John C
Well I finally did it. After several months of research and educating myself on solar hot water systems I purchased the I-120-96 system minus the tank. I also upgraded to the Eagle 2 controller to better monitor the temperature in four locations. The primary use of the system is for preheating the water going to my hot water heater. Secondly, I am using the system to supplement the heat in a room in the basement via radiant floor heat. For this I needed more storage than the 120 gallon tank that was available with the system. I chose to use a 313 gallon fuel oil tank that I modified. I cut two square access openings in the top and installed two heat exchanger coils that I made from ½†copper tubing used for refrigeration systems. For the exchanger on the bottom of the tank that will heat the water in the tank I used two 50’ lengths of copper tubing and formed them around a 4†drain pipe to make the coil then plumbed them in parallel. I soldered 2†long ¾†copper pipe to the bottom of the coils to raise the coils off of the bottom of the tank and then stretched the coils to fit the length of the tank. The second exchanger to preheat the domestic hot water I used another 50’ length of ½†copper and coiled it as I did the first coil except I cut the coil in two and paralleled them. This second coil is suspended just below the top water line in the tank. To use this system for supplement heating via radiant floor heat I am drawing water from the top of the tank and pumping it through the radiant tubing in the floor and then returning it to the storage tank through a copper pipe at the bottom of the storage tank with an elbow directing the flow across the lower coil. The added flow across the lower coil helps improve some of the system losses when using heat exchangers. Once the system was completed I charged the system with air to 30psi and let it sit for a day to check for leaks. Then I flushed the system with water and again charged it to 30psi with water. Noting no leaks, the system was drained and filled with a water/glycol mix and pressurized to 26psi. The air/water test is something that comes highly recommended because it can save lots of headaches should you have a leak somewhere in the system. The storage tank was insulated with batting used to insulate hot water heaters. I simply cut the insulation to fit and then sprayed adhesive on the tank and applied the insulation. The seams were covered with clear packing tape. To insulate the piping I used regular black foam pipe insulation on the cold side, meaning the water from the storage tank to the solar panels. On the hot side I used fiberglass pipe insulation, a tip from a friend that found out the hard way that the black foam can/will melt from the hot water coming from the solar panels if the water pump should fail. In the first few hours of operation in partial sunshine the water temperature in the storage tank increased from 59`F to 86`F, not bad considering 300 gallons in the tank. Hope this info helps someone…………
Of course all of this was made possible with the great help from Amy Beaudet(Slater)! Thanks Amy.........
Update:
Thus far the 300 gallon storage tank has been as high as 165 degrees F on a sunny day and about 140 degrees on a partly sunny day. I'm averaging between 25F to 30F across the heat exchanger in the storage tank. I turned off the oil fired hot water tank and running solely off the solar system. Several things I would change on the system is the pressure relief valve and the spring check valve. The pressure valve supplied with the kit is rated for 150psi and I'm looking to replace it with one around 60-70psi. In the event of a pump failure, I prefer that the system not see pressures beyond 70psi. The spring check valve reduces the system flow because of it's design. A better option is to use a 1/2" swing check valve instead. This will increase the system flow through the solar panels and the heat exchanger thus improving the total heat transfer.
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![](https://alteshowcase.s3.amazonaws.com/photos/cache/photos/imgs/100_0031_feed.jpg "Home made domestic hot water heat exchanger coil from 1/2" copper")
