Introduction: Solar Heater for My Shop

Picture of Solar Heater for My Shop

After changing TV providers, I found myself with this extra wide Satellite dish. I thought "Boy that would make a great reflector for a solar oven." So I sprayed some adhesive on it and grabbed a Mylar "Space Blanket" out of my "Go bag" and covered the face of the dish wit it. Then pointed it at the sun, and put my hand just about where the LNB would have been. Ouch! I will not try that again!

Step 1: Adding the "Black Box"

Picture of Adding the "Black Box"

After some experimenting, I added a small black "key lock box". Then I was getting readings of well over 500 degrees F.(260C) So I figured anything I was cooking would be burnt on the outside before it was done on the inside.

My next thought was "If I add a coil of copper tubing, It should heat water pretty fast"

Step 2: Coiled to Strike! Err, I Mean Heat.

Picture of Coiled to Strike! Err, I Mean Heat.

Using some 1/4 inch copper tubing, I made two small coils inside the box, drilled a couple holes for the ends to pass through at the bottom. And stuffed fiberglass insulation behind them so they would stay in contact with the dish side of the box.

Step 3: Adding Pump and Storage

Picture of Adding Pump and Storage

I had a 20 pound propane tank (the kind used for grills) that had the valve broken off. I twisted the remainder out of the tank with a pipe wrench. Then filled it with water so I could drill and tap a second hole without fear of any lingering propane igniting. I found a nipple at my local hardware that fit the original hole. Inside this I epoxied a 3/8th inch "drop tube" to send the hot water to the bottom. The second hole that I had drilled near the top, I tapped for a 3/8th inch pipe fitting. This would become the "output fitting"

I then purchased a 12 volt DC 50 psi "beverage" pump and some 3/8th inch ID plastic tubing that I routed up to the coils on the dish and down to my pump and storage tank.

Step 4: The Heat Exchanger

Picture of The Heat Exchanger

Being someone who keeps everything, (Much to my wife's dismay) I had a dead window air conditioner. After removing the cover, I decided the fan and outside heat exchanger would be about the right size. So I removed both and mounted them in an old PC case. (See I told you I never get rid of anything) I was able to leave the fan connected to the original control box after disconnecting the compressor wires. I the used my tubing cutter to cut the top and bottom copper tubes leading from the compressor.

My pump drawls from the top of this coil/heat exchanger and pumps to the up side of the dish coil. The down side or hot side attaches to the "drop tube" on the storage tank. The out put tube on the storage tank goes to the bottom of the fan/heat exchanger.

I point the dish at the sun, and turn the pump on for a bit before starting the fan. This heats the water in the storage tank quite quickly. Then when I turn on the fan, I get nice warm air out of my solar heater.

The photos above show first the room temperature, then the air temperature at my heater.

I have an old DisEqC rotor on the dish, I am working on a way to control it to automatically follow the sun, perhaps in my next instructable.

Have fun and stay warm!

Comments

SoylentGringo (author)2016-10-16

is it feasible to take another heat exchacher, paint it black, & put it at the focal point of the parabola?

anil8tor (author)SoylentGringo2016-10-16

Absolutely, if I had a small one on hand I would have done this. Thanks for the question!

Gordyh (author)anil8tor2016-12-02

You could probably increase the heat transfer of the box to the coils by pouring molten lead into the box, just enough to cover the coils, then fill the remainder of the box with insulation. When I do something like this I use a strong acid (the Works toilet bowl cleaner) in place of flux to prep the surfaces for good adhesion to both surfaces.

offseidjr (author)2016-11-20

wow good ible!

dubnikov (author)2016-10-26

Next step is to connect this to Arduino Sun Tracker Turret:

https://www.hackster.io/robotgeek-projects-team/arduino-sun-tracker-turret-06cba9?ref=explore&ref_id=trending___&offset=1

anil8tor (author)dubnikov2016-11-06

Check out my version at:

https://www.instructables.com/id/Solar-Tracking-Using-Arduino-and-Modified-DisEqC-R/

dubnikov (author)anil8tor2016-11-07

Great job!!!

anil8tor (author)2016-11-06

Update! Check out my Arduino controlled solar tracking system!

https://www.instructables.com/id/Solar-Tracking-Using-Arduino-and-Modified-DisEqC-R/

RadDog2 (author)2016-10-26

I would do some research, but antifreeze for RVs might work. It is made different than standard automobile antifreeze. People use it to cool their laser cutter tubes when the machines are not in a heated space.

GTO3x2 (author)2016-10-18

This is great. Just want to add this:

I'd suggest using propylene glycol. One way to get this is from AMSOIL (American Synthetic Oil (?) ) from independent dealers for automobiles. I believe this will be better against corrosion and I believe a similar chemical is used in building hot water heating systems. I would estimate a 50% solution will give a -25 degree F freezing point and will have a 15% reduction in heat transfer. (~$40/gal.)

Also, for reference, the sun, on a clear day and maximum impingement, estimate 430 Btu/s.f./hr. solar gain. (Keep in mind a typical house furnace is 48,000 Btu/hr output (80% eff., 60 MBH input (60,000 btu/hr.) (1400 s.f. house, above average insulation, 80 degree design delta T)). Natural gas is doing THAT much for you!

Don't expect any usable capacity from hot water storage from 20 gallons. (lol) You might need a bladder type expansion tank too (Watts domestic hot water (2 gal (?) - Home Depot, set for 20 psi (?)).

Great project. I'd be interested in your results and comments. (I bet I know what they'll be like (lol)) -Ohio

JohnC430 (author)GTO3x22016-10-23

well, he already took measurements and it shows about 17 Deg Celsius in crease in Temp. does that not show that his 20 Gal tank is working? After all he is only heating his shop. On the other hand what did you mean when u said " will have 15% reduction in heat transfer"? I thought the idea is to get maximum heat transfer from the dish to his shop. I agree Glycol is better than water and will keep the tubes from freezing and will also prevent oxidation of the tank. True 50% solution is good for -25C as it says on the Glycol jog.

GTO3x2 (author)JohnC4302016-10-24

The water volume in this tank in this scenario is a thermo-mass storage (buffer); it will also take longer to heat up. In heating hot water systems, it with be a bladder-type expansion tank. In contrast, in domestic hot water, it is your hot water ready for use. These are slightly different functions although both yield a hot water supply.
The use of glycol is primarilty because of the need of using an anti-freeze solution. Glycol has a different specific heat, and therefore different heat transfer rate. This medium at this concentration is this much less than water's heat transfer. Yes, it would be higher if only water could be used. Corrosion inhibition is the next desire.
Polyethylene glycol will get acidic. This is why there are/were problems with automotive engine cooling systems when trying to get 100,000 miles between changes. I mentioned it for this reason.

anil8tor (author)GTO3x22016-10-18

Okay, I am using the equivalent of a 4' parable, so radius is 2'
2' squared x 3.14 x .2 for the average depth = 25.12 square feet
25.12 x 430 BTU/Hr = 10801 BTU/Hr
say there is 8 hours usable sunshine = 86412.8 BTU/DAY
Guessing its 60% efficient thats 51847.68 BTU/day free added heat to my shop.
My pump and fan are run off of photo voltaic cells charging a deep cycle battery
Granted that's just over an hours worth of heat from my household furnace, but as there is no heat in my shop, I'll take it!
Thanks for all the info I didn't have to look up to make these calculations!

Murry1900 (author)2016-10-21

sorry for my ignorance, but what is a LNB and what is the black box ? Is it the unit that captures and transfers heat to the water - have you thought of using an oil as it has a greater calorific capacity than water.

Think you idea is great.

Murry

anil8tor (author)Murry19002016-10-23

Hi Murry,

An LNB is a low-noise block down converter, or essentially the part that captures the signal reflected from the dish for satellite TV. The black box in my design is simply a metal box with a black powder-coat paint that I wound copper tubing inside to collect the heat. And yest I have considered a great many different fluids, and will probably use a mixture of auto antifreeze and water (auto antifreeze is mostly propylene glycol)

Thanks for your interest!

kdarmr (author)2016-10-21

I am thinking a truck/tractor eaton transmission heat exchanger tank, or even an EGR cooler would work very well for mounting to the dish in place of your coil/key box. You could also use any automotive Radiator/heater core/ac condenser/ac evaporator as the interior heat exchanger, specially if your looking to upscale in size. I am a Diesel Mechanic, and I know I can go to work tomorrow and find all the components I need in the scrap bin, solder/braze up some holes and good to go. I may even go with a large air tank off of a truck for the storage tank, as well as a large aluminum Charged Intake Air Cooler as the heat exchanger, equipped with dual 12inch 12vdc radiator fans. Also a front wheel drive car ac condenser that already has a large dc powered fan and shroud attached to it would be ideal, I would think

Victor EmmanuelS (author)2016-10-20

I was wondering if water recirculation could be done drip-coffee-maker style where check valves and water temperature differences would control the recirculation

jaswant9 (author)2016-10-19

Oh wow ! Just the thing I was looking for. I was gonna try that too, but am too lazy. But now that you have done it. I'll surely do it.

Thanks for the inspiration and will be waiting for your solar tracking upgrade. If possible try to make it analog, I mean add a comparator instead of arduino to drive the motos.

MichaelAtOz (author)2016-10-18

What is the size of the dish?

anil8tor (author)MichaelAtOz2016-10-18

It is a 52 inch ellipsoid, designed for multi-sat HD TV on the Ku band.

Ericc815 (author)2016-10-18

I believe you could substantially improve efficiency using larger discarded water heater tank for thermal mass and mounting home baseboard radiator underneath the tank to eliminate need of pump outside sunshine hours. That would allow turning pump off when not collecting heat - and place checkvalves in the risers to your dish to prevent night time chilling of thermal mass. Your heated airflow would become more efficient and longer lasting.

nearboston (author)2016-10-18

For a tracking system i recently saw how someone used 2nsmall solar cells mounted at a 120(?)degree angle away from each other with the outputs connected to a very small motor. The difference in voltage would move the motor slightly until the two outputs were equal.

anil8tor (author)nearboston2016-10-18

That sir is a great idea! I could send the output to an arduino and have the arduino drive two relays to move my rotor. Fantastic! cant wait to try that! Many thanks!

German_MX (author)anil8tor2016-10-18

Hi, i can recommend this Blog. It´s from a College in Yucatan, México.

Even if this is in spanish, its very simple to understand, and they posted the code to reply their project.

https://girasolarduino.wordpress.com/

They used an Arduino, 2 Photocells and a Servomotor. Very simple, not very Strong to move your dish.

Instead, you could use 2 Solar Cells, and an "H" bridge, in order to control a DC motor, the strongest ones.

anil8tor (author)German_MX2016-10-18

Awesome! That helps very much! Many thanks!

German_MX (author)anil8tor2016-10-18

You're welcome. This is what i like about this community. Help one each others.

Furthermore, between all DC Motors (stronger than AC motors), i recommend one with a gearmotor included, for extra power.

The cheapest option i have found is a motor for a Car Windshield cleaner.

Those work on a 12VCD power supply (Car battery or a PC power source).

NOTE: Be very carefull on this ones, they may be slow, but have a lots of torque or a twisting force.

It´s tempting try to stop them with your hands (not my best idea), and could got hurt.

So, greetings, and i wish you success.

confu (author)anil8tor2016-10-18

Tracking with solar cells "might work" somehow, but isn´t very precise. Due to the high concentration of a parabolic dish you will need a very precise and 2 axis tracking.
You can build a 1 or 2 axis tracking device with some LEDs and some microcontroller (aka arduino or alike).
Check this site for more info:

http://www.redrok.com/

Site itself is indeed awful, but the most complete collection of ideas and solutions regarding solar energy I found yet.

nearboston (author)nearboston2016-10-18

But do you need to track when using a paroboloc mirror?

anil8tor (author)nearboston2016-10-18

I'll just maount the two small cells on either side of the coil box, Cool!

anil8tor (author)anil8tor2016-10-18

"mount" that is.

lee78 (author)2016-10-18

This 12' C-band satellite dish provided domestic hot water in 1983 and collected TV with a cassegrain feed. Sunlight was absorbed at collector, microwaves bounced off to LNB on dish surface.. I wrote the program for the VIC-20 (lower right) that computed the position of the sun every 5 minutes and adusted azimuth and elevation motors.

Cliffystones (author)2016-10-18

Another thought. If you can find a balance of flow rate and volume from the dish coil to the heat exchanger you can probably eliminate the need for a storage tank and simply circulate the anti-freeze between the exchanger and the dish. I'd think the easiest way to do this would be to add a variable speed control to the pump controlled by the fluid temperature via computer/Arduino. The down side would be no storage of heated fluid during cloudy days and night time.

Cliffystones (author)2016-10-18

Great idea! Now I know what to do with our old dish. One suggestion. Instead of water in the heat exchanger, use automotive anti-freeze. This will be mandatory if you live someplace that gets below freezing.

Dean Z (author)2016-10-17

Great Project!

With 500 degree F at the focal point how hot is the water getting there?

What type of hose and tubing did you use to get this very hot water back to the tank?

anil8tor (author)Dean Z2016-10-18

I tried slowing the flow to get greater temps, but the clear tubing I am using inside would get soft and leak at the band clamps. As budget permits, I will replace the inside tubing with something more "heat stable"

Great question! Thanks!

anil8tor (author)Dean Z2016-10-18

At the flow of my pump the water gets to around 200 degrees F.

And don't laugh, I cut up one of my air compressor hoses for the outside stuff. Its thick walled and just over 3/8th ID.

PRR5406 (author)2016-10-18

I'm wondering if this could elevate the temperature in an enclosed garage shop, in New England, during the winter? What a great use for all these discarded items! Might be a neat way to heat a swimming pool on sunny, but brisk days.

anil8tor (author)PRR54062016-10-18

I'm in Ohio, hoping to take the chill off my detached garage/workshop.

MaykeS1 (author)2016-10-17

Mind-blowing!

This could be a very nice water desalinator in remote islands with no electricity supply!

anil8tor (author)MaykeS12016-10-17

Thank you! and I didn't think of that, yes it could be used to distill for a

desalinator. That would be awesome.

Thanks!

YDandAss (author)2016-10-17

Nice project! I too save stuff - I'm of the opinion (and I've seen it happen!) that as soon as I throw some hardware away I'll find a use for it. That being the case, I have an old Primestar dish kicking around here as well as a few ACs. I may try something like this, or I may use the dish as part of a WiFi repeater. Hmm...

I'm guessing that's a 10M beam I see there, not 11M, as I also see what looks like a V/UHF dual-bander up there on top.

73

anil8tor (author)YDandAss2016-10-17

I find the dish antenna's are easy to come by, I have one on my shop with an external mount wifi antenna at the focal point with the dish aimed at my house (200' away) and get full bars on my Fedora "Shop computer". Good guess on the 10 meter beam, and the 2 meter/440 on top. Funny no one mentioned the Red Tail Hawk in the pic. A bit of advice, if you do use a dish to extend your wifi, the the "arm" that holds your wifi antenna needs to be about 30 degrees below horizontal to get a horizontal signal. The design only uses a part of the parable, unlike the old C band dishes. 73's and thanks!

CapeScanner (author)2016-10-17

what band is that Yagi for?

anil8tor (author)CapeScanner2016-10-17

That is a CushCraft 10 meter beam at around 65' on a tilt base tower. Thanks for the question! 73's

wixi (author)2016-10-16

great idea thanks

anil8tor (author)wixi2016-10-16

Thank you!

vikinggoat (author)2016-10-16

Gah, you beat me to it, I've been collecting bits and bobs for a project like this for my home hot water heater.

anil8tor (author)vikinggoat2016-10-16

Hey that's Cool! Let me know if you get the sun tracking worked out, I may dump the rotor in favor of stepper motors and an Arduino.

eudaly2 (author)2016-10-16

It looks as if you just circulate the water through the storage tank when B&C are open with A&D closed. What is the purpose of this

anil8tor (author)eudaly22016-10-16

I plan to heavily insulate the tank, and my hope is after sun down, to just circulate the hot water in the tank. This would prevent heat loss through the dish circuit.

About This Instructable

37,951views

325favorites

License:

Bio: I have always been a frustrated astronaut, but a hearing loss kept me grounded. Now after over 30 years in a highly technical public service ... More »
Add instructable to: