There are a few different materials used in the manufacture of wood burning hot tubs. In general, a wood burning hot tub requires materials that are water resistant, mould resistant, able to withstand high temperatures and also aesthetically pleasing. Below are some different materials offered to create a modern wood burning hot tub:

Cedar:

If you have been researching wood fired hot tubs, you’ve undoubtedly seen cedar wood mentioned as a common material. When cedar gets wet, it swells, leaving a watertight seal. As a durable wood, it’s just as strong wet as it is dry. Cedar also naturally discourages mould growth. Cedar even repels bugs and insects. Therefore, cedar is often used to line closets. For people using the hot tub, cedar gives off a lovely aroma that enhances the spa experience.

Spruce:

Spruce wood is very light in colour and a popular choice for hot tub finishes. Unlike cedar, it’s not naturally resistant to rot and does require some maintenance. Treating the wood is as easy as wiping it down with linseed oil. Spruce’s strong, stiff characteristics are what make it popular amongst hot tub enthusiasts.

Thermowood:

Thermowood is a processed and chemical-free wood that looks darker than cedar or spruce. It is far more weatherproof than natural wood. Also, unlike natural woods, Thermowood does not leak any resins when heated. Due to its manufacture, hot tubs made with Thermowood are lighter, less likely to become deformed, and perfect for outdoor use.

Polyethene:

Moulded polyethene, or PE, is commonly used for the inner shell of a wood burning hot tub. PE is recyclable, and for that reason, often the choice for eco-conscious consumers. In addition, PE holds heated liquids well, is easy to clean, and because there is no welding or seams, is leakproof.

Internal and External Heaters

Internal Heaters

Internal heaters sit directly inside of a wood burning hot tub. That means 100 per cent of the heat it generates goes into heating the water. It uses natural convection to heat the water. Naturally, less dense hot water rises to the top and cold water to the bottom. An internal heater needs to be installed on the side of the hot tub or fastened to the bottom otherwise the air volume in the heater would cause it to float. Wood is fed into the top of the heater with an air vent located above the water line that vents air into the heater. The chimney draws smoke away from those in the wood burning hot tub. The fire is adjusted by manipulating the air intake.

An internal wood fired hot tub heats quickly than its external counterpart, but it does take up more space in the tub.

External Heaters

External heaters are located outside the hot tub. Those who prefer an external heater will need to ensure they have the space to accommodate it. External heaters rely on a thermal syphoning, a process by which the heater, placed lower than the tub, circulates naturally rising hot water. This process does take time, however. Some large tubs require hours to heat. Of course, an electric pump can decrease the heating time significantly. For people who want a lot of tub space, the external heater is the best option.

Choosing Which Heater is Right for You

There are clear benefits to both types of tub heaters. To keep it simple, here are a few things to remember when choosing between an internal and external heated wood fired hot tub:

• • Internal heaters have less space within the tub but take less time to heat.
• • Internal heated hot tubs need less space for installation.
• • Externally heated tubs have larger tub capacity but take longer to heat.
• • External heaters need more space for accommodation.