LP Gas Pool Heaters – FAQs and Tips

heating your home pool

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Propane pool heaters are popular, especially given they’re relatively more energy-efficient even for large-sized pools. They are also ideal for infrequent heating and are a perfect fit for all weather conditions heating tasks. 

As per their name, they are powered by powered by propane. Hence, the gas you use for cooking, heating your house, and powering your generator can be handy in heating your pool. 

But how exactly do propane pool heaters work? How much propane gas to heat a pool do you require? What’s the ideal propane gas tank for pool heating applications? If you have such questions, you’re in for a great ride because we have prepared in-depth insights into these and other additional queries on propane pool heaters. 

Would you like to save money on your propane costs? If so, you’re in the right place! Click here to get 100% free, no obligation quotes from propane dealers in your area.

The biggest dilemma for many pool owners is picking the right heater size proportional to the pool dimensions. If one chooses a larger heater, the heating time will be reduced. But this may add to the heating costs as a large heater will consume more propane gas. 

We’ll bring you details on propane pool heaters and the critical factors to consider to ensure you pick the right heater size for your pool. 

Ready for the details? Let’s delve right into the article. Master propane pool heaters: Your comprehensive guide. Learn all about efficient heating solutions for your pool. Dive into comfort.

Why Manage the Pool Temperatures?

The American Red Cross recommends that you heat your pool to 78ºF if you intend to use it for competitive swimming. Nonetheless, if the elderly and young children use the pool, you will need to heat it to a higher temperature of at least 80ºF. This is warm enough to ensure their sensitive skins don’t freeze. 

So, the whole point of managing the pool temperature is ensuring you create the ideal swimming conditions. But notably, increasing the pool temperatures comes with an additional cost. Anytime you use a heater to increase the pool temperatures by a degree, you incur between 10% and 30% in energy costs. 

But again, there are times you aren’t required to use the pool, so at such times, there’s no point heating it. Managing pool temperatures means creating the ideal swimming conditions via controlled heating to ensure you don’t incur unnecessary energy costs. 

Can propane pool heaters be helpful in this cause? We’ll find out in the subsequent sections. 

What Size Propane Heater Do I Need?

Choosing a propane gas heater for your pool is quite complex because there are several factors to consider. Primarily, you need to consider the pool dimensions (its surface area) and the temperature difference between the pool and the ambient air. Also, there are additional, equally important factors, such as the following: 

  • Humidity levels
  • Wind exposure
  • Cool night temperatures.

Take the case of a pool allocated in an area with fast wind, low humidity, and relatively cool night temperatures. Such a pool will definitely require a large propane pool heater. But is a larger pool heater always the better option? Not really, because although such a pool heater gives a better BTU output than a smaller one, it’ll consume relatively more propane and thus incur more cost. 

So this begs the question: What is the ideal propane tank for pool heating applications you need? It is pretty simple; the primary factor to consider when choosing a propane pool heater size is the pool size. 

Calculating Pool Surface Area

Here are the typical formulas for different pool shapes to find the surface area. If you have a square or a rectangular-shaped pool, multiply the length of the pool with the width. 

Square or Rectangular Pool SA = Length x Width.

But, if your pool is round or looks like a perfect circle, you will need to measure its radius (distance from one end of the pool to the other divided by two) using a tape measure. Next, multiply a square of the radius with π. 

Circular pool SA =  π x (radius)2 

For those with oval-shaped pools, the surface area formula is quite different from if it were a perfect circle. You will need to measure its length from one end to the other and breadth. Then, use the following formula to find the surface area. 

Oval Shaped Pool Surface Area = π x 0.25 x length x width. 

Lastly, some pools sport a kidney shape. Their surface area formula is complicated, although you can still estimate it. First, using a tape measure, find the width on one end of the pool in one half of the kidney and then the other. So you will now have two widths. Ensure that you measure the width at the widest points of the kidney. 

Next, measure the length from one end of the pool to the other and use the following formula to find the surface area: 

Kidney-Shaped Pool surface area  = (Width 1 + Width 2) x Length x 0.45

Calculating Minimum BTU Requirements

Next, after calculating the pool area, you can estimate its Minimum BTU requirement. This is the least energy output you require to provide in the pool. Here’s the formula: 

Pool Minimum BTU Rating = Pool Surface Area ÷3 x 1000

For instance, take a rectangular pool with a length of 36 feet and a width of 20 feet. The surface area equals 36 x 20 = 720 square feet. 

Next, calculate the pool minimum BTU rating: 720/3 x 1000 = 240,000 BTU rating. 

This figure means you will require a propane pool heater with a minimum BTU rating of at least 240000. You may opt for one with a higher rating, as this is simply the minimum BTU rating of your pool heater to ensure it matches the pool size, but there are additional factors you need to consider, as we’ll explain below.  

Finding the Precise BTU Requirement

How do you calculate the actual BTU requirement for a propane pool heater when considering factors such as ambient air temperature? 

We calculated the average BTU needs or the base minimum heating requirements in the above example. Let’s now include the temperature differential in calculations to ensure we get the precise BTU requirement with respect to the ambient temperatures. 

Take a case whereby the ambient air temperature is 50ºF, and our desired water temperature is 80ºF. This means we have a temperature differential of 30º. 

Suppose we want to find the precise BTU requirement that takes care of this maximum temperature differential; we’ll need to multiply the pool’s surface area with the differential and a factor of 12. 

Hence, the Precise BTU Requirement for a 36 by 20 feet pool = 36 x 20 x 30 x 12 = 259200 BTUs. Note that this BTU rating will yield a 1ºF temperature rise/hour when the prevailing surface winds travel at a speed of 3.5 mph. 

Hence, if, for instance, you want to achieve a 2ºF temperature rise/hour for the same pool, you’ll require pool heaters with double the rating. This means that you can always find out the precise BTU requirement in relation to the rate per hour by multiplying it by a factor of the expected temperature increase in ºF. 

Why use a Propane Heater with a Higher Rating than the Calculated BTU Requirement? 

There are numerous factors at play that can lower the heat output of pool heaters. These include aspects such as: 

  • Altitude
  • Desired Temperature Increase Rate
  • Prevailing sun exposure
  • The presence of a Solar Roof Cover above the pool
  • Wind Speed.

Hence, the propane heater will ideally deliver a lesser BTU than its rating. This is why investing in a propane heater with a relatively higher rating than the BTU requirement is advisable. Ideally, the best propane pool heaters will be between 50k and 100k BTUs which is higher than the average requirement. 

When the pool also features a spa, you may need a propane gas heater with a higher BTU rating than the average. Ideally, one with approximately 400,000 BTUs will be sufficient to heat the pool and the spa. 

Does the Efficiency of a Propane Pool Heater matter?

a heated pool with two people lying on water

A propane heater’s efficiency is a percentage ratio of the energy input versus the output BTUs. It indicates the energy that goes into the heating and what goes to waste. For example, a propane heater with a 75% efficiency means that for every $100 invested in fuelling it, it produces heat output worth $75. Hence, $25 of your money goes to waste with such a heater. 

And this brings us to another fundamental question: Does investing in a used pool heater make sense? Rather, what are the downsides of such a heater? 

When you buy a new propane heater, you’ll enjoy an 82% to 96% output efficiency. Hence, say, for instance, your new heater shows an 88% efficiency. It means that if it is rated to generate 240,000 BTUs, the propane heater will produce 212,000 BTUs. Therefore, the higher the efficiency, the closer the heater will match its BTU rating. 

Notably, the heater’s efficiency wanes with continued use, so buying a used propane pool heater is not a great idea. Such a device will output remarkably lower BTU output than the efficiency percentage on its nameplate. Also, a lack of proper maintenance can hasten a propane heater’s efficiency decline. 

How Much Propane Does A Pool Heater Use?

If you are contemplating heating a pool with propane, what is the average usage of the gas do you expect? Taking such aspects into consideration is imperative because it can help you decide how expensive is it to heat a pool

A typical pool heater will consume approximately 4.5 gallons of propane per hour. So, if you take about five hours to heat a pool on a hot day, you will need 22.5 gallons of gas. The problem is leaving the propane heater on for the entire day as it will consume more than 100 gallons. 

From the above approximations, it is clear that propane pool heaters are among the heavy users of gas. Hence, if you use the heater continuously, you’ll be left with none to meet other household needs such as heating and cooking. 

The best propane pool heaters are used only when necessary. Also, it would help to install swimming pool covers to control the heat loss. In addition, it would be imperative to install a propane tank monitor to keep track of the pool heater’s usage. The device will signal your propane gas provider daily, indicating what’s left in the tank. 

The provider will notify you when you need to refill your propane gas tank. 

Is a Propane Pool Heater Worth the Investment?

A best pool heater retails at $1,500 – $6,000, depending on the heater size. The operating costs of the device also vary, although the rate for a 100,000 BTU rated heater, the consumption rate is one gallon per hour. 

Say a gallon of propane gas costs approximately $18. You will spend $90 to heat the pool for five hours on a cool day. The heating requirements vary depending on many factors, so it may be hard to estimate the overall operating costs. 

But given that propane gas is cheap and readily available, using the component to heat water makes sense. Also, the versatility of propane gas means you can use the gas for other applications when not heating your pool. 

The hook-up costs/fees with vary with what size propane tank applies with next-day delivery service. If you go with two 100-gallon above-ground tanks or one 250-gallon above-ground propane tank they will need to be at least 10 feet away from an exterior source of ignition i.e. your propane pool heaters themselves. So there is be some work for the propane company to run the lines and set the tanks. A ballpark figure for basic installation 10ft away from the tanks plus next-day delivery service is $350-$500. In addition, there may be an annual propane tank rental fee, and keep in mind that most residential deliveries include a free next-day delivery. Some companies might sell the tanks outright and you could expect the costs for propane tanks and installation to be roughly $2,000 and up.

The other option is to install an in-ground tank. This option would cost substantially more but if you don’t mind paying the cost to heat the pool you also might not mind the cost of burying a propane tank. The cost for 500 gallons in a ground propane tank ballpark is $3,500-$5,000. There are limitations where in-ground tanks can be installed. Because pools are most often in the back yard you need to be mind of staying 10 feet off the property line and 10 feet from any source of ignition. Other factors include keeping the propane tank out of tree root systems and making sure the propane tank is in a location where your propane company can reach it with their delivery hose. Most delivery hoses are 135-150 ft long. While it might cost more upfront, you will be able to buy propane in a greater quantity so your price per gallon will be reduced. Because most of the purchase will be made in the non-peak demand period for propane the prices are generally at the lowest rates of the year when you be ordering propane deliveries.

What to Consider When Buying A New Propane Pool Heater?

Existing Gas Line Size

First, consider your existing gas line size to determine if you need to install a new one. If the existing one can adequately supply your new heater, you’re good to go. But when changing to a new heater with a higher BTU rating, you may have to change the gas line to accommodate the new heater’s demands. 


Note that an upgrade to a larger BTU propane heater will also mean you need to spend more on a new heater. Also, investing in a new propane gas heater doesn’t make sense if it is not helping you save on power costs. 

So also calculate if the new propane gas heater results in savings using the following formula. Current Annual Cost x [1 – (Current Efficiency ÷ New Efficiency)]


Natural gas pool heaters are among the most popular heating solutions for your swimming pool and have an effective output as other heater types. However, you must understand the dimensions of the pool to help determine the ideal size for your heater. We have covered all that in detail above, so you don’t need to engage an expert. 

But if you are unaware of the different propane gas models, do adequate research before settling on one. Lastly, don’t settle for an old/worn-out propane heater, as it will cost you in the long run.

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Ryan McCabe

Ryan McCabe

Ryan is a home and small business energy expert, having overseen retail propane, heating oil, and HVAC services companies. On ComparePropane, Ryan writes about things that people should know when shopping for or using propane in their homes and businesses. 

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