Propane Vs Electric Water Heater Cost Calculator

Calculator Inputs

Hot water use per day, gallons

Incoming water temperature, F

Hot water set temperature, F

Operating days per year

Usage adjustment, percent

Analysis life, years

Electric rate, $ per kWh

Electric efficiency or UEF

Electric standby use, kWh per day

Electric fixed fee, $ per month

Electric installed cost, $

Electric yearly maintenance, $

Electric price escalation, percent

Electric CO2 factor, lb per kWh

Propane price, $ per gallon

Propane efficiency or UEF

Propane energy, BTU per gallon

Propane standby loss, BTU per day

Propane fixed fee, $ per month

Propane installed cost, $

Propane yearly maintenance, $

Propane price escalation, percent

Propane CO2 factor, lb per gallon

Discount rate, percent

Reset

Example Data Table

Scenario	Daily gallons	Temperature rise	Electric rate	Propane price	Electric UEF	Propane UEF
Small household	45	60 F	$0.14/kWh	$2.65/gal	0.92	0.82
Average household	64	65 F	$0.16/kWh	$2.85/gal	0.92	0.82
Large household	90	70 F	$0.20/kWh	$3.20/gal	0.95	0.86

Formula Used

Temperature rise = Hot water temperature - Incoming water temperature

Useful heat per year = Gallons per day x 8.345 x Temperature rise x Days x Usage factor

Electric kWh = Useful BTU / 3412.142 / Electric efficiency + Standby kWh

Propane gallons = Useful BTU / Propane efficiency / BTU per gallon + Standby fuel

Annual cost = Energy cost + Fixed yearly fees + Yearly maintenance

Lifetime present cost = Installed cost + Present value of escalated yearly cost

How to Use This Calculator

Enter the average hot water used each day. Add the cold inlet temperature and desired hot water temperature. Use real utility rates when possible. Enter efficiency from the heater label or product sheet. Add fixed fees, installation cost, maintenance, escalation, and discount rate. Press calculate. Review annual cost, lifetime cost, savings, fuel use, and emissions. Use CSV or PDF buttons to save the result.

Understanding Water Heater Cost

A water heater converts purchased energy into useful hot water. The main cost depends on heat demand, fuel price, and heater efficiency. Propane and electric units can both work well. Their running cost can be very different in each home.

Why Energy Input Matters

Water heating starts with temperature rise. Cold water enters the tank or heat exchanger. The heater raises it to the set outlet temperature. More gallons need more heat. A larger temperature rise also needs more heat. The calculator first finds this thermal load. It then adjusts the load for each heater efficiency.

Electric Cost Factors

Electric heaters are simple to estimate. One kilowatt hour equals 3,412.142 BTU. The calculator divides useful heat by electric efficiency. It then adds standby kilowatt hours when entered. The final electric cost includes rate charges, fixed monthly fees, maintenance, and installed cost. This helps compare low purchase prices against long term bills.

Propane Cost Factors

Propane is priced by gallon. One gallon has a default energy value of 91,452 BTU. Real cost depends on burner efficiency and standby loss. The calculator divides useful heat by propane efficiency and fuel content. It then adds pilot or standby fuel use. Delivery fees and tank rental can change the result.

Total Ownership View

Fuel cost alone can mislead buyers. A cheaper heater may cost more over its life. A high efficiency unit may pay back slowly or quickly. This depends on local rates and daily demand. The lifetime section estimates simple total cost. It includes installation, yearly maintenance, and operating cost over the selected life.

Using Results Carefully

The output is an estimate. Actual bills change with shower habits, laundry load, inlet water temperature, and utility pricing. Use recent bills for the best rates. Use the yellow energy guide label for efficiency. Check local code, venting needs, and electrical service before buying.

Physics Behind the Tool

The calculation uses heat transfer basics. One BTU heats one pound of water by one degree Fahrenheit. A gallon of water weighs about 8.345 pounds. This makes the method practical for daily use. It also makes the comparison transparent.

Small input changes can show important yearly differences for households quickly.

FAQs

1. What does this calculator compare?

It compares annual and lifetime costs for propane and electric water heaters. It uses water demand, temperature rise, efficiency, fuel price, fees, maintenance, and installation cost.

2. Is propane always cheaper than electric?

No. Propane can be cheaper where propane prices are low. Electric can be cheaper where power rates are low or propane delivery fees are high.

3. What is UEF?

UEF means uniform energy factor. It shows how efficiently a water heater converts energy into usable hot water under a test method.

4. Why is standby loss included?

Stored hot water loses heat over time. Standby loss estimates energy used even when no one opens a hot water tap.

5. What propane BTU value should I use?

The default is 91,452 BTU per gallon. You can change it if your supplier or engineering data uses another value.

6. Does the calculator include installation cost?

Yes. Enter installed cost for both heater types. The lifetime result adds installation to the present value of future operating cost.

7. Can I use this for tankless heaters?

Yes, if you know the correct efficiency and standby inputs. Set standby losses low when the heater has very little idle energy use.

8. Are the results exact utility bills?

No. They are planning estimates. Actual bills depend on weather, habits, water temperature, appliance loads, rate changes, and equipment condition.