outdoor unit. This ensures a clean finish and allows a future contractor to easily refinish the deck around the lineset. Great Room / Living Area: The unit wi
Hampstead, NH 03841
Merrimack, NH - Completed the Rheem tankless water heater maintenance today. I started off with running a cleaner through it for 40 minutes. Next I flushed 10 gallons of water through it. I cleaned the water inlet screen. I checked incoming gas pressure and that was according to manufacturer specifications. The clients weren't sure if the water filter has ever been changed so I wrote up an estimate to replace the filter and the O-ring. I also inspected all of the drains and fixtures and everything looked great. We will order those parts today and reach out to you when they come in.
Qwentin G.
Qwentin G. Checked in
Completed the Rheem tankless water heater maintenance today. I started off with running a cleaner through it for 40 minutes. Next I flushed 10 gallons of water through it. I cleaned the water inlet screen. I checked incoming gas pressure and that was according to manufacturer specifications. The clients weren't sure if the water filter has ever been changed so I wrote up an estimate to replace the filter and the O-ring. I also inspected all of the drains and fixtures and everything looked great. We will order those parts today and reach out to you when they come in.
Merrimack, NH 03054
Qwentin G.
Qwentin G. Checked in
Completed the plumbing maintenance today. I started off with draining down the water tank. I labeled a bunch of emergency shut offs. I inspected all the drains and fixtures and everything looked great. Lastly I bled the air out of the lines from the kitchen sink. Everything went great!
Pelham, NH 03076
Jack D.
Jack D. Checked in
GSMS HomeClub plumbing visit!
Manchester, NH 03103
Review
Quentin arrived in time, was courteous and professional and answered all my questions.
BJ - Merrimack, NH 03054
Review
Excellent and professional work , all great
Alison - Bedford, NH 03110
Review
Qwentin is awesome, very knowledgeable and an overall good guy
James - Manchester, NH 03104
Review
Excellent!!!
Kathleen - Merrimack, NH 03054
Review
When a GSMS contractor comes to your home, it’s not just another contractor doing a job, it’s a personable experience from someone who truly cares about the neatness and quality of their work to the quality of their relationship with you, the customer… they quickly feel like an extension of your family making you look forward to their visits and not feeling concerned in any way how it’s going to go. Always 5 stars from me and two thumbs up, if I can count my big toes, it’s 4 digits up from me!! 👍👍👍👍🙂🙂
Martin - Stratham, NH 03885
Review
Great work as always
Mark - Hollis, NH 03049
Review
Jack did a super job! Very thorough and competent. I feel like I’m in good hands with GSMS.
BJ - Merrimack, NH 03054
Review
Friendly and transparent. Explained all aspects of the service.
Jeffrey - Nashua, NH 03064
Review
Qwentin is a pleasure to have work at our house. He is friendly, informative, and clearly knows what he is doing.
Barry - Manchester, NH 03109
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
Adam, Quin and Mark did a wonderful job installing my replacement oil boiler and oil tank. I have trusted GSM for 3 installs at my house because of their professionalism, workmanship, honesty, transparency and integrity for how they conduct their family business. Everyone who has worked at my house has always been informative, on time and respectful. I would recommend GSM to anyone who needs to have major plumbing or heating/cooling done in their home. Gina in customer service is the best at relaying information and gets back to you in a timely fashion. Zak is wonderful to work with and the entire team at GSM treats you with kindness. Thank you again for another wonderful experience because when it comes to your home it is one of the largest investments you will make in your life, and I trust GSM to be there for me in the future.
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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