RV Water Heater Guide: Types, Troubleshooting & Replacement Tips

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).

Start with the appliance, not the symptom

Before you chase a water-heater symptom, settle one question: which brand and exact model is installed in your RV? That identity is the hinge for everything that follows, because the matching manufacturer’s documentation is written for a specific appliance rather than for RV water heaters in general. Dometic points owners who are unsure of their installed products toward its product information and manuals (Dometic owner resource hub), and the Dometic water-heater manual itself distinguishes model identification across different water-heater models (Dometic water-heater manual). Your first supported decision is therefore simple: identify the heater, then open the documentation that belongs to that exact unit.

Identify the brand and model from the unit’s own labeling

Brand comes first, because it tells you whose documentation to consult. Once you know the brand, capture the model and serial information from the labeling on your installed unit. For named Suburban water-heater families, Suburban gives the data-plate location along with the model and serial-number fields to record (Suburban find-model-number page). Treat that Suburban guidance as specific to Suburban’s named families; it is not a map to every other brand’s label. If your heater carries a different name, use that manufacturer’s own identification route instead of borrowing another brand’s instructions.

What you need	Where to look	What to record
Brand	The name on the appliance and its labeling	The manufacturer whose documentation you will follow
Model	The unit’s own data plate or label, per that manufacturer’s guidance	The exact model designation
Serial number	The same manufacturer-specific labeling	The serial field as printed
Documentation match	The identified manufacturer’s official manual or product page	The manual that names your model

Open the documentation that matches the identified unit

With the brand and model in hand, go to that manufacturer’s official material and select the document that names your appliance. Dometic’s owner resource hub is the starting point for Dometic product information and manuals (Dometic owner resource hub), while the Dometic water-heater manual shows that model identification is tied to particular water-heater models (Dometic water-heater manual). Suburban owners can use Suburban’s model-number guidance to capture the right fields before opening Suburban documentation (Suburban find-model-number page). The confirmation step is straightforward: the manual you open should name the brand and model you recorded.

Where this route stops

This is a documentation-identification route, and it ends at the matching official manual. Gas, combustion, carbon-monoxide, and live-electrical work sit outside what this section covers, so use the identified manufacturer’s documentation for any further guidance rather than improvising from a general article. (Official source)

Safety note: This guide stops at identifying your heater and finding its official documentation. It does not cover repair, fuel, combustion, carbon-monoxide, or live-electrical work.

Scope check before you start

This maintenance schedule applies to Atwood Models 4-E and 10-E. If the heater is not an Atwood 4-E or 10-E, stop and use the documentation for the installed model. Stop if the model plate is unreadable.

The three scheduled tasks

Task	Frequency	Reader condition	Stop condition
Drain the tank	At least once a year	The tank is cool and the water supply is off.	Stop if the tank is hot or still under pressure.
Flush the tank	Two or three times a year	The tank drains normally.	Stop if the drain valve is clogged or the tank will not drain.
Operate the relief valve	At least once a year	The heater is cool enough to service.	Do not plug the valve; stop if it will not reseat.

Drain the water heater at least once a year. Flush the tank two or three times a year. Operate the pressure-temperature relief valve at least once a year.

Branch: the relief valve weeps

If the relief valve weeps only while the heater is running, do not replace the valve solely because it weeps during operation. Weeping or dripping while the heater is running does not mean the valve is defective. Stop and inspect if it does not reseat after operation. Continuous leakage remains unknown from this evidence.

Branch: the burner shuts off unexpectedly

Check the thermal cutoff on the left side before replacing parts. The thermal cutoff is installed on the left side and shuts off the burner if the unit overheats. Do not bypass the thermal cutoff; stop if it is open. The reset or replacement procedure remains unknown from this evidence.

Stops

• Stop if the tank is hot or still under pressure.
• Stop if the drain valve is clogged or the tank will not drain.
• Do not plug the valve; stop if it will not reseat.
• Stop and inspect if it does not reseat after operation.
• Do not bypass the thermal cutoff; stop if it is open.
• Stop and use the documentation for the installed model.
• Stop if the model plate is unreadable.

Source: Atwood

Pre-Install Go/No-Go Checks

Use this checklist before mounting an Atwood 4-E or 10-E water heater. Each item is a stop point: if the condition cannot be met, stop the install.

Check	Requirement	Stop if
Venting	Combustion air must come from outside the RV and combustion products must vent outside the RV.	Either condition cannot be met.
Shared vent	Do not vent the water heater with another appliance’s venting system or into an outside enclosed porch area.	The only route is shared or porch venting.
Connections	Connect 1/2 NPT water lines and a 3/8 flared LP gas line, with enough flexibility to pull the unit forward one inch past the skin.	The lines cannot flex one inch past the skin.
Power	Use a circuit rated at 1400 watts or greater, a minimum 14 AWG cord, and a 15-amp attachment plug.	Any value is below the minimum.
Service clearance	Provide adequate rear clearance for service of the water connections.	The rear connections cannot be reached.
Model scope	These installation checks apply to Atwood Models 4-E and 10-E.	The model plate is unreadable or the unit is another model.

Venting

Confirm combustion air comes from outside and combustion products vent outside. Stop if either condition cannot be met.

Do not share another appliance’s vent or vent into an outside enclosed porch. Stop if the only route is shared or porch venting.

Connections and Power

Use 1/2 NPT water lines and a 3/8 flared LP line with flexible loops. Stop if the lines cannot flex one inch past the skin.

Confirm 1400 watts or greater, 14 AWG minimum cord, and a 15-amp plug. Stop if any value is below the minimum.

Clearance and Model Scope

Leave adequate rear clearance for water-connection service. Stop if the rear connections cannot be reached.

If the heater is not an Atwood 4-E or 10-E, stop and use the documentation for the installed model. Stop if the model plate is unreadable.

Sources: https://www.atwoodmobile.com

Five-Point Fit Check

These replacement checks apply to Atwood Models 4-E and 10-E. Measure the existing cutout against 12-5/8 by 16-1/4 by 17-5/8 for a 4-6 gallon model or 15-3/4 by 16-1/4 by 20-5/8 for a 10 gallon model. The 6 gallon model weighs 25 pounds and the 10 gallon model weighs 32 pounds. Provide adequate rear clearance for service of the water connections. Connect 1/2 NPT water lines and a 3/8 flared LP gas line, with outside combustion air and outside venting.

Check	What to confirm	Stop if
Cutout	Measure the cutout against the 4-6 or 10 gallon chart.	Stop if the cutout is smaller than the chart.
Weight	Confirm support for 25 pounds (6 gallon) or 32 pounds (10 gallon).	Stop if the surface cannot support the weight.
Service clearance	Confirm adequate rear clearance for water-connection service.	Stop if the rear connections cannot be reached.
Connections and venting	Confirm 1/2 NPT water lines, 3/8 flared LP, outside combustion air, and outside venting.	Stop if any connection or vent path cannot be matched.
Model scope	Stop and use the documentation for the installed model.	Stop if the model plate is unreadable.

Before You Buy

Measure the cutout against the 4-6 or 10 gallon chart. Stop if the cutout is smaller than the chart. Confirm support for 25 pounds (6 gallon) or 32 pounds (10 gallon). Stop if the surface cannot support the weight. Confirm adequate rear clearance for water-connection service. Stop if the rear connections cannot be reached. Confirm 1/2 NPT water lines, 3/8 flared LP, outside combustion air, and outside venting. Stop if any connection or vent path cannot be matched. If the heater is not an Atwood 4-E or 10-E, stop and use the documentation for the installed model. Stop if the model plate is unreadable.

Sources: https://www.atwoodmobile.com

Before you start

These start checks apply to Atwood Models 4-E and 10-E. If the heater is not an Atwood 4-E or 10-E, stop and use the documentation for the installed model; stop if the model plate is unreadable.

Fill the water heater tank and check all connections for water leaks before starting. Do not operate the water heater without water in the tank. Stop if the tank is not full.

If the heater has not been used for more than two weeks, open a hot faucet for several minutes before using an electrical appliance connected to the hot-water system. Stop if you hear escaping air or the line does not run clear.

Start sequence

Step	Condition	Action	Stop condition
1	The tank is empty or newly installed.	Fill the tank and check for water leaks before starting.	Stop if the tank is not full.
2	The heater has not been used for more than two weeks.	Open a hot faucet for several minutes before using an electrical appliance on the hot-water system.	Stop if you hear escaping air or the line does not run clear.
3	The gas control was off.	Wait at least five minutes before lighting the pilot.	Stop if you smell gas.
4	The pilot or burner does not light.	Stop after three attempts and let the unit lock out.	Stop if the red lockout lamp is on.
5	The heater is running.	Set the temperature between warm and hot.	Stop if the water is excessively hot.
6	The relief valve is being checked.	Leave the pressure-temperature relief valve unplugged.	Stop if the valve is plugged or capped.
7	The heater is not an Atwood 4-E or 10-E.	Stop and use the documentation for the installed model.	Stop if the model plate is unreadable.

Wait at least five minutes for accumulated gas to escape before lighting the pilot. The unit makes three attempts to light; if there is no ignition, it locks out and the red lamp illuminates. The reset procedure is not covered here.

After it lights

Set the temperature lever or dial between warm and hot. Do not plug the pressure-temperature relief valve.

Source: Atwood

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.

Related RV owner guides

• RV water pump maintenance