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 320 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

Deerfield, NH - The vent had a slight back pitch that collected water. There was a bunch of dead wasps in there as well. I cut the vent at 2 different sections to clean it out. I had to pull the induced to clean it. I also had to clean a few condensate hoses inside of the furnace as well. I checked combustion at the end and both vent reconnections for leaks. All set, thank you!
Jack D.
Jack D. Checked in
The vent had a slight back pitch that collected water. There was a bunch of dead wasps in there as well. I cut the vent at 2 different sections to clean it out. I had to pull the induced to clean it. I also had to clean a few condensate hoses inside of the furnace as well. I checked combustion at the end and both vent reconnections for leaks. All set, thank you!
Deerfield, NH 03037
Hudson, NH - I found that the drain line was extremely clogged from algae growth overtime. I flushed the line with a gallon of cleaner. I hooked up my vacuum to the line and ran cleaner about 10 different times. I gave the client some options if this happens again in the future. The client wanted to wait till next year to do the furnace maintenance so we will see him at the beginning of next year to do the water heater maintenance.
Qwentin G.
Qwentin G. Checked in
I found that the drain line was extremely clogged from algae growth overtime. I flushed the line with a gallon of cleaner. I hooked up my vacuum to the line and ran cleaner about 10 different times. I gave the client some options if this happens again in the future. The client wanted to wait till next year to do the furnace maintenance so we will see him at the beginning of next year to do the water heater maintenance.
Hudson, NH 03051
Jack D.
Jack D. Checked in
Triangle Tube recall repairs. Install all necessary hardware to ensure safe operation of boiler. Tested everything.multiple times and you are all set. We will find the missing parts for the service kit and contact you when we hear.
Manchester, NH 03102
I completed the gas boiler maintenance today. Everything looked good on the boiler. A lot of new stuff was replaced recently on it. I ran the unit and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was running great. The gasket on the heat exchanger will need to be replaced but the one on it right now is in a safe condition. I also found that the pressure and temperature gauge was acting up so that will be replaced as well. Completed the gas furnace maintenance on the second floor. I pulled the air filter and that was very clean. I checked the wiring connections and the capacitor and everything looked good. I pulled and cleaned the flame sensor. I tested incoming and outgoing gas pressures and they were low so I had to adjust the regulator at the tank. Performed a combustion analyzing test and all my readings looked good as well. Client mentioned how her water heater in the basement has sooted up in the past, so I ran it and pulled a combu
I completed the gas boiler maintenance today. Everything looked good on the boiler. A lot of new stuff was replaced recently on it. I ran the unit and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was running great. The gasket on the heat exchanger will need to be replaced but the one on it right now is in a safe condition. I also found that the pressure and temperature gauge was acting up so that will be replaced as well. Completed the gas furnace maintenance on the second floor. I pulled the air filter and that was very clean. I checked the wiring connections and the capacitor and everything looked good. I pulled and cleaned the flame sensor. I tested incoming and outgoing gas pressures and they were low so I had to adjust the regulator at the tank. Performed a combustion analyzing test and all my readings looked good as well. Client mentioned how her water heater in the basement has sooted up in the past, so I ran it and pulled a combu
Qwentin G.
Qwentin G. Checked in
I completed the gas boiler maintenance today. Everything looked good on the boiler. A lot of new stuff was replaced recently on it. I ran the unit and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was running great. The gasket on the heat exchanger will need to be replaced but the one on it right now is in a safe condition. I also found that the pressure and temperature gauge was acting up so that will be replaced as well. Completed the gas furnace maintenance on the second floor. I pulled the air filter and that was very clean. I checked the wiring connections and the capacitor and everything looked good. I pulled and cleaned the flame sensor. I tested incoming and outgoing gas pressures and they were low so I had to adjust the regulator at the tank. Performed a combustion analyzing test and all my readings looked good as well. Client mentioned how her water heater in the basement has sooted up in the past, so I ran it and pulled a combu
Milford, NH 03055
Review
Completed job in a timely fashion attention to detail would hire again
Edward - Goffstown, NH 03045
Review
👍
Guimont - Manchester, NH 03103
Jack D.
Jack D. Checked in
3 boiler maintenances. Each boiler needed expansion tank, relief valve, and air vent. Drain each boiler. Purge air and make sure no air. All set thank you!
Manchester, NH 03103
Mark D.
Mark D. Checked in
Mike install data logger
Windham, NH 03087
Qwentin G.
Qwentin G. Checked in
Replaced both of the control boards. I found that a mouse chewed through one of the wires on the display board. I put a piece of steel wool and siliconed the hole where the line set comes through. Turned the unit on and everything was working great.
Barrington, NH 03825
Mark D.
Mark D. Checked in
Replace bad pro press 90,look at his toe kick heater,he is going to open up kitchen floor so I can get at pipesintalled ks 2008 toe kick heater
Goffstown, NH 03045
I started off with replacing the burner tubes for the furnace in the basement. I cycled the unit about 10 times to make sure that it was firing off good. I performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything looked good. Next I replace the 16 x 25 x 5 air bear filter in the closet upstairs. The ERV in the basement was disconnected at some point and there is no drain line present. I told the client that we can come back and connect the drain line and complete the maintenance on the ERV so then we can turn it on for him.
I started off with replacing the burner tubes for the furnace in the basement. I cycled the unit about 10 times to make sure that it was firing off good. I performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything looked good. Next I replace the 16 x 25 x 5 air bear filter in the closet upstairs. The ERV in the basement was disconnected at some point and there is no drain line present. I told the client that we can come back and connect the drain line and complete the maintenance on the ERV so then we can turn it on for him.
Qwentin G.
Qwentin G. Checked in
I started off with replacing the burner tubes for the furnace in the basement. I cycled the unit about 10 times to make sure that it was firing off good. I performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything looked good. Next I replace the 16 x 25 x 5 air bear filter in the closet upstairs. The ERV in the basement was disconnected at some point and there is no drain line present. I told the client that we can come back and connect the drain line and complete the maintenance on the ERV so then we can turn it on for him.
Deerfield, NH 03037
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
I completed the gas furnace maintenance today. I started off checking all the electrical connections and everything looked good. Next, I pulled the flame sensor and I cleaned it. The air filter is a one year filter so for the AC maintenance we will replace it. I checked the incoming and outgoing gas pressures and everything was according to manufacture specifications. Lastly, I ran the unit in high and low fire and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was according to manufacture specifications as well. When I was talking to the client, she was saying that one of the fixtures that is the second closest will take about 2 to 3 minutes to get hot water too. I told her we would look into it for her.
I completed the gas furnace maintenance today. I started off checking all the electrical connections and everything looked good. Next, I pulled the flame sensor and I cleaned it. The air filter is a one year filter so for the AC maintenance we will replace it. I checked the incoming and outgoing gas pressures and everything was according to manufacture specifications. Lastly, I ran the unit in high and low fire and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was according to manufacture specifications as well. When I was talking to the client, she was saying that one of the fixtures that is the second closest will take about 2 to 3 minutes to get hot water too. I told her we would look into it for her.
Qwentin G.
Qwentin G. Checked in
I completed the gas furnace maintenance today. I started off checking all the electrical connections and everything looked good. Next, I pulled the flame sensor and I cleaned it. The air filter is a one year filter so for the AC maintenance we will replace it. I checked the incoming and outgoing gas pressures and everything was according to manufacture specifications. Lastly, I ran the unit in high and low fire and performed a combustion analyzer test that checks for CO, CO2 and oxygen levels and everything was according to manufacture specifications as well. When I was talking to the client, she was saying that one of the fixtures that is the second closest will take about 2 to 3 minutes to get hot water too. I told her we would look into it for her.
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
Quick service call to replace thermostat. Done in about 15 minutes, explained the workings. Very satisfied Great service as usual
Joseph - Merrimack, NH 03054
Review
Our furnace kept shutting off. Mark identified the issue and resolved the problem. Very much appreciate the service!
Oakwood Prop - Milford, NH 03055
Review
Jack was polite and very neat.
Sharon - Merrimack, NH 03054
Review
We have been working with GSMS for 8 years. They provide the best service for installs and maintenance. The people are very professional, friendly and do great work. Today Qwentin was the tech doing the service maintenance. This young man came at the time scheduled, knew what he was doing and did excellent work. If you are in need for heating, air conditioning and plumbing work, this is the company for you!
Claire - 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
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