Exterior Stoves

How They Work

An External TimberLine Wood Fired Heater is an ideal way to heat a hot tub or a pool using only fire wood. Best of all, there is no electricity required to circulate the water in the tub or pool! A physical principle called “thermosiphon” creates a natural convention pump that gently circulates the water through the wood fired hot tub heater.

Thermosiphon is the result of the fact that hot water is less dense than cold water and as such rises. This is the same theory that lifts a hot air balloon. By heating the water, the molecules vibrate more, and spread out more, and become lighter. The lighter hot water rises to the top of the hot tub, while bringing in colder water from the bottom of the tub. The hotter the fire inside the water heater, the faster the current becomes.

The TimberLine External Pool and Hot Tub Heaters use a double walled stainless-steel water jacket around a fire box. The burning fire inside the vessels heats the water indirectly surrounding the fire. The hotter water then rises out the back top port into the pool or tub, and the cold water is sucked in through the bottom port from the pool. The hotter the fire inside the fire chamber, the faster the water will be heated.

The TimberLine External Heaters control the rate of burn by controlling the amount of oxygen to the fire. Reducing the air flow to the fire by closing the door and the chimney damper will determine how hot wood fire burns inside the heater.