Contents of delivery
  • Rexener Wood Heater
  • Grate cradle (in place)
  • Grate (in place)
  • Wood heater door with air deflector (in place)
  • Drain plug
  • Two-piece chimney with chimney cowl (2×1,000 mm pipe)
  • Instruction manual
Additional parts
Rexener Wood Heater Basics

The energy-efficient wood heater will heat your hot tub quickly! Rexener Wood Heater is an efficient modern wood heater. It fits most hot tub models, as long as the pipe holes are approximately in the same places. It can even be connected to an outdoor swimming pool.

The high-capacity wood heater has a 55 cm long combustion chamber. Thanks to the modern design, heat loss is minimal, and under optimal conditions your hot tub will heat by up to 15°C per hour with a water volume of around 1,500 litres.

The wood heater’s drain hole is on the side of the wood heater, next to the front leg, where you will find an easy-to-open plug.

The wood heater is made of seawater-resistant aluminium with excellent thermal conductivity. The wood heater is painted with a durable powder coating throughout. The capacity of the wood heater is about 35 kW (the temperature of 1m3 of water rises by about 15°C per hour).

Preparing for installation

Install the wood heater so that it does not pose a fire hazard to buildings, trees or other combustible materials. For fire safety, there must be no wooden structures or other combustible material under or in front of the wood heater.
You can, for example, place a stone slab on the ground in front of the wood heater door.
Familiarize yourself with the local fire safety regulations and install the wood heater in accordance with them!

If you are unsure about the fire safety regulations in your area, you should check with your local fire authority.

Wood Heater Installation

The installation of the wood heater varies depending on the model of your hot tub or pool. The wood heater is installed and connected with rubber tubes and hose clamps. At the bottom of the wood heater’s combustion chamber, there is a grate cradle with a grate already in place. The combustion chamber also houses a bag, where you can find the wood heater’s drain plug. You should take these components out of the wood heater during installation to make the wood heater as light as possible.

All components must be in place when using the fireplace!

wood heater attachment

  1. Place the wood heater in the area you have prepared for it
    2. Attach the rubber hoses to the flow tube outlets located behind the wood heater
    3. Fasten the rubber tube clamps firmly
    4. Place the wood heater’s drain plug in the hole at the bottom of the wood heater’s wall
    5. Install the grate cradle and grate (if you have removed them)

The upper hose should always be installed to rise slightly from the wood heater towards the pool. The bottom hose should tilt slightly downwards when facing the pool.


The chimney is made of stainless steel that can withstand all weather conditions and changes in weather.
The diameter of the chimney pipe is 110 mm and the length of one pipe is always 1,000 mm. The pipe has a cowl pre-installed at its upper end.
The pipes can be extended with optional extension pipes if required.

Connect the chimney pipes with each other and install them to the collar on top of the wood heater. Check that the wood heater’s grate is in place in the combustion chamber.

The pipe is always included in the wood heater package. (2×1,000 mm with chimney cowl)
The chimney extension pipe, heat shield and fender cover are available as accessories. Handle the pipes carefully, the edges of the pipe are very sharp.

Drain plug

Place the wood heater’s drain plug into the drain hole on the side of the wood heater.


Check that the drain plug on the side of the wood heater is in place. Fill the pool with water so that the water level in the pool is at least 5–10 cm above the upper outlet. This minimum water level must always be maintained when heating the wood heater. Underfilling will cause damage to the wood heater.

Prefer dry wood in the fireplace. This makes the combustion cleaner and hotter, allowing the water to heat up faster. Light the fire using smaller pieces of wood, with the help of birch bark or some newspaper. The use of any lighter fluid is prohibited!

It is advisable to stir the water a few times during heating to allow the heat to even out more quickly.

If the pool is emptied immediately after use, care must be taken to ensure that the wood heater’s fire is completely extinguished first. The wood heater will be damaged if there is fire or embers in the wood heater, but no water in the pool or wood heater! The wood heater can be emptied by removing the drain plug located on one side of the wood heater. If you keep water in the pool during cold weather, make sure that the water does not freeze! Damage caused by freezing is not covered by the warranty.

Saftey Instructions

Do not overheat the water. The maximum recommended water temperature is 37 °C. Those with heart diseases should be especially careful and, if necessary, keep the water temperature low.

Do not touch the heated parts of the wood heater when there is a fire in the wood heater.

Never light the wood heater when the pool is empty or underfilled! Heating an underfilled pool causes damage to the wood heater. The pool must always be filled at least 5 cm above the wood heater’s upper outlet before you light a fire in the wood heater.

The pool must not be emptied until the wood heater’s fire is completely extinguished and the embers have died. Heating an underfilled pool causes damage to the wood heater.

The filled wood heater must not be allowed to freeze in winter. Always empty the pool and wood heater after use or keep them adequately warm.

The wood heater must not be connected to a circulation pump. The wood heater cannot withstand the pressure of a circulation pump, as the wood heater is only designed for gravity circulation.

Before using it for the first time, you should rinse the wood heater by letting water through pipe into the wood heater. Any debris coming out of the wood heater will be flushed out through the drain hole. When filling the pool for the first time, also check that the rubber hoses used for connection are tightly sealed and adjust the tension of the clamps if necessary.

On first use, the new wood heater creates a lot of condensation, which presents itself as condensing water coming out of the front edge of the wood heater. This is not dangerous and usually ends once the wood heater has been used a few times.

Wood Heater Care

The wood heater’s combustion chamber and ash pan should be emptied after each use. This improves combustion, makes the next fire easier to light, as well as significantly extends the wood heater’s service life. Always clean the pipes at regular intervals. Be sure to empty the wood heater after each use. It is also advisable to regularly rinse the wood heater and water container. Slip a water hose inside the wood heater through the upper outlet and wash the water container with high pressure.

Fire Safety

If you place the wood heater close to buildings, e.g. on the edge of a terrace, you must make sure that the chimney is sufficiently far away from all combustible structures. Remember to check the distance both laterally and vertically to avoid the risk of fire. The minimum distance to combustible materials is three (3) meters laterally from the mouth of the chimney. For the rest of the chimney, a smaller lateral distance is sufficient.

Contact your local fire authority for more information.

Please also note the fire safety of the area in front of the combustion chamber, i.e. there must be no combustible material in front of the chamber. In practice, this means that there should be a non-combustible material in front of the wood heater, such as concrete, sand or sheet metal.

Technical Specifications
  • Power ca. 35 kW
  • Material marine grade aluminium, painted black
  • Weight ca. 40 kg
  • Width 400 mm
  • Height 600 mm
  • depth 600 mm
  • Combustion chamber depth 550 mm
  • Water pipes x2 (return and suction outlets)
  • Water pipe outlet diameter 50 mm
  • Drain hole diameter 20 mm

Chimney pipes

  • Pipe material stainless steel
  • Diameter 110 mm
  • Length of one pipe 1,000 mm
  • Supplied with delivery (2×1,000 mm with cowl)


  • Size 405×210 mm



The product has a 24-month warranty, starting from the date of delivery.
The warranty only covers defects in materials or manufacturing.
The warranty requires that the installation complies with the applicable regulations, instructions and a generally accepted installation method. The warranty does not cover defects or breakages caused by:

  • Incorrect installation
  • Improper care of the device
  • Abnormal operating conditions
  • Overload or excessive voltage fluctuation
  • Damage due to thunder or weather
  • Damage due to freezing
    The warranty is void if:
  • The product is repaired or modified without the permission of the manufacturer
  • The product is stored in an unsuitable space
  • The product is used for a purpose for which it was not intended

More detailed warranty conditions can be found on our website www.rexnordic.com