What is the consumption rate of a tankless water heater when it’s connected to propane? Naturally, you run into this question when your tankless water heater is fueled with propane. You hear about how expensive tankless water is all the time. That’s why it’s critical to calculate propane usage regularly. 

The average output of a tankless water heater burning propane is 40,000 BTU per hour or 1.5 gallons per day. Propane is an energy-efficient fuel gas well-known for its energy savings potential. Calculating your propane usage can help you understand and evaluate your annual energy consumption.

How Much Propane Does A Tankless Water Heater Use?

According to the Energy Star program, a tankless water heater standard annual usage is 200 gallons. That’s approximately $482 per year. The cost of operating a propane tankless water heater varies considerably depending on where you live. In the US, propane is measured in gallons and liters everywhere else. But in this post, we’ll use gallons instead of liters because that makes more sense. So how many gallons will you need?

If your family consists of 2 people, you’ll only need 15 gallons. 25 for 3-4 members, and 35-40 if there are more than 5 of you.

The location’s temperature, water quality, and tankless water heater maintenance are all factors in this calculation. Start by learning about your tankless water heater capabilities. A gallon of propane costs a mere $2.20. So based on the cost, you can conclude that a family of two will require 33$ each month. 

A household with three to four people will need to spend $55 monthly, while a home with more than five members will have to pay between $77 and $88 per month.

The size of the heater and the sort of heater (expensive or inexpensive) influence things like: how much propane does a tankless water heater use? And how much is required to heat a given space. If you have a large, pricey heater, you’ll need more propane than a tiny, cheap one. The effectiveness of the heater also has an impact on how much propane is needed. More efficient tankless water heaters use less propane than less efficient ones. Finally, the temperature outside also affects how much propane is required to heat a specific area. If it’s cold outside, you’ll need additional propane than if the weather is warm. 

Identifying Your Propane Usage

Tankless water heaters provide consistent, hot water on-demand and cost less to operate than traditional gas tank models. Of the many fuel options available, propane is the most energy efficient one.

How much hot water you use depends mainly on your family’s size and usage patterns. Monitoring your tankless heater’s activity will help ensure everyone in your household always has enough hot water when needed – something that’s especially important in more prominent families.

With this simple approach, you can estimate your monthly propane usage easily. The average cost of a gallon of propane gas is between 2 and 2.75 dollars. Depending on the simultaneous activities in the household, annual propane consumption for the whole family might cost up to 100 dollars or more each year. You may choose to create a budget plan for your propane expenditures by keeping track of your monthly usage habit. Collecting this data may help you calculate your overall propane spending.

How To Calculate Propane Usage For Tankless Water Heater?

Water is so hard to heat up due to its high specific heat (4.19 kJ/kg°C). With a propane tank heater, you can heat more than 10+ GPM of water in less than 15 seconds. However, this requires a lot of energy from burning propane.

To figure out the question:how much propane does a tankless water heater use and how much these on-demand tankless water heaters use to heat water, we must first calculate the energy density of propane. We once again turn to the US Energy Information Administration and find out that the energy value for a gallon of propane is 91,452 BTU. Burning a gallon of gas generates 91,452 BTU (at 100% efficiency).

Rinnai, which produces the best propane tankless water heaters on the market, offers units that range from 5.3 GPM to 11 GPM. The 5.3 GPM unit produces a 53,000 BTU heating output at 100% capacity, while the 11 GPM one produces a 199,000 BTU heating output at 100%.

Let’s take the giant residential propane tankless heater as an example. It being an 11 GPM Rinnai RU199iP; this ‘199’ in the model number indicates that this propane tankless heater generates 199,000 BTU/hr when operating at total capacity.

We know that such a device will generate 199,000 BTU of heating output by burning propane. We also understand that utilizing 1 gallon of propane creates 91,452 BTU of heat. With this information, we can determine how much propane is consumed each hour by a sizable tankless propane heater. Here’s the formula: