7 Simple Steps How to Heat Your Hot-Tub

As fun as it gets heating the tub, you don’t want that process to take too long, though. 1-2 hours in summer, 3-4 hours in winter should do the job.

Even a perfect tub will not heat fast if you don’t follow some best practices. Below, you’ll find our tried and tested tips that have proven to deliver the best results.

1. Fill with water

Estimated time: 1 hour

Put the water hose in the hot tub and start filling it with water. The water level should reach 10-20 cm below the top ridge of the tub.

Use a 3/4 in diameter hose for faster filling and save time.

NEVER start the fire if the water has not reached the required level.

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2. Prepare the firewood in advance

You will need approximately 12-25 kg of firewood to heat up the hot tub once. Prepare different sizes of firewood in advance: make some kindling, finely chopped firewood, and then have your larger logs ready. Make sure you’re using kiln dried firewood to avoid smoke and ensure quick heating. Use hardwood (oak, beech, etc.) only or combine softwood (e.g. pine, fir) with hardwood in equal amounts.

Recommended size is 25-30cm long logs, split in halves and quarters.

Barkless firewood will produce less smoke.

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3. Empty the ash drawer before starting the fire

Estimated time: 5 minutes

It’s not mandatory to empty the ash drawer every time, but do check it occasionally before starting the fire.

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4. Check the water level of the hot tub

The minimum fill level is 10-20cm (4-8in) below the top ridge of the tub. Once the water reaches the required level, turn it off and take the hose out. Put a floating thermometer into the water so you can observe the temperature.

NEVER start the fire if the water has not reached the required level.

NEVER empty the tub after bathing when the embers are still in the heater! Otherwise, put the fire/embers out and then drain the water.

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5. Start the fire with kindling

Estimated time: 10 minutes

Use some ready firelighters (avoid burning paper) and a long reach lighter to start the fire. Use kindling for building up the fire. Keep the heater air vents open. Check if the smoke is going out through the chimney top.

Start with softwood kindling for faster results. Continue with hardwood.

Place the firewood inside the heater as low as possible to avoid smoke coming out through the heater door.

Start with the heater door open for better airflow. Once the fire is going, close the door and leave the air vents fully open.

Cover the hot tub so the water heats up more quickly.

NEVER leave the fire unattended!

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6. Heat up the water

Estimated time: 2-4 hours

Heat up the water to the recommended temperature of 39ºC by burning medium sized firewood. If you just use large firewood as soon as you have the fire going, it will take longer to heat up the water and will produce more smoke.

Stir the water with a paddle or switch on the air jets to distribute the water evenly.

Check the fire every 15 to 20 mins and aim to keep the fire well alight.

Check the thermometer about 5 minutes after stirring the water to get a more accurate reading.

In 1 hour, the water temperature will rise by 7-10ºC.

NEVER leave the fire unattended!

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7. Enjoy the hot tub!

Estimated time: 1 hour

Once the water temperature has reached the desired level of 39°C, the hot tub is ready for use. Do not add any more logs to the fire! Close the heater air vents.

You can always drain some water out if there is too much in the hot tub.

If the water gets too hot, open the lid of your hot tub and let the water cool down for a bit before getting in.

You can add some cold water with the hose to make the temperature more comfortable.

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8. Maintain the heat

  • If you are planning to use the hot tub for longer periods of time, you can maintain the heat by placing some large firewood in the heater.

  • Use more hardwood at this stage as it will burn longer.

NEVER leave the fire unattended!

NEVER empty the tub after bathing when the embers are still in the heater!

Have the air vents open just a bit to keep a steady slow fire.

After the fire is out and you finish bathing, with the water still warm, put the lid on.

In summer, the hot tub will maintain the water temperature for quite a few hours. 

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