Heating & appliances
Propane water heaters: tank and tankless
A propane storage water heater keeps a tank of hot water ready, while a tankless model heats water only as it flows, so it never runs out but needs a larger gas line and burner. Compare models by their Uniform Energy Factor (UEF), and size a storage unit by first-hour rating and a tankless unit by flow rate in gallons per minute.
Updated · American River Gas office, Newcastle
Two ways to heat water with propane
A storage (tank) water heater holds a set amount of water, and a burner under the tank keeps it hot. It is simple, familiar and usually the easiest swap for an existing unit.
A tankless (on-demand) water heater has no storage tank. When you open a hot tap, water runs through a heat exchanger and a burner fires to heat it. Because nothing is stored, there is no standby heat loss from a tank sitting at temperature all day, and hot water keeps flowing as long as the burner can keep up.
How to compare efficiency
The U.S. rating to look for is the Uniform Energy Factor, or UEF. The higher the UEF, the more efficient the water heater. ENERGY STAR sets separate bars for gas storage models and gas tankless (instantaneous) models, and certified tankless gas models carry a noticeably higher UEF than certified storage models. The yellow EnergyGuide label and the ENERGY STAR product finder make side by side comparison easy.
Sizing: first-hour rating versus flow rate
- Storage models: look at the first-hour rating, the amount of hot water the unit can deliver in a busy hour. Match it to your household's peak, like back-to-back showers plus a dishwasher.
- Tankless models: look at flow rate in gallons per minute at your needed temperature rise. Well and municipal water arrive colder in winter, so the heater has to raise the temperature further and flow drops. Size for winter, not summer.
- Large homes sometimes use two tankless units, or a storage tank plus tankless, to cover several showers at once.
What a tankless heater means for your propane system
A whole-home tankless heater has a large burner, often much larger than a storage unit's. It only fires while water flows, but when it does, it asks for a lot of gas at once. That affects gas line size and regulator capacity, and it may affect tank size in a home that also runs a furnace, range and fireplace. Tankless units also need proper venting and, in most cases, an electrical outlet for controls and fans.
If you are switching from a storage unit to tankless, bring us in before the plumber orders the heater. We can look at your tank and line and tell you whether anything needs to change.
Hot water during a power outage
Foothill homes see power outages, so it is worth asking how a water heater behaves without electricity. Tankless models, and storage models with a power vent or electronic ignition, need power to run. Some storage models with a standing pilot and a conventional vent can keep heating water without electricity. The manual says which type you have. If backup hot water matters to you, choose with that in mind.
Maintenance
Storage heaters benefit from draining a little water from the bottom now and then to clear sediment, following the manual. Tankless heaters in areas with hard water benefit from periodic descaling, as the manufacturer directs. Both should have the burner and venting checked by a qualified technician.
Installing or replacing a water heater safely
Any new appliance connection gets a leak test, and each appliance needs its own shut-off valve within 6 feet. Propane is heavier than air, so California's Mechanical Code restricts propane appliances in pits, basements and similar low spots. Install carbon monoxide alarms on every level and outside sleeping areas. If you smell gas, leave the building first, then call 911 and us from outside.
Questions
Straight answers
Is a propane tankless water heater better than a tank?
It depends on the home. Tankless models avoid standby heat loss and do not run out, but need a larger gas line and venting. Storage models are simpler to swap in and deliver a set amount of stored hot water.
What does UEF mean on a water heater?
Uniform Energy Factor, the U.S. efficiency rating for water heaters. A higher UEF means a more efficient unit.
Will a tankless water heater need a bigger propane tank?
Not always, but its large burner can change the gas line, regulator and sometimes tank size needed. Call us before you buy so we can check your system.
Why is my tankless heater weaker in winter?
Incoming water is colder, so the heater has to raise the temperature more, which lowers the flow it can deliver. Size a tankless unit for winter water temperatures.
Sources: ENERGY STAR: water heaters (opens in a new tab) · ENERGY STAR: residential water heater key product criteria (UEF) (opens in a new tab) · Propane Education & Research Council: water heating with propane (opens in a new tab) · Placer County Building Services: propane appliances (handout) (opens in a new tab)
Newcastle yard · since 1966
Questions about propane?
Call the office and talk to a real person. Or leave your details and we call you back.
Monday-Friday 8:00 AM-4:30 PM (closed noon-1:00 PM)
After hours, weekends and holidays, our answering service reaches a staff member.
