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Our Service Area

Proudly serving New Hampshire homeowners with local heating, air & plumbing services.

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.

From air conditioning and heating services to plumbing repairs and installations, we ensure your home remains comfortable and efficient year-round. Our commitment to quality and customer satisfaction sets us apart as the trusted choice for all your home comfort needs.

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 118 customer reviews

Customers say: The reviews exhibit a positive overall sentiment, with a slight inclination towards the positive. The majority of the reviews express satisfaction with the services provided by GSMS, highlighting their professionalism, courtesy, and expertise. Customers appreciate the timely arrival, thorough explanations, and effective problem-solving. Positive mentions of the company's reliability, trustworthiness, and quality of service are also evident. Additionally, customers express gratitude for the helpfulness, knowledge, and timeliness of the staff, as well as the overall positive experience. However, there are a few negative reviews, primarily focused on issues with heating and cooling systems. However, the negative reviews are outweighed by the positive ones, indicating that the positive experiences of customers significantly outweigh the negative ones.

Job Locations and Reviews

Jack D.
Jack D. Checked in
Replace flow restrictor, install new humidifer housing with new humidifer pad, replace coroded saddle valve with a real angle valve. During the plumbing visit we found a waste line hanger that cane undone in the basement. We also reccomend adding a check valve to the p trap drain for your RO system. We found a failed expansion tank and replaced it.
Merrimack, NH 03054
Jack D.
Jack D. Checked in
The upstairs bathroom under sink drain piping was back pitched towards the trap, I reccomend replacing the drain piping. The upstairs bathroom faucet has an aerator cap that leaks. I tried tightening it but the threads are no good on it. The upstairs bathroom tub spout diverter doesn't seal and the shower valve cartridge does not seem to seal when in the off position. The basement bathroom toilet is wobbly, I tried tightening the flange nuts but they are plastic and will not tighten enough. The basement bathroom sink drains very slowly due to not having a vent.
Amherst, NH 03031
Jack D.
Jack D. Checked in
We diagnosed the unit heater as having a plugged pilot orifice. We tried unclogging it but it did not prove effective. My universal pilot would not work on this heater. The blower motor had substantial axial play in the shaft. We cleaned the burners and the heat exchanger as there was a lot of soot. We will send an estimate to replace the pilot assembly and replace the blower motor. In order to wire a smart thermostat in the garage we will have to run a new wire to the thermostat and the unit heater because the current wire does not have enough conductors. We cleaned the fire place and found that the ignitor needs to be replaced. I recommend doing the ignitor and the pilot assembly too. We found that training room first floor and two upstairs thermostats have enough wires for smart thermostats. We will provide an estimate to replace those as well.
Wilton, NH 03086
Mark D.
Mark D. Checked in
Aqua sure water system
Merrimack, NH 03054
Review
Plumbing review
Colleen - Manchester, NH 03104
Jack D.
Jack D. Checked in
Everything went great. I sent the estimates for the necessary work that I found, to your email. Thank you!
Hooksett, NH 03106
Qwentin G.
Qwentin G. Checked in
I started off with inspecting the kitchen sink. I looked for any signs of corrosion or leaks and everything looked very good. Next, I went to the three bathrooms. The bathroom on the first floor everything looked and operated good. The bathroom upstairs with the tub, the toilet would run for a couple minutes after flushing. The other bathroom with the stand up shower the sink drain looked like it had some buildup on the threaded connection. I took pictures of the toilet and the sink drain for our plumbing team to take a look at. Everything else in the two bathrooms looked and operated good. Next, I went downstairs and inspected all of the pipes in the boiler room for corrosion or leaks. I didn’t find any leaks, but I did find the relief valve on the water storage tank to be dripping. I took a look at the water meter and everything looked good there. I did find under the oil tank to be a little wet. I attached photos of the toilet, drain and oil tank. Lastly I checked the washer machine
Manchester, NH 03104
Mark D.
Mark D. Checked in
We found 3 more leaks. We will continue the effort tomorrow.
Salem, NH 03079
Mark D.
Mark D. Checked in
I removed the old burner tubes and replaced them with new ones. After assembling it all back together, I used soapy bubble as a gas detector and found no leaks. I checked the incoming manifold pressure and it was 12 inches water column. I checked outgoing gas pressure and it was 10 inches water column on high fire and low fire was 4.8 inches water column. I cycled the unit five times to make sure everything operated correctly. Lastly, I checked the combustion for the high and the low fire. I added the combustion data with pictures to the job. I went over and I double checked all the joints that I loosened with soapy bubbles and once again found no leaks. Mark came in the beginning and replaced the expansion tank on the water heater.
Derry, NH 03038
Review
Quentin did a great job and was a pleasure to work with. He is typical of all the employees of GSMS. Top quality work and friendly
Barry - Manchester, NH 03109
Response from GSMS Air•Heating•Plumbing:

Thank you, Barry! Qwentin is an excellent addition to our GSMS family and I'm so pleased to hear he took great care of you. Your nest thermostat that was acting up on us, was replaced under warranty with a new generation 4 nest thermostat. Thank you for being a Home Club member!

Qwentin G.
Qwentin G. Checked in
After doing a few test, I found that the thermostat upstairs that we installed last year was faulty. I was going to replace it with the same generation three thermostat, but they didn’t have any in the color that he had. I upgraded to the generation four nest thermostat.
Manchester, NH 03109
Review
Nice clean work and very professional! I’m happy with my new heating system! Communication was great!
Matt @ swains lake - Barrington, NH 03825
Mark D.
Mark D. Checked in
Gas pressure test system held pressure for 15min
Raymond, NH 03077
Review
GSMS was punctual, thorough, and did a great job of explaining their procedures (and test outcomes). Highly recommend!
JD - Barrington, NH 03825
Review
Excellent service
Ronald - Merrimack, NH 03054
Review
Great service!
Dragan - Derry, NH 03038
Review
Mark was super responsive with our no-heat situation and quickly able to fix!
DWS - Barrington, NH 03825
Review
Called when heat went down and they were there in the hour.
Rick - Salem, NH 03079
Review
Mark did a great job identifying the problem and resolving it to get the heat turned on again. I am confident that when Mark is on site the problem will get resolved.
Oakwood - Milford, NH 03055
Review
Fantastic. I couldn’t be more satisfied. I don’t have heat yet but I didn’t expect to. As long as he returns with the required parts in a reasonable length of time, I’ll be happy.
Edmund - Windham, NH 03087
Response from GSMS Air•Heating•Plumbing:

Thank you for the wonderful review and for taking the time to share your feedback.

Review
As usual, Adam'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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