Water Heating Calculator
Litres of water:
Start temperature (°C)
End temperature (°C)
Heating power
Result:
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Water Heating Calculator
Below are volume guidelines for standard baths, spas and pools.
- Cast Iron bath: 200L – a perfect match for the 6Kw bath heater
- Standard spa pool: 1000L – an ideal partner for the 16Kw Spa Heater
- Hot tub: 1500L – a prime sidekick for the 24Kw Hot tub / pool heater
- Swimming pool 20000L + a great fit for the 24Kw Hot tub / pool heater
It is important to choose the wood-fired water heater that is appropriate for your volume of water.
Purchased the full outdoor bath set up , fire, ashtray and drill bit, great product, videos were excellent to help show how to set up even with out them it’s pretty simple to set up. Used on a cast iron bath.
After one load of wood and about 40mins the bath was heated and I made the mistake of topping it up which made it too hot. Very impressed so far highly recommend!!
Matthew SeniorWood Fired Water Heaters 
Paul and his team are fantastic , understand deadlines and understand thinking outside the square . keep it up team
Jarrod Clarke
Awesome Kiwi family business. These guys have been around for a while and have kept that old-school personal service. Friendly, helpful, professional and they make a huge range of products. Hands-down the most knowledgeable bunch when it comes to flues and wood-fired heating. Very clever, innovative and real.
Al YoungFlues & Fittings
First trial 24kw spirolok water heater. 1700 litres 13 degrees to 40 degrees in 3.5 hours wrapped. This hot tub has no insulation. Paul from Spiroloc knows his stuff and the unit he choose for the project did the job extremely well . Thanks
Stephen BrennanWood Fired Water Heaters
I bought the 6 ltr. thermette today and what an awesome next level take on the original concept. Great guys and absolutely no hesitation in recommending them.
Colin WalshThermettes