External heater design
Installed outside the tub to leave more room inside for comfortable bathing.
Build Your Own: Hot Tub Wood Burners & Kits
Whether you're a hot tub manufacturer or planning your own DIY wood-fired hot tub project, our heaters are designed to deliver reliable performance across a wide range of builds. We offer complete heater kits, so all parts needed for installation arrive together with the heater.
AISI 316 Stainless Steel Heaters for Wood-Fired Hot Tubs
Available in S, M, and L, our Octa heater is made from premium AISI 316 stainless steel — a high-quality choice valued for its durability and long-term performance
AISI 304 Stainless Steel Heaters for Wood-Fired Hot Tubs
Choose an AISI 304 heater with a complete kit. In this category, we also offer a barrel-shaped heater — a traditional design for those who want a better match with the oval shape of the hot tub
Octa Heater for DIY Hot Tub Builds
A reliable external wood-fired heater for self-build hot tub projects
Built for Custom Wooden Hot Tub Projects
The Octa Heater is a classic choice for DIY hot tub builds, valued for its durability, heating performance, and timeless design. It works well with fibreglass, acrylic, wooden, and barrel-style hot tub configurations.
Ideal for DIY builds
A practical solution for self-build wooden hot tubs, flat-pack projects, and custom outdoor bath setups.
Durable and versatile
Designed for long-term outdoor use and compatible with a wide range of wood-fired hot tub heater setups.
Double-Pass Heat Exchanger for Faster, Cleaner Heating
Built into Octa M and Octa L outdoor heaters
Engineered for More Efficient Heating
Designed for DIY wood-fired hot tub projects, the double-pass heat exchanger helps improve heating efficiency, reduce wood use, and deliver better overall performance.
Improved heat transfer
Hot air travels a longer path inside the heater, helping warm the water more efficiently.
Larger contact surface
The doubled heat exchange area supports faster and more effective heating.
Lower emissions
A more efficient burn means less wood consumption and cleaner performance.
A practical solution for self-build hot tubs, cedar hot tub kits, and off-grid wood-fired bath projects where heating speed and efficiency matter.
Safety Features
Our heaters are engineered with essential safety features. If you're working on a diy wood fired hot tub, safety matters. The external wood fired hot tub stove body stays cool to the touch, as the internal fire chamber is surrounded by a water jacket. The outer surface warms only to water temperature levels.
To support diy wood fired hot tub builders and homemade wood fired hot tub users, the heater chimney features a lower thermal guard to prevent burns. Always follow key fire safety guidelines: maintain a 2-metre distance from roofs or flammable items.
Choose the Right Firewood for Better Heating
Get the most out of your wood-fired heater with proper fuel
Optimized for Efficient Burning
Using the right firewood ensures your wood-fired hot tub heater performs efficiently, heats faster, and produces less smoke.
Hardwood performance
Oak, ash, birch, maple, and beech provide steady heat and clean burning.
Higher heat output
Dense hardwoods burn hotter and longer, improving overall heating efficiency.
Proper moisture level
Well-seasoned wood with under 20% moisture ensures cleaner combustion and better results.
Why Choose our Heaters for Your DIY Wood-Fired Hot Tub Build?
Gardenvity heaters are designed for safe, efficient, and reliable performance — making them a practical choice for self-build wood-fired hot tub projects
Safety First
Built with essential safety features for secure and comfortable everyday use.
Fast Heating
The double-pass heat exchanger helps heat water faster and more efficiently.
CE Certified
High-quality heater solutions certified to meet EU requirements.
Easy Maintenance
Designed for simple upkeep and reliable long-term performance.
We’re Here to Help Before and After Your Purchase
Get expert help choosing the right model, features, delivery option, or anything else on your mind.
Expert technical guidance and support
Trusted after-sales care and maintenance tips
Advice on delivery, placement, and installation
