Across Nassau and Suffolk, many homes were built around a brick fireplace that now sits mostly unused: drafty in January, smoky when lit, and one more thing to clean. A direct vent gas insert turns that opening into a fire you will actually use, at the touch of a remote, without rebuilding the wall around it. Here is how inserts work, how to size one, and the models we recommend.
The short answer
For an existing masonry fireplace on Long Island, a direct vent gas insert is usually the best upgrade: it slides into the firebox, vents through two liners run up the old chimney, and becomes a sealed, controllable heater. Our top picks are the Majestic Ruby and Trilliant, the Napoleon Oakville X3 and Rosedale 3, the Kingsman Capri IDV44 and the Montigo Illume DVCP34. Size the insert to the firebox, not the face. New York's all-electric law covers new buildings, not inserts in existing homes.
Key takeaways
- Two chimney liners bring combustion air in and send exhaust out, so the fire is sealed from the room.
- Front width, rear width, height and depth must all meet the manufacturer's minimum opening.
- Published ratings for these models run from about 25,000 to 35,000 BTU per hour.
- A blower and a thermostatic remote matter more than most buyers expect.
- Existing Long Island homes are outside the all-electric law, but a town or village permit is still typically required.
In this guide
- The best gas inserts at a glance
- Gas inserts in Nassau and Suffolk homes
- How does a gas fireplace insert work?
- What size gas insert do I need?
- How much heat does a gas insert put out?
- Do you need a blower and a remote?
- How is a gas insert installed, and how long does it take?
- Our recommended models
- Which should you choose?
- Frequently asked questions
The best gas inserts at a glance
Natural gas figures from each manufacturer. Openings are front width by height by depth.
| Insert | Best for | Max rating (NG) | Minimum opening | Blower |
|---|---|---|---|---|
| Majestic Ruby 30 | Standard brick fireboxes | 32,700 BTU input | 31 5/8 x 21 x 15 in | Standard |
| Majestic Trilliant 35 | Larger openings, more heat | 35,000 BTU input | 36 5/8 x 24 1/4 x 15 in | Standard |
| Napoleon Oakville X3 | Traditional rooms, app control | 30,000 BTU | See Napoleon manual | Included |
| Napoleon Rosedale 3 | Smaller rooms and openings | 25,000 BTU | See Napoleon manual | Confirm configuration |
| Kingsman Capri IDV34 | Deeper fireboxes | 31,000 BTU input | 28 5/8 x 21 1/2 x 17 3/4 in | Standard |
| Kingsman Capri IDV44 | Large, tall masonry openings | 34,250 BTU input | 32 7/8 x 25 3/4 x 18 in | Standard |
| Montigo Illume DVCP34 | Big view, modulating burner | 32,000 BTU input | 34 1/2 x 24 1/2 x 18 1/2 in | Standard |
Gas inserts in Nassau and Suffolk homes: what should you know?
The housing stock is why inserts make so much sense here. From the Capes and colonials of the South Shore to older homes on the North Shore and out toward the Hamptons, many Long Island houses have a masonry fireplace and flue. That chimney is exactly what an insert is designed to use.
A common question this fall is whether New York's gas ban changes this. For an existing home, it does not. The All-Electric Buildings Act (Energy Law section 11-104) covers new buildings and states that it does not apply to buildings that existed before its effective date, including the installation of fossil-fuel equipment in them. As of October 19, 2026, the state law is also not yet being enforced. Our guide to the NY gas ban and gas fireplaces on Long Island walks through the timeline and what it means for new construction.
What does apply is the local permit, issued by your town, city or village rather than the county: Hempstead, North Hempstead or Oyster Bay in Nassau, for example, or Huntington, Islip, Brookhaven or Southampton in Suffolk. The Town of Islip's insert checklist is typical: the manufacturer's installation instructions, a listed appliance, and a plumbing permit with a gas riser diagram from a licensed plumber. Condo boards and homeowner associations may add their own approvals.
From our install team
On Long Island installs, the chimney tells us more than the fireplace. A firebox can look perfect while the crown is cracked or a flue tile has shifted, so plan on an inspection before you settle on a model.
How does a gas fireplace insert work?
A gas insert is a sealed fireplace in a steel box that slides into your existing firebox. The glass is fixed, so no room air feeds the flame. Most inserts use a co-linear system: two flexible liners run side by side up the chimney. One brings outside combustion air down to the burner; the other carries exhaust out to a termination cap at the top. Majestic sells this as a kit, such as its co-linear insert kit with two 30 foot liners, and Kingsman and Montigo publish their own matched kits. Montigo's Illume DVCP34, for example, calls for a 3 inch air inlet and a 4 inch exhaust liner, vertical only, from 10 to 40 feet.
An open wood fire pulls heated room air up the flue; a sealed insert keeps it in the house. Our comparison of a gas insert versus a new direct vent fireplace covers when a full replacement makes more sense.
What size gas insert do I need?
Size comes from the firebox, not from how big the fireplace looks. Every manufacturer publishes a minimum opening, and your firebox must meet every number: front width, rear width, height and depth. Traditional fireboxes taper toward the back, so rear width and depth are where most fits fail. The damper area must also leave room for two liners, and the face must be large enough for the surround to cover the gap. Majestic offers several surround sizes for each insert width.
Our guide on how to measure a fireplace opening shows exactly where to put the tape.
From our install team
Choose the largest insert your firebox comfortably accepts, not the largest it barely accepts. A little room makes the liner connections cleaner.
How much heat does a gas insert put out?
Manufacturers publish heat differently. Majestic lists input: 32,700 BTU for the Ruby 30 and 35,000 for the 35 inch sizes. Napoleon lists output: up to 30,000 BTU for the Oakville X3 and 25,000 for the Rosedale 3. Kingsman gives 31,000 high and 20,900 low input for the IDV34, and Montigo 21,000 to 32,000 for the DVCP34. Input is what the burner consumes; what reaches the room depends on efficiency.
Majestic publishes EnerGuide efficiency ratings (CSA P.4.1): 71 percent on natural gas for the Ruby 30 and Trilliant 30, 72 percent for the 35 inch models and 68 percent for the Jasper 30. A wide flame range matters as much as the peak figure, because it lets you enjoy the fire in October without overheating the room.
Do you need a blower and a remote?
A blower moves room air around the hot firebox and back into the room: the difference between heat you feel at the glass and heat that reaches the sofa. It is standard on the Majestic Ruby and Trilliant, the Kingsman Capri inserts and the Montigo DVCP34, included with the Napoleon Oakville X3, and optional on the Majestic Jasper. Owners on hearth forums generally say a blower is worth it and that lower speeds are quieter, so variable speed control helps.
The Ruby and Trilliant come with Majestic's RC400 touchscreen remote. Napoleon includes a remote with the Oakville X3 and Rosedale 3, and the Oakville X3 adds eFIRE app control. Kingsman's Proflame II models include a remote. A thermostatic remote holds the room at a set temperature by modulating the flame. For winter outages, Kingsman and Napoleon document battery backup that lets the fire light without power, though the blower waits for power to return.
Not sure what fits your space? Send us your firebox measurements and a chimney photo and we will tell you which inserts fit. Book a free design consultation and we will help you narrow it down.
How is a gas insert installed, and how long does it take?
We would rather describe the sequence than promise a date before seeing your chimney.
- Consultation and measurement of the firebox, face, hearth and gas route.
- Chimney inspection and cleaning, with any crown or masonry repair done before liners go in.
- Selection and ordering of the insert, front, surround, media and liner kit together.
- Permits filed with your town or village, manufacturer's manual attached.
- Gas line run and tested by a licensed plumber.
- Liners and insert connected, set and leveled, with the termination cap installed on top.
- Finishing and startup: surround, front and media, then a walk-through of the remote.
The calendar depends on what the chimney inspection finds, how long your town or village takes to review the permit, and whether your configuration is in stock. We give you a realistic schedule once those are known. For a fire by the holidays, measure and book the inspection early. Our guide to what a gas fireplace costs installed covers the budget side.
From our install team
Many inserts need a media set and a surround or front ordered separately. We build the parts list from the manufacturer's manual at quote time, so nothing arrives incomplete.
Our recommended models
Direct vent inserts we carry and install, chosen for proven venting systems, published specifications and fronts that suit Long Island homes.
Also consider the Kingsman Capri IDV34 for mid-size deep fireboxes and the Majestic Jasper 30, a simpler insert with the Ruby 30's opening size.
Gas inserts All fireplace inserts Majestic Napoleon fireplaces Kingsman Montigo
Which should you choose?
Choose the Majestic Ruby or Trilliant if:
- Your firebox is a standard brick box at least 15 inches deep.
- You want a fan and touchscreen remote included.
Choose Napoleon if:
- You want a traditional look with brick panels.
- App control appeals, or a smaller room needs less heat.
Choose Kingsman or Montigo if:
- Your firebox is tall or about 18 inches deep or more.
- You want the largest glass you can fit.
For most Long Island masonry fireplaces, we start with the Majestic Ruby 30: it fits the common firebox and includes the features people actually use. For larger openings, the Trilliant 35, Kingsman IDV44 or Montigo DVCP34 will fill it properly. Let the tape measure make the final call.
Frequently asked questions
Can I still install a gas fireplace insert on Long Island with the gas ban?
Yes, in an existing home. New York's All-Electric Buildings Act applies to new buildings and states that it does not apply to existing ones. As of October 19, 2026 it is also not yet being enforced. A town or village permit is still typically required.
Do I need a chimney liner for a gas insert?
Yes. A direct vent insert vents through two flexible liners run up the existing chimney: one brings in outside air, one carries exhaust out. The manufacturer specifies the exact kit for each model.
Will a gas insert fit my fireplace?
It will if your firebox meets the manufacturer's minimum front width, rear width, height and depth. Majestic lists 31 5/8 inches wide, 21 inches high and 15 inches deep for the Ruby 30. Measure the inside of the firebox, not the face.
How much heat does a gas fireplace insert produce?
The models we recommend are rated from about 25,000 to 35,000 BTU per hour. Majestic publishes EnerGuide efficiencies of 68 to 72 percent on natural gas for its Ruby, Trilliant and Jasper inserts.
Talk to a specialist
Enjoy the fireplace you already have this winter
We have been designing, selling, installing and servicing fire features and outdoor kitchens for over 30 years across New York City, Long Island, Westchester, New Jersey and South Florida. Send us your firebox measurements and a few photos, and we will match an insert to your chimney and room.
Book a free consultation Call 718-326-4328Showroom: 58-30 Maspeth Ave, Maspeth, Queens. Our Greenvale, Long Island showroom at 13 Glen Cove Road opens winter 2026. Plan your visit.
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Written by the NYC Fireplaces & Outdoor Kitchens team. Last reviewed October 2026. We sell, install and service the products discussed here.
Sources: NY Energy Law 11-104, Barclay Damon alert on the Second Circuit rehearing denial, Town of Islip fireplace and insert permit requirements, Majestic gas inserts brochure, Napoleon Oakville X3, Napoleon Rosedale 3, Kingsman Capri IDV34 and IDV44 installation manual, Montigo Illume DVCP34 installation manual. This article is general information, not legal advice. Confirm specifications with the current manual and rules with your building department.