RV Furnace Crossover Chart — Find Your Replacement Model

RV Furnace Replacement Crossover Chart | The RV Surplus
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Suburban Furnace Core Replacement Modules

Suburban's core replacement modules slide directly into your existing furnace cabinet — no ductwork, no cabinet removal, no hassle. Match your original model number below to find the right core, then shop it directly on our site.

SF-Q Series

Low-profile ducted furnaces (7½" high). Optional exterior access door with side/rear gas & electrical connections. 20K–40K BTU range.

Current Model Orig. Part # BTU Repl. Core # Model Type Shop
SF-20SF-20QSF-Q (2552A)
2512A2386A
20,000 BTU20K
2605A
RP-20Q
Ducted
SF-25QSF-30QSF-Q (2556A)SF-Q (2559A)
2516A2519A2387A2388A
25,000–30,000 BTU25–30K
2607A
RP-30Q
Ducted
SF-35QSF-42QSF-Q (2564A)
2524A2527A2398A2399A
35,000–40,000 BTU35–40K
2609A
RP-35Q
Ducted
SF-FQ Series

Interior-service low-profile ducted furnaces (7½" high). Front inside gas connection — optional exterior access door. Great for flush-wall installs.

Current Model Orig. Part # BTU Repl. Core # Model Type Shop
SF-20FSF-20FQSF-FQ (2551A)
2511A2389A
20,000 BTU20K
2606A
RP-20FQ
Ducted
SF-25FSF-25FQSF-30FSF-30FQSF-FQ (2555A)SF-FQ (2558A)
2515A2518A2390A2391A
25,000–30,000 BTU25–30K
2608A
RP-30FQ
Ducted
F-42FSF-35FSF-35FQSF-42FQSF-FQ (2563A)
2523A2526A2400A2401A
35,000–40,000 BTU35–40K
2610A
RP-35FQ
Ducted
NT-SQ & NT-SEQ Series

Compact, lightweight furnaces for smaller RVs, trailers, truck campers & pop-ups. NT-SQ is ducted; NT-SEQ is direct-discharge with optional side duct.

Current Model Orig. Part # BTU Repl. Core # Model Type Shop
NT-16SQNT-20SQ
2444A2450A
16,000–19,000 BTU16–19K
2611A
RP-16NQ
Ducted
NT-16SEQ (White)NT-16SEQ (Black)NT-20SEQ (White)NT-20SEQ (Black)NT-SEQ
2503APW2503ABK2504APW2504ABK
16,000–19,000 BTU16–19K
2612A
RP-16NEQ
Direct Discharge
NT Series & Park Models

High-capacity 12V DC ducted furnaces (NT) and 120V AC park model furnaces (P-40). Uniform cabinet sizing makes installation straightforward.

Current Model Orig. Part # BTU Repl. Core # Model Type Shop
NT-30SPNT-34SP
2453A2454A
30,000–34,000 BTU30–34K
2613A
RP-30N
Ducted · 12V
NT-40
2455A
40,000 BTU40K
2614A
RP-40N
Ducted · 12V
P-40P-40 (2456A)
2456A
40,000 BTU40K
2615A
RP-40P
Park · 120V
How to read this chart: Find your furnace's model number on the label inside the cabinet. Match it to "Your Current Furnace Model(s)" to get the replacement core part number. The new core slides directly into your existing cabinet — no ductwork removal needed. Grille not included with NT-SEQ core (2612A). Cabinet assembly not included with any core.
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Dometic / Atwood HydroFlame — Full Model Crossover

Dometic acquired Atwood and continued the HydroFlame furnace line under new model names. Legacy Atwood 79-series, 85-series, and 89-series units map directly to the Dometic AF-series, and then to the current DF-series "Mojave" line. Use this chart to find the current Dometic equivalent for any Atwood or older HydroFlame furnace.

🔑 How to Read a Dometic AF / DF Model Number

Prefix — Generation

AF___Atwood-era (Dometic transition)
DF___Current Dometic "Mojave"

Size Class

_SD_Small — 7" high, compact
_MD_Medium — 7" high, standard
_LD_Large — 9" high

BTU (in model number)

__1212,000 BTU
__1616,000 BTU
__2018,000–20,000 BTU
__2525,000 BTU
__3030,000 BTU
__3535,000 BTU
__4040,000 BTU

3-Digit Config Suffix

111Standard + access door
121Doorless (no ext. door)
131–151Alternate duct orientations
SD — Small / Compact (7" High · 12K–18K BTU)

Common in tent campers, truck campers, small trailers, and van conversions. The 7900-series HydroFlame furnaces (7912, 7916, 7920) are the primary legacy models in this class.

Legacy Model Gen. BTU AF Series DF Mojave Configs Shop
7912-IIHF 7912
Legacy 12,000 BTU12K
AFSD12
DFSD12___
111121131141
7916-IIHF 7916
Legacy 16,000 BTU16K
AFSD16
DFSD16___
111121131141
7920-IIHF 7920
Legacy 18,000 BTU18K
AFSD20
DFSD20___
111121131141
MD — Medium (7" High · 16K–35K BTU) — Most Common Atwood

The 85-series (I through IV) and 89-series DC furnaces are the most frequently replaced Atwood units. They cross directly to the AF-MD and then DF-MD Mojave line by BTU size.

Legacy Model Gen. BTU AF Series DF Mojave Configs Shop
85-I 1685-II 1685-III 1685-IV 168516-IV
85-Series 16,000 BTU16K
AFMD16
DFMD16___
111121131141
85-I 2085-II 2085-III 2085-IV 208520-IV8525
85-Series 20,000 BTU20K
AFMD20
DFMD20___
111121131141
85-I 2585-II 2585-III 2585-IV 258525-IV
85-Series 25,000 BTU25K
AFMD25
DFMD25___
111121131141
85-I 3185-II 3185-III 3185-IV 318531-IV89-I DC89-II DC89-III DC
85/89-Series 30,000 BTU30K
AFMD30
DFMD30___
111121131141151
85-I 3585-II 3585-III 3585-IV 358535-IV89358940
85/89-Series 35,000 BTU35K
AFMD35
DFMD35___
111121131141151
LD — Large (9" High · 40K BTU)

High-capacity large-format furnaces used in larger motorhomes and coaches. 9" cabinet height — measure your existing opening before ordering.

Legacy Model Gen. BTU AF Series DF Mojave Configs Shop
AFLD35AFMD40
AF-Era 35,000–40,000 BTU35–40K
AFLD (series)
DFLD40___
111121
Choosing the Right Config Suffix (111 / 121 / 131…)

Once you know your base Dometic model (e.g. DFMD30), the 3-digit suffix tells you which physical variant to order. Match it to your existing install.

Suffix Access Door Description Best For
111 Required Standard — requires exterior access door Most common; direct replacement for door-accessible installs
121 None Doorless — no exterior access door needed Interior-service installs; cleaner exterior appearance
131141151
Required Alternate duct port orientations Use when existing ductwork requires a different port placement
Important installation notes: Dometic DF-series "Mojave" furnaces feature a redesigned one-piece tubular heat exchanger and can be mounted horizontally or vertically — more flexible than legacy Atwood units. LP connection location may differ slightly from your original furnace and may require a short adapter line. Always verify access door cutout dimensions before ordering. Note on 2-stage models: Dometic discontinued the two-stage Excalibur/XT furnace line; the standard single-stage DF-series is the current OEM replacement.
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