How to Choose a Tankless Water Heater for Off-Grid Living
Why Tankless Water Heaters Are Perfect for Off‑Grid Living
Traditional tank water heaters are a poor fit for off‑grid properties. They consume energy continuously to keep a large reservoir hot — even when nobody’s using it. For a cabin, homestead, or remote property where energy efficiency matters, that’s a significant waste.
Tankless water heaters solve this by heating water only when you need it. No standby heat loss, no massive tank to maintain, and in many cases, no indoor venting required. For off‑grid living, they’re not just a convenience — they’re often the smarter, more practical choice.
But with so many models available, how do you choose the right one? This guide walks you through every decision you’ll need to make.
Step 1: Choose Your Fuel Type
The first decision is fuel: propane (LP) or natural gas. For most off‑grid properties, propane is the default choice since natural gas lines don’t reach remote locations. However, if your property has natural gas service, those models tend to have lower operating costs.
Propane (LP)
Propane tankless heaters are the go‑to for cabins, homesteads, and off‑grid properties. You store propane in tanks on your property and refill as needed. Models like the 5.3 GPM Outdoor Tankless Propane Water Heater (120,000 BTU) are purpose‑built for this use case — outdoor installation, no venting required, and Wi‑Fi control so you can monitor performance remotely.
Natural Gas
If you have natural gas service, these models offer the same on‑demand performance with potentially lower fuel costs. The 5.3 GPM Outdoor Tankless Natural Gas Water Heater is a direct equivalent to the propane model, with the same 120,000 BTU output and 0.82 energy factor.
Step 2: Determine the Right GPM for Your Property
GPM — gallons per minute — is the most important spec to get right. Too low and you’ll run out of hot water when multiple fixtures run at the same time. Too high and you’re paying for capacity you don’t need.
Typical Fixture Flow Rates
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Shower: ~2.0 GPM
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Kitchen faucet: ~1.5 GPM
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Bathroom faucet: ~0.5 GPM
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Dishwasher: ~1.5 GPM
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Washing machine: ~2.0 GPM
Add up the fixtures you’re likely to run simultaneously. A small cabin with one bathroom can get by with a 5.3 GPM unit. A larger home with multiple bathrooms and higher demand needs 9.8 GPM or more.
Our GPM Lineup at a Glance
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5.3 GPM — 1–2 bathroom cabins, small off‑grid homes
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7.1 GPM — Small to medium homes, moderate simultaneous demand
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8.5 GPM — Medium homes, 2–3 bathrooms
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9.8 GPM — Medium to large homes, high simultaneous demand
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10.0–11.0 GPM — Large homes, whole‑home coverage, light commercial
Step 3: Indoor vs. Outdoor Installation
This is often determined by your property layout, but the trade‑offs matter.
Outdoor Installation
Outdoor tankless heaters mount directly on an exterior wall and require no venting. This dramatically simplifies installation and reduces cost. They’re ideal for cabins, sheds, and properties where running vent pipes is impractical.
The trade‑off is exposure to the elements. Most outdoor models are built for it, but in climates with hard freezes, you’ll want to winterize or choose a model with freeze protection.
Our outdoor lineup includes models from 5.3 GPM up to 11.0 GPM, in both propane and natural gas.
Indoor Installation
Indoor models require venting — either direct vent (two pipes: intake and exhaust) or power vent. They’re better suited for properties where the heater needs to be protected from weather or where an exterior wall location isn’t practical.
Our indoor lineup includes:
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11.0 GPM Indoor Condensing with Smart Sense (auto‑adjusts for NG or LP)
Step 4: Condensing vs. Non‑Condensing
This affects efficiency and installation complexity.
Non‑Condensing
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Simpler
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Lower cost
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Vents hot exhaust directly
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~0.82 energy factor Most of our lineup falls into this category.
Condensing
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Higher efficiency (0.97–0.98 EF)
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Extracts additional heat from exhaust
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Lower long‑term fuel consumption
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Higher upfront cost
Our condensing models include:
Step 5: Features Worth Paying For
Not all tankless heaters are created equal. These features matter for off‑grid use:
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Wi‑Fi control — Monitor performance, adjust temperature, receive alerts remotely.
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Smart Sense gas valve — Automatically adjusts for natural gas or propane.
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Low NOx emissions — Required in states like CA and TX.
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Strong warranty — Look for 10–15 years on the heat exchanger.
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Elevation rating — Some models are approved up to 10,200 ft.
Our Top Picks by Use Case
Best for Small Off‑Grid Cabins: 5.3 GPM Outdoor Propane
Simple outdoor installation, no venting, Wi‑Fi control, and enough output for a 1–2 bathroom cabin. The 120,000 BTU range handles cold groundwater temperatures reliably.
Best for Medium Off‑Grid Homes: 9.8 GPM Outdoor Non‑Condensing
Available in natural gas or propane, this model handles whole‑home demand for medium‑sized properties. Outdoor installation keeps things simple, and Wi‑Fi monitoring is ideal for part‑time or seasonal properties.
Best High‑Efficiency Option: 11.0 GPM Indoor Condensing with Smart Sense
For larger homes or heavy users, this model delivers 0.98 UEF efficiency and automatically adapts to your fuel type. Long lifespan and a 15‑year heat exchanger warranty.
Best for High‑Demand or Light Commercial: 11.0 GPM Outdoor Commercial
For homesteads with multiple bathrooms, laundry, and kitchen demand — or small commercial operations — this 199,000 BTU outdoor unit delivers continuous output without indoor venting.
Installation Tips for Off‑Grid Properties
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Size your gas line correctly. High BTU demand requires proper sizing.
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Check your water pressure. Most units operate between 20–150 PSI.
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Winterize outdoor units. Drain before hard freezes if the property sits vacant.
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Use a sediment filter. Protects the heat exchanger from well‑water debris.
Final Thoughts
The right tankless water heater for your off‑grid property comes down to four things: fuel type, GPM output, indoor vs. outdoor installation, and efficiency level. Get those right and you’ll have reliable, on‑demand hot water for years with minimal maintenance.
Browse our full tankless water heater collection at Miles Off Grid — propane and natural gas models from 5.3 GPM to 11.0 GPM, built for every property size and budget.
