http://www.dutchtub.com/FAQ (from website)
—Children and fire
The dutchtub is as dangerous as any other pool or bbq. The water is wet and the fire is hot. But the spiral doesn’t get red hot. It cools itself because of water circulation. Caution must be taken whenever children are in the presence of these two elements.
—Comfortable
There is a convex sphere in the bottom of the tub making every seat in the tub equal and ergonomic. It is as comfortable as a nice chaise lounge.
—Durable
The spiral is made of chemical/element proof stainless steel, this is absolutely the best there is (also used for wind turbines at sea). The polyfiber can be compared with a sailboat. It can stand really cold winters and stay outdoor all year. Some boats do live 50 years …
—Heating time
The heating time of a dutchtub depends on a couple of factors. The temperature of the water, the outside temperature, the sort of wood and the ability to make a nice fire. As an average we can conclude a heating period of two hours till 38 degrees Celsius / 100 degrees Fahrenheit. The record is 1 hour and 15 minutes and heating a tub at our experience centre in Austria with an outside temperature of - 20 Celsius, -4 Fahrenheit, took 5 hours.
—Hygiene
The water can be treated with salts, soaps, hydrogen peroxide, and small amounts of shock treatment (contact your local pool supply). We recommend emptying the tub after each time of use. Enjoying chemically treated water next to a wood fire is not our way of enjoyment. Non chemically treated water can be used again on landscape or recycled into a grey water system (contact us for project details)
—Maintenance
The tub can be cleaned with a towel and some cleaner (Like Simple Green). Small scratches can be polished and buffed just like a car. After every party it’s good to flush the spiral with clean water. If you do have a turbo use it to flush the spiral
—Regulate the heat of the water
What happens in the spiral will happen in the tub. Hot water on top of cold water. To heat efficiently one needs to stir the water once in a while. When the water gets too hot, you can allow the fire to burn slower or simply spin the basket up within the coil (exposing fewer coils to heat) to regulate the circulation. The higher the basket, the lower the circulation. This option preserves the ambiance of the flame.
—Roof terrace
When the dutchtub is placed on a terrace or platform check your construction with an official contractor. Weight of the dutchtub can reach 1400 KG / 3000 LBS, with a small platform under the tub one can spread the total weight on more square meters than just the four legs of the tub. Lots of people with a roof terrace are enjoying their dutchtub momentarily.
—Sort of energy
To get your tub to a comfortable 38 degrees Celsius (100 degrees Fahrenheit) you will need approximately two bags of wood (2.5 cubic feet), and one for the hours afterwards. Use the driest wood as possible and the smaller the peaces the better.
—Water circulation
The volume of warm water is bigger than cold water, though the heat of the fire, warm water expands, forcing the flow up in the spiral and comes out of the upper pipe. The pressure of the 800 litters of the tub refills the spiral and it starts all again. This is a simple exercise in natural convection system … drawing cold water form the bottom and circulating it to the top.
—Weight
Without water the tub only weights 75 kilo (165 Lbs.), so easily to carry with 2 persons. Including water the total weight can go up to more than 1000 kilo’s (2200 Lbs.) depending on the users …
—Wintertimes
In the winter it’s great to take a nice warm soak but it is not recommended keep the water in the tub if temperatures drop below freezing. The water inside can freeze and damage the spiral. Remember frozen water expands and would make a very expensive ice cube!
