Your Trusted Heating, AC & Plumbing Experts in Londonderry, NH
Since 1987, GSMS has been proud to offer top-notch HVAC services to residents of Londonderry, NH. With over three decades of experience, our family-owned business has built a reputation for excellence, reliability, and outstanding customer service. We provide a comprehensive range of HVAC services, including air conditioning repair, replacement, and maintenance, as well as heating services for furnaces and boilers. Our expert technicians are also skilled in installing and maintaining ductless mini-split systems, ensuring that your home stays comfortable year-round. At GSMS, we use only the highest quality products from leading manufacturers, guaranteeing efficient and long-lasting solutions for your HVAC needs. Whether you need a quick repair, a complete system installation, or regular maintenance, our team is dedicated to providing personalized service tailored to your specific requirements. Don’t let HVAC issues disrupt your comfort—call GSMS today at 603-424-8258 to schedule your HVAC service in Londonderry, NH, and experience the difference of working with trusted local professionals.
In addition to our heating and air conditioning services, we offer top-quality plumbing services to the residents of Londonderry, NH. With over three decades of experience, our family-owned business has established a reputation for trust, reliability, and exceptional customer care. Our comprehensive plumbing services include water heater repair, replacement, and maintenance for both tank and tankless models, ensuring your home has a consistent supply of hot water. We also specialize in kitchen plumbing, from faucet and sink installations to dishwasher and water line services. In the bathroom, our expert plumbers handle everything from toilet and shower repairs to vanity plumbing and pipe replacement. At GSMS, we use only the highest quality materials and the latest techniques to provide efficient and long-lasting solutions for your plumbing needs. Whether you require a quick repair, a complete installation, or regular maintenance, our team is committed to delivering personalized service tailored to your home’s unique requirements. Don’t let plumbing issues disrupt your daily routine—call GSMS today at 603-424-8258 to schedule your plumbing service in Londonderry, NH, and experience the peace of mind that comes with working with trusted local professionals.
Recent Jobs and Reviews in Londonderry, NH
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Job Locations and Reviews

Every thing looks good.

I washed the indoor coils with Dawn soap and water. I cleaned off the air filters. I noticed outside there is a piece of the cover garden missing.

Filters

Replaced 3 20x20x1 air filters and 1 20x24x1 air filter on the upstairs air handler.

Laars Neotherm boiler maintenance. Everything looks great.
Jack is always very knowledgeable and kind and helpful when servicing our home. Thank you!
We're thrilled to hear that you enjoyed your experience with us. Thanks for the kind words!

Modify the existing bathroom fans, which currently share a 4" vent via a tee fitting that goes to the exterior gable end. Insulated 4" flex venting will be installed for each run, leading to the gable end exhaust. The current exhaust will be replaced, and a second exhaust will be installed for the second fan. All runs will be insulated with R8 to prevent condensation.

Rinnai tankless maintenance went great. The heat exchnager was dirty! The inlet screen has sediment in it as well. Right sink drain in master bathroom needs a new pop up drain tail piece. It is leaking. It also drains slowly. I reccomend replacing it instead of taking it apart. The upstairs bathroom sink drains slowly, it should be taken apart and cleaned. I replaced two toilet flapper valves today on the toilets that had a weak flush.

Plumbing repair at a residential home. Arrived to address a leaking tub spout and quickly identified a worn-out washer as the cause. After replacing the washer with a new one, the spout was restored to proper working condition, eliminating the leak. The customer was pleased with the fast and efficient repair.
Service with a smile
Thanks for sharing your review with us and the community.

Add zoning system with minimal ductwork to provide supplemental heating for the newly finished basement space. Zoning will provide independent control over the system for the basement. A bypass is installed which will allow the required minimum airflow to move through the system to protect the heating & cooling system.
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We thank you for sharing your positive experience. It made our day.

Install basement zone.

Replaced shower valve

Replace the control board on the shop furnace. We believe this is the cause to the intermittent shorting of fuses.
We are so glad to have found GSMS. Jack is very knowledgeable and courteous. We had a bad experience with our previous company and really needed to find someone who services System 2000. We are very pleased with the work and would highly recommend them. Their prices are very fair too.

Repairs flue pipe going into chimney. Seal with high temp furnace cement. Install brackets to secure flue to chimney. Replace expansion tank and relief valve on water heater.

Purge all zones of air causing heating issues. Replace failed circulator pump, relief valve, and air vent.

I replaced all on the indoor filters.

Mini split maintenance Heating 1, on a 4 systems.

First I started off with replacing the 3 air filters in the ceiling down stairs. I then went upstairs and replaced the air filter for the air handler. I inspected electrical connections and everything looked good. Finally I went outside and I tested the capacitors on the heat pump unit and they were in spec.

I started off with cleaning the indoor coils with hot Dawn soap and water. Next, I clean the filters with water. I wipe down the outside of the unit with a rag. I checked the supply temp coming out and it was around 110°. Then went outside and checked the electrical connections on the outdoor unit. Everything looked and operated well.

All three of the gas furnaces were maintained in this same order. I started off with cleaning the flame sensor. I then checked the capacitor and everyone was in spec. I checked all electrical connections to make sure everything was tight and not damage. I inspected the burner tubes and they all looked good. I did a visual inspection on the outside and on the inside of the furnace to look for leaks or corrosion and they all looked great. I replaced the 20x25x5 Air Bear filters. I checked natural gas pressure incoming and at the manifold and they were all perfect, none needed to be adjusted. I bubbled and used an electronic leak detector after I disconnected my manometer from the gas valve. Lastly, I used the combustion analyzer to make sure my oxygen, CO2 and CO levels were in range. Every furnace had good combustion readings.
A very nice young man that replaced my condensate pump and did a nice job. He represents GSMS as a Pro just like the rest of the group. You can not go wrong with this company.
Thank you so much for taking the time to leave us this amazing review!

I started off with removing the old condensate pump. Next I installed the new condensate pump with neutralizer beads. When I plugged the pump in it kept running and never shut off. I found that the float switch was sticking. The new condensate pump was faulty from the factory, so I got a replacement one. After installing the new one, I poured water into it to test operation and it worked as it should.

Removed burners to clean them

I found the shop ventilation exhaust blower motor to be seized. I reached out to our motor supplier for a motor quote. We will also have to rent a lift to safely access the fan.

The maintenance on your Goodman propane furnace went great. There are no recommended repairs at this time. Thank you.

Installed gas piping to the generator
Excellent service
Excellent Service

I found that the outdoor unit needs both control boards and a thermistor replaced.