Premier Heating, Air & Plumbing from a Family-Run New Hampshire Business

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HVAC Contractor & Plumber Services For Homes & Businesses

Heating Services

Cooling Services

Plumbing Services

Water Quality Services

Indoor Air Quality Services

We're Local - Since 1987

GSMS is a second-generation family business dedicated to doing things the right way

GSMS is a second-generation, family-owned business that answers to our neighbors, not a board of directors. We’ve grown one referral at a time by treating every Client like family and every home like our own. Our mission is simple: we want to be the name you trust to take care of you and your home.

Get to Know Us

The Specialist Standard

Specialists, not technicians

We send Specialists, not technicians. Each one takes ownership of your whole system, not just the part that broke.

The Great Service promise

Affordable pricing, 5-star service, and pride in our work. If you’re not satisfied, we’ll make it right. It’s how we’ve worked since 1987.

The independent alternative

While large out-of-state firms buy up local shops, GSMS stays family-owned and answers to our neighbors, not a board of directors.

Built on our values

Every visit is guided by four values: grateful daily, service comes first, make it matter, and success is teamwork.

The GSMS Learning Center

We have been keeping New Hampshire homes comfortable since 1987, and we love sharing what we know. Our Specialists break down heating, cooling, plumbing, and indoor air quality in plain language, so you can make confident decisions about your home.

Kohler vs. Delta vs. Moen: which faucet brand is right for your home?

Quick answer: Kohler, Delta, and Moen are all excellent, widely available faucet brands that we install and recommend. Kohler is our favorite for its design...

09/22/26 Read More

Water pooling around the base of your toilet? Here’s what it usually means

Quick answer: Water at the base of a toilet most often means the wax gasket, the seal between the toilet and the drain, has failed....

09/22/26 Read More

Thinking about a touchless faucet? What New Hampshire well water owners should know first

Quick answer: Touchless faucets are convenient and hygienic, but they rely on an electronic valve under the sink with a small strainer that can clog...

09/22/26 Read More

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Service with a local heart.

We believe a local business should be a pillar of the community. That’s why a portion of every service call we complete goes directly to a local NH non-profit through our We Local initiative.

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Since 1987

Excellence Defines GSMS

Comprehensive, Expert care for Every Room

Let's Make Home Enjoyable Again.

Total home protection, rewards, discounts, and smart monitoring. It’s all yours when you’re in the club.

Join the Club

Serving New Hampshire

No matter where you call home in New Hampshire, GSMS is here to ensure it remains a haven of comfort throughout the seasons. We work all across NH to deliver great service exactly where you need it.

Our Service Area