The best water heater for a short-term rental is sized for a full house, not your own family. Pick by first-hour rating or tankless flow for back-to-back showers, add leak detection with automatic shutoff, set it to 120°F, and choose a model you can monitor remotely, with a vacation setting for empty stretches.
How big a water heater does a short-term rental need?
Size it for full occupancy. The number of guests the listing allows, and how close together they shower, sets the demand. A family of four spreads showers across the day. A group of friends on a weekend trip often showers in a single morning rush before heading out.
For a tank, compare first-hour ratings. ENERGY STAR defines it as how much hot water "the unit can deliver during a busy hour under standard test conditions," and notes that a better rating means "you can get better hot water performance without having to buy a larger capacity water heater." For a rental, the first-hour rating matters more than the tank's gallon label.
For tankless, compare flow at your temperature rise. Maricopa County's water heater guideline says "Typical tankless water heaters can provide hot water at a rate of 3 to 6 gallons per minute, with a 60°F water temperature rise," and that "Gas-fired tankless water heaters usually produce significantly higher flow rates than electric tankless water heaters." It also warns that an undersized unit keeps the temperature but the "flow could slow to a trickle." In a rental with several bathrooms, two showers running at once is normal, so size for that.
| Rental setup | What to size for |
|---|---|
| Studio or casita, 2 guests | One shower at a time; a standard tank or point-of-use unit may be enough |
| 3 to 4 bedrooms, 6 to 8 guests | Back-to-back and overlapping showers; a high first-hour rating or high-flow gas tankless |
| Large house with a pool and several baths | Multiple showers at once plus laundry; consider a larger unit or two heaters |
Our page on what size water heater you need shows how to add up the demand, and why you run out of hot water fast in the shower covers what happens when a heater is too small.
Tank, tankless, or hybrid for a rental?
Each type trades something, and a rental changes the math because nobody lives there between stays.
- Gas tank. Simple, familiar, and quick to replace. A tank with a strong burner recovers fast between showers. It keeps the tank hot while the house sits empty, which costs some energy.
- Gas tankless. Never runs out while flow stays within its rating, and heats nothing between guests. It needs a properly sized gas line and venting, and regular descaling in hard water. See how often to descale a tankless water heater in Phoenix.
- Hybrid heat pump. The most efficient electric option, with a vacation mode for empty stretches. It recovers more slowly on heat pump alone, so it suits smaller rentals or a model with a strong high-demand mode. See what a hybrid water heater is.
- Electric tankless. Works for a casita or studio. For a whole house it needs a very large electrical service. See whether electric tankless works in Arizona.
The best choice is usually the type the property is already set up for, sized up for guest count.
What features matter most for a rental water heater?
The features that matter are the ones that protect you when you're not there. Guests won't notice a slow drip in the garage, and they won't call about a heater until the water is already cold.
### Leak detection and automatic shutoff
A leak in an empty rental can run for days. Some water heaters now include their own leak protection. Rheem's ProTerra hybrid with LeakGuard, for example, comes with a "factory installed 360° leak detection cable and auto shutoff valve," and Rheem says the shutoff "limits leaks to no more than 20 ounces of water" under its test conditions. Stand-alone leak sensors and shutoff valves can be added to most other heaters.
Code already requires a pan where a leak would cause damage. Section 504.7 of the plumbing code Phoenix uses calls for one where "water leakage from the tank will cause damage." A pan catches a drip. A shutoff valve stops a flood. Our page on water heater drain pan overflow explains the pan.
### Remote monitoring
A heater that reports problems to your phone lets you fix things between guests. The same Rheem model lists "Built-in Wi-Fi" and a "free mobile app" for "customizable temperature, vacation settings, energy savings and system monitoring at home or away." Many tankless and tank models offer similar apps. It needs a working internet connection at the property.
Arizona's short-term rental law also expects someone to respond. A.R.S. 9-500.39 lets cities require owners to provide "emergency contact information for the owner or the owner's designee who is responsible for responding to complaints or emergencies in a timely manner." An alert from the water heater gets that person moving sooner.
### A scald-safe temperature
Guests don't know your water, and some are young children or older adults. The U.S. Consumer Product Safety Commission "urges all users to lower their water heaters to 120 degrees Fahrenheit." It warns that "Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds," and that burns also occur "with a six-second exposure to 140 degree water." Set the heater to 120°F and keep the controls out of guests' reach, such as in a locked garage or utility closet. See what temperature a water heater should be set to.
How should you handle vacant weeks?
Use the vacation setting, then bring the water back up to temperature before the next guests arrive. Rheem's ProTerra, for example, has a "Vacation/Away" mode for "2-28 days (or placed on hold indefinitely)." That saves energy while the house is empty.
The trade-off is warm, still water. The CDC's guidance for building water systems says Legionella bacteria grow best in water between 77°F and 113°F, and recommends that owners "Flush low-flow piping runs and dead legs at least weekly." A rental that sits empty for weeks has a lot of still water in its pipes. Before guests return, return the heater to its normal setting, let it recover fully, and run each hot and cold tap for a few minutes. A cleaner or property manager can make this part of the turnover checklist.
What does code require for a rental's water heater?
The same rules apply as for any home. A short-term rental's water heater needs a temperature and pressure relief valve under Section 504.4, a pan where a leak would cause damage under Section 504.7, and the rest of the install rules. Garage heaters also have to meet the 18 inch rule for garage water heaters, and a replacement may need a permit in Phoenix. Our guide on what to know before buying a water heater walks through the rest of the choice.
HQ Plumbing & Air installs and replaces water heaters for homes and rental properties across the Phoenix area, 24/7, with free estimates and upfront pricing. See our water heater service.
Size for a full house, stop leaks automatically, and keep it at 120°F. The guests will only notice that the showers stay hot.