10 years with a wood burning tub.

A look at wood burning tubs after 10 years of use.

The original idea for the twin turbo wood-burning hot tub came from an article in Mother Jones. While traveling up and down the coast in my camper, I'd crossed paths with wood-burning hot tubs before, but I was always a little disappointed in how warm they got and how long they took. When I decided to set up shop in the Gorge 10 years ago, I knew I wanted to set up a hot tub to help manage the cold and wet climate. I took the recipe from the article in Mother Jones, a 400-gallon stock tank with a Chofu stove, and doubled it.

Starting in March of 2014 and ending in the early summer, we piecemealed the set-up seen here in a few weekend pushes. We built the platform out of dimensional doug fir, with some old railroad ties as footings. We burned out a dying doug fir, cut it in half with a chainsaw, and turned it into a cold plunge. 

During the treehouse build, the hot tub came into being.  Tucker and I would often talk about the next day's work while lying in the tub. Discussing what we needed from the next home depot run, we'd take turns stoking the wood stoves.

On cold days in late summer, when the marine layer from the Pacific makes its way 100 miles up from Astoria and the afternoon temperatures make it to the high 70s, the hot tub keeps warm through the night, and with a little coaxing from one of the stoves around dawn, it heats up by the time coffee is ready. 

Over the years, I've learned a few things about how to use the tub most efficiently. The hottub works on the theory of thermal syphon: water goes through the openings surrounding the stove, heats up,  rises,  displaces cold water on top of the tub, forcing cold water into the bottom of the stove and repeating the cycle. The larger the temperature gradient, the more efficient the flow through the stoves. Most of the lessons I've learned deal with proper wood stove techniques. For best results, I use Douglas fir, chopped small, and check the fires every half hour. Getting lazy with fire maintenance just prolongs the whole process. How long the tub takes to warm up depends on ambient temperatures and how attentive I am to the fires, but usually ranges from 3 to 5 hours. I suspect with a better insulated top and bottom,  this time could be reduced by maybe 25%. I don't stir the tub until I'm ready to get in. 

In a snowstorm, the lightly insulated tub takes twice as long to heat up. Laying in the tub after a day of work, thawing out the hose to fill up the tank, carrying loads of wood from the wood shed, splitting it, and keeping the fires stoked every half hour, the falling snow sizzles when it hits the stove's chimneys.

When I overheat, I jump out and lay in the snow, looking up at the tree houses.

Many nights have come to an early end for me, after overheating in the tub and laying in the grass as the rain falls, before walking up the stairs to the tree houses wearing only a pair of crocs and brandishing a jug of water, dead set on passing out and avoiding dehydration. 

A full break down of the specifics of the old hot tub build is in The Cinder Cone Book, which is out of print but available to Substack founding members.

Now, the sauna is in need of a rebuild, if not a serious refresh. The deck is covered with tarped cedar tongues and grooves for the sauna rebuild. The galvanized 500-gallon stock tank is starting to rust. The cedar hot tub cover, after being thrown on the ground for the last time, met its demise courtesy of a barbecue fire last week. The twin stoves have seen better days, but they still have a lot of life left in them. It will be rebuilt; there's no question about that, just how it will be done. Cedar tanks are expensive, if no assembled right can leak. I’ve been looking through craigslist and Facebook market place and if one pops up for a good deal, I’ll jump on it. Most likely, I’ll get another stock tank and focus more on insulating the sides, top, and bottom and wrapping it in cedar. Hopefully, with a bit of luck, the next iteration will last another 10 years. Rest assured, I'll document the build here.