Residential heating & air conditioning contractor in Merrimack, NH
GSMS is proud to serve the residents of Merrimack, NH, with top-quality heating and air conditioning services. As a family-owned business with over three decades of experience, we are dedicated to providing reliable, efficient, and professional HVAC solutions tailored to your home’s specific needs.
GSMS is proud to be your Merrimack Lennox Premier Dealer!
Whether it's an emergency repair, a total replacement, or routine maintenance, we have you covered. Call 603-424-8258 today!
Air conditioner repair & replacement
- AC Repair: We handle cooling problems big and small with speed and attention to detail. Our technicians are trained to troubleshoot and fix refrigerant leaks, thermostat issues, electrical failures, compressor problems, and more.
- AC Replacement and New Installation: Time for a cooling upgrade? We offer high-quality systems from Lennox and other leading manufacturers to improve efficiency, enhance comfort, and reduce homeowners' carbon footprint.
Furnace repair & replacement
- Furnace Repair: Dealing with a broken furnace? GSMS technicians work efficiently to track down even the smallest of problems and repair them in no time. Common furnace issues we repair include pilot light problems, thermostat malfunctions, ignition system failures, and blower motor problems.
- Furnace Replacement and New Installation: Upgrading your furnace takes your home's winter warmth to the next level. Our energy-efficient systems provide consistent heating, reduced maintenance, and enhanced safety.
Boiler repair & replacement
- Boiler Repair: Common boiler problems with pressure, thermostats, pilot lights, and leaks, can be a homeowner's nightmare. GSMS technicians work quickly to repair your boiler and get your home warm again in no time.
- Boiler Replacement and New Installation: Whether you are considering switching to a boiler system or it's time to replace your existing system, GSMS is here to help you increase efficiency and reliability with advanced units.
Mini-split heat pumps
GSMS provides comprehensive services for mini-split heat pumps, including installation, maintenance, and repair. We specialize in Mitsubishi ductless units, known for their reliability and efficiency. Whether you’re looking to install a new system or need service for your existing mini-split heat pump, our technicians are here to ensure optimal performance and comfort in your home.
Ductwork cleaning & installation
- Duct Cleaning: Regular duct cleaning helps improve air quality, increase HVAC efficiency, extend system lifespan, and eliminate odors. We use an advanced Roto Brush system to reach every corner of the ductwork and keep your home clean and comfortable.
- Duct Installation: Proper ductwork installation is crucial for airflow, efficiency, comfort, and durability. Choosing GSMS to install your ductwork gives you peace of mind that your new air ducts are safe and secure.
Merrimack plumbing services
GSMS is proud to provide comprehensive plumbing services to homeowners in Merrimack, NH. Our experienced and professional team is dedicated to delivering reliable and efficient plumbing solutions tailored to your specific needs.
Quick plumbing repairs, complete installations, and preventative maintenance are what we do best. Call 603-424-8258 today!
Water heater plumbers
- Repair: Our skilled technicians can quickly diagnose and repair common water heater issues, including inconsistent temperature, leaks, and strange noises.
- Replacement: When it’s time to replace your old water heater, we offer professional installation of both traditional tank models and modern tankless systems.
- Maintenance: Regular maintenance is essential to keep your water heater running efficiently. Our comprehensive maintenance services include inspections, cleaning, and tune-ups.
- Tankless Water Heaters: Upgrade to a tankless water heater for endless hot water, improved energy efficiency, and space savings. We provide expert installation and maintenance for these advanced systems.
Kitchen plumber services
- Faucets: From repairing leaks to installing new faucets, we ensure your kitchen faucets are functioning perfectly.
- Sinks: We handle all sink-related services, including installation, repair, and replacement, to keep your kitchen fully operational.
- Garbage Disposals: Our team can install and repair garbage disposals, ensuring efficient waste management in your kitchen.
- Dishwashers: We provide installation and repair services for dishwashers, making sure they are properly connected and running smoothly.
- Water Lines: Whether you need new water lines installed or existing ones repaired, GSMS ensures a reliable water supply for your kitchen appliances.
Bathroom plumber services
- Toilets: From fixing leaks and unclogging blockages to installing new toilets, we provide comprehensive toilet services.
- Showers and Tubs: We offer repair, replacement, and installation services for showers and bathtubs to keep your bathroom comfortable and functional.
- Sinks and Vanity Plumbing: Our team can install and repair bathroom sinks and vanity plumbing, ensuring everything operates seamlessly.
- Pipe Repairs and Replacements: Whether it’s a minor leak or a major pipe replacement, GSMS provides expert pipe repair and replacement services to prevent water damage and maintain optimal plumbing performance.
Why choose GSMS in Merrimack?
- Proven Track Record: With a long-standing presence in Merrimack, NH, GSMS has earned the trust of countless homeowners. Our dedication to excellence and reliability has made us a preferred choice for HVAC and plumbing services in the community. We are proud of our reputation and continually strive to uphold the high standards that have set us apart.
- Local Expertise and Dedication: GSMS has been serving the Merrimack, NH community for over three decades, building a reputation for excellence and reliability. As a family-owned business, we are deeply committed to our local community and understand the unique needs of Merrimack homeowners. Our local expertise allows us to provide tailored solutions that keep your home comfortable and efficient year-round.
- Comprehensive Range of Services: From HVAC to plumbing, GSMS offers a full spectrum of services to meet all your home comfort needs. Our skilled technicians are trained in the latest technologies and techniques, ensuring top-quality service for every job. Whether you need a quick repair, a new installation, or regular maintenance, we have the expertise to get the job done right.
Become a GSMS Home Club member today
Join the GSMS Home Club and enjoy exclusive benefits designed to keep your home’s HVAC and plumbing systems in top condition. Membership perks include:
- Priority Service
- No Diagnostic Fees
- 10% Off Repairs
- Home ID and Smart Monitoring
- Monthly Credits Towards Major Purchases
- Regular Maintenance
- Labor Warranty Upgrades
Call today for great service in Merrimack.
Trust the experts at GSMS to provide reliable, efficient, and top-quality services tailored to your needs. Whether you need a quick repair, a new installation, or regular maintenance, our dedicated team is here to ensure your Merrimack home remains comfortable and functional year-round.
Call 603-424-8258 today or fill out our online contact form to book an appointment!
Recent Jobs and Reviews in Merrimack, NH
Customers say: The overall sentiment across these reviews is overwhelmingly positive, reflecting high levels of customer satisfaction and appreciation. Customers consistently express enthusiasm about the quality of service they received, with recurring praise for professionalism, expertise, and efficiency. A dominant theme throughout is the technical skill and knowledge demonstrated by the service team, with many reviewers highlighting how thoroughly problems were diagnosed and resolved. The interpersonal qualities of the technicians emerge as another strong positive trend, with customers frequently describing them as friendly, personable, pleasant, and respectful. Communication stands out as a particularly valued aspect, with reviewers appreciating clear explanations, patience in answering questions, and being kept informed throughout the service process. Timeliness and punctuality are consistently mentioned as strengths, alongside respect for customers' property and maintaining clean, orderly work practices. Many customers express strong loyalty and trust in the company, with several indicating they are repeat customers or plan to continue using the service. The tone is enthusiastic and grateful, with multiple reviewers offering strong recommendations and expressing genuine happiness with the results. Overall, these reviews paint a picture of a service provider that excels in both technical competence and customer care, creating consistently positive experiences that foster long-term customer relationships.
Our Local Reviews by City
- Amherst, NH (10)
- Atkinson, NH (2)
- Auburn, NH (3)
- Barrington, NH (23)
- Bedford, NH (36)
- Bow, NH (2)
- Candia, NH (3)
- Chester, NH (2)
- Concord, NH (11)
- Deerfield, NH (1)
- Derry, NH (3)
- Dover, NH (1)
- Durham, NH (2)
- Epping, NH (3)
- Exeter, NH (1)
- Gilford, NH (1)
- Gilmanton, NH (1)
- Goffstown, NH (8)
- Greenland, NH (2)
- Hampstead, NH (2)
- Hampton, NH (3)
- Henniker, NH (3)
- Hillsborough, NH (1)
- Hollis, NH (18)
- Hooksett, NH (20)
- Hudson, NH (8)
- Lee, NH (1)
- Litchfield, NH (3)
- Londonderry, NH (15)
- Madbury, NH (1)
- Manchester, NH (70)
- Merrimack, NH (62)
- Milford, NH (9)
- Moultonborough, NH (1)
- Nashua, NH (68)
- New Boston, NH (4)
- Newbury, NH (1)
- Newmarket, NH (2)
- Northfield, NH (1)
- Northwood, NH (2)
- Pembroke, NH (1)
- Raymond, NH (1)
- Rochester, NH (2)
- Salem, NH (4)
- Sandown, NH (3)
- Strafford, NH (1)
- Stratham, NH (11)
- Tilton, NH (1)
- Weare, NH (8)
- Windham, NH (10)
- York, ME (2)
Job Locations and Reviews
I am so sorry to hear about the stressful weekend with the system catching fire! Because the 25-year-old compressor suffered a catastrophic electrical failure, it released its refrigerant and caused what we call an "acid burnout" inside the copper pipes. Due to this severe damage and the age of the system, a safe repair is simply not possible. This option upgrades your replacement to a mid-tier, high-efficiency air conditioning system. This equipment operates much more quietly, provides far better summer dehumidification, and will lower your monthly utility bills compared to a standard unit. Even with the upgraded equipment, I have still engineered this quote to reuse as much of your existing, safe infrastructure as possible to help keep your overall costs down. Scope of Work 1. Equipment Removal & New Line Set Demolition: We will safely dismantle and remove your burned-out outdoor unit and the aging air handler up in the attic. Mandatory Line Set Replacement: Because the compress
Found Ed’s sensor unplugged and changed thermostat
Need to send price on 11/4 backflow
great service!
Found that the anti siphonor on the condensate pump was plugged up. I cleaned it out and cycled the pump multiple times and it did not make the sound anymore. If the sound comes back then the anti siphoner should be replaced.
Replace faucet for basement sink. Replace braided supply hoses.
GSMS HomeClub plumbing visit. Replace vacuum relief.
Great job
Replacement of existing 40-gallon electric water heater with a new heater. Since heater is installed in a finished space, a safety shut-off valve will be installed.
Replace kitchen faucet.
Qwenten contacted us before his arrival to let us know he was on his way and arrived promptly. He was very knowledgeable and answered all our many questions. He provided different possible solutions for at this time and went with our decision with no pressure. Very friendly and easy to discuss options with.
Completed the AC maintenance today. Everything went great. I cleaned the drain pan and the drain line with a bunch of drain cleaner. Please see the attached form.
Found that the mini split system was low on refrigerant. I added a pound and a half of refrigerant and UV dye. We will schedule a return visit in the next 2 to 4 weeks to find where the leak is coming from. I will send out the estimates in the next couple of days. We will also schedule Zak to come out to give an estimate on the system replacement.
Mitsubishi distributor remote in via Maintenance Tool. Ran report and sending off. Will hear back by next Tuesday.
Completed the AC and mini split maintenance today. Everything went great! Please see the attached forms.
Was called over because of outdoor unit on fire. Terminals on compressor failed. Causing electrical fire then burning Freon as well. Unit is 20 plus years old. See pictures for replacement.
Completed the mini split maintenance. Everything went great! Please see the attached form.
Based on our complete load calculation of your home, a 2-ton system is the exact, proper size required for your space. This option replaces your aging attic AC system with a premium Mitsubishi Heat Pump. Not only will this provide whisper-quiet, incredibly efficient cooling in the summer, but based on your home's balance point, this system will also efficiently handle the vast majority of your heating load during the cooler months! Scope of Work 1. Indoor Equipment & Airflow Upgrades (Attic) Air Handler: We will remove your old equipment and suspend a brand-new Mitsubishi multi-position air handler in the attic. We will cleanly adapt the new unit to your existing, intact supply ductwork. Return Air Modification: To ensure the new system "breathes" correctly, we will upsize one of your ceiling return registers to a larger 12x14 size. Filtration Upgrade: We will remove the restrictive filters currently located in your ceiling grilles, converting them to standard free-flowing grilles
Found the GFCI breaker was tripped. I reset it and the condensate pump turned on. I ran a gallon of cleaner through the condensate pump and it turned on, it was operating as it should. I told the client that it could have been moisture that tripped it and I did find a wire to be loose inside of the outlet. I told him to keep an eye on it for a few days.
Excellent service!
Mini Split preventative maintenance. I made an adjustment to help with cooling on the master bedroom unit. I also reccomend operating that unit with the fan on high. Thank you!
Serviced 2 a/c units,put dye and sealant in second floor unit has a leak
GSMS HomeClub AC maintenance. Replaced Lennox PureAir filter kit.
Completed the AC maintenance today. Everything went great. Please see the attached form.
Arrived on time, excellent service
Completed the AC maintenance today. Everything went great! Please see the attached form.
AC maintenance. Everything went great. Thank you!
Removed Ewc zone damper and installed foam tape to fill void
Completed the AC maintenance today. Everything went great. Please see the attached form.
Completed both AC maintenances today. The outdoor unit for the garage I found that the hard start had exploded and fried some wires. I replaced the hard start and repaired the wiring. Other than that both ACs were running great. Please see the attached form.
Mark was on time (on the early side of the timeframe) and throughly checked out the ac and plumbing. Pleasant demeanor and went over everything he did and gave the systems a good bill of health.
Excellent service!
Arrived in a timely manner with a cheerful attitude. He went straight to work and completed the job quickly/efficiently. Thank you Jack.
Qwentin was on-time. Friendly, polite, and conscientious. All work was performed and verified. Would recommend to anyone looking for HVAC service or installation.
good service
Excellent Service
Excellent service.
Amazing service as usual!!!
Quentin arrived in time, was courteous and professional and answered all my questions.
Excellent!!!
Jack did a super job! Very thorough and competent. I feel like I’m in good hands with GSMS.
Jack from GSMS came today and serviced our tankless hot water heater. Excellent job as always
Arrived on time, organized equipment. Friendly, answered all my “many questions”. Adam made sure all the equipment was in working order. Excellent service.
Always amazing service, every team member at GSMS has always been great and performed exceptionally great service.
Jack was once again on time, diagnosed the problem quickly and fixed it. All GSMS staff are courteous and extremely professional. I wouldn’t go with anyone else.
The experience started with Gina in the office who was very responsive and accommodating and made the scheduling process super efficient and friendly. Then Mark came and brought his expertise to my home and systems to point areas of installation failures by the company that installed my system. Just using the basic manual to point out how they cut corners. Mark spent the time to correct the exhaust piping to fix leaks and improve air flow. He was friendly and accommodating.
Very happy with the job done.
Quick service call to replace thermostat. Done in about 15 minutes, explained the workings. Very satisfied Great service as usual
Jack was polite and very neat.
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!







