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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 476 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

Qwentin G.
Qwentin G. Checked in
I found that the AC system was low on refrigerant. I added in a pound and a half of r410a refrigerant. The blower motor was squealing a little bit so I added oil to the bearings and the sound went away. Lastly I ran the unit and everything was running great.
Stratham, NH 03885
Review
Qwentin was knowledgeable, friendly, & got the job done quickly.
Kelly - Londonderry, NH 03053
Found that the blower motor capacitor was failing so I replaced it. Checked over everything on the outdoor unit and indoor unit, the system was running good. I noticed that the breaker was loose in the breaker panel and extremely hot so I turned it off and told the client that they need to get an electrician out as soon as possible.
Found that the blower motor capacitor was failing so I replaced it. Checked over everything on the outdoor unit and indoor unit, the system was running good. I noticed that the breaker was loose in the breaker panel and extremely hot so I turned it off and told the client that they need to get an electrician out as soon as possible.
Qwentin G.
Qwentin G. Checked in
Found that the blower motor capacitor was failing so I replaced it. Checked over everything on the outdoor unit and indoor unit, the system was running good. I noticed that the breaker was loose in the breaker panel and extremely hot so I turned it off and told the client that they need to get an electrician out as soon as possible.
Londonderry, NH 03053
Mark D.
Mark D. Checked in
Replacement of failed macerator toilet system with a new Liberty system. Includes new toilet and pumping system. Existing connections must be rated for new unit and have proper venting per building code.
Londonderry, NH 03053
Review
Excellent and professional
Shawn - Gilmanton, NH 03237
Completed the furnace maintenance today. Everything went great. Please see the attached form.
Completed the furnace maintenance today. Everything went great. Please see the attached form.
Qwentin G.
Qwentin G. Checked in
Completed the furnace maintenance today. Everything went great. Please see the attached form.
Windham, NH 03087
Jack D.
Jack D. Checked in
Repair AC by adding 2lbs R22 refrigerant. I highly recommend replacing system or setting up a maintenance visit.
Hooksett, NH 03106
Qwentin G.
Qwentin G. Checked in
I replaced the door gasket and the igniter assembly. I made sure to sniff around the door gasket and make sure there was zero CO present. I tested operation and everything was running perfectly.
Manchester, NH 03102
Completed the boiler maintenance today. Everything went great. Please see the attached form.
Completed the boiler maintenance today. Everything went great. Please see the attached form.
Qwentin G.
Qwentin G. Checked in
Completed the boiler maintenance today. Everything went great. Please see the attached form.
Manchester, NH 03103
Mark D.
Mark D. Checked in
Replaced drain for water equipment. Preventactive maintenance on all heating equipment as well as both thankless water heaters. The boiler in the barn needs a bee low water cut off sensor as it did not deactivate the burner when the test button was pressed. I also noticed the condensation trap to be full of silver metallic particles which indicates the heat exchanger is deteriorating internally. The boiler was left shut off with a red tag as a safeguard.
Moultonborough, NH 03254
Qwentin G.
Qwentin G. Checked in
I found that the unit was low on refrigerant. I added 2 and a half pounds of 410A refrigerant and a UV/Dye. While it was running a 24 volt wire hit the 240 and shorted out the indoor board and the thermostat. It also fried the contactor. I replaced the thermostat, board, contacter and tested operation. Everything was working and the unit was running great. We will be out in the next 2-3 weeks to find the leak on the system.
Manchester, NH 03109
After careful consideration and research, this proposal outlines the complete removal of your existing wood-fired furnace to upgrade your home to an ultra-efficient, fully automated Lennox Hybrid Propane system.

We will be installing the Lennox SLP99 modulating gas furnace paired with the high-efficiency EL18 Heat Pump. This dual-fuel approach gives you the absolute best of both worlds: the heat pump will handle the heating load efficiently during milder weather, and the system will automatically switch over to propane gas heating when the temperatures drop. This is all orchestrated by the Lennox S40 Smart Thermostat to guarantee you the lowest possible energy costs and perfectly even comfort all winter long.

Scope of Work

1. Demolition & System Decommissioning

Removal: We will safely dismantle and remove the existing wood furnace system.

Water Heater Disconnect: We will disconnect and safely cap off the hot water loop that currently runs from the wood boiler to your water heater.
After careful consideration and research, this proposal outlines the complete removal of your existing wood-fired furnace to upgrade your home to an ultra-efficient, fully automated Lennox Hybrid Propane system.

We will be installing the Lennox SLP99 modulating gas furnace paired with the high-efficiency EL18 Heat Pump. This dual-fuel approach gives you the absolute best of both worlds: the heat pump will handle the heating load efficiently during milder weather, and the system will automatically switch over to propane gas heating when the temperatures drop. This is all orchestrated by the Lennox S40 Smart Thermostat to guarantee you the lowest possible energy costs and perfectly even comfort all winter long.

Scope of Work

1. Demolition & System Decommissioning

Removal: We will safely dismantle and remove the existing wood furnace system.

Water Heater Disconnect: We will disconnect and safely cap off the hot water loop that currently runs from the wood boiler to your water heater.
Adam P.
Adam P. Checked in
After careful consideration and research, this proposal outlines the complete removal of your existing wood-fired furnace to upgrade your home to an ultra-efficient, fully automated Lennox Hybrid Propane system. We will be installing the Lennox SLP99 modulating gas furnace paired with the high-efficiency EL18 Heat Pump. This dual-fuel approach gives you the absolute best of both worlds: the heat pump will handle the heating load efficiently during milder weather, and the system will automatically switch over to propane gas heating when the temperatures drop. This is all orchestrated by the Lennox S40 Smart Thermostat to guarantee you the lowest possible energy costs and perfectly even comfort all winter long. Scope of Work 1. Demolition & System Decommissioning Removal: We will safely dismantle and remove the existing wood furnace system. Water Heater Disconnect: We will disconnect and safely cap off the hot water loop that currently runs from the wood boiler to your water heater.
Barrington, NH 03825
Review
Fast resolution
Eric - Exeter, NH 03833
Review
Excellent service, neat and professional
Shawn - Gilmanton, NH 03837
Review
As usual everyone from your company is great. Always the best service.
Scott - Merrimack, NH 03054
Review
Professional, knowledgeable and friendly.. Qwentin from GSMS did a great job with our annual maintenance.. Always uses show coverings, cleans up when he’s done- and tolerates our 100 pound Black Lab who insists on helping!
Mark - Bedford, NH 03110
Review
He was extremely polite and knowledgeable. Outstanding service.
Ryan - Lee, NH 03861
Review
Jack did a great job checking our mini split and explaining how it should operate. He took the time to answer all our questions.
Joe - Nashua, NH 03060
Review
Jack was thorough and answered all questions. He’ll be our requested service tech from now on
Len - Newmarket, NH 03857
Review
It is always great to see Jack! GSMS never disappoints.
Karen - Nashua, NH 03063
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.

Trusted Quality & Service