{"product_id":"dometic-dfldh40121-mojave-rv-furnace-40k-btu-hall-effect-doorless","title":"Dometic DFLDH40121 Mojave RV Furnace | 40K BTU | Hall Effect | Doorless","description":"\u003cp\u003eHeat your RV efficiently and quietly with the \u003cstrong\u003eDometic DFLDH40121 40,000 BTU Mojave Series RV Furnace\u003c\/strong\u003e — the \u003cstrong\u003edoorless, Hall Effect sensor version\u003c\/strong\u003e of the Mojave platform. Compact, lightweight LP gas furnace for interior-access installations where no exterior door is cut into the coach. Available at The RV Surplus.\u003c\/p\u003e\n\n\u003ch3\u003e⭐ What Makes The DFLDH40121 Different\u003c\/h3\u003e\n\u003cp\u003eTwo distinguishing features vs. earlier Mojave furnaces:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e\"H\" = Hall Effect sensor\u003c\/strong\u003e — solid-state airflow sensing in place of the mechanical sail switch\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e\"121\" = Doorless\u003c\/strong\u003e — designed for installations with NO exterior access door cut into the coach\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⚠️ Doorless Install — Confirm Your Space BEFORE Ordering\u003c\/h3\u003e\n\u003cp\u003eThis furnace is built for \u003cstrong\u003einstallations without an exterior access door\u003c\/strong\u003e. Important fitment notes:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eNo exterior access door is included or required — \u003cstrong\u003edo not order door #33058\u003c\/strong\u003e\n\u003c\/li\u003e\n  \u003cli\u003eIf you're \u003cstrong\u003ereplacing a doored furnace with this doorless unit\u003c\/strong\u003e, you may need to \u003cstrong\u003emodify your existing space\u003c\/strong\u003e — the housing requirements are different from a doored install\u003c\/li\u003e\n  \u003cli\u003eIf you want the exterior-access (doored) version instead, order the \u003ca href=\"\/products\/dometic-dfldh40111-mojave-rv-furnace-40000-btu-hall-effect\"\u003e\u003cstrong\u003eDFLDH40111\u003c\/strong\u003e\u003c\/a\u003e and matching door #33058 separately\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⭐ Hall Effect Sensor vs. Sail Switch\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong\u003e\"H\" in DFLDH40121\u003c\/strong\u003e denotes \u003cstrong\u003eHall Effect sensing\u003c\/strong\u003e in place of the traditional sail switch:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSail switch (older design):\u003c\/strong\u003e physical paddle in the airstream closes a contact when airflow is strong enough. Common failure point — dust buildup, bent paddles, worn contacts, cold-weather sticking.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHall Effect sensor (this furnace):\u003c\/strong\u003e solid-state magnetic sensing that detects blower-wheel rotation directly. No moving contacts in the airstream, nothing to gum up, nothing to bend.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eUpdated control board\u003c\/strong\u003e is matched to the Hall Effect circuit — the furnace ships ready to run, no sail-switch retrofit or board swap required.\u003c\/p\u003e\n\n\u003ch3\u003e⚠️ Board + Sensor Matched Set — Not Interchangeable\u003c\/h3\u003e\n\u003cp\u003eThe DFLDH40121 control board and Hall Effect sensor are a \u003cstrong\u003ematched system\u003c\/strong\u003e. You cannot drop a Hall Effect sensor into an older sail-switch board, or run the new board with a sail switch. For replacement scenarios, commit to one platform \u003cstrong\u003ebefore\u003c\/strong\u003e ordering parts.\u003c\/p\u003e\n\n\u003ch3\u003e⭐ 40,000 BTU — Substantial Heating Capacity\u003c\/h3\u003e\n\u003cp\u003eThe DFLDH40121 delivers 40,000 BTU of heating output — appropriate for:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eLarger fifth wheels and toy haulers with serious heating demand\u003c\/li\u003e\n  \u003cli\u003eClass A motorhomes with substantial interior volume\u003c\/li\u003e\n  \u003cli\u003eRVs in cold climates where heating capacity matters\u003c\/li\u003e\n  \u003cli\u003eSetups with multiple slide-outs that add cabin space requiring heat\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⭐ Tubular Pipe Heat Exchanger — Quieter, Smoother Airflow\u003c\/h3\u003e\n\u003cp\u003eDometic's standout engineering feature is the \u003cstrong\u003etubular pipe design heat exchanger with smooth, rounded bends\u003c\/strong\u003e. Compared to conventional sharp-cornered designs:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAir flows and heats more evenly through the rounded pipe geometry\u003c\/li\u003e\n  \u003cli\u003eAir doesn't get \"trapped\" or slowed in sharp corners\u003c\/li\u003e\n  \u003cli\u003eLess turbulence means \u003cstrong\u003emeaningfully quieter operation\u003c\/strong\u003e — a real comfort improvement when you're trying to sleep with the furnace cycling\u003c\/li\u003e\n  \u003cli\u003eMaximum airflow at a given fan speed\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⭐ Up to 9 Duct Configurations — Most in the Industry\u003c\/h3\u003e\n\u003cp\u003eThe DFLDH40121 offers up to \u003cstrong\u003e9 possible duct configurations\u003c\/strong\u003e — the most flexibility on the market for distributing heat throughout your RV. Whether your installation needs ductwork running forward, aft, side-to-side, or some combination, the DFLDH40121 likely supports the configuration you need without compromise.\u003c\/p\u003e\n\n\u003ch3\u003e⭐ Horizontal OR Vertical Installation\u003c\/h3\u003e\n\u003cp\u003eThe compact low-profile design installs in \u003cstrong\u003eeither horizontal or vertical orientation\u003c\/strong\u003e — adapting to existing space constraints in different RV layouts.\u003c\/p\u003e\n\n\u003ch3\u003e⭐ Wide Replacement Coverage\u003c\/h3\u003e\n\u003cp\u003eThe DFLDH40121 is the doorless Hall Effect option in a platform that replaces an extensive range of earlier Atwood\/Dometic furnaces. Cross-reference: if your existing furnace has any of these part numbers AND your install is (or will be) doorless, this is a candidate replacement:\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eOlder item numbers:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e8940DC, 32659, 32661, 32803, 32806, 35600, 38351\u003c\/li\u003e\n  \u003cli\u003e32803SU, 32806SU, 35600SU\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eOlder model numbers:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAFLD40111, AFLD40131, DFLD40131 (BP, SP, or SU variants)\u003c\/li\u003e\n  \u003cli\u003eDFLD40121 (sail-switch doorless predecessor to this Hall Effect version)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003e⚠️ If you're going from a doored installation to this doorless one (or vice versa), you may need to modify your existing space\u003c\/strong\u003e — the housing requirements are different.\u003c\/p\u003e\n\n\u003ch3\u003e⭐ Electric Ignition + 12V DC Operation\u003c\/h3\u003e\n\u003cp\u003eElectric ignition for reliable starts without manual lighting. The furnace runs on 12V DC power from your RV electrical system (12.5 amp draw during operation) and burns LP propane as the heat source.\u003c\/p\u003e\n\n\u003ch3\u003e⚠️ Before Calling It a Furnace Failure\u003c\/h3\u003e\n\u003cp\u003eHall Effect sensing eliminates one major failure mode (the sail switch), but other faults still happen. Work through:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLP gas supply\u003c\/strong\u003e — tank valve open, regulator working, lines bled of air\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e12V battery voltage AT the furnace\u003c\/strong\u003e — not just at the battery (long wire runs cause drop)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThermostat calling for heat\u003c\/strong\u003e — verify with a jumper at the furnace terminals if in doubt\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReturn air blockage\u003c\/strong\u003e — the blower must reach full speed for the Hall Effect sensor to prove airflow\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExterior vents clear\u003c\/strong\u003e — wasps, spider webs, and debris block combustion and exhaust\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBlower wheel free and balanced\u003c\/strong\u003e — Hall Effect senses rotation; a dragging bearing or broken wheel reads as \"no airflow proven\"\u003c\/li\u003e\n  \u003cli\u003eListen for the \u003cstrong\u003esequence of events on a call for heat\u003c\/strong\u003e: fan starts → Hall Effect proves rotation → gas valve opens → spark → flame → steady run. Where it stops narrows the fault.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⚠️ Professional Installation Recommended\u003c\/h3\u003e\n\u003cp\u003eFurnace installation involves propane connections, ducting, exhaust venting, and electrical work. \u003cstrong\u003eImproperly installed gas furnaces are a serious fire, carbon monoxide, and safety risk.\u003c\/strong\u003e Installation should be performed by a qualified RV service technician. Always leak-test propane connections after installation and verify proper exhaust venting.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e(1) DFLDH40121 Furnace with Hall Effect sensor and updated control board\u003c\/li\u003e\n  \u003cli\u003e(2) Mounting Brackets\u003c\/li\u003e\n  \u003cli\u003e(2 to 4) Duct Adapters (quantity depends on configuration)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e⭐ No Door Required\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eNo exterior access door is needed or included with this furnace.\u003c\/strong\u003e This is the doorless configuration — do NOT order door #33058 (that door is for the doored DFLDH40111 version).\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003cstrong\u003eDoorless configuration — no exterior access door required\u003c\/strong\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003cstrong\u003eHall Effect airflow sensor (replaces sail switch)\u003c\/strong\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003cstrong\u003eUpdated control board matched to Hall Effect sensing\u003c\/strong\u003e\u003c\/li\u003e\n  \u003cli\u003e40,000 BTU heating capacity — substantial output for larger RVs\u003c\/li\u003e\n  \u003cli\u003eDometic Mojave Series tubular pipe heat exchanger design\u003c\/li\u003e\n  \u003cli\u003eQuieter operation via reduced air turbulence\u003c\/li\u003e\n  \u003cli\u003eUp to 9 duct configurations — most in the industry\u003c\/li\u003e\n  \u003cli\u003eHorizontal OR vertical installation\u003c\/li\u003e\n  \u003cli\u003eLow-profile compact design\u003c\/li\u003e\n  \u003cli\u003eElectric ignition\u003c\/li\u003e\n  \u003cli\u003eLP gas heat source\u003c\/li\u003e\n  \u003cli\u003e12V DC operation, 12.5 amp draw\u003c\/li\u003e\n  \u003cli\u003eDucted circulation\u003c\/li\u003e\n  \u003cli\u003eCompact dimensions: 16-1\/2\" W × 9\" H × 20\" D\u003c\/li\u003e\n  \u003cli\u003eWeight: 39 lbs\u003c\/li\u003e\n  \u003cli\u003eBacked by a limited 2-year manufacturer warranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eBrand: Dometic\u003c\/li\u003e\n  \u003cli\u003eSeries: Mojave\u003c\/li\u003e\n  \u003cli\u003eModel: DFLDH40121\u003c\/li\u003e\n  \u003cli\u003eType: RV Furnace\u003c\/li\u003e\n  \u003cli\u003eConfiguration: Doorless (no exterior access door)\u003c\/li\u003e\n  \u003cli\u003eAirflow Sensing: Hall Effect (updated vs sail-switch DFLD40121)\u003c\/li\u003e\n  \u003cli\u003eControl Board: Updated — matched to Hall Effect sensor\u003c\/li\u003e\n  \u003cli\u003eBTU Output: 40,000 BTU\u003c\/li\u003e\n  \u003cli\u003eHeat Source: LP gas (propane)\u003c\/li\u003e\n  \u003cli\u003eIgnition: Electric\u003c\/li\u003e\n  \u003cli\u003ePower: 12V DC\u003c\/li\u003e\n  \u003cli\u003eCurrent Draw: 12.5 amps\u003c\/li\u003e\n  \u003cli\u003eCirculation: Ducted\u003c\/li\u003e\n  \u003cli\u003eDuct Configurations: Up to 9 possible\u003c\/li\u003e\n  \u003cli\u003eInstallation Orientation: Horizontal OR vertical\u003c\/li\u003e\n  \u003cli\u003eFurnace Access: Doorless (no exterior door)\u003c\/li\u003e\n  \u003cli\u003eAccess Door: NOT required, NOT included\u003c\/li\u003e\n  \u003cli\u003eDoored Alternative Model: DFLDH40111 (requires door #33058, sold separately)\u003c\/li\u003e\n  \u003cli\u003eFurnace Dimensions: 16-1\/2\" W × 9\" H × 20\" D\u003c\/li\u003e\n  \u003cli\u003eWeight: 39 lbs\u003c\/li\u003e\n  \u003cli\u003eReplaces (older models — verify fitment): 8940DC, 32659, 32661, 32803, 32806, 35600, 38351, 32803SU, 32806SU, 35600SU, AFLD40111, AFLD40131, DFLD40121, DFLD40131 (BP\/SP\/SU)\u003c\/li\u003e\n  \u003cli\u003eReturn Policy: 30 days after delivery\u003c\/li\u003e\n  \u003cli\u003eSpecial Order: No\u003c\/li\u003e\n  \u003cli\u003eWarranty: Limited 2-year manufacturer warranty\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Dometic","offers":[{"title":"Default Title","offer_id":58822240174383,"sku":null,"price":1199.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0729\/7663\/0063\/files\/61434-primary_1_84fc572e-ff0a-4861-af8a-d1600f8218f5.webp?v=1794337214","url":"https:\/\/thervsurplus.com\/products\/dometic-dfldh40121-mojave-rv-furnace-40k-btu-hall-effect-doorless","provider":"The RV Surplus LLC","version":"1.0","type":"link"}