Harvia WP500 Harvia Cauldron 50 Liter Water Heater
The Harvia WP500 Cauldron is a 50-litre (13.2 US gallon) wood-burning water heater designed for cottage sauna settings where a large supply of hot water for washing or rinsing after the sauna session is needed. It is not a sauna heater - it does not heat the sauna room. The WP500 is a standalone water heater in the Finnish sauna tradition: a wood-fired cauldron that sits near the sauna, burns firewood to heat a large reservoir of water, and holds it ready throughout the session. Harvia's own description captures its purpose and atmosphere precisely: the Harvia Cauldron 50 is designed for heating larger amounts of water in cottage settings. The traditional sauna cauldron adds a genuine Finnish old-time lakeshore sauna atmosphere. The outer casing is stainless steel. The inner cauldron is also stainless steel and can be removed for cleaning. The fire chamber is replaceable, extending the product's lifespan. Heat from the fire chamber is distributed directly under the inner cauldron for efficient water heating. 88 lbs of stones (2 boxes, 10-15 cm, sold separately) are required for operation. A 6" North American flue adapter is required for the 4.5" rear smoke outlet. UL listed. CE certified. Made in Finland by Harvia. 2-year warranty (consumer).
A wood-fired water cauldron - the Finnish cottage sauna tradition
In the traditional Finnish cottage sauna, the wood-burning stove heats the sauna room while a separate cauldron heats water for washing. The WP500 is Harvia's modern implementation of this second piece - a 50-litre stainless steel cauldron heated by a wood fire underneath, designed to be filled and fired alongside the sauna stove so that hot water is ready when the bathing session is over. Harvia's description of the resulting atmosphere is direct: it gives your sauna an authentic Finnish cottage atmosphere. For a cottage sauna without running hot water, an outdoor sauna, or any sauna installation where a large supply of hot water for post-session washing is needed without electric water heating infrastructure, the WP500 provides 50 litres (enough for multiple users) from a single wood-fired unit that requires no electrical connection whatsoever.
Efficient fire chamber design - heat directed under the cauldron
The WP500's fire chamber is designed so that the burning process is smooth and the heat is directed directly under the inner cauldron - this concentrates the fire's thermal output at the base of the water tank rather than losing heat to the sides or ambient air. The result is efficient water heating: a relatively small fire heats the 50-litre water volume effectively. The replaceable fire chamber is the feature Harvia most consistently highlights for long-term ownership: because the fire chamber is the most thermally stressed component, making it replaceable extends the operational lifespan of the cauldron significantly compared to a design where the fire chamber is integrated and non-serviceable. The lid, inner cauldron, fire chamber door, and ash box are all labelled parts (A through F) in the installation manual for clear reference during setup and maintenance.
Key operating requirements and safety notes
The WP500 requires 88 lbs of stones (2 boxes, 10-15 cm, sold separately) placed around the fire chamber - these are not heating the water but are part of the structural fire management system around the combustion area. The inner cauldron must always be kept full of water while the fire is burning - operating with an empty or partially drained cauldron while hot will damage the inner tank. The Harvia installation manual is explicit: the inner cauldron will be damaged if it is empty or drained when the cauldron is hot. Boiling the water must also be avoided - boiling water can splash from under the lid and cause burns. The rear smoke outlet (4.5" / 115mm) requires a 6" North American adapter for connection to a standard 6" chimney run - the same adapter used with all Harvia wood-burning stoves. Clean household water or quality lake water is recommended. Sea water and heavily mineralised water can corrode the stainless steel over time.
50-litre (13.2 gallon) wood-burning water heater cauldron - not a sauna heater. Harvia Cauldron WP500 - designed for cottage sauna settings where large amounts of hot water for post-session washing are needed. Stainless steel outer casing and removable inner cauldron. Replaceable fire chamber for long lifespan. Heat directed directly under inner cauldron for efficient water heating. 88 lbs stones required (2 boxes, 10-15 cm, sold separately). Rear smoke outlet 4.5" - 6" North American adapter required (sold separately). Adjustable legs. Safety distances: front 19.7", sides and back 9.8", ceiling 39.4". Do not operate with empty cauldron. Do not boil the water. Dimensions: 30.3"H x 19.7"D x 17.1"W. Weight: 80 lbs. UL listed. CE certified. 2-year warranty (consumer). Made in Finland by Harvia.
50-litre (13.2 gallon) water capacity Wood-burning water heater - not a sauna heater Designed for cottage sauna settings Stainless steel outer casing and inner cauldron Removable inner cauldron for easy cleaning Replaceable fire chamber - extended lifespan Heat directed under cauldron for efficient heating 88 lbs stones required (2 boxes, 10-15 cm) Rear smoke outlet 4.5" - 6" adapter required Safety: front 19.7", sides/back 9.8", ceiling 39.4" Adjustable legs 30.3"H x 19.7"D x 17.1"W - 80 lbs UL listed - CE certified 2-year warranty (consumer) Made in Finland by Harvia
Specifications
Water capacity and function
| Purpose |
Water heater - not a sauna room heater |
| Water tank capacity |
50 litres (13.2 US gallons) |
| Fuel type |
Wood-burning |
| Stones required |
88 lbs (2 boxes, 10-15 cm) - sold separately |
| Heating method |
Heat directed under inner cauldron for efficient heating |
| Fire chamber |
Replaceable - extends product lifespan |
| Inner cauldron |
Removable stainless steel - easy cleaning |
Safety distances (combustible materials)
| Front |
19.7 in (500 mm) |
| Sides and back |
9.8 in (250 mm) |
| Ceiling clearance |
39.4 in / 3.28 ft (1,000 mm) above top |
Smoke outlet
| Diameter |
4.5 in (115 mm) |
| Location |
Rear of cauldron |
| Height from floor to centre of outlet |
22.8 in (579 mm) |
| North American adapter |
6" adapter required - sold separately |
Physical dimensions and weight
| Height |
30.3 in (769 mm) |
| Depth |
19.7 in (500 mm) |
| Width |
17.1 in (434 mm) |
| Weight |
80 lbs (36.3 kg) |
| Legs |
Adjustable |
| Installation |
Floor-mounted |
Construction
| Outer casing |
Stainless steel |
| Inner cauldron |
Stainless steel - removable |
| Fire chamber |
Replaceable |
| Lid |
Included |
| Ash box |
Included |
Certifications and warranty
| US certifications |
UL listed |
| European certification |
CE certified |
| Origin |
Designed, engineered, and made in Finland by Harvia |
| Warranty |
2-year limited (consumer use) |
What's included
Harvia WP500 Cauldron 50-litre wood-burning water heater
Lid
Removable inner stainless steel cauldron
Replaceable fire chamber
Ash box
Adjustable legs
Installation manual
2-year limited warranty (consumer use)
Required (not included): 88 lbs stones (2 boxes, 10-15 cm); 6" North American flue adapter for 4.5" rear smoke outlet; chimney connection. A licensed chimney professional is recommended for all flue installations.
Why the Harvia WP500 Cauldron stands out
50 litres of hot water - enough for multiple users post-session
At 50 litres (13.2 US gallons), the WP500 holds enough hot water to serve multiple users after a sauna session. For a cottage sauna without running hot water, or an outdoor sauna where a shower is not available, 50 litres provides a generous supply for washing. The cauldron is fired simultaneously with the sauna stove - both are started at the same time, and by the time the sauna has reached bathing temperature, the cauldron holds a full reservoir of hot water. The traditional Finnish practice of ending the session with a wash from the cauldron is central to the lakeshore cottage sauna experience the WP500 is designed to deliver.
Heat directed under the cauldron - efficient water heating
The WP500's fire chamber directs heat from the burning wood directly under the base of the inner cauldron rather than distributing it to the sides or surrounding air. This concentrates thermal energy at the most efficient point for water heating - the bottom surface of the tank - and produces faster, more complete heating of the full 50-litre volume than a side-heating or ambient-heating design would. Harvia's description of the result: the burning process is smooth and the heat is distributed directly under the inner cauldron. The water is heated up efficiently in this way. A smaller, well-managed fire heats the full 50-litre volume effectively when the fire chamber is designed correctly.
Replaceable fire chamber - long service life
The fire chamber is the component of a wood-burning water heater that experiences the most direct thermal stress over years of use. Harvia designed it as a replaceable part specifically because of this: the replaceable fire chamber makes the product long-lasting. When the fire chamber reaches the end of its service life - through warping, cracking, or reduced performance - it can be swapped out without replacing the entire cauldron. For a product used seasonally at a cottage sauna over many years, this replaceability is a meaningful long-term ownership advantage. Spare fire chambers are available through Harvia's authorized dealer network.
Removable inner cauldron - cleaning without disassembly
The inner stainless steel cauldron lifts out of the outer casing for cleaning. This is a practical maintenance advantage: mineral deposits, scale from hard water, and any sediment that accumulates on the interior of the water tank can be cleaned thoroughly with the cauldron removed and placed in a convenient position. Harvia's installation manual recommends cleaning the inner cauldron carefully prior to first use, and periodic cleaning throughout the cauldron's service life. The stainless steel material resists most deposits and is easy to clean with standard household products. Using clean household water or quality lake water - avoiding sea water and heavily mineralised water - keeps the cleaning requirement minimal.
Authentic Finnish cottage atmosphere
Harvia's description of what the WP500 creates in a sauna setting is direct: it adds a genuine Finnish old-time lakeshore sauna atmosphere. The wood-fired cauldron is one of the defining visual and functional elements of the traditional Finnish cottage sauna - the fire, the rising steam from the cauldron, and the supply of hot water ready for the wash after the session are all part of the same unified experience. The WP500 brings this specific element of Finnish sauna heritage to any installation - cottage, outdoor sauna building, or any space where off-grid wood-fired water heating is the right specification. No electrical connection is required at any point.
WP500 in the Harvia product lineup
The WP500 is Harvia's 50-litre cauldron. Harvia also produces the WP800, an 80-litre cauldron for larger water volume requirements. For sauna installations where a smaller or more integrated water heating solution is preferred, Harvia's pipe-model chimney water heaters (WHP-series) mount on the sauna stove's chimney pipe and heat water using the flue's waste heat - a compact solution that requires no separate fire. The WP500 is the right specification when a large, standalone, wood-fired hot water supply is the goal, and the traditional cauldron format is part of the desired sauna atmosphere. UL listed. CE certified. Made in Finland. We are an authorized Harvia dealer.
About Harvia
Made in Finland - UL Listed - CE Certified - Traditional Cauldron
Harvia WP500 Cauldron. 50 litres. Wood-burning. Finnish cottage sauna atmosphere. Replaceable fire chamber.
Harvia is a Finnish sauna and spa company established in 1950. The WP500 Cauldron is a 50-litre wood-burning water heater for cottage sauna settings - stainless steel outer casing, removable inner cauldron, replaceable fire chamber, and heat directed under the cauldron for efficient water heating. 88 lbs of stones (2 boxes, 10-15 cm) and a 6" flue adapter are required and sold separately. Not a sauna heater. We are an authorized Harvia dealer.
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50-litre wood-burning water heater - not a sauna heater
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Finnish cottage sauna tradition - hot water for post-session washing
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Replaceable fire chamber - removable inner cauldron - adjustable legs
- Safety: front 19.7", sides/back 9.8", ceiling 39.4"
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88 lbs stones required (2 boxes) - 6" adapter required - UL listed - CE certified
WP500 vs WP800 vs chimney pipe water heater - Harvia water heating options
WP500 vs WP800 vs chimney pipe water heater - choosing the right Harvia water heating solution
Three Harvia approaches to heating water at a wood-burning sauna. Harvia WP500 (this listing): 50-litre standalone wood-burning cauldron, separate from the sauna stove, traditional Finnish cottage format, requires its own fire and chimney connection. Right when a large (50L) standalone wood-fired water heater and the traditional cauldron atmosphere are the goals. Harvia WP800: 80-litre standalone wood-burning cauldron, same design approach as the WP500 but 60% more water volume. Right when a very large post-session water supply is needed for many users. Harvia pipe-model chimney water heaters (WHP-series): a water tank that mounts on the sauna stove's existing chimney pipe and heats water from the flue's waste heat - no separate fire required, no separate chimney, the cauldron water heats simultaneously with the sauna room as a byproduct of the same fire. Right when a compact, integrated solution is preferred and the traditional standalone cauldron aesthetic is not a priority. The WP500 is the right choice when the traditional cottage cauldron experience, a 50-litre hot water supply, and the standalone wood-burning format are the priorities.
Manuals and Documents
Warranty
2-year limited warranty (consumer use)
The Harvia WP500 Cauldron is covered by Harvia's 2-year limited warranty from the date of purchase for consumer use. The warranty covers defects in manufacturing and materials under normal use conditions. The warranty does not cover damage caused by improper installation, operating the cauldron without water in the inner tank while the fire is burning, operating without the required stones, failure to follow the installation and operating guidelines in the manual, or damage from inadequate chimney maintenance. The inner cauldron is made of stainless steel but can be damaged by extended use with heavily mineralised, salty, or chemically treated water - use clean household water or quality lake water as specified in the manual. Proof of purchase from an authorized Harvia dealer is required for warranty claims. We are an authorized Harvia dealer.
