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

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Our Services

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.

GSMS joins the Barrington Chamber of Commerce board and welcomes Mary’s Dogs to town

We have always believed that being part of a community means showing up for it. So we are proud to share that Zak Downing, owner...

10/27/26 Read More

Furnace repair or replace? How to decide before winter

New Hampshire winters do not ease into things. One week you are raking leaves, the next you are asking your furnace to run for months...

10/27/26 Read More

How to prevent frozen pipes (and what to do if they freeze) in New Hampshire

If you live in New Hampshire, you already know how cold it gets once the season turns. That cold is exactly what puts your plumbing...

10/27/26 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