Tuesday, January 28, 2014

A New Invention...

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This week we spent some time finding ways to live "off the grid".  While the boat is fairly self sufficient already, we took on a couple of projects this week that we hope will make life cheaper and easier for us.  Our first acquisition was a SOLAR oven.  We found this oven on You Tube and realized that with very little effort we could cook all kinds of food using ONLY energy from the sun.  the whole story about the oven is at a place called Emergency Essentials

They also have an neat You Tube Video:

This is about a 12 minute video which shows what this unit is capable of.  We hope to use it to save as much propane as possible...

This oven lead me to invent one more item.  This will be a SOLAR HOT WATER HEATER. On the boat we have a 12 gallon hot water tank that either heats water with shore power (110 volts AC) or the engine, which has coolant line going to and from the engine.  Thus when the engine is running, the coolant travels through an element inside the hot water tank and makes hot water.  If we are at anchor for any period of time we will not be hooked up to shore power and we would prefer not to run the engine just to make hot water.  So the Solar Hot Water Heater should do the trick.

If you can see the terrible diagram I drew, you see that I will add a 3 way valve to the supply and return coolant lines which will take the engine in and out of the heating loop.  With the valves in one direction, the engine will heat the water as it always has, however, when the valves are the other way, then with the help of a small 30 gallon per hour 12 volt pump, we will circulate coolant through 2 (or maybe 4) black tube coils inside a sealed black box with a clear Lexan lid.  To power the motor I will use a small solar panel.  Lastly the whole thing can be put in and taken out with 2 quick connect couplers.  If it all works the way it should, whenever the sun is out I should be making hot water with NO draw on our existing electrical system.  And when the sun goes down the solar panel will stop supplying the motor and the system will turn itself off until it next "sees" the sun. With all the bits and pieces I hope to make this for around $100...  I have found the 2 valves for $20 each and the pump motor for $20.  I'll post an update on this when I have these 2 solar appliances working.



  1. There are a few things you need to be aware of with your solar water heater plan:
    If your solar coils are above your engine header tank (almost certain they will be) you will need to seal the cap on your engine header tank and add another fill point at the top of the system. Otherwise you are unlikely to be able to purge the air from the system and you may get leakage from the engine coolant fill cap (certainly if you open the cap while the solar loop is connected).
    Solar shower bag or a plastic weed sprayer (painted black) are much simpler.

    1. You make some very good points... As for shower bags, we have 3 on board already, so we are fully prepared to go the simple route. I am motivated to try this mostly because I have never seen it done before... That said, as for coolant leaking from the engine header fill cap, I hope that isn't a problem unless I forget to switch BOTH 3 way valves before I attempt to run the solar heater. If they are both in the correct position there doesn't seem to be any way for the two systems to interact. As for purging, you are absolutely correct, and after I posted this I realized my problem and have added another step in the setup. That is to disconnect the output side of the solar coil and and feed that line into a small bucket filled with coolant. After I start the pump and when coolant starts flowing from the coil, I should have all the air out. Further, I plan to use some kind of connector that will attach (and detach) from the coil hoses that will only allow flow when they are connected. (I will be looking at a couple of hydraulic hose connectors, like the ones on a farm tractor), with any luck, once I have all the air out of the system, I hope it will continue to work even attaching and detaching the solar coil from the two hoses. I will store the solar coil in the Lazarette and coil up the hose to & from the hotwater tank and switch the 3 way valves back to the engine lines... At the end of the day, this project is really to find out if it can be done economically and safely. The worst outcome for this project will be to re-connect the engine coolant lines and endure harsh criticism from my beautiful wife...Again, thank you for your thoughts, any other ideas are gratefully encouraged, cheers, Kyle...

    2. Ok, you were not dissuaded :( some more things to think about: Without a header tank, pressure relief, overflow system there will be nowhere for the coolant to go as it heats up and expands (will happen quickly if the solar loop is closed and the sun is shining); Something will have to give, spilling the hot coolant. If you fix that, the next issue is you don't have any way to control the temperature of the fresh water.

      It's an interesting idea, but by the time you add everything needed to make it safe and reliable it will be a lot more than $100.

    3. lol... It is becoming evident that I am not the smartest apple on the tree... Just don't tell my wife how much it will cost to make it reliable and safe... Time to research expansion tanks and thermostats... :)