Quick Answer: Most food trucks should buy the Eccotemp FVI12 — a 74,500 BTU propane unit rated 4.0 GPM at a 38°F rise that Eccotemp markets specifically for food trucks and conversion vans, since only its fan and igniter need a 120-volt outlet while the heat itself comes from gas. If your cart or trailer has no electrical hookup at all, the Camplux BW264-N (2.64 GPM, 68,000 BTU) runs on 2 D-cell batteries with no wiring. If you have no propane setup and only need to cover a handwash sink, the Rheem RETEX-04T is a 120V point-of-use option. The catch that trips up most first-time builds: county mobile-food codes size hot water heaters in gallons, and a tankless unit has zero gallons to point to on an inspection form — you’ll need to translate GPM into fill time instead.
Most tankless buying guides start with flow rate and BTU. For a food truck, that’s the second question. The first is whether your local health department’s plan reviewer even knows how to evaluate a tankless unit, because most county mobile food unit codes were written assuming a tank heater with a fixed gallon capacity. This guide covers the three realistic power setups — propane with a 120V hookup, propane with no electricity at all, and electric-only — and walks through the gallon-vs-GPM translation before you order equipment your inspector can’t sign off on.
The 100°F rule that catches first-time builds
The Snohomish County Health District’s minimum requirements for mobile food units state that “a hot water heater must be installed and able to provide hot water (100°F or above) to all sinks,” that “the water system must have a mechanical pump capable of pressurizing both the hot and cold water systems to 15 psi,” and — for an occupied truck or trailer — that “the hot water heater must be large enough to completely fill two compartments of the 3-compartment sink with hot water (100°F) without the temperature dropping below 100°F.” That last line is written for a tank heater: pick one with enough stored gallons and you’re done. A tankless unit stores nothing, so the question isn’t gallons, it’s whether your unit can sustain 100°F+ output at your GPM for however long it takes to fill two sink compartments without the burner falling behind.
In practice, that math works in a tankless unit’s favor — a 4.0 GPM unit like the FVI12 fills a typical 2-gallon compartment in about 30 seconds and keeps delivering 100°F+ water indefinitely as long as propane and water supply hold out, which a tank heater can’t do once its stored gallons run cold. The friction is almost always the paperwork, not the physics: bring your unit’s GPM-at-rise spec sheet to your plan review and be ready to explain the fill-time math yourself, since Snohomish County’s wording (and most county codes like it) is representative, not universal — confirm your own jurisdiction’s exact phrasing before you buy.
Our top picks at a glance
| Model | Best for | Fuel / Power | Flow / BTU | Power needed | Price |
|---|---|---|---|---|---|
| Eccotemp FVI12 | Best overall (propane + 120V truck) | LP/NG + 120V fan | 4.0 GPM at 38°F rise / 74,500 BTU | Standard 120V outlet | ~$350–450 |
| Camplux BW264-N | Best no-electricity cart/trailer | Propane (LP) | 2.64 GPM / 68,000 BTU | 2 D-cell batteries | ~$240–300 |
| Rheem RETEX-04T | Best all-electric, handwash-only | 120V electric · 3.5 kW | ~0.4–0.68 GPM | Dedicated 120V circuit | ~$180–230 |
1. Eccotemp FVI12 — Best Overall for Propane + 120V Trucks
Eccotemp FVI12 Indoor Propane/Natural Gas Tankless Water Heater
- Eccotemp markets the FVI12 specifically for tiny and micro homes, cabins, food trucks, RVs, and conversion vans, per the manufacturer's own product description.
- 74,500 BTU at 4.0 GPM comfortably clears the "two sinks, light warewashing" (1.5–2.0 GPM) and most 3-compartment chemical-sanitizing sizing tiers published by food-truck equipment guides.
- Only needs a standard 120-volt outlet for the fan, display, and ignition board — the water heating itself comes from the propane tank, not the generator.
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The FVI12 is the one unit on this list a manufacturer actually names food trucks as a target use case for, which matters when you’re trying to explain your equipment choice to a county plan reviewer. At 4.0 GPM and a 38°F rise it outperforms the portable battery units below, and because only its fan and igniter draw from the panel, it doesn’t eat into the generator headroom your refrigeration and cooking equipment already need. It’s sized to fit the same small enclosure a tank heater would have occupied, so swapping in mid-build is usually a direct retrofit. See our tiny house tankless guide for more on this same unit’s space and power tradeoffs, and our full Eccotemp lineup if the FVI12 doesn’t match your BTU need.
2. Camplux BW264-N — Best for a Cart or Trailer With No Electricity
Camplux 2.64 GPM Portable Propane Tankless Water Heater (BW264-N)
- Fires on 2 D-cell batteries with zero wiring or outlet needed — the pick for an unoccupied cart or trailer that has a propane tank and a hose bib but no generator or shore-power hookup at all.
- Rated 3–110 psi minimum-to-maximum, comfortably above the 15 psi pressurization floor several county mobile-unit codes set for hot and cold water systems.
- 2.64 GPM at 68,000 BTU fills a 2-gallon sink compartment in roughly 45 seconds — slower than the FVI12 but still well inside most sizing guidance for a single-operator cart.
A mobile cart or an unoccupied trailer — the kind a single person pushes between locations or that has no operator inside while serving — often has no electrical system at all beyond maybe a 12V battery for lighting. The BW264-N doesn’t care: it needs only propane and a water line, with CSA safety certification, a flame-failure device, and overheat protection built in. It’s outdoor-rated only, so plan on draining and storing it once temperatures drop near freezing between service days. See our full Camplux lineup for the RV-permanent and ultra-light options if your build differs from a cart.
3. Rheem RETEX-04T — Best All-Electric, Handwash-Only
Rheem RETEX-04T 120V Point-of-Use Tankless Water Heater
- No propane tank, no combustion venting, no LP refill logistics — the simplest build if your truck runs entirely on shore power or generator electricity.
- 3.5 kW (about 11,942 BTU/hour) supports roughly 0.68 GPM at a mild 35°F rise, but real flow drops closer to 0.4 GPM with a cold winter fill — enough for a single handwash sink, not a 3-compartment warewashing sink.
- Needs its own dedicated 120V circuit; check that against your generator or shore-power panel before committing to an all-electric build.
The RETEX-04T only makes sense for a specific build: no propane setup anywhere on the truck, and a menu simple enough that a single handwash sink covers your hot-water obligation. Don’t try to stretch it to a 3-compartment warewashing sink — the GPM math doesn’t support it at any realistic winter inlet temperature. See our full point-of-use water heater guide for the mini-tank alternative if even 0.4 GPM isn’t enough burst flow for your handwash station.
How to choose by what your truck actually has
- Propane tank plus a standard 120V outlet or small inverter: the Eccotemp FVI12 — highest GPM here, and the only unit a manufacturer explicitly names for food trucks.
- Propane tank, zero electrical system (cart or unoccupied trailer): the Camplux BW264-N — D-cell batteries only, no wiring.
- No propane anywhere, shore power or generator available, handwash-only menu: the Rheem RETEX-04T — simplest build, lowest GPM ceiling.
- Full 3-compartment sink with chemical sanitizing and a busy menu: size up within the FVI12’s propane category rather than down to electric point-of-use — see our best propane tankless water heater guide for higher-GPM fixed units if your commissary hookup supports a larger install.
- Before you buy anything: confirm your county health department’s exact hot-water wording and bring your chosen unit’s GPM-at-rise spec sheet to plan review — don’t assume the gallon-based language in an older code section rules out tankless by default.
The bottom line
For most food trucks, the Eccotemp FVI12 is the best tankless water heater — 74,500 BTU at 4.0 GPM, needing only a 120V outlet for its fan while the heat comes from propane, and the one unit on this list a manufacturer actually markets for this exact use case. If your build has no electrical system at all, the Camplux BW264-N runs entirely on D-cell batteries. If you have no propane setup and only need to cover handwashing, the Rheem RETEX-04T is the simplest all-electric option. Whichever you choose, translate its GPM into a fill-time number before your health inspection — most county mobile-food codes were written for tank heaters and won’t automatically know how to read a tankless spec sheet. For sizing math beyond a food truck, see our tankless water heater sizing guide.