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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 382 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
Found that the evapartor coil has been leaking and leaked all the refrigerant out. The client approved the estimate to replace the evaporator coil. We will be reaching out with when we can come and replace it.
Manchester, NH 03104
Jack D.
Jack D. Checked in
Error 11. Lightning storm could've caused issue. Everything checked out fine. Thank you.
Manchester, NH 03104
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance today. I started off with cleaning the indoor coil with coil cleaner. I flushed and brushed the trap with cleaner. Next I went outside and I cleaned the outdoor units coil with coil cleaner and water. I checked the capacitor and all the electrical connections, everything looked good. Lastly I connected my gauges and ran the unit in cooling. Everything was running great. The client mentioned that the sink furthest from the tankless water heater takes a while to get hot and has reduced pressure. I told her that we would let her know about scheduling someone to come out to take a look at it.
Manchester, NH 03104
Jack D.
Jack D. Checked in
GHC HOMECLUB AC VISIT.
Nashua, NH 03062
Estimate
Estimate
Jack D.
Jack D. Checked in
Estimate
Nashua, NH 03062
Qwentin G.
Qwentin G. Checked in
Completed the mini split maintenances today. I started off with washing both outdoor units coils with water. I cleaned the outside of the units with a cleaner and a rag. I checked electrical connections and everything was good. I went inside next and I cleaned both of the indoor heads coils with coil cleaner. I washed the filters with soap and water. I replaced the two return filters for the unit in the attic. Lastly I ran all the units in max heating and my supply temperature was 120°. Everything was running very good!
Exeter, NH 03833
Mark D.
Mark D. Checked in
Sewer main clogged. Stuck open flapper on second floor caused water to come out of toilet near kitchen. Need snake and camera inspection. Thank you!
Amherst, NH 03031
Nashua, NH - Proposal to replace the three existing A/C systems at Montcalm Properties: 
System A (serving the second floor of Corriveau Insurance Agency)
System B (serving the third floor area for the church / conference room)
System C (serving the front offices of the third floor).

System A (Corriveau Insurance Agency - Second Floor): This will be a direct replacement. The existing wall return grille in the hallway space will be upsized to a larger size to provide proper airflow for the new system. Due to installation limitations, the existing lineset for System A will remain in place and be thoroughly flushed and cleaned out for the new unit.

System B (Church / Conference Room - Third Floor): This will be a direct replacement. This system is sized to handle capacity for either the conference room or church space. System B will receive a new lineset.

System C (Front Offices - Third Floor): This system will be upsized to a 5-ton capacity. Two return grilles in the hallway will be replaced and i
Mark D.
Mark D. Checked in
Proposal to replace the three existing A/C systems at Montcalm Properties: System A (serving the second floor of Corriveau Insurance Agency) System B (serving the third floor area for the church / conference room) System C (serving the front offices of the third floor). System A (Corriveau Insurance Agency - Second Floor): This will be a direct replacement. The existing wall return grille in the hallway space will be upsized to a larger size to provide proper airflow for the new system. Due to installation limitations, the existing lineset for System A will remain in place and be thoroughly flushed and cleaned out for the new unit. System B (Church / Conference Room - Third Floor): This will be a direct replacement. This system is sized to handle capacity for either the conference room or church space. System B will receive a new lineset. System C (Front Offices - Third Floor): This system will be upsized to a 5-ton capacity. Two return grilles in the hallway will be replaced and i
Nashua, NH 03060
Furnace switch was off due to the unit being red tagged. I made sure both gas valves were off and I unwired the W wire from the board. The AC was working good. I noticed that behind the toilet on the second floor water was leaking. I also noticed a pipe in the basement is leaking.
Furnace switch was off due to the unit being red tagged. I made sure both gas valves were off and I unwired the W wire from the board. The AC was working good. I noticed that behind the toilet on the second floor water was leaking. I also noticed a pipe in the basement is leaking.
Qwentin G.
Qwentin G. Checked in
Furnace switch was off due to the unit being red tagged. I made sure both gas valves were off and I unwired the W wire from the board. The AC was working good. I noticed that behind the toilet on the second floor water was leaking. I also noticed a pipe in the basement is leaking.
Manchester, NH 03104
Mark D.
Mark D. Checked in
We will safely remove your existing, cracked double-basin wash sink and upgrade your basement laundry area with a new, durable Mustee utility tub. During this installation, our team will also upgrade the surrounding water lines and reconfigure the drainage to a highly reliable, gravity-fed system. Scope of Work: Demolition & Removal: Disconnect and carefully remove the existing leaking double-basin sink. (The existing back wall will remain in place and untouched). New Sink Installation: Provide and install a new Mustee 40-inch floor-mount utility wash tub. Faucet & Water Lines: Provide and install a standard center-set, polished chrome utility faucet. We will modify the existing copper water piping and install brand-new, reliable shutoff valves for the new sink. Drainage Reconfiguration (Pump Elimination): Originally, we discussed installing a mechanical drain pump to handle the wastewater. However, after our Master Plumber reviewed your specific plumbing stack, we engineered a be
Manchester, NH 03102
Review
Seems like a thorough inspection and update....great job Qwentin.
Phil - Windham, NH 03087
Review
The service was really good. He did great work.
Ann - Derry, NH 03038
Review
Always GREAT service
37 - Manchester, NH 03103
Review
Qwentin did a great job. Highly recommend him.
Gary - Stratham, NH 03885
Review
Excellent, prompt service
John - Hollis, NH 03049
Review
It’s always a pleasure when Qwentin stops by; a polite and personable young man who is an asset to the formidable GSMS team who did another super, duper jobby! 😉 Hope he had a great time at the party celebrating multiple birthdays this weekend?! Cheers 👍🙂🥃🥃
Martin - Stratham, NH 03885
Review
Adam & Quinn just left after finishing the installation of my new Lennox Air Conditioning unit. As always, they are very personable and professional. Adam explains everything to me before he leaves and I am very comfortable with my new system. I would not hesitate to recommend GSMS and have done so in the past.
Deb - Hooksett, NH 03106
Review
Qwentin was thorough and diagnosed the issue
Gary - Stratham, NH 03885
Review
Great service
Lori B - Hollis, NH 03049
Review
Excellent Service
Ronald - 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
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