Quick Answer: Before you compare GPM or brands, check one thing first: manufactured homes built to the HUD Code (24 CFR Part 3280) require every water heater to carry a HUD certification tag, and most tankless units sold at a big-box store don’t have one out of the box. The Rinnai V53DeP — an outdoor 120,000 BTU propane unit rated 5.3 GPM and HUD-approved for manufactured housing — is the best overall pick because it clears that bar and needs no interior closet space. If your home runs on upgraded 150-200 amp electrical service with no gas line, the Rheem RTEX-13 (13 kW, 240V) is the best whole-home electric option; on an older 100-amp panel, the smaller EcoSmart ECO 8 (40-amp breaker) is the safer electrical fit.
Most tankless roundups start with flow rate. For a mobile or manufactured home, that’s the second question. The first is whether the unit is legal to install at all — HUD Code homes are regulated differently from site-built houses, and that single fact rules out some otherwise-great tankless units before GPM ever enters the conversation. This guide sorts picks by that constraint first, then by your gas or electrical situation, because those two facts together determine what will actually work in your home.
The HUD rule that decides this before GPM does
Manufactured homes built after June 1976 fall under the HUD Code (24 CFR Part 3280), and every water heater installed in one must carry a HUD data tag certifying it meets those construction and safety standards. A standard residential tankless water heater pulled off a home-improvement store shelf doesn’t automatically carry that certification. Historically, a manufacturer had to obtain a HUD Alternative Construction (AC) letter under 24 CFR § 3282.14 before a tankless system could go into a HUD Code home, because the base code simply didn’t address tankless technology. According to a June 2025 policy update reported by the Propane Education & Research Council, HUD has since reduced that AC-letter requirement specifically for propane tankless units, now allowing manufactured-housing producers to install HUD-approved propane tankless water heaters directly on the production line rather than as an after-market upgrade.
That’s why the Rinnai V53DeP — 120,000 BTU, 5.3 GPM, 0.81 Energy Factor, HUD-approved for manufactured housing per Rinnai’s own product listing — is the safe default pick rather than just the highest-flow option. It also solves a second, purely physical problem: many manufactured homes, especially those built before 2000, have a dedicated water-heater closet sized for nothing bigger than a 30-40 gallon tank. Because the V53DeP mounts outdoors, it never has to fit inside that closet at all.
Our top picks at a glance
| Model | Best for | Fuel / Power | Flow | Panel/space need | Price |
|---|---|---|---|---|---|
| Rinnai V53DeP | Best overall (HUD-approved) | Propane · outdoor | 5.3 GPM at 120,000 BTU | No interior closet | ~$650–740 |
| EcoSmart ECO 8 | Best electric, 100A panels | 240V electric · 8 kW | 1.56 GPM (HD-rated) | 40A double-pole breaker | ~$210–260 |
| Eccotemp FVI12 | Best indoor propane | LP/NG · 120V (fan only) | 4.0 GPM at 38°F rise | Fits a small closet | ~$350–450 |
| Rheem RTEX-13 | Best electric, 150-200A homes | 240V electric · 13 kW | Up to 3.17 GPM (warm inlet) | 60A double-pole breaker | ~$255–365 |
1. Rinnai V53DeP — Best Overall, HUD-Approved
Rinnai V53DeP Outdoor Propane Tankless Water Heater
- HUD-approved for manufactured housing, clearing the single biggest legal hurdle a HUD Code home faces with tankless equipment.
- Mounts outdoors, so it never has to fit into the small 30-40 gallon water-heater closet common in pre-2000 manufactured homes.
- 120,000 BTU rated at 5.3 GPM covers a full single-wide or double-wide with two fixtures running at once.
- 0.4 GPM low-flow activation and continuous temperature monitoring for freeze protection, per Rinnai's published specs.
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The V53DeP is the pick that removes the most risk: it’s already HUD-approved, so you’re not relying on a park manager’s or inspector’s interpretation of a decades-old code section. Because it’s outdoor, there’s no direct-vent kit to plan for and no interior closet remodel — it replaces a tank heater in roughly the same footprint a propane grill tank would take up outside. Confirm your local park or state administrative agency still wants to see the HUD tag on file before installation; requirements can vary slightly by jurisdiction even with the 2025 federal policy change. See our full propane tankless roundup for other outdoor propane options if the V53DeP is out of stock.
2. EcoSmart ECO 8 — Best Electric for a 100-Amp Panel
EcoSmart ECO 8 Electric Tankless Water Heater
- Needs only a 40-amp double-pole breaker — the electric tankless option that leaves the most headroom on a code-minimum 100-amp manufactured-home service.
- Rated for one bathroom or point-of-use fixtures, matching the single-fixture-at-a-time reality of most single-wide layouts.
- 90% smaller footprint than a tank unit and wall-mounts directly where the old tank sat, per EcoSmart's own listing.
- No gas line, no combustion venting — the simplest retrofit if your home has no propane service at all.
The National Electric Code sets 100 amps as the floor for manufactured-home electrical service (NEC 550.32(C)), and a meaningful share of homes built before the early 2000s still sit right at that minimum. A 13 kW whole-home electric tankless heater draws 54 amps by itself — over half that entire panel — which is why we don’t recommend it for an unmodified 100-amp home. The ECO 8’s 40-amp draw is the electric option that actually respects that ceiling. It won’t run two showers at once, but for a single-bath manufactured home it’s a same-day plug-and-mount job with no gas-line work. See our full point-of-use water heater guide for smaller single-fixture options if one sink is all you need to cover.
3. Eccotemp FVI12 — Best Indoor Propane
Eccotemp FVI12 Indoor Propane/Natural Gas Tankless Water Heater
- 74,500 BTU rated at 4.0 GPM fits an existing small water-heater closet where an outdoor mount isn't allowed or practical.
- Eccotemp markets it specifically for compact dwellings — tiny and micro homes, cabins, and mobile builds, per the manufacturer.
- Only needs a standard 120-volt outlet for the fan and ignition board — the BTU output itself comes from gas, not the panel.
Some parks and some climates rule out an outdoor unit — no exterior wall clearance, or winters cold enough that an indoor, sealed-combustion unit is the safer bet. The FVI12 is sized to fit inside the same small closet a 30-40 gallon tank once occupied, without asking the electrical panel for anything beyond a standard outlet. It isn’t sold pre-tagged as HUD-approved the way the V53DeP is, so verify compliance with your state’s manufactured-housing administrative agency before installing it as a like-for-like tank replacement. We cover this same unit in more depth in our tiny house tankless guide, since the space and power constraints largely overlap. For Eccotemp’s whole-home and portable models beyond the FVI12, see our best Eccotemp tankless water heater guide.
4. Rheem RTEX-13 — Best Electric for an Upgraded 150-200A Home
Rheem RTEX-13 13 kW Electric Tankless Water Heater
- 13 kW delivers genuine whole-home flow — up to 3.17 GPM per Rheem's spec on a warm inlet — enough for back-to-back showers.
- Needs one dedicated 60-amp double-pole breaker, which only makes sense once your service has been upgraded past the 100-amp NEC minimum.
- No propane tank, no gas line, no combustion venting — a clean retrofit if your park has already upgraded its electrical pedestals.
Many manufactured-home communities have moved newer lots to 150- or 200-amp pedestal service, and on one of those a 60-amp double-pole breaker for the RTEX-13 is a manageable ask rather than a majority of the panel. If your home is still on the 100-amp code minimum, skip straight to the ECO 8 instead — this unit is sized for a home whose electrical service has already been modernized. See our full electric tankless roundup for step-up and step-down sizes in this same product line.
How to choose by what you actually have
- Not sure if your home is HUD-tagged, or want the least regulatory risk: the Rinnai V53DeP — already HUD-approved for manufactured housing, mounts outdoors, no closet remodel.
- Older home stuck on a 100-amp panel, no gas line: the EcoSmart ECO 8 — 40-amp breaker leaves headroom the 13 kW electric units don’t.
- Small existing closet, outdoor mount not allowed or too cold to run one exposed: the Eccotemp FVI12, but verify state HUD compliance before installing.
- Panel already upgraded to 150-200 amps, no gas line: the Rheem RTEX-13 for real whole-home flow on a single breaker.
- Building or buying new construction on the HUD line: ask the manufacturer whether they now install a HUD-approved propane tankless unit at the factory — the 2025 policy change makes this increasingly common rather than an after-market add-on.
The bottom line
For most manufactured and mobile homes, the Rinnai V53DeP is the best tankless water heater — HUD-approved for manufactured housing, 120,000 BTU at 5.3 GPM, and mounted outdoors so it never fights the tiny water-heater closet most of these homes were built with. If your electrical service has been upgraded to 150-200 amps and you have no gas line, the Rheem RTEX-13 is the best whole-home electric option; if you’re still on the 100-amp NEC minimum, the smaller EcoSmart ECO 8 is the electrically safer choice. Whichever you pick, confirm the HUD tag and your state administrative agency’s sign-off before installing — that’s the step this category lets buyers skip at their own risk. For the full sizing math across every fuel type, see our tankless water heater sizing guide, and for the complete fuel comparison, see our electric vs gas tankless guide.