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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 374 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

Primary side of transformer shorted out. Caused by power issue on 3/17. I replaced and tested operation. We will order limit switches to replace to help prevent intermittent low voltage short issue.
Primary side of transformer shorted out. Caused by power issue on 3/17. I replaced and tested operation. We will order limit switches to replace to help prevent intermittent low voltage short issue.
Jack D.
Jack D. Checked in
Primary side of transformer shorted out. Caused by power issue on 3/17. I replaced and tested operation. We will order limit switches to replace to help prevent intermittent low voltage short issue.
Londonderry, NH 03053
Jack D.
Jack D. Checked in
Shower valve, 2 new space kick heaters, bleed lines.
Manchester, NH 03104
Project Overview Supply and install a new Lennox Signature Series (SLP99V) Variable Speed Gas Furnace. This system offers the highest level of precision, modulating its output in 1% increments to maintain exact temperatures while integrating seamlessly with the existing Rheem AC and new Lennox S40 smart controls. Scope of Work 1. Equipment Installation & Adaptation Furnace: Install Lennox SLP99V Variable Speed Gas Furnace. Coil Adaptation: Fabricate custom sheet metal transitions to mate the new furnace width and height to the existing Rheem evaporative coil (installed 2020). Return Drop: Modify the existing return drop to accommodate the new filtration cabinet. 2. Venting & Drainage Venting Upgrade: Disconnect existing 3" venting. Install new 2" PVC intake and exhaust piping, utilizing the existing path to the exterior termination point. Condensate Management: Eliminate the existing floor drain setup. Install a new condensate pump and route vinyl tubing to discharge water to
Project Overview Supply and install a new Lennox Signature Series (SLP99V) Variable Speed Gas Furnace. This system offers the highest level of precision, modulating its output in 1% increments to maintain exact temperatures while integrating seamlessly with the existing Rheem AC and new Lennox S40 smart controls. Scope of Work 1. Equipment Installation & Adaptation Furnace: Install Lennox SLP99V Variable Speed Gas Furnace. Coil Adaptation: Fabricate custom sheet metal transitions to mate the new furnace width and height to the existing Rheem evaporative coil (installed 2020). Return Drop: Modify the existing return drop to accommodate the new filtration cabinet. 2. Venting & Drainage Venting Upgrade: Disconnect existing 3" venting. Install new 2" PVC intake and exhaust piping, utilizing the existing path to the exterior termination point. Condensate Management: Eliminate the existing floor drain setup. Install a new condensate pump and route vinyl tubing to discharge water to
Adam P.
Adam P. Checked in
Project Overview Supply and install a new Lennox Signature Series (SLP99V) Variable Speed Gas Furnace. This system offers the highest level of precision, modulating its output in 1% increments to maintain exact temperatures while integrating seamlessly with the existing Rheem AC and new Lennox S40 smart controls. Scope of Work 1. Equipment Installation & Adaptation Furnace: Install Lennox SLP99V Variable Speed Gas Furnace. Coil Adaptation: Fabricate custom sheet metal transitions to mate the new furnace width and height to the existing Rheem evaporative coil (installed 2020). Return Drop: Modify the existing return drop to accommodate the new filtration cabinet. 2. Venting & Drainage Venting Upgrade: Disconnect existing 3" venting. Install new 2" PVC intake and exhaust piping, utilizing the existing path to the exterior termination point. Condensate Management: Eliminate the existing floor drain setup. Install a new condensate pump and route vinyl tubing to discharge water to
Sandown, NH 03873
Qwentin G.
Qwentin G. Checked in
I found that the fan limit switch was acting up. It is sticking and not allowing the blower to run long enough to cool down the heat exchanger. That is why it keeps short cycling. I'll send over an estimate to replace the fan limit switch.
Stratham, NH 03885
Qwentin G.
Qwentin G. Checked in
Found that one of the stand pieces is broken on the outdoor unit. I ran the unit in heat pump mode and everything operated perfectly. We will be reaching out to you for when we can come and replace the part.
Stratham, NH 03885
Qwentin G.
Qwentin G. Checked in
Replaced the collector box and gasket. Replaced the trap and re-piped it. Tested the operation and ensured that there was no more leaks.
Manchester, NH 03104
Jack D.
Jack D. Checked in
Both boilers faulted out. See invoice line item for details. Thank you!
Londonderry, NH 03053
Review
Great service
Lori B - Hollis, NH 03049
Jack D.
Jack D. Checked in
Replace filter housing.
Henniker, NH 03242
Londonderry, NH - See invoice line item descriptions* Connected the temperature and pressure relief valve overflow pipe correctly.
Jack D.
Jack D. Checked in
See invoice line item descriptions* Connected the temperature and pressure relief valve overflow pipe correctly.
Londonderry, NH 03053
Qwentin G.
Qwentin G. Checked in
Deep cleaned the mini split in structures.
Londonderry, NH 03053
Review
Excellent Service
Ronald - Merrimack, NH 03054
Review
Excellent service and communication. A great family business.
Paul - Nashua, NH 03062
Review
Quentin gave me all the information I requested and was exceptionally polite and did a through job. I highly recommend him and GSMS company !
John - Weare, NH 03281
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
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
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.

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