Dometic DFSD20121 RV LP Furnace | 18K BTU | Half-Door

Heat your RV efficiently with the Dometic DFSD20121 18,000 BTU RV Furnace. Compact 18K BTU LP furnace with automatic ignition and reduced air turbulence for quieter operation. Horizontal OR vertical configuration for flexible installation. Half-door cover configuration — designed to be installed WITHOUT a full exterior door.

⚠️ Half-Door Configuration — NOT for Full-Door Installations

Critical fitment note: this DFSD20121 comes with a half-door/cover (as pictured) and is NOT designed to use a full exterior door.

If your installation requires a furnace with full-door allowance, use the Dometic DFSD20111 18K Furnace instead — same 18K BTU platform, designed for full-door installations.

Half-Door vs Full-Door — Which Do You Need?

• DFSD20121 (this listing) — half-door/cover included, NOT for full-door installations
• DFSD20111 — designed for full exterior door installations

Verify your existing installation type before ordering.

18,000 BTU Heating Performance

• 18,000 BTU output — right-sized for many mid-size RV coaches
• Automatic ignition for easy start-up
• LP gas + DC voltage
• Low-profile design for improved airflow
• Quiet operation — reduced air turbulence

Horizontal OR Vertical Installation

Flexible installation configuration — mount horizontal OR vertical depending on your available space.

Physical Dimensions

• Base Dimensions: 20" × 12" × 7.5"
• ⚠️ Note on gas reroute steel tube: The gas reroute tube creates an approximate 1" overhang on the edge. Effective dimensions can be treated as ~21" × 12" × 7.5" when planning your cutout and clearances.

⚠️ Access Door NOT Included

This unit ships with the half-door/cover pictured but does NOT include an exterior access door. Source separately if needed.

⚠️ Thermostat NOT Included

Thermostat sold separately. In most cases, you can reuse your existing thermostat. If a new thermostat is needed, compatible Dometic thermostats:

• White: Part #38453
• Black: Part #32300

⚠️ Condition Disclosure — May Not Come in Manufacturer Box

These units are new but may or may not come in the manufacturer box. All units are double-boxed to prevent damage during shipping.

Included Duct Collars

Comes with 2 duct collars. Additional collars available for purchase if your HVAC system requires more — chat with us if you need more.

What's Included

• Furnace unit (DFSD20121)
• Half-door/cover (as pictured)
• Vent
• 2 duct collars
• Manual

What's NOT Included

• Full exterior door (not applicable — this unit is not for full-door installations)
• Thermostat (reuse existing, or purchase compatible #38453 white / #32300 black)

Cross-Reference Part Numbers

• Part Number: DFSD20121

⚠️ Professional Installation Required

Installation involves LP gas connections, 12V DC electrical wiring, ductwork integration, and precise cutout dimensions accounting for the 1" gas reroute tube overhang. Installation should be performed by a qualified RV service technician.

2-Year Manufacturer Warranty

Genuine Dometic OEM

Key Features

• Genuine Dometic OEM RV LP furnace
• Part number: DFSD20121
• 18,000 BTU output
• Half-door/cover configuration — NOT for full-door installations
• Full-door sibling available: Dometic DFSD20111
• Automatic ignition
• LP gas + 12V DC operation
• Horizontal OR vertical installation
• Low-profile design for improved airflow
• Quiet operation — reduced air turbulence
• Compact 20" × 12" × 7.5" (~21" with gas reroute tube overhang)
• 2 duct collars included (more available for purchase)
• Thermostat NOT included — reuse existing or use #38453 (white) / #32300 (black)
• Access door NOT included
• New — may not come in manufacturer box (double-boxed for shipping)
• Backed by 2-year manufacturer warranty

Specifications

• Brand: Dometic
• Part Number: DFSD20121
• Type: RV LP Furnace (Half-Door / Cover Configuration)
• BTU Output: 18,000
• Fuel: LP Gas
• Voltage: DC (12V)
• Ignition: Automatic
• Installation Orientation: Horizontal OR Vertical
• Base Dimensions: 20" × 12" × 7.5"
• Effective Dimensions (w/ gas reroute tube overhang): ~21" × 12" × 7.5"
• Duct Collars Included: 2 (more available)
• Half-Door/Cover: Included (as pictured)
• Full Exterior Door: NOT included (not compatible — use DFSD20111 for full-door installations)
• Thermostat: NOT included (reuse existing, or use #38453 white / #32300 black)
• Full-Door Sibling: Dometic DFSD20111
• Condition: New (may not come in manufacturer box; double-boxed for shipping)
• Warranty: 2-year manufacturer warranty