Superior VRT3500 Series Vent-Free Gas Firebox
Superior VRT3536 36" Vent-Free Gas Firebox – Radiant Smooth-Faced Design
The Superior VRT3536 is a 36-inch radiant smooth-faced vent-free gas firebox enclosure designed to provide a clean built-in foundation for an approved vent-free gas fireplace installation. It features a large 36" wide × 28" high opening, refractory-lined interior, included mesh fire screens, and compatibility with listed ANSI Z21.11.2 vent-free gas log room heaters that meet the firebox and installation requirements.
Model
VRT3536
Nominal Size
36"
Opening
36" W × 28" H
Configuration
Firebox Only
Design
Radiant / Smooth-Faced
Venting
Vent-Free
Max Heater Input
40,000 BTU/H
Warranty
20-Year Limited
Important: Firebox Enclosure Only
The Superior VRT3536 is not a complete gas fireplace system. A compatible listed vent-free gas log/burner system, applicable controls, fuel configuration, and required installation components must be selected separately.
Clean 36" Louverless Vent-Free Fireplace Foundation
The Superior VRT3536 provides the built-in enclosure for a compatible vent-free gas fireplace installation while allowing the gas log presentation, burner, fuel type, controls, and accessories to be selected separately.
Its radiant smooth-faced design eliminates conventional louvers and creates a cleaner architectural appearance around the fireplace opening.
The tall 36" × 28" opening creates an unobstructed front view of the refractory interior and the separately selected vent-free gas log system.
Superior VRT3536 at a Glance
Brand
Superior Fireplaces
Product Type
Vent-Free Gas Firebox Enclosure
Fire Screens
Mesh Screens Included
Gas Log System
Sold Separately
Is the Superior VRT3536 Right for Your Project?
Best For
- Projects requiring a 36" built-in vent-free firebox.
- Homeowners wanting a clean smooth-faced fireplace without conventional louvers.
- New-construction or remodeling projects.
- Projects needing a tall 28" fireplace opening.
- Buyers wanting a refractory-lined masonry-style interior.
- Installations using a compatible listed ANSI Z21.11.2 vent-free gas log heater.
- Projects where optional blower capability is desired.
- Projects where optional outside-air or decorative-screen accessories are useful.
- Buyers who want to choose the burner, logs, fuel, and controls separately.
Consider Another Fireplace If
- You want a complete burner-and-log fireplace package.
- Your project requires a wood-burning firebox.
- Your selected heater exceeds 40,000 BTU/H.
- Your selected gas-log heater does not fit the VRT3536 interior dimensions.
- Your framing cavity cannot accommodate the required dimensions.
- You cannot meet the required combustion-air or combustible-clearance provisions.
- You need installation in a bedroom or bathroom.
What Is the Superior VRT3536?
The VRT3536 is the firebox enclosure for a qualifying vent-free gas fireplace system.
The firebox provides the built-in structure, refractory interior, hearth, front opening, and mesh fire screens. The separately selected vent-free gas log heater determines:
- Natural gas or propane/LP fuel
- Burner design
- Ignition system
- Control type
- Flame presentation
- BTU input
- Specific gas-log appearance
Maximum compatible heater input: The listed unvented decorative room heater installed in the VRT3536 must not exceed 40,000 BTU/H.
What's Included with the VRT3536?
Included
- Superior VRT3536 vent-free firebox enclosure
- Refractory interior components
- Refractory hearth
- Mesh fire screens
- Textured powder-coat finish
Sold Separately / Optional
- Compatible vent-free gas log/burner system
- Applicable gas-log controls
- Optional blower kit
- Optional outside-air kit
- Optional decorative twin-pane screen
- Optional heat-deflection hood
Do not choose a gas-log heater by nominal size alone. Verify the exact heater's minimum firebox dimensions, fuel configuration, controls, input rating, and installation requirements before ordering.
VRT3536 Opening & Appliance Dimensions
| Nominal Firebox Size |
36" |
| Firebox Opening Width |
36" |
| Firebox Opening Height |
28" |
| Appliance Width |
41-3/4" |
| Appliance Height |
41-1/4" |
| Appliance Depth |
20" |
Do not confuse visible opening dimensions with appliance or framing dimensions. All three sets of measurements serve different installation purposes.
VRT3536 Interior Firebox Dimensions
Superior provides specific interior dimensions to help determine whether the selected gas-log heater will fit inside the VRT3536.
| Interior Front Width |
35" |
| Interior Rear Width |
23-1/4" |
| Interior Depth |
17-3/8" |
| Interior Height |
28" |
Compatibility rule: Compare all four interior dimensions with the minimum requirements of the exact gas-log heater being considered.
VRT3536 Framing Requirements
For the documented installation configuration, Superior lists the following framing dimensions:
| Framing Width |
42-1/4" |
| Framing Height |
44-1/4" |
| Framing Depth |
20-1/2" |
Construction planning: Use Superior's installation and specification documents for the complete enclosure layout, corner installation, mantel, trim, finish, floor, and accessory requirements.
Do not scale dimensions from illustrations or product photographs. Manufacturer diagrams and images are not scaled construction drawings.
Clean, Smooth-Faced Fireplace Design
Louverless Front
The radiant smooth-faced design removes conventional louvers for a cleaner built-in appearance.
Tall Firebox Opening
The 36" wide × 28" high opening emphasizes the selected log and flame presentation.
Refractory Interior Options
White Stacked Refractory
The white stacked refractory treatment creates a traditional horizontal masonry appearance.
White Herringbone Refractory
The white herringbone refractory treatment provides an alternate patterned masonry appearance.
Configuration note: Manufacturer literature shows both White Stacked and White Herringbone refractory treatments. Verify the exact selected product configuration before ordering.
Compatible Vent-Free Gas Log Requirements
The VRT3500 Series is designed for use with listed ANSI Z21.11.2 vent-free gas log room heaters that meet the available firebox dimensions and installation requirements.
Maximum heater input: 40,000 BTU/H. Do not install a vent-free decorative room heater that exceeds the manufacturer-specified maximum input.
Gas Log Compatibility: What to Verify
Front Width
The VRT3536 provides 35" of interior front width.
Rear Width
The interior rear width is 23-1/4".
Depth
The available interior depth is 17-3/8".
Height
The available interior height is 28".
Fuel
Natural gas or propane/LP depends on the selected heater.
Controls
Ignition and control options depend on the selected burner system.
Nominal gas-log size alone does not establish compatibility. Always compare the exact gas-log system's minimum firebox requirements with the VRT3536 interior dimensions.
Superior Vent-Free Gas Log Styles Shown for the VRT3500 Series
Superior's VRT3500 literature shows multiple vent-free gas-log presentations. The exact size, fuel, control version, and firebox fit must still be verified.
Boulder Mountain
Part of Superior's Glow-Ramp Series, with rear yellow flames, a glowing center area, and ember presentation.
Wild Timber
Part of the Triple-Flame Series with a multi-burner flame presentation and glowing ember bed.
Rugged Stack
A Triple-Flame Series presentation combining detailed concrete logs with layered flame and ember effects.
Mossy Oak
A Mega-Flame Series presentation with triple-burner flame activity and a glowing ember bed.
Giant Timbers
A Mega-Flame Series presentation with substantial concrete logs and multi-level flame activity.
Compatibility note: Showing a gas-log family in VRT3500 literature does not mean every size, fuel type, or control version of that family fits the VRT3536.
Optional Accessories
Decorative Twin-Pane Screen
Provides an alternate architectural front-screen treatment.
FBK-100 Blower
Optional single-speed blower configuration.
FBK-200 Blower
Optional variable-speed blower configuration.
Outside-Air Kit
Optional outside-air gate and duct kit for applicable installations.
Heat-Deflection Hood
Optional hood that changes applicable mantel and trim clearance requirements.
Optional Blower Planning
FBK-100
Single-speed blower configuration.
FBK-200
Variable-speed blower configuration.
Electrical planning: If a blower may be installed, review Superior's electrical provisions before the firebox is framed and enclosed.
Optional Heat-Deflection Hood
The VRT3500 literature identifies the heat-deflection hood as an optional accessory.
Clearance effect: Combustible mantel and trim clearance requirements differ depending on whether the approved hood is installed. Use the applicable manufacturer clearance diagram for the final configuration.
Vent-Free Operation & Combustion Air
A vent-free gas heater installed in the VRT3536 uses air from the room for combustion.
The installation must provide adequate combustion and ventilation air according to the manufacturer procedures and applicable codes.
Vent-free does not mean air-free. Do not install the heater in a space that fails the required combustion-air calculation unless an approved source of additional fresh air is provided.
Other fuel-burning appliances in communicating spaces can affect the total air-volume calculation and must be considered.
Floor & Finishing Considerations
The VRT3536 can be installed on an appropriately supported combustible floor.
When installed directly over carpeting, vinyl tile, or certain other combustible floor coverings, Superior requires a metal or wood panel extending the full width and depth of the appliance.
Approved noncombustible finish materials may overlap the black front facing when installed according to the manufacturer instructions.
Examples of noncombustible finish materials: Manufacturer guidance identifies materials such as marble, stone, tile, and brick as examples when installed correctly.
Installation & Safety Requirements
Approved Heater Only
Use a compatible listed ANSI Z21.11.2 vent-free gas log room heater.
40,000 BTU/H Maximum
The installed heater must not exceed the stated maximum input.
No Solid Fuel
Do not burn wood or other solid fuels in the VRT3536.
No Bedroom Installation
Do not install the firebox in a sleeping room.
No Bathroom Installation
Do not install the firebox in a bathroom.
Qualified Installation
Gas piping and applicable electrical work should be completed by qualified tradespeople.
- Maintain required side-wall, ceiling, mantel, trim, flooring, and combustible-material clearances.
- Keep furniture, draperies, clothing, gasoline, and other flammable materials away from the firebox.
- Avoid fans or drafts that alter the burner flame pattern.
- Provide the required combustion and ventilation air.
- Follow both the firebox instructions and the manual for the selected gas log system.
- Have the installation inspected and serviced according to manufacturer requirements.
Local-code verification: Vent-free appliance requirements vary by location. Verify that the planned installation is permitted and appropriate before purchase and installation.
Complete Superior VRT3536 Specifications
| Manufacturer |
Superior Fireplaces |
| Series |
VRT3500 |
| Model |
VRT3536 |
| Product Type |
Vent-Free Gas Firebox Enclosure |
| Nominal Size |
36" |
| View Style |
Front View |
| Firebox Design |
Radiant / Smooth-Faced |
| Installation Type |
Built-In |
| Venting |
Vent-Free |
| Firebox Opening Width |
36" |
| Firebox Opening Height |
28" |
| Appliance Width |
41-3/4" |
| Appliance Height |
41-1/4" |
| Appliance Depth |
20" |
| Framing Width |
42-1/4" |
| Framing Height |
44-1/4" |
| Framing Depth |
20-1/2" |
| Interior Front Width |
35" |
| Interior Rear Width |
23-1/4" |
| Interior Depth |
17-3/8" |
| Interior Height |
28" |
| Standard Interior |
White Refractory Interior |
| Refractory Treatments Shown in Literature |
White Stacked / White Herringbone |
| Refractory Hearth |
Included |
| Fire Screens |
Mesh Fire Screens Included |
| Exterior Finish |
Textured Powder Coat |
| Compatible Gas Log Standard |
Listed ANSI Z21.11.2 Vent-Free Gas Log Room Heater |
| Gas Log / Burner System |
Sold Separately |
| Maximum Compatible Heater Input |
40,000 BTU/H |
| Optional Blower |
Yes |
| Optional Outside-Air Kit |
Yes |
| Optional Decorative Screen |
Yes |
| Optional Heat-Deflection Hood |
Yes |
| Bedroom Installation |
Not Permitted |
| Bathroom Installation |
Not Permitted |
| Solid-Fuel Use |
Not Permitted |
| Warranty |
20-Year Limited Warranty |
Flame Authority Expert Recommendation
Choose the Superior VRT3536 when your project calls for a 36" built-in vent-free gas firebox with a clean smooth-faced appearance and the flexibility to select the gas-log heater, fuel type, controls, and accessories separately.
Its 36" × 28" opening, 35" interior front width, 23-1/4" rear width, 17-3/8" interior depth, 28" interior height, refractory interior, included mesh screens, optional blower capability, and 40,000 BTU/H maximum compatible heater input make it a flexible foundation for qualifying residential vent-free fireplace installations.
The most important purchasing step is verifying the selected gas-log heater dimensions, BTU input, framing space, fuel configuration, combustible clearances, combustion-air requirements, accessory plan, and local installation requirements before construction.
Need Help Choosing the Right Configuration?
Need assistance determining whether the Superior VRT3536 is right for your project or selecting a compatible vent-free gas log system?
Talk to a Flame Authority expert at +1-800-923-4556 or email support@flameauthority.com for help choosing a suitable fireplace configuration.
Official Manufacturer Resources
Superior VRT3500 Series Product Brochure
Series overview covering VRT3500 firebox designs, refractory treatments, accessories, and specifications.
Superior VRT3500 Series Vent Free Gas Logs Brochure
Manufacturer information covering compatible Superior vent-free gas-log families and configurations.
Superior VRT3500 Series Smart Sheet
Quick-reference features, sizing, refractory, accessory, and technical information.
Superior VRT3500 Series Installation and Operation Manual
Manufacturer framing, combustion-air, clearance, gas-line, electrical, operation, maintenance, and safety requirements.
Superior VRT3500 Series Specification Sheet
Manufacturer appliance, framing, interior, opening, and technical dimensions.
Superior VRT3536 FAQs
Is the Superior VRT3536 a complete gas fireplace?
No. The VRT3536 is a vent-free firebox enclosure. The compatible gas-log burner system, fuel configuration, and applicable controls are selected separately.
Does the VRT3536 require a chimney?
No conventional chimney or flue is used for the approved vent-free configuration, but all combustion-air, clearance, gas-piping, and installation requirements still apply.
What size is the Superior VRT3536?
The VRT3536 is the 36-inch VRT3500 model with a 36" wide × 28" high firebox opening.
What are the framing dimensions for the VRT3536?
The manufacturer specifies framing dimensions of 42-1/4" W × 44-1/4" H × 20-1/2" D.
What are the VRT3536 interior firebox dimensions?
The interior measures 35" wide at the front, 23-1/4" wide at the rear, 17-3/8" deep, and 28" high.
What gas logs are compatible with the Superior VRT3536?
The firebox is designed for a listed ANSI Z21.11.2 vent-free gas log room heater that fits the VRT3536 interior and satisfies all manufacturer installation requirements.
Are gas logs included with the VRT3536?
No. The compatible vent-free gas log/burner system and applicable controls are selected separately.
What is the maximum heater input allowed in the VRT3536?
The installed listed unvented decorative room heater must not exceed 40,000 BTU/H.
Can I burn wood in the Superior VRT3536?
No. The manufacturer states that wood or other solid fuel must not be burned in this vent-free firebox.
Can the VRT3536 be installed in a bedroom or bathroom?
No. The manufacturer prohibits installation of the VRT3536 in sleeping rooms and bathrooms.
Does the VRT3536 include a blower?
No. Blower kits are optional accessories. Superior identifies both single-speed and variable-speed blower configurations for the VRT3500 Series.
Does the VRT3536 include fire screens?
Yes. Mesh fire screens are included.
Is the heat-deflection hood required?
The VRT3500 literature identifies the hood as optional. Mantel and trim clearance requirements differ depending on whether it is installed.
Can an outside-air kit be added?
Yes. Superior lists an optional outside-air gate and duct kit for applicable VRT3500 installations.
Does a vent-free VRT3536 installation still require combustion air?
Yes. The installed heater uses room air for combustion, so adequate combustion and ventilation air must be provided according to the manufacturer instructions and applicable codes.
What warranty does the Superior VRT3536 have?
The VRT3500 Series is offered with a 20-year limited warranty, subject to the manufacturer's warranty terms, exclusions, component coverage, and installation requirements.
Before You Order
Confirm Before Purchase
- You specifically need the Superior VRT3536.
- Your project can accommodate the 42-1/4" W × 44-1/4" H × 20-1/2" D framing requirements.
- You understand that the product is a firebox enclosure only.
- You have identified a compatible listed vent-free gas-log heater.
- The selected heater does not exceed 40,000 BTU/H.
- The heater fits within the 35" front width, 23-1/4" rear width, 17-3/8" depth, and 28" height.
- You can meet all required mantel, wall, trim, flooring, and finishing-material clearances.
- The installation space provides adequate combustion and ventilation air.
- The installation is not in a sleeping room or bathroom.
- You have planned any optional blower electrical requirements before enclosure.
- You have confirmed the intended refractory and accessory configuration.
Do Not Assume
- That the VRT3536 includes gas logs or a burner.
- That every 36" gas-log system will fit.
- That nominal gas-log size alone establishes compatibility.
- That the firebox itself produces 40,000 BTU/H.
- That vent-free operation eliminates combustion-air requirements.
- That wood or solid fuel can be burned inside the firebox.
- That bedroom or bathroom installation is permitted.
- That the optional hood has no effect on mantel or trim clearances.
- That a blower can always be added later without electrical planning.
- That product photographs or diagrams can be used as scaled construction drawings.
Final planning check: Use the Superior VRT3500 Installation & Operation Manual, Specification Sheet, Smart Sheet, and documentation for the exact selected gas-log heater to verify framing, firebox compatibility, BTU input, fuel configuration, combustion air, clearances, electrical provisions, accessories, and final installation before construction.
