Kozy Heat Chaska 335S Gas Insert
The Kozy Heat Chaska 335S is the premium variant of Kozy Heat's slim-profile gas insert line — engineered to drop into existing masonry fireplaces (including older shallow openings most inserts can't fit) while delivering the highest efficiency rating in the entire Kozy Heat insert lineup at 80% on natural gas. With a modulating 22,000 to 36,000 BTU/hr burner, just 16 inches of depth, and fan kit, co-linear venting kit, millivolt valve system, and traditional brick lining all included as standard features, the Chaska 335S is the right answer for customers who want maximum efficiency, premium standard features, and the ability to fit existing shallow fireplace cavities — without paying à la carte for upgrades.
What Makes the Chaska 335S Different
The Chaska 335S sits at the premium end of Kozy Heat's dedicated insert lineup. Compared to the Chaska 34 (same slim-profile form factor), the 335S includes as standard features what the Chaska 34 typically requires as separate purchases:
| Feature | Chaska 335S | Chaska 34 |
|---|---|---|
| Fan Kit | Included standard | Optional (sold separately) |
| Co-Linear Vent Kit | Included standard (3" combustion air / 3" exhaust) | Sold separately |
| Millivolt Valve System | Included standard | Configuration-dependent |
| Traditional Brick Lining | Included standard | Optional upgrade |
| Upper Hood & Lower Grill | Included standard | Optional accessory |
| Efficiency (NG) | 80.0% | 77.0% |
| BTU Range (NG) | 22,000–36,000 modulating | 18,500–34,000 modulating |
If you've been comparing slim-profile gas inserts and finding that the price differences between models are mostly explained by what's "included" vs "sold separately," the Chaska 335S is the option that packages everything together — the math typically favors this approach unless you're certain you won't want the fan kit or premium refractory.
Will the Chaska 335S Fit Your Fireplace?
This is the most important question for any gas insert purchase, and the one to answer BEFORE ordering. The Chaska 335S's slim 16-inch depth is its key advantage — it fits existing masonry fireplaces that won't accommodate deeper inserts. Minimum specifications for the existing fireplace opening:
| Existing Fireplace Requirement | Minimum |
|---|---|
| Opening width | At least 33-1/2" |
| Opening height | At least 23-1/2" |
| Opening depth | At least 16-1/2" (the Chaska 335S's key advantage — many other inserts require 20"+ depth) |
| Chimney condition | Solid-fuel masonry or factory-built non-combustible chimney in good structural condition; must be able to accept 3" co-linear vent piping |
| Hearth/floor protection | Non-combustible hearth in front of the fireplace per local code requirements |
| Gas line access | Existing gas line or ability to route a new gas line to the insert location |
Specifications
| Brand | Kozy Heat |
|---|---|
| Model | Chaska 335S |
| SKU | CSK-335S |
| Product Type | Direct Vent Gas Fireplace Insert |
| BTU Input (Natural Gas) | 22,000 – 36,000 BTU/hr (modulating) |
| BTU Input (Liquid Propane) | 22,000 – 36,500 BTU/hr (modulating) |
| Efficiency (Natural Gas) | 80.0% |
| Efficiency (Liquid Propane) | 76.2% |
| Vent Type | Direct Vent (Co-linear through existing chimney; 3" combustion air / 3" exhaust) |
| Vent Kit | Included standard |
| Fuel Type | Natural Gas or Liquid Propane (specify at order; conversion kits available) |
| Overall Width | 33-3/8 in. |
| Overall Height | 23 in. |
| Overall Depth | 16 in. (slim profile) |
| Weight | 150 lbs. |
| Viewing Area | 29-3/8 in. (W) × 15-13/16 in. (H) |
| Glass | Ceramic |
| Burner Type | Modulating (continuous BTU adjustment) |
| Valve System | Millivolt (standard — operates without household electricity) |
| Fan Kit | Included standard |
| Brick Lining | Traditional brick refractory (standard) |
| Upper Hood & Lower Grill | Standard |
| Screen Front Options | 9 different styles available in variety of colors |
| Refractory Options | Multiple alternatives to traditional brick |
| Bedroom Approved | Yes (direct vent design) |
| Min Fireplace Width | 33-1/2 in. |
| Min Fireplace Height | 23-1/2 in. |
| Min Fireplace Depth | 16-1/2 in. |
| Warranty | Limited Lifetime Warranty |
| Estimated Heating Area | Up to ~1,300 sq. ft. (varies by insulation, ceiling height, climate) |
| Made In | USA (Hussong Manufacturing, Minnesota) |
Available Options & Accessories
Most key features come standard on the Chaska 335S. The decisions you make during the order process focus on style and aesthetic choices:
- Fuel Type — Natural Gas or Liquid Propane (specified at order; conversion kits available)
- Screen Front Style — 9 different screen front options in a variety of colors, ranging from traditional ornate patterns to contemporary minimalist designs
- Refractory Choice — Traditional brick (standard) or alternative refractory finishes for different interior aesthetics
- Shroud Trim — decorative metal frame integrating the insert with your existing fireplace surround; multiple style options available
- Decorative Fronts / Surrounds — exterior trim around the firebox opening. Browse our Fireplace Fronts collection for additional compatible styles.
- Remote Control Options — basic on/off remote, thermostat remote, or programmable remote options available
For configuration assistance — choosing the right screen front, refractory, and shroud combination for your interior — contact us. We do this every day.
Brand
Kozy Heat®
Transform your existing wood-burning fireplace into a clean, convenient, and efficient source of warmth with a Kozy Heat gas fireplace insert. Designed to fit inside many masonry or factory-built wood fireplaces, Kozy Heat gas inserts deliver realistic flame presentation, dependable heat, and the everyday convenience of natural gas or propane.
A gas insert uses a sealed firebox and venting system to draw combustion air from outdoors and exhaust fumes safely outside through the existing chimney chase.
Distinctive Features
Convert an Existing Fireplace Without Starting Over
Enjoy the charm of your existing fireplace with the push-button convenience of gas. Kozy Heat gas inserts are a great solution for replacing messy wood fires with steady, controllable comfort.
Direct Vent Performance
Get warmth where you want it most. Kozy Heat direct vent gas inserts are built to deliver dependable heat while using your existing chimney as the venting path.
Traditional or Contemporary Fireplace Looks
Whether your home leans rustic, transitional, or modern, Kozy Heat gas inserts give you design flexibility with realistic flame options, decorative fronts, and finish choices that complete the room.
Kozy Heat Gas Insert FAQs
What is a Kozy Heat gas fireplace insert?
A gas fireplace insert is a gas-burning appliance installed inside an existing wood-burning fireplace. It updates the old fireplace with a sealed gas firebox, burner system, and venting.
Can a Kozy Heat gas insert go into my existing fireplace?
In many cases, yes. Gas inserts are designed for existing masonry or approved factory-built wood fireplaces, but exact fit depends on the fireplace opening, chimney condition, venting requirements, and the specific Kozy Heat model.
Do Kozy Heat gas inserts use natural gas or propane?
Many Kozy Heat gas inserts are available for natural gas or propane. Fuel availability depends on the model and installation setup.
Do I still need my chimney?
Yes, but not in the same way as a wood fire. A direct vent gas insert commonly uses the existing chimney as a chase for the intake and exhaust venting system.
Are gas inserts good for zone heating?
Yes. A Kozy Heat gas insert can help heat the room or area where you spend the most time, reducing reliance on whole-home heating in some situations.
Do Kozy Heat gas inserts require professional installation?
Yes. Gas inserts should be measured, selected, vented, connected, and tested by a qualified fireplace professional. At all Leisure Time Inc. locations we offer the services necessary to get your fireplace insert properly installed.
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