Thursday, January 10, 2013

Solat Water Heater Diagram

Our solar water heater will use standard parts. It will include two standard electric water heaters, one will be used as a solar tank. The heat will be transferred to the main water heater with a heat exchanger. The two electric heating elements will be removed from the solar tank, providing two access ports to connect the heat exchanger. The lower heating element on the main tank will also be removed, and a special tee will be connected to provide inlet and outlet to the heat exchanger. The upper heating element will stay for backup. The temperature settings will be 140F for the solar tank, and 130F for the main tank. A mixing valve will keep the hot water going out at 100F. The electric element will be set at 100F, which will be the min hot water temperature. Total cost (not counting the existing water heater) is about $1200. Payback is 2 years, assuming $50/month savings.
Assembly should start soon, and hopefully it will be installed on time to collect some of our summer heat.

Sunday, October 21, 2012

Hot Tub Heat Exchanger

Brazetek has shell and tube heat exchangers, suitable for hot tubs. The smallest is 55KBTUh. I will have to measure the compartment inside the hot tub to make sure it fits. I will also have to decide if I want to keep the hot tub electric heater or not.

[ Hot tub heat exchanger ]

Physical dimensions for the hydronic coil

The furnace area where I intent to insert the hydronic coil has a maximum inside dimension of 25"x25". The air channel is 22"x22".
The brazetek catalog has several dimensions for coils. There is a pdf that lists all dimensions. A 20"x20" coil will have 20"x20" coil area, and 24.5"x24.5" outside dimension, not counting the inlet/outlet pipes. This is the size that will fit. The inlet and outlet pipes will come out of the duct through pipes.
I looked for a coil that I could insert at an angle, to increase the coil area, but there is none that would fit, and it would make installation more difficult, so I will order a 20"x20" coil and install it in the furnace. The coil won't be plumbed yet, since there isn't a solar system yet to connect it to. There will be a 20"x20" paper filter installed against the coil, upstream of it. I may also install filters at the two inlet grilles. This will improve air quality and prevent the hydronic coil from clogging with dust, which would decrease its efficiency. Due to the low temperature of solar heated water, I will need the coil to keep optimal performances.

Sunday, September 30, 2012

Solar Panel Set

The solar panel was set this afternoon. I was too busy and forgot to take pictures. The panel is very heavy. For the next panels, I will change the design to make it lighter, using 1x cedar instead of 2x pine for the frame, 1/2 inch plywood for the backing, or remove the plywood and replace it with narrow cedar planks under the pex pipes, the end of the aluminum heat spreaders will not be backed, which should be OK.

I still have to connect the panel to the hot tub.

Saturday, September 1, 2012

Blue Moon

The Blue Moon, Friday morning. Magical light.

Wednesday, August 8, 2012

Sunsets on Mars, and on Earth

Curiosity lander shot its first sunset on Mars.
Compare this to a sunset on Earth:
One would have to make sure the zooming was the same, that the aspect ration was respected ... but it still gives a good appreciation about how the Sun would look like on Mars, compared to Earth.
In reality, Mars being on average 1.5 times further from the Sun than Earth, the Sun should appear 1.5 times smaller there.

Saturday, July 21, 2012

First Solar Panel Started.

I spent the whole afternoon today building the solar collector to heat our hot tub. This is an experiment to familiarize myself with the technology. About half of the panel is built, and hopefully, I will have it running by the end of the weekend. First was putting the heat spreader plates on top of the plywood sheet and mark each pex run.
Each line is where the pex tubing will lay. This will help, particularly with the problem I will encounter in the next step.
At the end of the first pex run, I had to bend the pex tubing to lay on the next line. Just to be sure I would not kink the tube, I checked on line the minimum bending radius: 5". My mistake was to think diameter instead of radius. I have 5.5" between lines, so that is 2.75" radius, too short. The solution was to go every 2 or 3 lines, and come back on the next run. Here the first two lines are laid.
Next, the four fist lines laid.
Seven lines laid so far, three more to go.
One more to go. All this done with a bending radius no less than 5".
Now the painting, after cleaning the plates with alcohol. One spray can of black rustoleum is not going very far.
I went tonight and bought a liquid can of high temp black paint. Writing the blog, I realized that there will be a problem with this design. With the way I laid the lines, it won't drain properly. That is OK for a hot tub that can be drained for the winter. For the hot water heater however, I will have to get pex that can be bent with a 2.75" radius, or find another way, such as running two lines in parallel. And that is why I started my solar projects with an experiment :-)