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Frequently Asked Questions
The Concrete Freestanding Tub
We position the Ohku tub more as a soaking tub than a hot tub, meaning that the main use is for warmth and relaxation.
Our tub is designed to be luxurious for one and comfortable for two.
Our concrete tubs are extremely durable and made to withstand the elements in your garden. Each bathtub is finished with multiple layers of high-performance waterproof sealer that penetrates the surface and forms a protective layer over the product to ensure maximum durability and minimum maintenance required.
Our tub measures 69.5″ x 36.125″ x 19.375″. We use a lightweight formula for our tubs, so it weighs 60% less than traditional concrete tubs at 660lbs.
All components of the tub are manufactured in the USA, except for the Chofu wood-fired stove, which is imported from Japan. The concrete tub is manufactured in Las Vegas, NV by Concretti Designs.
Any biodegradable bathing products (soaps, shampoos, bubble bath, or salts) can be used in the tub.
COMING SOON
We will be offering a cedar wood cover, a handcrafted cedar wood paddle, and biodegradable soaking products.
Our tub is ergonomically designed to be comfortable a water-saving, using 50% less than other two-person rectangular tubs on the market. The recommended fill-line is 60 gallons and the total maximum water volume is 120 gallons.
Our tub is designed to be used with fresh and chemical-free water, mimicking a natural hot-spring.
Fresh, chemical-free water is completely safe! With our wood-fired tub, the temperature cools down when the tub is not in use, making it difficult for bacteria to thrive.
Many companies claim that their tub can be used up to two weeks with the same water, which frankly, doesn’t ring true from our experience with wood-fired hot tubs. This is why we have designed our tub to use 50% less water than other two-person hot tubs on the market, so you can soak in fresh water every time without worry of using too much water.
If the tub is for personal use, you can reuse the water for multiple soaks or up to a week of use. When draining the tub, filter it back into the ground water and water the garden.
Ordering and Shipping
We ship anywhere in the US and Canada for a flat rate of $500. We also ship internationally to mainland Europe and the UK – please contact us for a quote.
The tub and the platform will be delivered via Freight curbside shipping. Once the tub leaves the warehouse, the shipping company will contact you directly to organize a specific time and date. Please visit our Shipping page for more information.
We currently have a 6-8 week lead time on orders.
Heating With Wood
Start your fire with small, dry kindling. For this, you can use any small dry branches, pine cones, or brush. Paper, cardboard and newspaper are also helpful in igniting the fire. Make sure the adjustable draft is all the way open to allow for optimum airflow. If you are using good kindling, the fire should take quickly. Once it has, then you can add larger logs and stoke the fire.
You can use any type of dry hardwood up to 17in in length. For the most efficient heating option, we recommend stoking the fire using 17-in. x 11/2-in. x 11/2-in. wood, loaded at 30-40-min. intervals.
The hot tub heater operates like a conventional wood stove, achieving the fastest heating rate from burning dry hardwoods.
The temperature of the water coming from the stove measures around 110°F when the stove is up to temperature. This allows for the tub to efficiently reach 105°F when mixing with cold water. If the temperature of the tub feels too hot, just mix in some cold water from the garden hose.
Absolutely. The heating rate is controlled by the amount of air let into the firebox through the adjustable draft in the door – wide open for fast heating, and closed for a trickle of heat once water reaches 90°F.
The Ohku wood-fired tub heats up to 90°F in 45-60 minutes.
We have reduced the possibility of chimney sparks and smoke emissions with a vented collar that provides secondary combustion of unburned gases.
Our external stove connects to the tub with piping, and heats the water in the tub using the principal of “thermosiphon” – the pumping action created by rising hot water.
Our external wood-fired stoves are imported from Japan, a country where bathing is a cultural tradition. They are specifically designed to heat soaking tubs, or ofuro, as they are called in Japanese, so they are incredibly durable and efficient. Some unique features of the stove include:
High-Efficiency Heat Transfer
The stove is designed to achieve high efficiency heat transfer by using 20-gauge stainless steel in the firebox wall. A double-walled water jacket is surrounds the entire firebox, increasing the surface area for maximum heat transfer. When a fire is burning inside the firebox, water is constantly flowing through the water jacket and into the tub, replaced by cold water from the bottom of the tub. The stainless steel wall of the firebox/water jacket never gets too hot because it is constantly being cooled.
Internal Fire Baffle
This hollow, water-circulating baffle plate, located above the firebox, receives direct contact with the flames. It increases the heat transfer surface area and routes the hot gases in a circuitous path – extending contact to the water-jacket.
Reflective Heat Shield
Located behind the heavy steel front is a polished stainless steel heat shield that reflects heat back into the firebox. It’s backed with refractory insulation to prevent heat loss.
Maintenance & Cleaning
Our concrete tubs are incredibly easy to clean. With no wood on the interior of the soaking tub, you don’t have to worry about any mildew build-up. No scrubbing necessary, just give it a rinse after use.
The best way to clean the tub is using water and a gentle and neutral pH soap.
Avoid usage of abrasive cleaners, soaps or harsh scrubbers that could potentially wear down the sealer. We recommend using mild, non-abrasive, non-ammonia, non-acidic, non-vinegar, non-bleach soaps and cleaners.
If your product gets in contact with any of the below chemicals or liquids, clean promptly to avoid staining. This includes highly acidic liquids (lemon juice, mustard, vinegar, wine, soda, citric acid, tomatoes) and other harsh chemicals or solvents (perfumes, ammonia, acetone, hydrogen peroxide, etc.).
We don’t treat the platform because we only use high quality western red cedar, which is incredibly durable and naturally resilient to rot. We only put a small amount of natural end grain sealant to ensure a uniform wear. Your cedar wood platform is designed to naturally age into a beautiful grey silver over the life of your tub.
You can use your tub in any temperature. To use your tub safely in winter, it is necessary to drain the tub and the water jacket of the heater completely in sub-zero temperatures between uses. This prevents the sitting water from freezing and damaging the pipes or the tub.
Assembly & Setup
The tub, decking, and stove need to be installed on a flat surface. There are many ways to create a flat foundation, a few examples include: mulch, sand, stone, a concrete slab, or decking. If you are using a washed stone foundation, we recommend using at least 1inch diameter stone, or smaller angular stone to reduce displacement.
No electricity or additional plumbing is necessary. We provide all of the attachements needed to connect the tub to the external heater. All you need on your end is access to a garden hose.
If you’ve already prepared a flat surface for the tub to go on, then we estimate you can set up the tub with stove and decking in under an hour from receiving it.
It is possible to move the tub with two straps and four people; however, due to the weight of the tub, it is recommended to use professional movers to install the tub.
The platform is shipped via Freight and is flat-packed. Please see our assembly video for instructions for a clear demonstration of how to assemble. We reckon this should take under one hour.
We provide all hardware and necessary parts for your tub and platform to function. All that you require is a flat foundation, and a power drill with a star head and phillips head attachment.
This will highly depend on the location where you will be putting the tub. The tub comes boxed on a pallet – we recommend keeping the tub in this packaging while positioning it closer to your platform. We recommend moving with a tractor or hiring professional movers to help install the tub due to its heavy weight. The tub can be finally positioned onto the platform using straps and 4-6 people.
AirBnB and Rental Properties
Concrete is incredibly durable and easy to clean, making it a viable option for commercial use.
A hot tub is the most searched for term on Airbnb. You can increase your visibility and your nightly rate.
Our wood-fired tub is extremely easy to maintain compared to an electric hot tub. No chemicals means no maintenance. It is as easy to clean as a regular bathtub.
The stove is very straight-forward, and functions just like a regular wood-fired stove. In two simple steps, the hot tub is ready in under an hour and a half: fill with water and heat with wood.