Did you know that it's possible to replace a wood-burning stove with a gas stove and connect it to pre-existing connection pipes, 50 mm or 75 mm in diameter. See the pictures below that show how simple it is.
The advantage of gas heater is that it heats faster and that it does not require the same degree of fittingto the hot tub as a wood stove does. What is needed is a gas bottle with gas reducers (30 mbar, 2 kg / h). Reducers are also available from us and are also common in eg. DIY and construction stores.
It is also possible to use the gas heater in the winter and then the connection pipes can be closed and the water connection can be donw as shown below, which protects against freezing. See product PORTABLE PROPANE HEATER FOR HOT TUBS below.