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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 370 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

Found that some wires were chewed by a mouse. Waiting for Mitsubishi to call me back to get availability on parts and or a new unit. We will let you know as soon as we hear back from them.
Found that some wires were chewed by a mouse. Waiting for Mitsubishi to call me back to get availability on parts and or a new unit. We will let you know as soon as we hear back from them.
Qwentin G.
Qwentin G. Checked in
Found that some wires were chewed by a mouse. Waiting for Mitsubishi to call me back to get availability on parts and or a new unit. We will let you know as soon as we hear back from them.
Weare, NH 03281
Jack D.
Jack D. Checked in
Found R&W shorted. I rewired using the cooling wire. We will send estimate to replace thermostat cable.
Hudson, NH 03051
Nashua, NH - This is the ultimate purity option, using advanced "smart" technology and a space-saving design.

Scope of Work: Install a DROP Smart RO unit horizontally in the cabinet beneath the kitchen sink.

Space-Saving Design: Because this unit is an all-in-one system, it does not require a separate large holding tank. We will install it horizontally in front of the garbage disposal to maximize your remaining cabinet space.

Primary Benefit: Removes up to 99% of contaminants (lead, fluoride, arsenic, and PFAS) while delivering the highest quality drinking water available.

Smart Features: * Built-in Leak Protection: Automatically shuts off the water if it detects a leak under the sink.

Real-Time Monitoring: Sends alerts to your phone via the DROP App when it's time to change filters.

UV Disinfection: Includes a built-in UV stage to ensure the water is bacteriologically safe.

Utility Requirements: This unit requires a 110V electrical outlet to power the internal pumps and smart features.

Gra
Mark D.
Mark D. Checked in
This is the ultimate purity option, using advanced "smart" technology and a space-saving design. Scope of Work: Install a DROP Smart RO unit horizontally in the cabinet beneath the kitchen sink. Space-Saving Design: Because this unit is an all-in-one system, it does not require a separate large holding tank. We will install it horizontally in front of the garbage disposal to maximize your remaining cabinet space. Primary Benefit: Removes up to 99% of contaminants (lead, fluoride, arsenic, and PFAS) while delivering the highest quality drinking water available. Smart Features: * Built-in Leak Protection: Automatically shuts off the water if it detects a leak under the sink. Real-Time Monitoring: Sends alerts to your phone via the DROP App when it's time to change filters. UV Disinfection: Includes a built-in UV stage to ensure the water is bacteriologically safe. Utility Requirements: This unit requires a 110V electrical outlet to power the internal pumps and smart features. Gra
Nashua, NH 03062
Jack D.
Jack D. Checked in
Investigate ticking noise caused by second floor sink. I found the pantry shelves to be screwed into the 3" stack going upstairs. I cut out the section and replaced it. Tested for leaks and all set. Thank you!
Manchester, NH 03104
Qwentin G.
Qwentin G. Checked in
I called in to tech support and confirmed that the blower motor is starting to fail. I need to call around and find out if the parts would be covered under warranty. We will be reaching out to soon to let you know if they're under warranty and regarding the estimate.
Bedford, NH 03110
Completed the plumbing visit today. I started off with doing the maintenance on the Rinnai tankless water heater. I started off with running a cleaner through it for 35 minutes. After that I flushed 10 gallons of water through it. I cleaned the water inlet screen which was very dirty. I vacuumed out the inside and vacuumed the filter. I checked incoming gas pressure and that was according to manufacturer specifications. I checked all the fixtures and drains in the house and everything looked great!
Completed the plumbing visit today. I started off with doing the maintenance on the Rinnai tankless water heater. I started off with running a cleaner through it for 35 minutes. After that I flushed 10 gallons of water through it. I cleaned the water inlet screen which was very dirty. I vacuumed out the inside and vacuumed the filter. I checked incoming gas pressure and that was according to manufacturer specifications. I checked all the fixtures and drains in the house and everything looked great!
Qwentin G.
Qwentin G. Checked in
Completed the plumbing visit today. I started off with doing the maintenance on the Rinnai tankless water heater. I started off with running a cleaner through it for 35 minutes. After that I flushed 10 gallons of water through it. I cleaned the water inlet screen which was very dirty. I vacuumed out the inside and vacuumed the filter. I checked incoming gas pressure and that was according to manufacturer specifications. I checked all the fixtures and drains in the house and everything looked great!
Amherst, NH 03031
Review
We use GSMS for all our bathroom remodels! Mark, Jack and Zak have been awesome to work with.
Peggy - Granite State Home Improvements - Strafford, NH 03884
Review
Excellent service.
Kathleen - Merrimack, NH 03054
Jack D.
Jack D. Checked in
Try to find "pump" noise.
Merrimack, NH 03054
Qwentin G.
Qwentin G. Checked in
Completed the mini split maintenance. Cleaned the coils with coil cleaner and water. Washed the filters. Turned them all back on to heat.
Manchester, NH 03109
Completed the furnace maintenance. Checked all the wiring. Replaced the air filter. Cleaned the flame sensor. Checked incoming and out going gas pressures. Performed the combustion analyzer test. Everything looked great.
Completed the furnace maintenance. Checked all the wiring. Replaced the air filter. Cleaned the flame sensor. Checked incoming and out going gas pressures. Performed the combustion analyzer test. Everything looked great.
Qwentin G.
Qwentin G. Checked in
Completed the furnace maintenance. Checked all the wiring. Replaced the air filter. Cleaned the flame sensor. Checked incoming and out going gas pressures. Performed the combustion analyzer test. Everything looked great.
Manchester, NH 03109
Scope of Work

1. Laundry Relocation
Water & Waste: Relocate hot and cold water lines, washing machine drain, and vent piping into the newly built closet area.
Framing Coordination: Adjust framing as discussed (specifically the double stud) to accommodate the new plumbing layout.
Exclusions: This quote does not include the installation of dryer venting or gas piping for the dryer.

2. Shower Installation
Drainage: Install a new 2" shower drain, pulling the location back to the center of the new shower floor layout. Connect to the existing vent system.
Water Supply: Route new hot and cold water lines.
Valve: Install a standard pressure-balancing shower valve and a drop ear elbow for a single shower head outlet.

3. Toilet (Same Location)
Drainage: Install a new 3" toilet flange to ensure a proper seal.
Water Supply: Install a new cold water supply line and shut-off valve.

4. Vanity (Same Location)
Rough-in: Install two (2) new water supply valves and adjust the drain trap.
Trim: Connec
Scope of Work

1. Laundry Relocation
Water & Waste: Relocate hot and cold water lines, washing machine drain, and vent piping into the newly built closet area.
Framing Coordination: Adjust framing as discussed (specifically the double stud) to accommodate the new plumbing layout.
Exclusions: This quote does not include the installation of dryer venting or gas piping for the dryer.

2. Shower Installation
Drainage: Install a new 2" shower drain, pulling the location back to the center of the new shower floor layout. Connect to the existing vent system.
Water Supply: Route new hot and cold water lines.
Valve: Install a standard pressure-balancing shower valve and a drop ear elbow for a single shower head outlet.

3. Toilet (Same Location)
Drainage: Install a new 3" toilet flange to ensure a proper seal.
Water Supply: Install a new cold water supply line and shut-off valve.

4. Vanity (Same Location)
Rough-in: Install two (2) new water supply valves and adjust the drain trap.
Trim: Connec
Mark D.
Mark D. Checked in
Scope of Work 1. Laundry Relocation Water & Waste: Relocate hot and cold water lines, washing machine drain, and vent piping into the newly built closet area. Framing Coordination: Adjust framing as discussed (specifically the double stud) to accommodate the new plumbing layout. Exclusions: This quote does not include the installation of dryer venting or gas piping for the dryer. 2. Shower Installation Drainage: Install a new 2" shower drain, pulling the location back to the center of the new shower floor layout. Connect to the existing vent system. Water Supply: Route new hot and cold water lines. Valve: Install a standard pressure-balancing shower valve and a drop ear elbow for a single shower head outlet. 3. Toilet (Same Location) Drainage: Install a new 3" toilet flange to ensure a proper seal. Water Supply: Install a new cold water supply line and shut-off valve. 4. Vanity (Same Location) Rough-in: Install two (2) new water supply valves and adjust the drain trap. Trim: Connec
Strafford, NH 03884
Review
Amazing service as usual!!!
Scott - Merrimack, NH 03054
Review
Professional service
Paul - Nashua, NH 03062
Review
Qwentin, once again, did a exceptional job. He is always professional, courteous and gets the job done right and quickly. Qwentin and GSMS never let me down!
Jared - Hooksett, NH 03106
Review
Full explanation of the work to be completed and suggestions for future services . Answered all my questions. Very professional and knowledgeable.
Paul - Nashua, NH 03062
Review
Qwentin is professional, friendly, and efficient! Excellent service.
Ginger - Hollis, NH 03049
Review
Both guys very helpful & solved the problem
Steve - Nashua, NH 03064
Review
Fantastic service
Laszlo - Manchester, NH 03104
Review
Very knowledgeable & very helpful
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 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.

Trusted Quality & Service