This Fall Only: 0% Financing for Your New System
Request Service Call Now Contact Us Coupons

Our Service Area

Book Online

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 330 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

Completed the gas boiler maintenance. Started off with checking all the electric connections and everything looks good. I pulled and cleaned the burner tubes. Vacuumed out the burner box as well. I cleaned the flame sensor. I checked incoming and outgoing gas pressures and those looked good. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. I found that the expansion tank has failed. I found that the air eliminating vent is leaking water. I also found that the pressure relief valve is sticking. The temperature and pressure gauge has failed as well. I sent over an estimate for those replacements.
Completed the gas boiler maintenance. Started off with checking all the electric connections and everything looks good. I pulled and cleaned the burner tubes. Vacuumed out the burner box as well. I cleaned the flame sensor. I checked incoming and outgoing gas pressures and those looked good. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. I found that the expansion tank has failed. I found that the air eliminating vent is leaking water. I also found that the pressure relief valve is sticking. The temperature and pressure gauge has failed as well. I sent over an estimate for those replacements.
Jack D.
Jack D. Checked in
Completed the gas boiler maintenance. Started off with checking all the electric connections and everything looks good. I pulled and cleaned the burner tubes. Vacuumed out the burner box as well. I cleaned the flame sensor. I checked incoming and outgoing gas pressures and those looked good. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great. I found that the expansion tank has failed. I found that the air eliminating vent is leaking water. I also found that the pressure relief valve is sticking. The temperature and pressure gauge has failed as well. I sent over an estimate for those replacements.
Manchester, NH 03102
Mark D.
Mark D. Checked in
Replaced trap on water system,it had 2 lines from basement HVAC system and dehumidifier drain line going into air gap on water system line.When water softener back washed it splash against the other lines.Installed 2"trap with 2" wye to separate the lines.Got model numbers off radiant thermostat to look up new ones.Have to do more research on floor heating odor.
Bedford, NH 03110
The first level zone was frozen in multiple locations. I had to go around with a heat gun and thaw them out. I was able to get everything thawed. The windows were cracked near the affected areas. I ensured both zones were functioning properly. Thank you. I performed a PM on the new boiler we installed as well.
The first level zone was frozen in multiple locations. I had to go around with a heat gun and thaw them out. I was able to get everything thawed. The windows were cracked near the affected areas. I ensured both zones were functioning properly. Thank you. I performed a PM on the new boiler we installed as well.
Jack D.
Jack D. Checked in
The first level zone was frozen in multiple locations. I had to go around with a heat gun and thaw them out. I was able to get everything thawed. The windows were cracked near the affected areas. I ensured both zones were functioning properly. Thank you. I performed a PM on the new boiler we installed as well.
Manchester, NH 03102
I completed the gas boiler maintenance today. Started off with checking all the electrical connections and everything looked good. I pulled the heat exchanger cover off and cleaned inside of the heat exchanger with vinegar and water. I vacuumed out the heat exchanger and the inside of the boiler as well. I cleaned the flame sensor. I ran the boiler in low and high fire. Formed a combustion analyzer test that checks the boiler CO, CO2 and oxygen levels and it was in manufacturer specifications. Found that the air vent on the flat plate was leaking and should be replaced. We will send over a estimate for that.
I completed the gas boiler maintenance today. Started off with checking all the electrical connections and everything looked good. I pulled the heat exchanger cover off and cleaned inside of the heat exchanger with vinegar and water. I vacuumed out the heat exchanger and the inside of the boiler as well. I cleaned the flame sensor. I ran the boiler in low and high fire. Formed a combustion analyzer test that checks the boiler CO, CO2 and oxygen levels and it was in manufacturer specifications. Found that the air vent on the flat plate was leaking and should be replaced. We will send over a estimate for that.
Jack D.
Jack D. Checked in
I completed the gas boiler maintenance today. Started off with checking all the electrical connections and everything looked good. I pulled the heat exchanger cover off and cleaned inside of the heat exchanger with vinegar and water. I vacuumed out the heat exchanger and the inside of the boiler as well. I cleaned the flame sensor. I ran the boiler in low and high fire. Formed a combustion analyzer test that checks the boiler CO, CO2 and oxygen levels and it was in manufacturer specifications. Found that the air vent on the flat plate was leaking and should be replaced. We will send over a estimate for that.
Manchester, NH 03102
Mark D.
Mark D. Checked in
Replaced expansion tank and purged zones
Candia, NH 03034
Qwentin G.
Qwentin G. Checked in
The pressure relief valve started to leak. I also found that the expansion tank had failed. I replaced the pressure relief valve and the expansion tank. Refilled the boiler and tested operation. Return water came back very hot.
Manchester, NH 03103
Took measurements for furnace replacement
Took measurements for furnace replacement
Mark D.
Mark D. Checked in
Took measurements for furnace replacement
Loudon, NH 03307
Completed the gas boiler maintenance today. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the burner tubes. I vacuumed the burner tubs and the burner box. I noticed that the expansion tank had failed and two out of the three high vents were leaking as well. The pressure relief valve was leaking water out of it. The client approved the estimate for those parts to be replaced. I tested incoming and outgoing gas pressures and everything was according to manufacturer specifications. I 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. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the burner tubes. I vacuumed the burner tubs and the burner box. I noticed that the expansion tank had failed and two out of the three high vents were leaking as well. The pressure relief valve was leaking water out of it. The client approved the estimate for those parts to be replaced. I tested incoming and outgoing gas pressures and everything was according to manufacturer specifications. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great.
Jack D.
Jack D. Checked in
Completed the gas boiler maintenance today. I started off with checking all the wiring connections and everything looked good. I pulled and cleaned the burner tubes. I vacuumed the burner tubs and the burner box. I noticed that the expansion tank had failed and two out of the three high vents were leaking as well. The pressure relief valve was leaking water out of it. The client approved the estimate for those parts to be replaced. I tested incoming and outgoing gas pressures and everything was according to manufacturer specifications. I performed a combustion analyzer test that checks the CO, CO2 and oxygen levels and the boiler was running great.
Nashua, NH 03060
Review
GSMS is a great Family owned Company to work with. I am very happy with my new Boiler heating system. Zak explained all my options and was prompt to call back with any questions I had. Adam, the lead Technician was outstanding with the installation. Gina was great coordinating the scheduling. Mark also came out for a final inspection. You can tell they take pride in their work! I would definitely recommend them.
Sandy - Nashua, NH 03060
Jack D.
Jack D. Checked in
I adjusted multiple settings on the thermostat to tightly maintain the setpoint. You will notice a difference in comfort. Thank you!
Manchester, NH 03102
Mark D.
Mark D. Checked in
Replaced flapper with factory one
Nashua, NH 03064
Review
Jack was prompt and did a great job tuning our furnace.
Vincent - Nashua, NH 03064
Review
Very happy with the job done.
Barb - Merrimack, NH 03054
Review
Did annual maintenance on the furnaces so we are all set for winter!
Lori B - Nashua, NH 03060
Review
Did annual maintenance on the furnaces so we are all set for winter!
Lori B - Nashua, NH 03060
Review
Great seeing Mark again.
Bob - Nashua, NH 03062
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
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
  • Best Of The Best
  • Expertise 2024
  • Lennox Premier Dealer
  • Mitsubishi Diamond Contractor
  • Rinnai