Best RV Tankless Water Heater: Propane Picks by BTU and GPM
Size by BTU first: 60,000 BTU gives about 1.8 GPM at a 57 F rise. Fogatti InstaShower 7 suits most rigs. No 110V electric unit runs an RV shower.
The best RV tankless water heater for most rigs is the Fogatti InstaShower 7, a propane on-demand unit holding 4.5 stars across 472 Amazon ratings. Size any RV tankless water heater by burner rating rather than brand: 60,000 BTU produces roughly 1.8 GPM at a 57 °F temperature rise, which covers one shower running alone.
How many BTU does an RV tankless water heater need?
Sixty thousand BTU covers one shower for most people, and the number comes from arithmetic rather than opinion. Heating water takes 500 BTU per hour for every gallon per minute and every degree Fahrenheit of rise. Multiply your flow by the rise you need, then divide by about 0.85 for burner efficiency, and you have the rating to shop for.
| Where and when you camp | Water entering the rig | Rise to a 105 °F shower | Burner needed at 1.8 GPM |
|---|---|---|---|
| Gulf coast or Arizona, summer | 78 °F | 27 °F | About 29,000 BTU |
| Midwest campground, spring or fall | 60 °F | 45 °F | About 48,000 BTU |
| Mountain west, early season | 48 °F | 57 °F | About 60,000 BTU |
| Late fall, cold well water | 40 °F | 65 °F | About 69,000 BTU |
The trap is buying for July. A 42,000 BTU unit gives a family in Florida everything they want and then hands them a lukewarm shower the first week of October in Colorado, because the same burner now has to lift the water 25 degrees further. Propane heaters do not fail gracefully at this: they hold their temperature setting by cutting flow, so what you feel is not cooler water but a thinner stream that suddenly runs cold when someone opens the galley tap.
Flow matters as much as the burner. A standard RV shower head moves 1.5 to 2.5 GPM, a galley faucet 1.0 to 1.5 GPM. If two of those run together on a 60,000 BTU unit in 50 °F water, you are asking for a 3 GPM output the burner cannot deliver, and both fixtures go tepid. Buy 65,000 BTU or more if your rig has a second bath, and accept a one-fixture-at-a-time rule regardless. If you are still weighing whether to make the swap at all, the tankless versus tank water heater comparison runs the five-year cost both ways.
The 11 RV tankless water heaters compared
Every built-in unit below runs its fan, igniter and control board off the 12V house battery, so none of them work on shore power alone with the battery disconnected. Price bands: $ is under $350, $$ is $350 to $550, $$$ is above $550.
| Heater | Mount | Burner rating | Star rating (ratings) | Price band | Best for |
|---|---|---|---|---|---|
| Built-in, 3 door sizes | Not stated in listing | 4.5 (472) | $$ | The straight tank replacement | |
| Built-in, CSA listed | 65,000 BTU, 3.9 GPM | 4.3 (606) | $ | Most burner per dollar | |
| Built-in, black door | 68,000 BTU, 3.9 GPM | 4.2 (171) | $ | Cold inlet water on a budget | |
| Built-in, 12V DC | Not stated in listing | 4.4 (115) | $ | Fast-selling newcomer | |
| Built-in, mixing tank | Not stated in listing | 4.4 (266) | $$$ | Killing the cold-water sandwich | |
| Built-in, 3 door sizes | Not stated in listing | 4.4 (407) | $$ | Two fixtures back to back | |
| Built-in, 18.11 in square door | 60,000 BTU | 4.3 (402) | $$$ | Matching a factory Furrion cutout | |
| Built-in, freeze protection | 60,000 BTU | 3.9 (215) | $$ | Suburban tank owners | |
| Built-in, compact | 42,000 BTU | 4.1 (556) | $$ | Vans and warm-climate rigs | |
| Built-in, US built | Not stated in listing | 4.0 (legacy pick) | $$$ | Freezing mornings and low flow | |
| Portable, hangs outside | 55,000 BTU, 2.11 GPM | 4.1 (714) | $ | No cutting into the wall |
Fogatti InstaShower 7: the tank replacement that fits the hole you already have
Fogatti InstaShower 7 RV Tankless Water Heater
The moment that sends people shopping is the third morning of a trip, when the 6-gallon tank runs out halfway through the second shower and the recovery clock says 20 minutes. The InstaShower 7 removes that clock entirely. Water is heated as it passes, so the fourth shower is the same temperature as the first.
Three things decide whether it fits your rig. The door comes in three sizes, which is why this model is the default recommendation for anyone replacing an Atwood or Suburban tank rather than building a new opening. It has 472 ratings at 4.5 stars, a sample large enough that a lemon rate would already be visible in the one-star reviews. And it wants a working 12V supply, so a rig sitting on shore power with the battery disconnect pulled will not produce hot water at all.
Who it is not for: anyone who cannot tolerate the restart slug, since the InstaShower 7 has no mixing reservoir, and anyone shopping on published specs, because Fogatti keeps the burner and flow numbers out of the listing. If you want a stated 65,000 BTU on paper, buy the Ranein instead.
- 4.5 stars across 472 ratings, the highest score of any built-in unit in this roundup
- Sold in three door sizes, so the existing sidewall cutout usually needs no sheet-metal work
- Removing the 6-gallon tank it replaces takes about 75 lb of water and steel off your travel weight
- Fogatti does not publish a BTU or GPM figure in the Amazon listing
- Needs the 12V house battery live before it will fire, shore power alone does nothing
- No mixing tank, so the cold slug on restart is still there
Ranein RA65EH: 65,000 BTU and a CSA listing for the price of a budget unit
Ranein RA65EH 65,000 BTU RV Tankless Water Heater
Most sub-$350 tankless heaters answer the BTU question with silence. Ranein prints 65,000 BTU on the box and backs it with a CSA listing, and that combination at $339 is what earns it the value slot rather than the star rating.
The numbers that matter to you: 65,000 BTU input works out to roughly 55,000 BTU delivered, which is 1.7 GPM at a 65 °F rise, so a single shower stays hot on 40 °F inlet water. The CSA mark matters more than it sounds, because uncertified gas appliances are a live argument with insurers after any fire claim. And 606 ratings means the failure modes are documented rather than theoretical.
Not the unit for you if you plan to run the shower and the galley sink together. That 3.9 GPM figure describes what the plumbing passes, not what the burner can lift 60 degrees. Ask for two fixtures at once and both go lukewarm.
- 65,000 BTU rated, which is a 65 °F rise at 1.7 GPM, enough for late-October well water
- CSA certified, so an insurer or a park inspector has a listing mark to look at
- 606 ratings, the largest review base of any built-in RV tankless heater in this set
- 4.3 stars, so roughly one buyer in eight is unhappy enough to say so
- 3.9 GPM is a plumbing maximum, not something the burner can heat in cold water
- GEN IV means earlier hardware is out there; check you are buying the current revision
APUS 68,000 BTU: the largest burner here for under $300
APUS 68,000 BTU RV Tankless Water Heater
Cold inlet water is what separates a hot shower from a lukewarm one in the shoulder season, and the only cure is burner capacity. At 68,000 BTU, the APUS delivers about 58,000 BTU to the water, which holds 1.8 GPM through a 65 °F rise. That is a genuine shower in 40 °F water, and it costs less than a set of trailer tires.
Two other numbers frame the buy. It carries a CSA listing, which most $299 gas appliances do not. And it holds 4.2 stars across 171 ratings with more than 100 units moving a month, so the sample is growing fast enough to trust the direction of it.
Where it stops: a big burner is a big vapor draw. A 20 lb propane bottle at 20 °F cannot always vaporize fast enough to feed 68,000 BTU continuously, and the symptom is a heater that fires, runs four minutes, then drops out. Twin 30 lb bottles or a larger onboard tank solve it. Skip this unit if you camp exclusively in summer, where the extra burner does nothing you will notice.
- 68,000 BTU is the biggest burner in this roundup, about 1.8 GPM at a 65 °F rise
- CSA certified at $299, which is unusual at that price
- Black door finish matches the trend on 2020-and-newer trailers
- 4.2 stars across 171 ratings, the second-lowest score in the set
- A bigger burner needs more propane vapor draw; a single 20 lb bottle in freezing weather can struggle to keep up
- Door dimensions must be checked against your cutout before ordering
ORBEK 12V DC tankless: the newcomer selling faster than it is reviewing
ORBEK RV Tankless Water Heater (12V DC)
There is a pattern in RV appliances: a new brand appears, sells hard on price for two seasons, and either builds a parts pipeline or disappears leaving owners with an orphan gas valve. ORBEK is at the start of that curve, moving over 200 units a month at 4.4 stars with 115 ratings behind it.
What is verifiable today: the star average sits level with Fogatti’s mid-range units, the unit runs from the 12V house battery like every other built-in here, and the price is $299.98, which is $120 under the Fogatti InstaShower 7. What is not verifiable is what happens in year three when a control board fails.
Not for you if you are a full-timer whose hot water cannot be down for two weeks waiting on a part. Buy Suburban or Furrion for parts availability, and buy ORBEK if you are comfortable being early and keeping the old tank heater in the shed.
- 200+ units bought per month, the fastest sales rate in this roundup
- 4.4 stars, matching heaters that cost $200 more
- Runs on the standard 12V DC house supply with no converter box to mount
- Only 115 ratings, so long-term failure data does not exist yet
- ORBEK does not publish BTU or GPM in the listing
- Support history is unproven compared with Suburban or Furrion
Fogatti InstaShower 9 Pro: the mixing tank that ends the cold sandwich
Fogatti InstaShower 9 Pro with Mixing Tank
Turn the shower off to soap up on a plain tankless unit and the heat exchanger cools. Turn it back on and you get warm, then cold, then hot, in about eight seconds. Everyone who has done it in a 40 °F bathroom knows the flinch. A mixing tank fixes this by keeping a small buffer of heated water on the outlet side, so the restart draws from the buffer while the burner relights.
Three reasons this is the upgrade pick and not the main pick. It solves the one complaint that a bigger burner cannot touch. It carries 266 ratings at 4.4 stars, so the added complexity has not cost it reliability points against the simpler InstaShower 7. And it uses the same door sizing as the rest of the Fogatti line, so an owner upgrading from an earlier InstaShower does not touch the sidewall.
Skip it if you shower straight through without shutting the valve, or if your rig is weight-critical. The buffer holds water, and water is 8.34 lb per gallon that you were trying to leave behind.
- Built-in mixing tank holds heated water so the restart is warm instead of cold then scalding
- 4.4 stars across 266 ratings
- Same Fogatti door ecosystem, so it drops into an existing InstaShower opening
- $699 is more than double the APUS with a similar burner class
- The mixing tank adds water weight back, which is part of why you went tankless
- Still requires 12V power and a live propane supply
Fogatti InstaShower 8 Plus: the middle unit for back-to-back showers
Fogatti InstaShower 8 Plus RV Tankless Water Heater
The case for the 8 Plus is not the spec sheet, because Fogatti does not print one. It is the queue. Four people showering back to back is where a 6-gallon tank humiliates you and where any tankless unit shines, and the 8 Plus has 407 owners rating it 4.4 stars while doing exactly that.
Practically, it gives you the same three door sizes as the InstaShower 7, the same 12V requirement, and a body designed to sit in an existing water heater opening. The step up from the 7 buys capacity headroom rather than a feature you can point at.
Do not buy it as a value play. At $512.99 you are $213 above the APUS with its stated 68,000 BTU, and $187 below the Pro with its mixing tank. It makes sense if you are already committed to the Fogatti door system and want more margin than the 7, and very little sense otherwise.
- 407 ratings at 4.4 stars, the second-largest Fogatti sample here
- Three door sizes, same as the InstaShower 7, so the fit question is already answered
- 12V DC controls with the heater body sized for a standard sidewall opening
- $512.99 sits awkwardly between the $299 APUS and the $699 mixing-tank Pro
- No published BTU or GPM figure
- No mixing tank at this price point
Furrion 60,000 BTU: the one that matches a factory cutout
Furrion 60,000 BTU RV Tankless Water Heater
Furrion is one of very few brands here that publishes the door dimension, and for a replacement job that single number is worth more than a BTU rating you cannot verify. At 18.11 inches square it matches the openings Furrion cut into trailers built from about 2018 on, which is exactly the crowd that needs this: a factory tankless unit that died out of warranty.
The rest is straightforward. Sixty thousand BTU delivers roughly 51,000 BTU to the water, which is 1.9 GPM at a 55 °F rise. Four hundred and two ratings at 4.3 stars is a mature sample. And because Furrion supplies trailer manufacturers, the gas valve and control board are stocked by dealers rather than by one seller on a marketplace.
The wrong buy for anyone coming off a 6-gallon tank. An 18.11 inch door will not cover a 12.5 inch opening the way a smaller unit does, it needs a larger hole in the sidewall, and that is a job with a sealant failure waiting behind it if you rush it.
- Door measures 18.11 by 18.11 inches, published in the listing so you can measure before you buy
- 60,000 BTU rated, about 1.9 GPM at a 55 °F rise
- 402 ratings at 4.3 stars, with an OEM parts network behind it
- $670 is the second-highest price here
- 18.11 inch door is larger than a 6-gallon tank opening, so a tank swap means cutting
- White door only in this listing, which stands out on a black-trim rig
Suburban ST-60: familiar brand, freeze protection, and the lowest rating here
Suburban ST-60 60,000 BTU RV Tankless Water Heater
Suburban built the tank heater in half the trailers on the road, and that history is the reason the ST-60 keeps selling at 3.9 stars while better-rated units sit next to it. The argument is not performance, it is that a service center in a strange town will have the part.
The specifics: 60,000 BTU input, about 1.9 GPM at a 55 °F rise, and a freeze protection circuit that keeps the exchanger above freezing while the rig is powered. That last item is the one people misread. It draws from the 12V system, so it protects a plugged-in rig in a driveway in January and protects nothing at all in a storage lot with the battery disconnected.
Who should look elsewhere: anyone buying on numbers. A 3.9 star average across 215 ratings is a real signal, and at $455.65 the ST-60 costs $155 more than a CSA-listed 68,000 BTU unit. Buy it for the parts network or do not buy it.
- 60,000 BTU with built-in freeze protection on the water side
- Suburban parts are stocked at almost every RV dealer in North America
- 215 ratings, so the complaint pattern is documented rather than guessed at
- 3.9 stars, the only sub-4.0 score in this roundup
- $455.65 buys 8,000 fewer BTU than the $299 APUS
- Freeze protection needs 12V power, which means it does nothing in unpowered storage
RecPro 42,000 BTU: sized for a van, not a fifth wheel
RecPro 42,000 BTU RV Tankless Gas Water Heater
A van with a 6-gallon propane bottle and a 20 gallon fresh tank does not need 68,000 BTU, it needs a heater that will not empty the bottle in a weekend. The RecPro is that size class: 42,000 BTU, which delivers about 36,000 BTU to the water. In 78 °F Gulf coast inlet water that is 2.6 GPM, more than any single shower head will pass. In 40 °F water it is 1.1 GPM, which is a deliberate trickle.
The other reasons it makes the list: 556 owners have rated it, second only to the Camplux portable, and the compact body fits openings that will not take a full-size unit. Propane consumption scales with the burner, so a 42,000 BTU unit burns about 0.46 gallons per hour of actual firing against 0.75 for the APUS.
Do not put this in a family trailer that winters in Montana. It is a warm-climate, one-fixture, small-rig heater, and asking it to do more produces exactly the lukewarm shower you replaced your tank heater to escape.
- 42,000 BTU means a smaller propane draw, so a single 20 lb bottle lasts noticeably longer
- 556 ratings, the second-largest sample in this roundup
- Black door and a compact body for rigs with no room for an 18 inch cutout
- 42,000 BTU is only 1.1 GPM at a 65 °F rise, so cold-climate showers run thin
- Not the unit for a two-bathroom fifth wheel
- $484.95 is high for the burner you get
PrecisionTemp RV-550: the one built for mornings below freezing
PrecisionTemp RV-550 Tankless Water Heater
Boondocking changes what a water heater has to do. You are not chasing endless hot water, you are rationing 40 gallons of fresh water across four days, which means showering at half the flow a campground shower uses. Most tankless units have a minimum activation flow around 0.4 to 0.6 GPM, and a low-flow shower head with the cold mixed in can fall under it. The burner drops out mid-rinse and you are standing in cold water with soap in your eyes.
The RV-550 exists for that scenario. It fires at flow rates that shut other units down, its freeze protection is designed in rather than bolted on, and PrecisionTemp answers a phone in Ohio when something goes wrong, which is a different experience from opening a marketplace dispute.
The reasons most people should not buy it: price, first and last. It is a professional-grade appliance in a category where $300 buys something workable, and a fair-weather camper will never see the difference. This is also the one product here where I have deliberately not quoted a BTU or GPM figure, because the listing data behind this roundup does not include one.
- Designed to keep firing at very low flow, so a navy shower does not drop the burner out
- Freeze protection is part of the design rather than an add-on circuit
- Built in the United States with a direct parts and service line, not a marketplace seller
- Costs several times the price of the Chinese-built units in this list
- PrecisionTemp does not sell through the same volume channel, so review counts are small
- Overkill for anyone who camps between May and September
Camplux 55,000 BTU portable: hot water without cutting the sidewall
Camplux 55,000 BTU Portable Propane Water Heater
The install is what stops most people going tankless. Cutting a 16 inch hole in a fiberglass sidewall, running a new propane line, sealing the flange, and hoping the first rain proves you right is a weekend and a real risk. A portable unit skips all of it: hang it off the ladder, connect a hose and a propane bottle, and shower outside.
The numbers are the clearest here because Camplux publishes them: 55,000 BTU and 2.11 GPM, which is a 52 °F rise at full flow, plus 714 ratings at 4.1 stars. At $218.49 it is a third the price of the Furrion and needs no installation labor at all.
Who it is wrong for: anyone who wants hot water at the galley sink, in the rain, or in January. Portable units are outdoor appliances, they do not tie into your plumbing, and using one inside an RV is a carbon monoxide hazard, not an inconvenience. If your rig has a working outside shower and you camp in mild weather, it is the cheapest hot water on this page.
- 55,000 BTU and 2.11 GPM stated, the clearest spec sheet at this price
- 714 ratings, the largest review base in this roundup
- $218.49 with no installation, no gas line work and no sealant to fail
- Runs outside only, so it needs hanging and stowing every trip
- Wind blows the flame out; it wants a sheltered wall
- Hose runs mean you lose the first quart to cold water every time
What is the best 110V electric tankless water heater for an RV?
There is no 110V electric tankless water heater that will run an RV shower, and the arithmetic rules it out before any brand does. A 120V, 15-amp circuit supplies 1,800 watts, and continuous duty caps it near 1,440 watts, which is 4,914 BTU per hour. Divide by 500 and you get the whole budget: a 10 °F rise at 1 GPM. Your incoming water is 55 °F. You would step into a 65 °F shower.
Scale it up and the picture stays the same. A 30-amp RV service delivers 3,600 watts total, or 12,283 BTU per hour, which is a 24 °F rise at 1 GPM with nothing left for the air conditioner, the converter or the microwave. A real 1.8 GPM shower at a 55 °F rise needs 49,500 BTU per hour, which is 14.5 kilowatts. That is a 60-amp 240V circuit, a load no RV pedestal in North America provides.
| Power source | Continuous watts | BTU per hour | Rise at 1.0 GPM |
|---|---|---|---|
| 120V household outlet | 1,440 | 4,914 | 10 °F |
| 20-amp 120V circuit | 1,920 | 6,552 | 13 °F |
| Entire 30-amp RV service | 3,600 | 12,283 | 24 °F |
| Propane at 60,000 BTU | equivalent to 17,600 | 51,000 delivered | 102 °F |
So what should you do if you want electric hot water at a full-hookup site where propane costs more than the electricity you already paid for? Use a tank, not a tankless. A 6-gallon tank with a 1,440 watt element works precisely because it stores energy over time: it takes about 43 minutes to lift 6 gallons by 70 °F, and then it holds it. That is the trade a tankless unit cannot make, and it is why every gas-and-electric RV water heater on the market is a tank. Fogatti’s HybridShower 6 Ultra is the current version of that idea, a 6-gallon hybrid at 4.1 stars across 322 ratings, and it is a tank heater, so buy it knowing you are giving up the endless hot water you came here for.
Check the Fogatti HybridShower 6 Ultra priceThe 110V electric tankless units sold on Amazon are not lying, they are being read wrong. A 3.5 kW point-of-use unit genuinely works at a hand-washing sink at 0.5 GPM in a heated house. Put it on an RV shower in a 45 °F campground and you get 0.5 GPM of barely-warm water while your breaker trips.
Will a tankless heater fit the hole your old tank came out of?
Usually yes, if you buy a unit sold with multiple door sizes, and no if you buy a large OEM unit. Measure the outside opening before you order anything, because the door flange has to cover it. The two you will find most often on a travel trailer are around 12.5 inches square for a 6-gallon tank and around 16 inches square for a 10-gallon.
Three things bite people. The first is ordering on body size rather than door size, then finding a 2 inch gap of daylight around the flange. The second is propane line capacity: a 42,000 BTU tank heater’s line may be undersized for a 68,000 BTU burner sitting 20 feet from the tank, and the symptom is a heater that lights and then starves. The third is the seal, because you are cutting into a wall that has kept water out for a decade. The full sequence, including the framing and the sealant order, is in the step-by-step tankless conversion guide.
What does an RV tankless water heater cost to run?
About 45 cents of propane per 10-minute shower, and a 20 lb bottle covers roughly 40 of them. A 60,000 BTU burner consumes 0.66 gallons of propane per hour of actual firing, since propane carries about 91,500 BTU per gallon. At $4.00 a gallon that is $2.64 per burner hour, and a 10-minute shower at 1.8 GPM only fires the burner for 10 minutes.
| Usage | Burner time | Propane used | Cost at $4.00/gal |
|---|---|---|---|
| One 10-minute shower | 0.17 hr | 0.11 gal | $0.44 |
| Family of four, showers and dishes, one day | 0.9 hr | 0.59 gal | $2.36 |
| A 20 lb bottle (4.7 gal) | 7.1 hr | 4.7 gal | $18.80 |
| Two weeks of full-time use | 12.6 hr | 8.3 gal | $33.20 |
The saving against a tank heater is not in the showers, it is in the standby. A 6-gallon tank heater relights all day to hold 6 gallons at 130 °F whether or not anyone is home, and it does that in a rig parked in 40 °F air. Tankless burns nothing between showers. Full-timers in cold weather commonly report the difference as one extra week per 20 lb bottle, which is roughly what the standby arithmetic predicts.
The cost that offsets it is the 12V draw. The fan and control board pull a couple of amps whenever the heater fires, and the freeze-protection circuits on units that have them draw whenever the temperature falls, which matters if you are boondocking on two batteries and 200 watts of solar in November.
Why a tankless heater goes cold: flow, pressure and propane
Three failures cover almost every complaint, and none of them is a defective heater. Understanding which one you have takes 30 seconds at the shower valve.
- Flow below the minimum. Every unit needs a minimum flow, usually 0.4 to 0.6 GPM, before the flow sensor tells it to fire. Mix in enough cold at the shower valve and the hot side drops under that threshold, the burner shuts off, and the water goes cold. The counterintuitive fix is to turn the hot tap up and the cold tap down. If it happens constantly, your pump is the problem more often than the heater, and a 12V RV water pump that holds 45 to 55 PSI keeps the flow sensor above its trigger point.
- Pressure sag from two fixtures. Open the galley faucet while the shower runs and the shower flow halves. On a tankless system that shows up instantly as a temperature swing, because the burner modulates to the new flow with a two-second delay.
- Propane vapor starvation. A 20 lb bottle at 20 °F cannot vaporize fast enough to feed a 68,000 BTU burner. The heater lights, runs three or four minutes, and drops out with a fault code. The bottle will feel cold and sweat frost. Switching to a larger bottle or twin bottles fixes it, and nothing you do to the heater will.
If your unit fires, runs and still delivers cold water regardless of flow, the fault is upstream of all three: a closed gas valve, a failed igniter or a bypass valve still set for winter storage. The RV water heater troubleshooting sequence works through those in order.
Do RV tankless water heaters survive freezing weather?
Only if you drain them or keep them powered, and the second option fails the moment the battery goes flat. A tankless heat exchanger holds a small volume of water in narrow copper passages, and narrow passages split faster than a 6-gallon tank does, not slower. The small water volume is an advantage for weight and a liability for freezing.
Units advertising freeze protection, including the Suburban ST-60, run a small heating element or recirculation circuit from the 12V system. That protects a rig plugged in on a driveway. It does nothing in a storage lot with the disconnect pulled, and nothing at all when the battery dies at 3 a.m. in a cold snap, which is the most common way people discover it.
If you camp through winter rather than storing, keep the heater in a compartment that shares heated space with the rig, keep 12V available, and run the water briefly on nights below 20 °F. Moving water does not freeze in the time it takes to cross an exchanger.
Portable or built-in: which one belongs on your rig?
Built-in for anyone who wants hot water at the sink and the shower on demand, portable for anyone who cannot or will not cut the wall. The two are not quality tiers, they solve different problems.
Built-in tankless
- +Feeds every fixture through your existing plumbing
- +Sealed to the sidewall, so it works in rain and wind
- +Runs from the onboard propane tank with no bottle to carry
- –3 to 5 hours of installation and a hole in the wall
- –$300 to $700 before any fittings
- –Freeze protection depends on 12V power
Portable tankless
- +$218 and no installation at all
- +Moves between an RV, a tent camp and a horse trailer
- +Nothing permanent to leak or fail a resale inspection
- –Outdoor use only, and a real carbon monoxide hazard indoors
- –Needs setup and stowing every single trip
- –Wind puts the flame out on an exposed site
The middle path most van owners land on: a portable unit for the first season to find out how often you actually shower off-grid, then a built-in the following winter if the answer is daily. Renting the rig out or planning to sell within two years pushes the same way, because an uncut sidewall is worth more than a heater upgrade at trade-in.
FAQ
Frequently asked questions
What is the best RV tankless water heater?
The Fogatti InstaShower 7 for most travel trailers, at 4.5 stars across 472 ratings and sold in three door sizes so it replaces a 6-gallon tank without new sheet-metal work. If you want a published burner rating instead, the Ranein RA65EH gives 65,000 BTU with a CSA listing for around $339. For freezing mornings and low-flow boondocking showers, the PrecisionTemp RV-550 is the one built for it.
What is the best 110 volt tankless water heater for an RV?
None of them work for a shower. A 120V outlet at 1,440 continuous watts supplies 4,914 BTU per hour, which raises water by 10 °F at 1 GPM. Even your entire 30-amp service only manages a 24 °F rise. If you want electric hot water on a full-hookup site, use a gas-and-electric tank heater with a 1,440 watt element, which stores heat over 43 minutes instead of trying to make it instantly.
How many BTU do I need for an RV tankless water heater?
Multiply your shower flow in GPM by the temperature rise you need, then by 500, then divide by 0.85. At 1.8 GPM and a 57 °F rise, that is about 60,000 BTU. Buy 65,000 BTU or more if you camp in cold water or have a second bathroom, and 42,000 BTU is enough only for a small rig in warm climates.
Do tankless water heaters use more propane than a tank heater?
They use more per minute and less per week. A 60,000 BTU burner consumes 0.66 gallons an hour while firing, so a 10-minute shower costs about 44 cents at $4.00 a gallon. A 6-gallon tank heater burns nothing during that shower but relights all day to hold water hot, which is where the tank loses. A 20 lb bottle covers roughly 40 showers on a tankless unit.
Why does my RV tankless water heater go cold when I turn the shower down?
You dropped below its minimum activation flow, typically 0.4 to 0.6 GPM. The flow sensor stops calling for the burner and you get raw cold water. Open the hot tap further and close the cold one instead of throttling both. A weak water pump makes this happen constantly, because the hot side never reaches the trigger flow in the first place.
Can I leave an RV tankless water heater full of water over winter?
No. The heat exchanger uses narrow copper passages that split sooner than a tank does, and the freeze protection built into units like the Suburban ST-60 only functions while 12V power is live. Pull the heater's drain plugs, let the exchanger empty, and include those drain points in your normal winterizing routine.
Is a tankless water heater worth it in a small trailer?
Only if you shower in it. The payoff is a fourth consecutive shower and about 75 lb less travel weight, and neither matters much on a weekend rig with a 20 gallon fresh tank. A teardrop or van used for two-night trips is better served by a $218 portable unit hung off the back than by a $500 built-in and a hole in the wall.
Three things to sort out the same weekend you fit it
A tankless heater turns a 6-gallon problem into a flow problem, and flow is now the thing that decides whether your shower is any good. Start with supply: a pump that sags to 30 PSI will drop the burner below its activation flow no matter which heater you bought, which is why the best RV water pumps matter more after this upgrade than before it. Then handle the cold months, because a drained exchanger takes 10 minutes and a split one takes a dealer appointment in April, and the order of operations is in the RV winterizing guide. Finally, keep the old unit’s fault sequence somewhere you can find it, since a water heater that stops making hot water is usually a gas or flow fault rather than a dead appliance. The rest of the plumbing chain, from the pedestal to the shower head, is in the Water and Plumbing hub.
RV owner since childhood trips in a Class C. Mr RV Expert is where I write down what actually works after fixing, replacing and testing the gear myself.
About Mr RV Expert →Keep reading in Water & Plumbing
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