Understanding RV Water Heater: A Practical Guide

The best RV water heater for your rig comes down to one deciding factor: how often you camp with full hookups. If you’re plugged into shore power 80% of the time, a tankless electric or propane-on-demand unit gives you endless hot water without burning propane. If you’re off-grid 80% of the time, a propane storage tank uses less fuel and is simpler to maintain. That single question changes the recommendation for every buyer.

Tank vs. Tankless: Which Works for Your Camping Style?

Storage-tank heaters (6 or 10 gallons) hold a fixed amount of hot water, then need 20–40 minutes to recover. Tankless units heat water on demand, delivering unlimited showers as long as propane or electricity lasts. Neither is universally better; the fit depends on your typical campground.

Factor	Storage Tank (6–10 gal)	Tankless (on-demand)
Hot water supply	Limited to tank; about 6–8 minutes of shower per fill	Unlimited as long as fuel or power lasts
Recovery time	20–40 min (propane) or longer (electric)	Instant; no recovery needed
Propane consumption	Moderate; burner cycles on/off	Higher peak draw but can save if showers are short
Winterization	Easy: drain and bypass	Requires antifreeze; more components to protect
Installation complexity	Drop-in replacement in most RVs	May need venting changes, gas line upgrade, or electrical work
Best for	Boondockers, cold-weather campers, budget buyers	Full-hookup campers, large families, long showers

Real-world example: A 6-gallon propane tank gives roughly 6 minutes of continuous hot water at typical flow (1.5 GPM). In a family of four taking back-to-back showers, the second person often gets a lukewarm rinse unless you wait 30 minutes between.

Propane, Electric, or Both? Choosing Your Fuel

Most RVs come with a propane-only storage tank. Aftermarket options include:

• Propane-only: Works off-grid, simple to repair, but burns fuel even when the burner cycles on briefly.
• Electric element (120V AC): Great for campgrounds with electric hookups, but recovery is slow (30–60 minutes per tank). A 1,500-watt element draws about 12.5 amps—on a 30-amp rig, that plus the fridge and converter can overload the circuit.
• Propane/electric combo (dual-fuel): Use electric when plugged in, propane when off-grid. Common in newer RVs (e.g., Suburban SW6DE). Higher upfront cost, but you avoid burning propane at hookup sites.

What many buyers miss: An electric-only tankless water heater typically draws 13–18 amps at 120V. On a 30-amp RV, you’d have to turn off the air conditioner, fridge, and converter to run the shower—impractical. Stick with propane or dual-fuel for 30-amp rigs.

Sizing: How Much Hot Water Do You Actually Need?

Storage tank sizes are almost always 6 or 10 gallons. A 10-gallon tank gives about 10 minutes of shower time before recovery kicks in, which works for two quick showers back-to-back.

Tankless units are rated in gallons per minute (GPM) at a given temperature rise. Most RV tankless models deliver 1.5–2.0 GPM at a 45°F rise. In cold climates where incoming water is 40°F, that rise becomes 60°F, and actual flow drops to about 1.2 GPM—a weak shower. In warm climates (incoming 60°F), the same unit pushes 2.0 GPM, which is fine.

Sizing rule of thumb: If you have a family of four and camp where groundwater temps fall below 50°F, oversize the tankless (look for 2.5+ GPM at a 50°F rise) or stick with a 10-gallon storage tank.

Five-Point Fit Check Before You Buy

Run these five pass/fail checks against your RV and camping habits. If you fail two or more, reconsider your choice.

1. Electrical capacity: Does your RV have 50-amp service? If no, avoid electric-only heaters unless you plan to run the generator during showers.

2. Altitude: Do you camp above 6,000 feet? Many propane tankless units (and some tank models) lose performance or fail to light. Look for “high altitude ready” (e.g., rated to 9,800 ft) or plan to install a derate kit.

3. Gas line size: Tankless units often require a 3/8-inch or larger propane line. Older RVs may have 1/4-inch lines that starve the burner. Measure before buying.

4. Venting: Tankless units need a direct vent through the sidewall or roof. Can your RV accommodate the vent location without interfering with windows, slide-outs, or a nearby awning?

5. Freeze protection: Do you camp in freezing weather? A tank heater with a 12V electric element is easier to winterize. Tankless units have more freeze-prone components (heat exchanger, control board).

Installation Realities: What to Expect

If you’re doing a direct swap (same fuel type and size), plan on 2–4 hours of work. Changing from tank to tankless can take a full day and may require a propane system upgrade. Here’s the step-by-step flow that catches most problems before they waste your weekend.

Likely Causes of Installation Failure

• Undersized gas line that starves the burner.
• Vent path blocked by a slide-out mechanism or window frame.
• 12V wiring that can’t handle the control board draw on tankless units.
• Bypass valves never installed, making winterization impossible.

Ordered Installation Steps

1. Confirm gas line diameter. Measure the inner diameter of your propane supply line. If it’s smaller than 3/8-inch for a tankless unit, stop and order a gas line upgrade kit.

2. Test vent placement. Hold the new unit in position (or use a cardboard template) and verify the vent cap clears all obstructions by at least 12 inches.

3. Pressure-test the gas line. Use a manometer to verify 11–13 inches water column at the appliance connection. If pressure is low, the regulator or line size is the issue.

4. Install and seal the vent. Use high-temperature silicone at every joint. A leak here means carbon monoxide inside the RV.

5. Fill and purge air. Open a hot water faucet inside the RV, then open the gas supply. Let the water run for 30 seconds to clear air from the heat exchanger.

6. Light and verify. Fire the unit and confirm the flame is blue with a sharp cone. Yellow or lazy flame means incomplete combustion—shut it down and check the orifice size or gas pressure.

Success Check and Escalation Signal

You’re good when the unit lights on the first attempt, holds temperature within ±5°F for two minutes, and the vent exhaust feels hot but not smoky. If the burner cycles on and off rapidly (short-cycling) or the unit fails to light after three tries, stop. Call a certified RV technician—you may have a gas pressure problem or a faulty control board.

PDI (Pre-Delivery Inspection) for New Installs

If you’re paying a dealer or technician, verify these points before signing off:

• Gas line pressure checked with a manometer (should be 11–13 inches water column for propane).
• All vent connections sealed and no leaks.
• Pressure-relief valve installed and plumbed to the outside.
• Bypass valves operational (for winterization).

Comparison: Gidrox Tankless Options

The three Gidrox models listed below are the same unit in different white shades—Bright White, True White, and Pearl White. All are 12V DC propane, rated to 9,800 ft altitude, CSA certified, and include a digital display.

Product	Color	Link
Gidrox Tankless Water Heater (Bright White)	Bright White	View on Amazon
Gidrox Tankless Water Heater (True White)	True White	View on Amazon
Gidrox Tankless Water Heater (Pearl White)	Pearl White	View on Amazon

Top Pick: The Gidrox Tankless Water Heater in Bright White is the best seller and matches most RV exterior panels. The high-altitude rating and CSA certification make it a solid choice for mountain campers. Because it’s a tankless propane model, it requires a proper gas line size and vent installation—not a drop-in replacement for a 6-gallon tank.

When Common Recommendations Fail

• “Tankless saves propane” – Only true if you take short showers (3–4 minutes). Run the water for 10+ minutes and a tankless burns more propane per minute than a tank heater cycling on and off.
• “Tank heaters are bulletproof” – Suburban and Atwood tank heaters are reliable, but the anode rod needs annual replacement. Skip that and you’ll have a rusted tank in 2–3 years.
• “You can always upgrade later” – Changing fuel type (e.g., propane to electric) often requires new wiring, a different thermostat, and possibly a larger inverter. It’s not a weekend project.
• “A used water heater is a bargain” – A used tank heater with a rusted anode rod or a tankless unit with a scaled heat exchanger can cost more in repairs than a new entry-level unit. Demand a video of it firing and heating water before you hand over cash.

New vs. Used: The Depreciation Reality

RVs depreciate steeply in the first 2–3 years, and water heaters follow a similar curve—but with a twist. A used tank heater that has been poorly maintained (no anode replacement) is already halfway to failure. A used tankless unit with a scaled heat exchanger may need a $200 flush or a new burner assembly. Your best move: if you must buy used, get a video of the unit running hot water for at least two minutes, and check the date code on the tank (stamped on the side). Anything older than 8 years is a gamble.

Financing and Warranty: What’s Worth It

• Extended warranty: For a tank heater, skip it. Repairs are cheap (thermostat, element, control board). For a tankless, a 3-year warranty can be worth it because heat exchanger replacement runs $300–500. But read the fine print—many “extended warranties” don’t cover labor on installation mistakes.
• Financing terms: If you’re buying a new RV with a water heater upgrade, expect 10–20 year loan terms at 6–9% APR. Rolling a $1,500 water heater upgrade into a $40,000 RV loan adds about $15/month—painless. Don’t finance a standalone water heater purchase; pay cash or use a 0% promo card.

Dealer vs. Private Sale for the Water Heater Itself

• Dealer (RV parts counter or online retailer): You get a warranty, return policy, and often free tech support. Markup is 20–40% over wholesale.
• Private sale (Facebook Marketplace, Craigslist): Risk is high. Many sellers pull a water heater from a wrecked RV and don’t know its history. Only buy private if you can test-fire it, see the anode rod condition, and confirm the tank isn’t rusted inside.

FAQ

Can I install a tankless water heater in any RV?

Not without checking venting, gas line diameter, and electrical capacity. Many older RVs need modifications. If your RV was built before 2010, assume some upgrades will be required.

How long do RV tank water heaters last?

With annual anode replacement, 8–12 years. Without it, 3–5 years. Tankless heaters can last 15+ years if the heat exchanger is flushed periodically with a descaling solution.