How To Heat a Pool Without a Heater (7 Effective Tips)

Pool heaters are the most expensive piece of equipment for swimming pools. However, you can heat the water without using gas or electricity. There are many ways to increase your pool’s temperature, especially when it’s under direct sunlight.

To heat a pool without a heater, try these suggestions:

• Add a solar blanket
• Use a black hose
• Try liquid solar blankets and pills
• Install pool solar panels
• Run the pump often
• Consider solar domes
• Enclose the pool

In this article, I’ll dive into every way to heat your pool if you don’t have a heater. I’ll also share the quickest way to heat a swimming pool during any time of the year.

Use a Solar Blanket

Solar blankets are some of the most effective ways to heat your swimming pool. You can use them with or without a pool heater. Make sure the solar cover’s bubbles face the correct direction to absorb as much heat as possible. If the bubbles face the wrong direction, the solar blanket will deteriorate.

The Sun2Solar Pool Cover is a 12-mil solar blanket that lasts several years. It absorbs up to 90% of the sun’s UV rays to provide optimal heating and chemical retention. These solar blankets also prevent your pH from being affected by rain, evaporation, and phosphates from natural debris.

Keep these tips in mind when using a solar blanket to heat a pool:

• Your pool needs to ‘breathe,’ which means it needs time to off-gas the chlorine and other chemicals. Remove the pool cover once per week for a couple of hours. Many people do this when they swim, so you might not have to worry about making a routine out of it.
• Spray the solar cover with a garden hose to remove the dried chlorine every time you remove it. Chlorine and other chemicals will inevitably damage the solar cover, especially if they’re baked onto the material.
• Solar covers provide the best protection and heating when they’re under direct sunlight. Keep the solar cover on the swimming pool when it’s sunny unless you’re in the water. The same rule applies to all solar heating items for your swimming pool.

Pro Tip: Choose a 12-mil solar cover instead of a 10-mil solar cover. The 2-mil difference increases the solar cover’s longevity by several years, prevents tears, and increases the heating properties.

Warm the Pool With a Black Hose

You can use a black hose to heat your swimming pool whenever it’s sunny outside. Coiled hoses offer the best temperature since they heat much quicker. Below, I’ll show you the step-by-step process of using a black hose to heat your pool:

1. Connect the black garden hose to the return line in your swimming pool. The return like is where the water goes from the pump into the water. Some pools have several return lines, so I suggest attaching the hose to the lowest line since heat naturally rises.
2. Lay the rest of the coiled hose on a nearby deck or anywhere with direct sunlight. It’s best to choose a location that stays hot throughout the day. The black color will absorb as much heat as possible, and the coiled shape provides excellent insulation.
3. Place the other end of the hose in the pool. This end will serve as the returning portion of heat from the sunlight. Wherever you place this side of the hose is where most of the heat will go. Again, I recommend placing the hose as low in the water as possible to heat as much of the pool as you can.
4. Turn on the pump to test your work. You’ll have to run your pump at a slower speed if you have a variable-speed pump. The high pressure coming out of the pump can push the hose off of the return line. Make sure it’s running slowly and for as many hours as possible to circulate and heat the pool water.

Try Liquid Solar Blankets and Pills

Liquid solar blankets and solar pills are the next best solution for those who prefer low-cost, low-maintenance heating solutions. You can use either of these products to increase the temperature and chemical retention in your pool.

Keep in mind that excessive use of liquid solar blankets will eventually require you to lower the CYA in the pool due to a lack of evaporation and dilution.

So, which one is best for your swimming pool?

Liquid Solar Blankets

Liquid solar blankets often require a weekly dose. They create a thin film over the pool water that holds a lot of the heat, preventing it from escaping. Furthermore, most liquid solar blankets are invisible and prevent excessive chlorine loss.

If you want to try a liquid solar blanket, I suggest the Natural Chemistry Cover Free Liquid Solar Blanket. This chemical is completely safe for swimming and preserves up to 70% of the heat in the swimming pool. It also lowers evaporation by up to 85%, saving you money on your water bill and chemical usage.

Solar Pills

Solar pills typically go in the skimmer basket. They disperse the previously mentioned liquid solar blanket. People often choose solar pills because they offer a set-it-and-forget-it routine. Place the ball in the skimmer and replace it as often as the company recommends. That’s all there is to it!

Those who want a solar pill for their pool should try the AquaPill Solar Pill. Each solar pill (also known as a solar ball) lasts for up to a month in a 12,000-gallon swimming pool. Remove the plug, set it in the skimmer basket, and you’ll be good to go. The Solar Pill works every time you turn on the pump and circulate its chemicals.

Add Pool Solar Panels

Solar panels are often thought of as energy-producing devices, but they can heat your swimming pool without requiring additional electricity. Unlike traditional solar panels, pool solar panels are often filled with a series of tubes. These tubes go back and forth, absorbing as much of the sun’s warm UV rays as possible.

As the water passes through the solar panels, it gets hotter. Some pool solar panels absorb the sun’s heat and put it into the plumbing, whereas other variants push the water directly through the panels.

Here are the two main things you should know about pool solar panels:

1. Pool solar panels are ineffective if they’re not placed in the sun. You should have the entire solar panel under direct sunlight for as many hours each day as possible. People often believe the panels can absorb the UV rays in the shade, but they’re much different than electrical solar panels.
2. It’s important to close the valve leading to the pool solar panels during the winter. They can freeze and crack if the water gets too cold. Hire a professional to install valves before and after the panels to ensure maximum control around the clock. Use diverter valves for the best results.

Circulate the Swimming Pool

Circulating the pump will increase the water’s temperature by a few degrees. In fact, a gentle trickle is often enough to prevent the pump from freezing when it’s below 32 degrees Fahrenheit (0 Celsius). Your pool pump should run during the hottest hours during the warmer months and during the coldest hours in the colder months.

Running your pool pump also provides the following heating benefits:

• Circulating the water encourages liquid solar blankets and solar pills to cover more surface area. These chemicals develop a thin, invisible layer on top of the water. They can’t disperse if the pump doesn’t operate enough. Always follow the manufacturer’s instructions to know how long the water needs to circulate.
• Moving water encourages pool solar panels and black hoses to heat the water quicker. These devices only work when there’s water moving through them. Run the pump when the hose or panel is at its hottest. The rushing water also prevents these surfaces from cooling down.

There are countless reasons you should circulate the pool more often. Ask a local pool rep to know how many hours you should run the pump in your climate. The general idea is to run it for one hour per ten degrees outside.

Install Solar Domes into the Plumbing

Solar domes aren’t very popular for in-ground pools, but they can work wonders in above-ground swimming pools. These domes are spiraled black coils in a dome-like structure. Some of them have plastic covers for additional heating properties. All solar domes connect to the plumbing, so make sure you know if they require PVC or corrugated plastic hoses.

The Kokido Solar Dome is an above-ground pool heating device. It has angled feet to help the dome catch as much heat as possible.

Connect each dome to the existing corrugated hoses for the best results. These solar domes collect the sun’s heat, spiral them through the plumbing, and back into the pool. They don’t require electricity or gas to operate.

Solar domes offer incredibly energy-efficient heating. One dome can increase your pool’s temperature by several degrees without costing a dime. They’re most effective for swimming pools that are less than 10,000 gallons because they can’t handle too much water at a time. Never convert a plastic hose solar dome into a PVC dome (it’ll explode with water pressure).

These solar pool domes work the same as the black hose trick. The coiled shape provides insulation while the black color absorbs tons of heat. The primary benefit of using a solar dome over other heating options is that these domes don’t require a lot of space. They’re out of sight and out of mind.

Enclose the Pool

Enclosing your swimming pool provides a greenhouse effect that amplifies the sun’s heat. It’s one of the most expensive heating options, but you don’t have to worry about gas or electricity. Furthermore, pool enclosures provide protection from rain, debris, and other contaminants that could lead to algae in the water.

Review these quick details about pool enclosures:

• Keep your equipment out of the enclosure if possible. Gas heaters, pumps, and other equipment will get too hot in the enclosed space, reducing their longevity.
• All pool enclosures need air vents to bring oxygen into the space. If there’s nothing bringing air into the enclosure, it can lead to headaches and other unwanted side effects.
• Some pool enclosures will develop condensation and mold from the warm water and swimmers. It’s important to remove the mold as quickly as possible to prevent it from spreading and causing health issues.
• You can get a partial enclosure or a black net to collect sunlight without completely closing off the swimming pool. These options are better for those who live in extremely hot climates.

What Is The Fastest Way To Heat A Pool?

The fastest way to heat a pool is by combining a gas heater with a solar blanket. However, you can combine a solar blanket with a solar pill and a solar dome if you don’t want to install a heater. Enclosing the swimming pool will also limit evaporation and encourage heat retention during the warmer months.

Pools are heated quickly with gas and electric heaters. However, they have pricey startup and maintenance costs. Below, I’ll show you the process of quickly heating a pool without a heater in the plumbing.

1. Get a solar blanket as quickly as possible to retain the sun’s heat throughout the day.
2. Run the pump when the sun is directly above the pool to encourage temperature increases.
3. Install pool solar panels or solar domes (solar panels are better for in-ground pools, whereas solar domes work best for above-ground pools).
4. Enclose the pool or put a pool net about 15 feet above the pool to heat the pool and keep debris out of the water.

There are several ways to get your pool hotter without using a heater. While they’re more effective during the summer, you can still increase the water’s temperature by several degrees with these tricks during any time of the year.

Jonah Ryan

Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he’s not writing for Temperature Master, he’s usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.