The Complete Guide to Running a Hot Water Heater Off a Propane Tank

As an expert in home renovations with over 10 years of experience, I‘m often asked if it‘s possible to run a residential hot water heater off a portable 20lb propane tank. The short answer is yes – with the right heater size and proper setup, a 20lb tank can supply enough propane to fuel small to mid-sized water heaters for limited periods of time.

However, there are many important factors you need to consider before going the 20lb propane tank route for your hot water needs. In this comprehensive guide, I‘ll provide key information to help you determine if a propane tank water heater is the right choice for your home, and how to size, connect, operate, and maintain one safely.

How Do Propane Tank Water Heaters Work?

First, let‘s review the basics of how propane tank water heaters work:

• Propane is stored in liquid form under pressure in the tank. It vaporizes into a gas that ignites to heat water.

• Combustion of the propane gas occurs via a pilot light or electronic ignition. The flame heats a heat exchanger around the water tank.

• An inlet regulator reduces the high tank pressure to safe levels for the appliance burner.

• Hot water flows from the tank to fixtures when taps are opened. A thermostat controls temperature.

Propane water heaters provide an endless hot water supply without needing an electrical connection, so they can be used for off-grid or backup purposes.

What Size Propane Tank Will You Need?

The size of propane tank required depends on your hot water usage needs and heater specifications:

Water Heater Size:

• Small heaters (20-30 gallons): A 20lb tank may work for 1-2 people if conservatively sized.

• Medium heaters (40-60 gallons): Need 100lb tanks minimum.

• Large heaters (80-120 gallons): Require 250lb or larger tanks.

Usage Considerations:

• Number of people in household

• Fixtures (showers, faucets, laundry, etc)

• Peak usage times

• Climate and groundwater temperature

Heater Specifications:

• Recovery rate or gallons per hour (gph)

• Energy factor (EF) – higher is more efficient

• Input BTU rating – related to fuel consumption

As a general rule of thumb, plan for 100-200 gallons of propane fuel per 10 gallons of tank volume over a 10 year lifespan.

Here‘s a table showing approximate propane tank sizes needed based on some typical water heater configurations:

Heater Size	Household	EF Rating	Tank Size
30 gal	1-2 people	0.55+	100 lb
50 gal	2-3 people	0.60+	250 lb
75 gal	4-5 people	0.67+	500 lb
105 gal	Large family	0.80+	1000 lb

To confirm your specific needs, consult with a propane supplier and share details on your household, fixtures, and heater model.

You‘ll also need to consider convenience factors – larger tanks require less frequent refilling. For most homes, 500 gallon tanks are preferred for a good balance.

Estimating Your Propane Usage

To estimate your propane consumption:

1. Find your heater‘s BTU input rating on the technical specs or nameplate.

2. Convert BTU to potential gallons per hour usage: BTU / 91,500 BTUs per gallon

3. Multiply gph by your average daily use hours.

4. Factor in thermostat settings, weather, tankless fixtures, and other variables.

For example, a standard 50,000 BTU heater uses 0.55 gph. Running it 4 hours daily would equate to 2.2 gallons per day, or about 66 gallons monthly.

Here are some typical water heater propane usage estimates:

• Small tankless unit (4,500W): 3 gallons/month

• 30-50 gallon tank unit: 20-30 gallons/month

• 75-105 gallon high-efficiency unit: 60-100 gallons/month

Monitor your propane tank fuel gauge monthly to determine actual usage. Experts recommend budgeting for 10-20% higher than calculated to be safe.

Step-By-Step Guide to Hooking Up a Propane Tank

When installing a propane water heater, safety should always be your top priority. Follow these steps precisely:

1. Select an Approved Location

Propane tanks must be located outdoors and follow clearance requirements for combustibles and openings. Consult building codes for specific rules in your area.

2. Install Proper Gas Piping

Run approved rigid copper, steel, or plastic gas supply lines between the tank and heater. Do not use rubber hose within the building.

3. Attach Regulators and Gauges

Use a two-stage regulator to reduce tank pressure to 11" w.c. Install a flow limiting orifice fitting too. Add leaks detectors as an extra precaution.

4. Perform Gas Leak Checks

Pressurize system and spray all connections with non-corrosive leak solution. Fix any leaks detected immediately.

5. Connect Propane Supply Lines

Attach all gas lines securely. Use pipe dope or Teflon tape on male threads to prevent leaks.

6. Ignite Pilot and Verify Operation

Bleed all air from lines. Ignite pilot light per manufacturer instructions and confirm burner ignition and proper flame quality.

7. Review Safety Tips

Revisit the user manual and have all household members understand propane safety tips before operating the system.

When in doubt, hire a qualified technician for installation. NEVER take risks with propane leaks or malfunctioning equipment.

Propane vs Electric Water Heaters: Operating Costs

When choosing between propane and electric, energy costs are a key factor. Propane typically costs less to operate:

• Electricity: $0.12 – $0.20+ per kWh

• Propane: $1.50 – $3.00+ per gallon

To compare, check the EF rating – it represents the energy output divided by input. A higher EF indicates greater efficiency.

For example, a 0.67 EF electric heater with 4500 watt elements uses 6.7 kWh per load. At $0.15/kWh, each tank would cost ~$1 to heat.

A comparable propane heater with a 0.67 EF rating uses ~0.67 gallons per tank, costing $1-2 with propane at $2/gallon.

Cost Savings Example

Heater Specs	Electric	Propane
EF Rating	0.67	0.67
Energy Used	6.7 kWh	0.67 gallons
Energy Cost	$1.00	$1.34
Heats/month	30	30
Monthly Cost	$30	$40

As you can see, the propane unit would save $10 per month in this scenario.Savings improve further with high electric rates or inefficient units.

Consider your rates carefully when choosing between electric and propane water heating.

Maintaining Your Propane Water Heater

To keep your propane water heater operating safely and efficiently for years to come, follow these maintenance practices:

• Annually inspect gas control valves, relief valves, piping, and venting. Fix any issues immediately.

• Check and recharge propane tank regularly. Don‘t let it fall below 30% full.

• Drain and flush sediment from tank every 6-12 months following manufacturer instructions.

• Test carbon monoxide and propane alarms monthly to verify proper operation.

• Clear dust, debris and flammable materials away from heater. Don‘t store anything near it.

• Monitor for any signs of trouble – smelly gas, pilot outages, noisy burner operation.

• Keep records of all inspections, repairs, tank recharges and alarm tests.

You can perform basic maintenance yourself, but leave complex repairs to qualified technicians only. Safety should always take priority.

Key Propane Safety Tips

Propane is highly flammable, so there are crucial safety steps that must be followed:

• Make sure tank is sized appropriately and placed outdoors away from windows and doors.

• Never store propane indoors or in attached garages. Vapors are heavier than air.

• Install UL-approved carbon monoxide and propane leak detectors.

• Learn the smell of propane – if a "rotten egg" odor is present, evacuate immediately and call 911.

• Keep ignition sources away from tanks and lines. No smoking!

• Have a qualified technician perform a pressure test on the entire system annually.

• Keep the tank valve closed at all times when not in use.

• Consider installing propane tank monitors that automatically shut off the gas supply if leaks are detected.

• Know how and when to safely shut off the propane supply in an emergency.

Follow all propane safety codes and tank manufacturer guidelines precisely to protect your home and family.

Is a 20lb Propane Tank Water Heater Right for You?

While it is possible to run smaller water heaters off 20lb propane tanks, I only recommend this approach for limited or temporary applications such as:

• Minimal use cabins or retreats

• Off-grid tiny homes

• Backup power during outages

• RV/camper travel

For most residential homes, the small tank size would require very frequent refilling and provide limited hot water capacity. I‘d suggest a minimum 100lb propane tank for standard household needs.

That said, propane tank water heaters can provide an efficient and cost-effective option over electric heaters, especially if you have access to low-cost propane. Maintenance and safety are paramount however – be sure to follow all guidelines precisely.

I hope this detailed guide has provided you with a complete overview of sizing, installing, operating and maintaining a propane tank water heater. Please let me know if you have any other questions!