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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 324 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

Jack D.
Jack D. Checked in
Boiler maintenance for apt #3. Everything went great on
Nashua, NH 03060
I completed the steam oil boiler maintenance today. I replaced both of the oil filters and the pump strainer. I pulled the cleanout off of the boiler and brushed and vacuumed out the heat exchanger. I cleaned the screen on the auto fill valve. I started up the unit and performed a smoke test and there was zero smoke. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. We have to come back out to complete the other oil boiler maintenance, the furnace maintenance and replace the oil nozzle on the steam boiler with a 1.25x60B nozzle.
I completed the steam oil boiler maintenance today. I replaced both of the oil filters and the pump strainer. I pulled the cleanout off of the boiler and brushed and vacuumed out the heat exchanger. I cleaned the screen on the auto fill valve. I started up the unit and performed a smoke test and there was zero smoke. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. We have to come back out to complete the other oil boiler maintenance, the furnace maintenance and replace the oil nozzle on the steam boiler with a 1.25x60B nozzle.
Qwentin G.
Qwentin G. Checked in
I completed the steam oil boiler maintenance today. I replaced both of the oil filters and the pump strainer. I pulled the cleanout off of the boiler and brushed and vacuumed out the heat exchanger. I cleaned the screen on the auto fill valve. I started up the unit and performed a smoke test and there was zero smoke. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. We have to come back out to complete the other oil boiler maintenance, the furnace maintenance and replace the oil nozzle on the steam boiler with a 1.25x60B nozzle.
Milford, NH 03055
Called State to get warranty number for new heater,bad refrigerant system
Called State to get warranty number for new heater,bad refrigerant system
Mark D.
Mark D. Checked in
Called State to get warranty number for new heater,bad refrigerant system
Madbury, NH 03823
Boiler maintenance for apartment #4. I had to replace the pilot tube because it was kinked and leaking at the pilot assembly. There were no other repairs thst were found to be neended during today servicing. Thank you!
Boiler maintenance for apartment #4. I had to replace the pilot tube because it was kinked and leaking at the pilot assembly. There were no other repairs thst were found to be neended during today servicing. Thank you!
Jack D.
Jack D. Checked in
Boiler maintenance for apartment #4. I had to replace the pilot tube because it was kinked and leaking at the pilot assembly. There were no other repairs thst were found to be neended during today servicing. Thank you!
Nashua, NH 03060
I completed the gas furnace maintenance today. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the flame sensor. I checked the capacitor and that was inspect. I replaced the air filter with a 20 x 20 x 1 filter. I checked incoming and outgoing gas pressures and everything was according to manufacturer specifications. Ran the unit and performed a combustion analyzer test that check for CO, CO2 and oxygen levels and everything was running great.
I completed the gas furnace maintenance today. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the flame sensor. I checked the capacitor and that was inspect. I replaced the air filter with a 20 x 20 x 1 filter. I checked incoming and outgoing gas pressures and everything was according to manufacturer specifications. Ran the unit and performed a combustion analyzer test that check for CO, CO2 and oxygen levels and everything was running great.
Qwentin G.
Qwentin G. Checked in
I completed the gas furnace maintenance today. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the flame sensor. I checked the capacitor and that was inspect. I replaced the air filter with a 20 x 20 x 1 filter. I checked incoming and outgoing gas pressures and everything was according to manufacturer specifications. Ran the unit and performed a combustion analyzer test that check for CO, CO2 and oxygen levels and everything was running great.
Nashua, NH 03060
Qwentin G.
Qwentin G. Checked in
Did a safety inspection of the Empire furnace. Sniffed all the gas joints and no gas leaks. Sniffed for CO around the unit and the vent and zero CO. Tenant mention that they have to relight the pilot often and that the blower motor is making a sound. Pilot assembly could be going out because of a downdraft or is becoming faulty. if issue keeps happening, we recommend to replace the pilot assembly. Blower motor sound isn’t enough for cause of concern.
Nashua, NH 03060
Boiler maintenance on apartment 6. Everything on this boiler went well during visit. There are no reccomended repairs that were found. Thank you.
Boiler maintenance on apartment 6. Everything on this boiler went well during visit. There are no reccomended repairs that were found. Thank you.
Jack D.
Jack D. Checked in
Boiler maintenance on apartment 6. Everything on this boiler went well during visit. There are no reccomended repairs that were found. Thank you.
Nashua, NH 03060
Mark D.
Mark D. Checked in
Had to change thermocouple
Manchester, NH 03102
Completed the gas boiler maintenance today for unit three. Pulled the burner tubes and cleaned them. Vacuumed out the burner box. Checked the electrical connections and everything looked good. Checked all the boiler trim and most of it got replaced last year. Ran the boiler and performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great.
Completed the gas boiler maintenance today for unit three. Pulled the burner tubes and cleaned them. Vacuumed out the burner box. Checked the electrical connections and everything looked good. Checked all the boiler trim and most of it got replaced last year. Ran the boiler and performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great.
Qwentin G.
Qwentin G. Checked in
Completed the gas boiler maintenance today for unit three. Pulled the burner tubes and cleaned them. Vacuumed out the burner box. Checked the electrical connections and everything looked good. Checked all the boiler trim and most of it got replaced last year. Ran the boiler and performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great.
Nashua, NH 03060
Boiler maintenance today for apartment #2. Everything was great. The only repair I found was an expansion tank that is starting to fail due to water in the air side. I reccomend replacing the relief valve at the same time. Thank you.
Boiler maintenance today for apartment #2. Everything was great. The only repair I found was an expansion tank that is starting to fail due to water in the air side. I reccomend replacing the relief valve at the same time. Thank you.
Jack D.
Jack D. Checked in
Boiler maintenance today for apartment #2. Everything was great. The only repair I found was an expansion tank that is starting to fail due to water in the air side. I reccomend replacing the relief valve at the same time. Thank you.
Nashua, NH 03060
Review
As always, your guys are on time, polite, efficient and friendly. No worries when any of your crew is here, or at the office texting. Thank you GSMS. Susan
Susan - Salem, NH 03079
Review
Excellent service!
Darlene - Manchester, NH 03109
Review
Very happy with the service. Technician was great!!!!
Susan - Hooksett, NH 03106
Review
Jack was awesome! Showed up for an emergency on a Sunday and was able to remedy the situation in no time! He took the time to explain everything throughout the process and was very thorough and efficient!
Chris - Barrington, NH 03825
Review
Completed job in a timely fashion attention to detail would hire again
Edward - Goffstown, NH 03045
Review
👍
Guimont - Manchester, NH 03103
Review
Home club member. Always great customer service from scheduling staff to HVAC technicians. Today, received maintenance furnace service from Qwentin Gauvin. Trustworthy, genuine and service oriented technician. Appreciate his efforts.
Manchester residential customer - Manchester, NH 03104
Review
Excellent service!
Travis - Concord, NH 03301
Review
Service
Guimont - Manchester, NH 03103
Review
Excellent Service!
E Z - Manchester, NH 03102
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