This project has been on my list since the day I discovered that Satori was setup to circulate hot water through the stove to heat up the hot water tank. I have pondered the way a new system would work and what components I would use to make sure it is working with as much efficiency and durability as possible. This is a way to harness the heat from the flame in the stove to move it using glycol into the hot water tank to heat up the freshwater. I’ve spoken with several experts on Dickinson stoves and spent countless hours on the internet trying to design a dependable system without spending money on a new stove. So instead of replacing the stove, I have elected to rebuild the existing one and add the coil myself. Along with rebuilding the stove, I have a chance to clean and rebuild other parts of the system so it works as best as I can make it. So a list of components was built:
- Mixer valve for preventing hot water scalding
- Sharkbite fittings for copper connections to hot water tank
- Temperature gauge
- Propylene glycol for hot liquid inside of loop to tank
- Stainless steel compression fittings to fit the copper flare fittings
- Various hose barbs with flare attachments
- 2 gpm, high-temp water pump, wiring and switch
- 1 gallon alloy expansion tank and radiator cap
- Replacement stainless bolts and screws
- Hybond Cement for sealing cracks and top of stove
- Two-turn hot water coil
- Fire brick
- Stove top clip fittings
- 1/4″ Trident fuel hose
- 3/8″ hose for blow-off valve on expansion tank
- Hose clamps
- CLR for cleaning existing copper lines and fittings
- Stove pot superheater
Most of the parts were ordered via mail order or through Sure Marine, just a mile down the road. They specialize in closed heating systems, LPG stoves, heaters and are a parts dealer for Dickinson. A couple of the employees have rebuilt stoves and also has installed hydronic systems so they have been a great resource for this project. Most of the stove parts and compression fittings came from their store. The first part of the project was to drill out the existing screws from the top of the stove. Because the stove is alloy (an indifferent metal to the screws) and heats up quite a bit, the screws cannot handle the extremes so they rust and the screw heads are heavily corroded. It took about an hour and a half plus two drill batteries to get them out. At this point I think most people would give up.
Once the stove top was off I was able to begin scraping and cleaning out the firebox. The cement inside wasn’t entirely brittle so I decided to reuse much of the existing cement and then seal it with hybond cement. The fittings on the back of the stove took most of my physical strength and energy to pull them apart. Once I was able to get the individual fittings apart I could bathe them in a mild acid to remove the calcium deposits that come from fresh hot water getting super heated. I also wanted to replace all of the fuel lines so I bought hose barb fittings that fit the fuel regulator. I also disassembled it to clean any nasty fuel deposits and cleaned it up a little. Once I was able to remove all of the copper fittings, I built a drain at the lowest point using shark bite fittings. I cleaned out the lines by running CLR through them to help eliminate any calcium, lime and copper residue and it helped considerably to clear them and prep for the glycol liquid. A few flushes cleaned the lines up well enough for a good flow without restriction. There is still a small amount of calcium in the lines but it seems okay to leave since there is still sufficient flow. I was considering using pex if the lines were too clogged but I that presented several issues. Mainly I just wanted to be able to run the stove straight to the copper tubes so I didn’t have to run the pump just to use the stove. The old coil and copper pipe used thermosiphoning to circulate the water by heat convection so being able to do this was critical, but without the copper pipe would have been impossible without risking burning the pex tubing when the pump is not running.
Once I had the stove out of the way I could clean up the flashing and the stove itself. Decades worth of liquids oozing down the side of the stove cleaned away easily. The flashing and stove cleaned up nicely. I bought new cement thinking that I would just add new cement to replace the old stuff but the existing cement was in pretty good shape, minus some cracks. Once I cleaned up the cement, removed the fire brick and cleaned out the firepot I prepped the stove for sealing. Much of the old cement was put back into place and then the Hybond cement filled in any existing cracks and spaces, plus sealed the cement parts together. I also used a wire brush on the top of the stove to get rid of the old sealer and remove any buildup of soot or other materials. On the top of the stove I used a vibrating sander to remove the old surface material so I can season the top with something that will seal the alloy. I am planning on using flax seed oil since this is my seasoning for cast iron cooking pans. I also removed the stovepipe flange, cleaned it up, attached and sealed it back to the stove with Hybond.
The new hot water system uses a low flow pump to circulate hot water so I installed a toggle switch at the stove so I can turn the pump on when operating the draft assist fan. The fan motor was replaced a month ago after trying to troubleshoot the noise. It turned out to just be an imbalanced fan and once I figured it out the fan was considerably quieter. I also replaced the wiring back to the electrical panel so everything would last another thirty years. Once I added the hot water mixer I began to have issues with the existing water circulation and so I removed it and relocated it to the bathroom faucet. This way the water can be raised to above scalding temperature and circulated through the cabin but if I take a shower or use the sink water, there will be no risk of accidental burns. The first circulation pump was also defective so I ordered a new one and tested the circulation before connecting the stove to the copper fittings.
One tough engineering problem I had was with the compression fittings that came with the stove. They were ninety degree compression fittings on both ends. Not only was the angle incorrect but they did not connect directly to the copper flare female fittings. This could not be solved by anything that Sure Marine had in stock so I decided to give Motion and Flow Control Products a try. They not only solved the issue but also suggested that I switch to stainless steel compression fittings. This solved the link between compression and flared attachment but also provided a better material for the connection. Stainless pipe to stainless compression to copper flare is much better than stainless pipe to brass compression to copper. It’s a very unique issue and MFCP did an excellent job helping me solve it. They also provided excellent advice on the circulation pump and lines.
This project has been a great engineering challenge for me and the only other project of this scale was the new plumbing installation and the bathroom rebuild. Not only have I managed to unplug the water heater while operating the stove but I have also given new life to something that may be several decades old. The cabin has been uncomfortable while this project was underway and littered with debris from drilling and cleaning. The tools took every inch of space and the stove took some physical energy to get apart and back together again. Without the highly specialized people at my disposal the project might not have ever been completed the way I wanted it. This is one reason why I decided to take this project on now, while it is useful to have water heated as a byproduct of the stove heating the cabin. During the summer the solar panels can practically run everything but in the winter I become dependent on shore power for heat and to keep the batteries topped off. With a diesel stove running for twelve hours a day I can heat the water, the cabin, cook from the stovetop and almost completely eliminate the need for electricity, except to top off the batteries. Now that this project has been ticked off, I can now focus on the engine’s water pump, prevent any additional corrosion and prolong the life of the engine. Once I have used the hot water heating system enough to know it’s quirks, I will make sure to update the blog with any discoveries.