How do you heat a hot tub properly?
You have a hot tub in your garden – perhaps your first one. You want to get into the warm water, but don’t know exactly how to heat up the hot tub? Then you’ve come to the right place.
In this article, we show you step by step how to heat up your hot tub properly. Without any frills. Without mistakes. And with the good feeling of being in control of your fire and water.
Why heating the hot tub correctly is crucial.
A hot tub doesn’t work like a whirlpool at the touch of a button. You work with wood, fire and patience. That’s the deal – and that’s what makes it wild, real and archaic. If you have a hot tub, you don’t want to use an app, you want to feel the experience.
But: If you heat up the wrong way, you’ll be waiting forever. Or risk damaging the stove.
The good news: with the right method and a few tips, you can reliably heat your hot tub to your desired temperature in around 2 to 3 hours.
Preparation: Before the fire blazes
Before you reach for the match, make sure everything is ready. Nothing is more annoying than having to go back into the house in the middle of heating up. So:
1. clean the hot tub
Leaves out, dirt out, the stove itself should also be free of old ash. Not a myth – a clean start saves you time and wood.
2. chop wood
Split dry wood. It doesn’t matter which wood you use, as long as it’s dry! Otherwise it will be tough. If you want to be a wood professional or world champion stoker, then you can work with a combination of softwood (e.g. spruce, pine) for firing up and hardwood (e.g. beech, ash) for the power phase. But it doesn’t have to be.
3. empty the oven
Old embers, ashes or half-burnt remains? Get rid of them. Your fire wants fresh air and a clean room.
4. prepare the firelighter
Prepare newspaper, wood wool or kindling. If you want it stylish, use birch bark from the forest. But please: no barbecue lighter from a plastic bottle. Nature bathes with you.
5. check the water source
Connect the hose or clear the water source. You need plenty of volume – around 1,200-1,500 liters for a fire water barrel. And: Never heat dry! The stove must be completely submerged in water when it is lit.
6. prepare the paddle
Heat does not spread by itself – stir every 30 minutes with a wooden paddle. Without movement, it stays cold at the bottom and warm at the top. Feuerwasser has a paddle with an integrated thermometer so you can mix the different temperature layers and check the temperature at the same time.
Being prepared in this way not only makes stoking the fire more efficient, but also stress-free. And you can devote yourself entirely to what it’s all about: Fire. Water. Wilderness.
Step-by-step: heating up the hot tub properly
Now you are ready to heat up your hot tub. Please follow the steps below to ensure you have a self-determined, successful experience that is truly enjoyable.
7. let in water
Fill the hot tub well with water. The water level must be above the highest point of the heat exchanger, otherwise there is a risk of material damage due to overheating of the heater. With the firewater barrel and the firewater cup, you should fill the barrel/cup with water at least up to the top opening of the stove. It is even easier with the firewater tray, as only the entire inner stove needs to be surrounded by water.
→ Never heat dry. Never. No compromise.
8. layering wood
Stack small pieces of wood loosely on top of each other. Leave enough air between the logs – fire needs room to breathe.
A good lighting tower consists of:
- Newspaper or other highly flammable material at the bottom,
- thin slit material on top,
- 1-2 slightly thicker pieces of wood on top.
→ No barbecue lighter fluid! Your water should smell like wilderness, not like chemicals.
9. light & give air
Now light the newspaper or the firelighter. Leave the oven door open until there is a good draught. You recognize a good fire:
- Flames that do not smoke,
- Smoke that rises brightly and quickly and
- audible crackling.
As soon as the fire is stable, you can close the stove door and regulate the air supply. With the firewater barrel, cup or firewater tray, this is easily done using the regulator on the stove door.
→ More air = more heat, therefore faster, but also slightly more wood consumption.
10. top up regularly
Put wood in the fire regularly. You can really fill up the stove and have a nice, big fire. Experience how the water in the hot tub gets warm. Let the fire burn until the water has almost reached the desired temperature.
How long does it take until the water is warm?
The big question when the stove is burning and your anticipation is rising is: How long will it be before I can get into the hot water?
Honestly? This depends on several factors:
- Amount of water: The more liters, the more energy is needed.
- Starting temperature: Ice-cold well water takes longer than preheated tap water.
- outside temperature: Logically, it takes longer in winter than in summer.
- Wood quality and firing technology: Dry hardwood, a clean stove and regular refueling make all the difference.
With the Feuerwasser hot tub with up to 1,500 liters of water, it takes on average between 2 and 3 hours to heat up at an outside temperature of 10 °C – provided you use dry wood, top up regularly and cover the tub. The Feuerwasser cup will be warm in a good 2.5 hours and the Feuerwasser garden tub will be ready for bathing after just 1 hour.
With less optimal wood, an open lid or in frosty weather, it can take longer. So if you’re in a hurry, make a fire early enough – or use a firewater garden tub.
Tips for heating the hot tub
Tip 1: Put the lid on – save time
If you want your hot tub to heat up faster: close the lid! This keeps the heat in the tub, minimizes heat loss to the top – and saves you up to 30 minutes of heating time.
For firewater, we offer the corresponding cover for every hot tub and garden tub, which you can easily use for this too.
Tip 2: Stir like a wild man
Keyword heat coating: hot on top, cold on the bottom – you don’t want that.
Stir vigorously every 30 minutes, using the Feuerwasser wooden paddle.
This distributes the heat evenly – and you’ll be in hot bliss much faster.
Conclusion: Whoever masters the fire deserves the bath.
Heating up a hot tub properly is not rocket science – but it is an archaic ritual. Once you’ve got the hang of it, you’ll never want to go back.
With the firewater hot tub, you not only get a real hot tub, but also a system that is efficient, robust and clearly built.
Outdoor bathing has never been so wild.
Fire. Water. Wilderness.
Now you know how to do it right.
Own the wild.
About the author
Sophie Auer is the wife of Martin Auer, the founder of Feuerwasser. She has been with Feuerwasser since the early days. She loves the simple life in nature, bathing in the open air and the crackling of a real wood fire.
In her texts, she writes about natural self-care, real experiences without filters and the good life – away from the screen. As the provocative voice of the Own The Wild mission, she inspires people to get back in touch with themselves, with nature and with their own wildness.