Table of contents
- Inspiration from Scandinavia
- Build external fire barrel
- Costs
- building instructions
- shape flow
- application and mode of action
- Alternative: solar heating
A private swimming pool in the garden is a real luxury. Pool heating is necessary so that this oasis can also be used when the outside temperatures are cooler. Wood appears to be an attractive method to effectively heat the water. The raw material is renewable and burning it creates a campfire romance at the same time. Building such a variant is not difficult and does not involve large expenses.
Inspiration from Scandinavia
Wooden hot tubs are common in Sweden. Heating with pine, spruce or birch is normal not only in the house but also in the sauna and pool. For more efficient use of the heat from the fire, the Swedes build stainless steel ovens directly in the basin. These models are fired through an opening at the top. Exhaust gases enter the air via a chimney. The advantages of this variant are manifold:
- Stainless steel conducts heat directly to the water
- no energy loss via hose lines
- Firing from the pool possible
Building your own stainless steel furnace requires not only welding skills, but also expensive materials. But this Scandinavian variant offers inspiration for alternative solutions. With recycled materials and some DIY skills, you can build a wood-fired pool heater that stands outside the pool.
Build external fire barrel
With this variant, the pool water is routed through copper pipes that run through a fire barrel. The fire heats the water, which then flows back into the pool. This variant is suitable for pools with a volume of around 30,000 liters. For larger pools, the efficiency is not sufficient to bring the water temperature to a comfortable level. To build the instantaneous water heater you will need:
- an old oil barrel: 60 liter capacity
- thin-walled copper tube: 10m length, 15mm diameter
- Metal saw and metal drill
- Disused grill grate, perforated sheet metal or stable wire plate
- hammer and nails
- Crimp connectors and hose connections
Costs
The copper pipe represents the largest cost factor in this construction project. Depending on the provider, you have to calculate four to six euros per meter for a 15 millimeter thick pipe. If you don't have an oil drum available, look for discarded models at thrift stores. A new tin barrel of this size costs about 30 to 40 euros. Nails and fasteners cost about ten to 15 euros.
Tip:
For a smaller model, you can convert an old beer keg into a combustion chamber. This gives the barrel a new use.
building instructions
Saw the lid off completely and drill holes in the bottom section in two staggered rows. These openings are used for air supply so that the fire can later burn well inside. Further openings in the upper area ensure the extraction of smoke and gases. The openings should be two to three centimeters in diameter. The smaller the holes, the more openings the fire barrel needs. Since the wood should ideally burn above the ventilation openings, a precisely fitting and coarse-meshed storage area for the wood is integrated in the middle area. Drive long nails into the barrel from the outside all the way around so that the ends point into the interior. They serve as a fixation for the wooden shelf. Slide the cut piece into the barrel from the top before placing the spirally bent copper tubing.
Tip:
Fill the copper pipe with sand and pour water into it. You can then bend the tube into shape over a resistor such as a wheel rim.
shape flow
The copper pipe runs along the walls of the fire barrel, with the water flowing through the pipe from the bottom up. To increase the efficiency of the self-made instantaneous water heater, you should also bend the upper part of the copper spiral into a spiral along the barrel opening. The flames burn below this spiral and the rising heat is optimally used. Inflow and outflow are routed through additional openings in the combustion chamber so that the system can be connected to the filter system outside the barrel:
- Inlet and outlet provided with crimp connectors
- Place hose adapters on the crimp connectors
- Connect the inlet to the return of the filter pump
- Drain into the basin
application and mode of action
Light a fire on the shelf in the combustion chamber and put the lid on the barrel. The chimney effect ensures optimal air supply, because the fire draws air through the openings into the interior. The metal wall of the combustion chamber concentrates the radiant heat of the fire. The smallest amounts of wood can be used efficiently. They burn completely, resulting in high temperatures. A fan ensures better burning effects. In this case, you should ensure optimal water flow so that the heated water quickly gets into the pool. A circulation pump supports the flow. With an air temperature of around 18 degrees Celsius, it can take up to eight hours for the pool to heat up to 28 to 30 degrees Celsius.
Alternative: solar heating
A wood-fired pool heater must be operated for a long period of time in order to achieve the desired effect. A more convenient option is to use alternative energy sources such as solar energy. A simple variant is to lay a 50 meter long garden hose on the roof of the gazebo in a spiral arrangement. The system is connected to the return from the pool filter. It needs a powerful pump to make the water flow through the hose.
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