0% Interest Financing and Lennox Rebates Up to $1,800
Request Service Call Now Contact Us Coupons

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 382 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

This proposal outlines the installation of high-efficiency 4-Zone Mitsubishi ductless mini-split system. This system is engineered to provide perfectly zoned, independent summer cooling, as well as highly efficient supplemental heating during the shoulder seasons for both the upstairs and basement living spaces.

Scope of Work

1. Outdoor Equipment Installation

Condenser Placement: Supply and install one (1) Mitsubishi 4-Zone outdoor heat pump condenser. The unit will be professionally mounted on the exterior gable end of the home, located to the right of the existing electrical meter.

2. Indoor Air Distribution (4 Wall-Mounted Units)

Supply and install four (4) precisely sized Mitsubishi wall-mounted ductless air handlers in the following dedicated zones:

Zone 1: Basement Living Room: Mounted on the entry wall adjacent to the electrical panel for optimal airflow distribution across the living space.

Zone 2: Basement Bedroom: Strategically mounted on the back wall near the right r
This proposal outlines the installation of high-efficiency 4-Zone Mitsubishi ductless mini-split system. This system is engineered to provide perfectly zoned, independent summer cooling, as well as highly efficient supplemental heating during the shoulder seasons for both the upstairs and basement living spaces.

Scope of Work

1. Outdoor Equipment Installation

Condenser Placement: Supply and install one (1) Mitsubishi 4-Zone outdoor heat pump condenser. The unit will be professionally mounted on the exterior gable end of the home, located to the right of the existing electrical meter.

2. Indoor Air Distribution (4 Wall-Mounted Units)

Supply and install four (4) precisely sized Mitsubishi wall-mounted ductless air handlers in the following dedicated zones:

Zone 1: Basement Living Room: Mounted on the entry wall adjacent to the electrical panel for optimal airflow distribution across the living space.

Zone 2: Basement Bedroom: Strategically mounted on the back wall near the right r
Adam P.
Adam P. Checked in
This proposal outlines the installation of high-efficiency 4-Zone Mitsubishi ductless mini-split system. This system is engineered to provide perfectly zoned, independent summer cooling, as well as highly efficient supplemental heating during the shoulder seasons for both the upstairs and basement living spaces. Scope of Work 1. Outdoor Equipment Installation Condenser Placement: Supply and install one (1) Mitsubishi 4-Zone outdoor heat pump condenser. The unit will be professionally mounted on the exterior gable end of the home, located to the right of the existing electrical meter. 2. Indoor Air Distribution (4 Wall-Mounted Units) Supply and install four (4) precisely sized Mitsubishi wall-mounted ductless air handlers in the following dedicated zones: Zone 1: Basement Living Room: Mounted on the entry wall adjacent to the electrical panel for optimal airflow distribution across the living space. Zone 2: Basement Bedroom: Strategically mounted on the back wall near the right r
Concord, NH 03303
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance / first startup. I started off with checking the electrical connections and the capacitor on the outdoor unit and everything was good. I checked the air filter and it was really clean. I hooked up my gauges and I ran the unit in cooling mode. Everything was working perfectly.
Nashua, NH 03062
Review
Seems like a thorough inspection and update....great job Qwentin.
Phil - Windham, NH 03087
Completed the AC maintenance today. Started off with washing the outdoor condensers coil with coil cleaner and water. I checked all the electrical connections and the capacitor and everything was good. Inside I replaced the air filter with a client supplied filter. I cleaned the indoor coil with coil cleaner. I brushed and flushed the condensate trap with cleaner. I connected my gauges and ran the unit in cooling. The system was running great! I took some pictures of the dock railing and we will be in touch soon.
Completed the AC maintenance today. Started off with washing the outdoor condensers coil with coil cleaner and water. I checked all the electrical connections and the capacitor and everything was good. Inside I replaced the air filter with a client supplied filter. I cleaned the indoor coil with coil cleaner. I brushed and flushed the condensate trap with cleaner. I connected my gauges and ran the unit in cooling. The system was running great! I took some pictures of the dock railing and we will be in touch soon.
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance today. Started off with washing the outdoor condensers coil with coil cleaner and water. I checked all the electrical connections and the capacitor and everything was good. Inside I replaced the air filter with a client supplied filter. I cleaned the indoor coil with coil cleaner. I brushed and flushed the condensate trap with cleaner. I connected my gauges and ran the unit in cooling. The system was running great! I took some pictures of the dock railing and we will be in touch soon.
Windham, NH 03087
Mark D.
Mark D. Checked in
I found the release valve dripping caused by a bad expansion tank. I replace the expansion tank and Purge the system
Hollis, NH 03049
Jack D.
Jack D. Checked in
Tighten cartridge nut and add thread lock to secure in place.
Nashua, NH 03064
Qwentin G.
Qwentin G. Checked in
Completed the mini split maintenance today. I started off with washing the coil at the outdoor unit. I washed it from the inside out with water. I used cleaner and a rag to clean the outside of the unit. I checked the electrical connections and everything looked good. Next I washed the air filters with cleaner and water. I rinsed the indoor coils with coil cleaner. I wiped the frame of the units with a wet rag. I ran the three indoor heads in cooling mode and everything was running great!
Litchfield, NH 03052
Jack D.
Jack D. Checked in
Replace ptrap in upstairs sink.
Manchester, NH 03102
This proposal outlines the replacement of your aging oil boiler and internal tankless hot water coil. We have designed this upgrade around the ultra-efficient Energy Kinetics System 2000 Resolute.

Unlike your current setup, this highly advanced, low-mass boiler eliminates standby heat loss, drastically reducing your annual oil consumption. Furthermore, the Resolute model allows for direct sidewall venting, which means we can completely eliminate your current noisy power vent setup in favor of a much quieter, cleaner, and safer dedicated intake and exhaust system.

Scope of Work

1. Equipment Removal & Venting Modernization

Demolition: Safely drain, disconnect, and remove the existing oil boiler.

Power Vent Elimination: We will completely remove the existing, noisy power vent. The new System 2000 Resolute utilizes direct sidewall venting, meaning we will pipe dedicated fresh air intake and exhaust directly through the exterior wall.

2. High-Efficiency Boiler & Hot Water Installation
This proposal outlines the replacement of your aging oil boiler and internal tankless hot water coil. We have designed this upgrade around the ultra-efficient Energy Kinetics System 2000 Resolute.

Unlike your current setup, this highly advanced, low-mass boiler eliminates standby heat loss, drastically reducing your annual oil consumption. Furthermore, the Resolute model allows for direct sidewall venting, which means we can completely eliminate your current noisy power vent setup in favor of a much quieter, cleaner, and safer dedicated intake and exhaust system.

Scope of Work

1. Equipment Removal & Venting Modernization

Demolition: Safely drain, disconnect, and remove the existing oil boiler.

Power Vent Elimination: We will completely remove the existing, noisy power vent. The new System 2000 Resolute utilizes direct sidewall venting, meaning we will pipe dedicated fresh air intake and exhaust directly through the exterior wall.

2. High-Efficiency Boiler & Hot Water Installation
Adam P.
Adam P. Checked in
This proposal outlines the replacement of your aging oil boiler and internal tankless hot water coil. We have designed this upgrade around the ultra-efficient Energy Kinetics System 2000 Resolute. Unlike your current setup, this highly advanced, low-mass boiler eliminates standby heat loss, drastically reducing your annual oil consumption. Furthermore, the Resolute model allows for direct sidewall venting, which means we can completely eliminate your current noisy power vent setup in favor of a much quieter, cleaner, and safer dedicated intake and exhaust system. Scope of Work 1. Equipment Removal & Venting Modernization Demolition: Safely drain, disconnect, and remove the existing oil boiler. Power Vent Elimination: We will completely remove the existing, noisy power vent. The new System 2000 Resolute utilizes direct sidewall venting, meaning we will pipe dedicated fresh air intake and exhaust directly through the exterior wall. 2. High-Efficiency Boiler & Hot Water Installation
Pembroke, NH 03275
Qwentin G.
Qwentin G. Checked in
Completed the AC maintenance. Started off at the outdoor unit. I checked all the wiring connections and the capacitor and everything was good. I washed the coil with water and coil cleaner. Inside I flushed and brushed out the trap with cleaner. The client replaces her own air filters. Lastly I ran the unit and all my readings were coming back great!
Exeter, NH 03833
Unit is making a tapping sound when ran in heating mode. Waiting to hear back from Mitsubishi tech support to figure out the cause of the problem.
Unit is making a tapping sound when ran in heating mode. Waiting to hear back from Mitsubishi tech support to figure out the cause of the problem.
Qwentin G.
Qwentin G. Checked in
Unit is making a tapping sound when ran in heating mode. Waiting to hear back from Mitsubishi tech support to figure out the cause of the problem.
Pembroke, NH 03275
Review
The service was really good. He did great work.
Ann - Derry, NH 03038
Review
Always GREAT service
37 - Manchester, NH 03103
Review
Qwentin did a great job. Highly recommend him.
Gary - Stratham, NH 03885
Review
Excellent, prompt service
John - Hollis, NH 03049
Review
It’s always a pleasure when Qwentin stops by; a polite and personable young man who is an asset to the formidable GSMS team who did another super, duper jobby! 😉 Hope he had a great time at the party celebrating multiple birthdays this weekend?! Cheers 👍🙂🥃🥃
Martin - Stratham, NH 03885
Review
Adam & Quinn just left after finishing the installation of my new Lennox Air Conditioning unit. As always, they are very personable and professional. Adam explains everything to me before he leaves and I am very comfortable with my new system. I would not hesitate to recommend GSMS and have done so in the past.
Deb - Hooksett, NH 03106
Review
Qwentin was thorough and diagnosed the issue
Gary - Stratham, NH 03885
Review
Great service
Lori B - Hollis, NH 03049
Review
Excellent Service
Ronald - 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
I needed to have shut off valves under my kitchen sink and a new hose attachment on my sprayer since the cheap plastic tubing was cracked. Mark was punctual, professional and extremely knowledgeable regarding the job. I am always impressed with GSM and how they run their family business. Mark completed the job quickly and efficiently. I can trust GSM and will continue to seek their help in the help in the future. GSM has installed a mini split, oil boiler, hot water heater in my home and I would highly recommend them to family and friends.
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