Wood-Fired Pool Heaters 2026: Real Prices, Real Output and How Much Wood a Pool Takes

Quick answer

A wood-fired pool heater is an outdoor stove with a stainless steel coil that your pool pump pushes water through. The best-known US maker, Warm Water Solutions, sells four models from $4,395 to $8,595 and rates its smallest at 100,000 to 125,000 BTU per hour into the water, with more wood needed every 1 to 1.5 hours. Raising a 20,000-gallon pool by 20°F takes about 3.3 million BTU, roughly a fifth to a third of a cord of firewood, so wood is the cheapest pool heat there is if you cut your own and one of the most expensive if you buy wood at $500 a cord. It only makes sense if you have cheap wood, time to tend a fire for a day or more, and no local rule against outdoor wood burners.

By the numbers (checked November 6, 2026):

• $4,395–$8,595: Warm Water Solutions’ four tankless wood pool heaters (WWS-80 to WWS-320), with free US shipping as a fall special.
• 100,000–125,000 BTU/h: the WWS-80’s rated heat into the water, with a wood reload every 1 to 1.5 hours.
• 3.3 million BTU: the heat needed to raise 20,000 gallons by 20°F (20,000 gallons × 8.34 lb × 20°F), before any heat loss.
• 25.3 million BTU per cord: oak, per University of Maryland Extension. The EIA uses 20 million BTU for an average cord.
• $200–$500 per cord: what Vermont buyers can expect to pay for firewood this season, per WCAX (October 2026).
• $11–$50: what bought firewood costs per million BTU delivered to the water, against about $38 for propane and $11 for a heat pump at current EIA prices.
• 100 ft and 18 ft: New York’s minimum distance to the property line and stack height for a new residential outdoor wood boiler.

How a wood-fired pool heater works

Every wood pool heater does the same job: it burns wood and moves that heat into pool water without mixing the two. The designs differ in where the water goes. We compared the three you can buy, plus the hot-tub stoves sometimes sold for small pools, using maker specs, manuals and published prices. We did not run any of these heaters ourselves.

The physics is the same as for any pool heater: one BTU raises one pound of water by 1°F, and a gallon weighs 8.34 pounds. A heater rated at 100,000 BTU per hour can raise a 12,000-gallon pool by about 1°F per hour, before the pool loses any heat to the air. That is the figure Warm Water Solutions itself gives for the WWS-80.

The wood-fired pool heaters you can buy in 2026

Warm Water Solutions WWS series: the main US-made option

Warm Water Solutions has sold wood pool heaters for more than 20 years and is the name most US buyers find first. The model number is the length of stainless pipe in the heat exchanger, so a bigger number means a hotter outlet temperature for the same fire. The maker publishes hourly output for the two smaller models only. Its site also lists order-ahead discounts of $400 to $1,300 for heaters delivered between mid-December 2026 and June 2027, because its spring order rush outruns production.

Two details are worth reading before you order. First, the gallon ratings disagree with each other. The price list calls the WWS-80 “best for pools under 15,000 gallons,” the spec block on the same page says “pools and spas up to 25,000 gallons,” and Canadian retailer Berry Hill sells the same SKU as a “20,000 gallon” heater with a litre figure that equals 15,000 gallons. Size by BTU per hour instead, using the table further down. Second, the homepage advertises a “5 year No Fault 100% Warranty,” but the separate warranty page describes a five-year limited warranty that excludes corrosion from poor water chemistry, PVC pipe that melts from low water flow, rust, firebrick and on-site service. Defective heaters ship back to the factory on a pallet, and the buyer pays the freight both ways if the problem is ruled improper use.

In Canada, Berry Hill (St. Thomas, Ontario) lists the same four heaters at C$5,999, C$6,780, C$8,325 and C$10,500, and warns US buyers about 10-50% tariffs plus brokerage fees.

Hyprotherm outdoor boiler pool heaters: stored heat, separate exchanger

An outdoor boiler is a different animal from a tankless stove. It heats its own tank of water, and the pool is heated by a separate exchanger, so it can also heat a house, shop or domestic hot water. The seller says you load it about every 4 hours during the first 1 to 3 days of heating, then about once a day to hold temperature.

Read the BTU figures carefully. “95,243 BTU” for the ECO-FLRH-85 and “229,704 BTU stored” for the FLRPH-205 are not hourly outputs. Divide each by the weight of the water in its tank (85 or 205 gallons × 8.34 lb) and both come out at the same 134°F temperature rise. They describe the heat held in a full tank, not how fast the boiler can deliver it. Prices also vary on the seller’s own site: one page lists $5,567 and $6,767, another $5,397 and $6,597, and the titanium exchanger is $665 on one page and $690 on the other.

The seller’s own pages carry a regulatory warning. Hyprotherm says that, with rare exceptions, its boilers are sold in the US for businesses, shops, outbuildings, pools and hot water heating, and its EPA page says that in its reading federal rules limit outdoor wood boilers to non-residential heating. It leaves it to buyers to check what their state and town allow. See the rules section below before you order.

LS Bilodeau Bilovax LS50: the Canadian option

LS Bilodeau is a Quebec maker of maple syrup evaporators and wood furnaces, and it sells two wood pool heaters. The LS50 is for chlorine pools only. The original Bilovax, listed in the maker’s 2018 spec sheet at 250,000 BTU, handles chlorine or salt systems and can go indoors with restrictions. LS Bilodeau describes both as “smoke free” after about 10 minutes when fired as it recommends. At 50,000 BTU per hour, the LS50 needs about 25 hours of burning to raise a 15,000-gallon pool by 10°F before losses, which fits its 10-15°F-per-day rating for an above-ground pool.

Hot-tub stoves are not pool heaters

Wood-fired hot tub stoves such as Northern Lights’ TimberLine CampFire (about 35,000 BTU), Blaze (55,000 BTU) and Inferno (105,000 BTU) are sometimes listed as pool heaters too. They are built for tubs of a few hundred gallons. At 55,000 BTU per hour, raising a 15,000-gallon pool by 10°F takes about 23 hours of steady fire before losses. For tubs, see our sister site’s wood-fired hot tub guide.

How much wood does it take to heat a pool?

The heat a pool needs depends only on its volume and how many degrees you want to add. How much wood that takes depends on the wood and on how much of its heat reaches the water. The table uses two cases: oak at 25.3 million BTU per cord (University of Maryland Extension) with 70% of the heat reaching the water, which is the efficiency the same Extension sheet uses for a wood stove, and an average cord at 20 million BTU (EIA) with 50% reaching the water. No wood pool heater maker we found publishes an efficiency figure.

These are heat-up figures only. A pool loses heat all the time it is warmer than the air, mostly through evaporation, and a slow wood heater gives it more hours to lose that heat. Warm Water Solutions’ own instructions say a full firebox with the draft closed will “usually only maintain the pool temperature at night,” and tell owners to use a solar or thermal blanket, especially overnight. A solar pool cover matters even more with wood than with gas. Wood quality matters too: the University of Maryland Extension says firewood should be below 20% moisture, and New York bans unseasoned wood in outdoor wood boilers.

Wood vs. gas, propane and a heat pump: what a million BTU costs

The fairest comparison is the cost of one million BTU that actually reaches the water. The fuel prices below are from the EIA: residential natural gas at $19.73 to $27.05 per thousand cubic feet from May to August 2026, residential propane at $2.820 a gallon on November 2, 2026 (before taxes), and electricity at the August 2026 US average of 18.16¢ per kWh. Gas heaters are calculated at 82%, the federal minimum thermal efficiency for gas pool heaters.

Wood is only “free” heat if the wood is free. Warm Water Solutions and Berry Hill both describe the running cost as free because any kind of wood can be used. That holds for an owner with a woodlot. For an owner buying split firewood at Vermont’s $200-$500 a cord, the same heat can cost more than natural gas and, with poor wood and a less efficient fire, more than propane. A heat pump beats bought wood on cost in warm weather, though its output falls as the air cools (see our heat pump picks). Our pool heating cost guide has monthly figures for each heater type.

The real cost is your time

The price table leaves out labor, and labor is what most wood heater owners give up on. This table shows how long each heater has to burn to raise a 20,000-gallon pool by 20°F, using each maker’s rated output and ignoring heat losses.

The outlet temperature tells the same story. Each GPM of flow carries about 500 BTU per hour for every degree of rise, so a 100,000 BTU heater with 65 GPM running through it raises the water only about 3°F per pass. That matches the 3 to 6°F difference between inlet and outlet that Warm Water Solutions’ instructions call normal. The water coming back to the pool will feel warm, but the whole pool moves slowly.

Rules: EPA, state setbacks and your neighbors

This is the part most sales pages skip.

• EPA. Since May 15, 2020, residential hydronic heaters must be certified at 0.10 pounds of particulate per million BTU of heat output for each burn rate, or 0.15 under the cordwood test option (40 CFR 60.5474). The rule defines a residential hydronic heater as a wood or pellet burner that heats building space and/or water by circulating a heated fluid through pipes. None of the three pool heater makers above lists an EPA certification, and none of them explains whether the rule applies to a pool-only heater. Ask the seller in writing.
• State rules. New York’s outdoor wood boiler rule (6 NYCRR Part 247) covers any outdoor wood-burning device that heats water piped through it. A new residential unit (up to 250,000 BTU/h) must sit at least 100 feet from the nearest property line and have a stack at least 18 feet above ground. It may burn only seasoned clean wood, and it may not send smoke into neighbors’ homes or set off their smoke detectors. If the rule applies to your heater, a Warm Water Solutions heater with its standard 24-inch chimney (about 5.5 feet to the top of the cap) would need a much taller stack.
• Town rules and HOAs. Many towns restrict outdoor wood burners or limit them by lot size, and burn bans can stop you mid-season. Check before you buy, along with the general pool heater setback rules for your town.

The CPSC recall database lists no recalls of wood-fired pool heaters as of November 6, 2026. Its recent pool heater recalls involve gas units (see our pool heater recall list).

Installing a wood-fired pool heater

Warm Water Solutions’ installation page gives the basic steps for a tankless stove, and they match how any pool heater is plumbed:

1. Location. Outdoors, at least 3 feet from buildings or other obstructions, never inside an enclosure. Check your state and town setbacks too, which can be far larger.
2. Plumbing. Cut into the pool return line after the filter and run 1-1/2 inch schedule 40 PVC to the heater’s inlet and back from its outlet. Use tees with drain plugs on both sides so the coil can be drained for winter. If any chlorinator or salt cell is installed, it belongs after the heater, with a check valve between them.
3. Bypass. If the filter pressure rises after the heater goes in, add a bypass line with a valve and open it just enough to relieve the back-pressure.
4. Flow first. The pump has to be running and pushing water through the heater before you light it. Warm Water Solutions says to put the fire out immediately if the flow stops for any reason, such as a power outage.
5. Firing. Kindling on the firebrick, no log rack and no liquid starters. Keep the firebox full while heating and use the draft doors to hold the chimney thermometer in the efficient range.
6. Winter. Pull the drain plugs and blow compressed air through the coil before the first freeze (see our winterizing guide).

For salt pools, buy the corrosion-resistant version from the start: a type 316 manifold from Warm Water Solutions, a titanium exchanger for a boiler setup, or the salt-rated Bilovax. Our salt water pool heater guide explains why standard metals fail.

DIY wood pool heaters: what goes wrong

Copper coils in a fire pit or barrel stove are the most common DIY build, and the problems are predictable:

• Copper and chlorine. Bare copper corrodes in chlorinated and salt water, and dissolved copper is a common cause of blue-green stains on pool surfaces. All the commercial heaters in this guide use stainless steel or titanium.
• No flow, no safety. A coil that loses flow while the fire burns can boil and build pressure. Commercial units have a pressure vessel (Bilovax) or a coil made to be drained and inspected. A DIY coil usually has neither, and no relief valve.
• Melting PVC. Pool plumbing is PVC, and PVC softens with heat. Even Warm Water Solutions excludes PVC that melts from low water flow from its warranty.
• Fire and smoke. An open fire next to a pool deck, fence or house is a fire risk, and town smoke rules apply to a barrel stove as much as to a factory-built heater.

If you want low running costs without a fire, solar pool heaters heat the water for the cost of running the pump you already have.

Who should buy a wood-fired pool heater

A wood heater makes sense if you have your own wood, a rural lot with plenty of room to the property line, no gas line, and you mostly want to warm the pool for spring and fall weekends. It also suits a pool far from power, because a tankless wood stove needs nothing but the pump. Choose the WWS-80 for pools up to about 12,000-15,000 gallons and the WWS-120 for about 20,000 gallons. Consider a boiler with an exchanger only if you will also heat a house or shop with it. Look elsewhere if you want heat on demand, live on a suburban lot, have a salt pool and won’t pay for the upgrade, or would be buying firewood by the cord. A propane heater or a heat pump will be less work, and with bought firewood it may not cost more to run.

The bottom line

Wood-fired pool heaters work, and the physics is simple: a 20,000-gallon pool needs about 3.3 million BTU for a 20°F rise, roughly a fifth to a third of a cord of wood. The catch is time and rules, not heat. The main US maker’s heaters cost $4,395 to $8,595, put 100,000 to 175,000 BTU per hour into the water on the two models it rates, and need a reload every hour or two. Bought firewood can cost as much per BTU as gas. If your wood is free, your lot is big and you don’t mind tending a fire, wood is the cheapest way to extend the season. If not, a heat pump, a solar heater or a gas heater is the easier buy.

Sources: Warm Water Solutions (models, prices, specs), Warm Water Solutions installation instructions, Warm Water Solutions warranty, Berry Hill: Warm Water Solutions 30,000-gallon heater (CAD), Hyprotherm wood pool heater (WNC Stoves), Hyprotherm FLRPH-205 large pool heater, Hyprotherm EPA regulations page, LS Bilodeau Bilovax LS50, LS Bilodeau pool heater spec sheet, Central Boiler FAQ, University of Maryland Extension FS-937: Buying and Storing Firewood, EIA: British thermal units, EIA natural gas prices, EIA weekly residential propane prices, EIA Electric Power Monthly Table 5.6.A, WCAX: Vermonters turn to wood stoves (October 2026), 40 CFR 60.5474 (EPA hydronic heater limits), 40 CFR 60.5473 (definitions), EPA 2015 hydronic heater fact sheet, 6 NYCRR 247.5 (New York outdoor wood boilers), 6 NYCRR 247.3, 10 CFR 430.32(k) (gas pool heater efficiency).