This is a great idea but if you wish this to heat your room or house first you need a normal size fan, second you need to have big opening for the airflow just like the size of your ducts, and last, you need to replicate the panels 3 more times to get the air to a higher temperature.
With zero restriction (open air application), that fan can exchange roughly 1 meter L,W, H of air every minute. Adding a duct with all those bends reduces the output significantly. You need to pull the return air from inside and keep it the same size as the supply. Drawing air from outside lower the efficiency of the heater and creates a small amount of positive pressure inside the house, forcing some of your comfortable air out.
Just an FYI, the theory behind adding rocks to the box is that the rocks will absorb the suns heat and release it as the sun goes down, while the aluminum ducting does absorb heat it doesn't retain heat so as soon as the sun stops shining on the box you loose all heating from the aluminum, try this, put some aluminum fool in an oven and heat it up, now pull it out and see how quickly it drops to room temp, the ducting isn't much thicker (thicker material retains more heat).
This just goes to prove that if the government really wanted people to conserve energy they would promote this idea.I did this same thing years ago to heat my pool.I took a roll of 2' or 3"black pipe,placed it in a wooden box up on the roof & had a valve hooked to my pool water pump.I had it where I could circulate it at any rate I wanted.It would produce water at 130º to 140º when not circulating.Opening the valve let free hot water into the pool or I could leave it circulating all day.It would only be slightly warmer with continuos circulation.It cost nothing to produce this energy because I was filtering the water anyway.
Let's do a little back of the envelope calculation using some kindergarten thermodynamics. Your heat captured, "Q" equals the mass flow rate of your working fluid times its specific heat times the change in temperature. Q=m*C*deltaT. 37 cfm,(which is a VERY optimistic estimate for one of those fans) is approximately 2.5 lbs/min or 150 lbs/hour. The specific heat of air is .24Btus/lb so with a 25 degree rise in temperature you are capturing a whopping 900 Btu/hr or the equivalent of about 264 Watts. To put that in perspective, you would get as much heat in your house from three 75W light bulbs, a laptop computer, or a TV set. At $.15/kWhr that's "THEORETICALLY" about 4 cents of energy per hour of operation. Lets say you can get this for an average of 4 hours a day, about 60 days a year, (again, an extremely optimistic estimate for Oregon), you COULD save $9.5/year so that's more like a 5-6 year pay back. And this doesn't even take into account the heat you will lose by compromising the air tight integrity of your window which would likely make this a net energy loss from your building envelope. I am a huge proponent of solar energy applications, especially homegrown applications, but this is little more than a fun experiment with no practical value. Capt. Carter, www.shipofimagination.com
Hi . It won't allow me to view your video on the solar furnace for 50. Is there another place/site I might view it ? Have you used tested this in the winter ? Thanks -:)
Could you check out the design in the video linked to below? I'm wondering about how much those heat the big screens might produce relative to your dryer vent piping or the can method. What are your thoughts about this design in general? ua-cam.com/video/OxCroNxU9eM/v-deo.html
This is a great idea but if you wish this to heat your room or house first you need a normal size fan, second you need to have big opening for the airflow just like the size of your ducts, and last, you need to replicate the panels 3 more times to get the air to a higher temperature.
With zero restriction (open air application), that fan can exchange roughly 1 meter L,W, H of air every minute. Adding a duct with all those bends reduces the output significantly. You need to pull the return air from inside and keep it the same size as the supply. Drawing air from outside lower the efficiency of the heater and creates a small amount of positive pressure inside the house, forcing some of your comfortable air out.
Grey Matter good call! you (thegulley) need to circulate air from the inside to increase your efficiency
Just an FYI, the theory behind adding rocks to the box is that the rocks will absorb the suns heat and release it as the sun goes down, while the aluminum ducting does absorb heat it doesn't retain heat so as soon as the sun stops shining on the box you loose all heating from the aluminum, try this, put some aluminum fool in an oven and heat it up, now pull it out and see how quickly it drops to room temp, the ducting isn't much thicker (thicker material retains more heat).
Cool solar furnace. BUT you might consider mounting a DIY solar collector on your roof.
This just goes to prove that if the government really wanted people to conserve energy they would promote this idea.I did this same thing years ago to heat my pool.I took a roll of 2' or 3"black pipe,placed it in a wooden box up on the roof & had a valve hooked to my pool water pump.I had it where I could circulate it at any rate I wanted.It would produce water at 130º to 140º when not circulating.Opening the valve let free hot water into the pool or I could leave it circulating all day.It would only be slightly warmer with continuos circulation.It cost nothing to produce this energy because I was filtering the water anyway.
Let's do a little back of the envelope calculation using some kindergarten thermodynamics. Your heat captured, "Q" equals the mass flow rate of your working fluid times its specific heat times the change in temperature. Q=m*C*deltaT. 37 cfm,(which is a VERY optimistic estimate for one of those fans) is approximately 2.5 lbs/min or 150 lbs/hour. The specific heat of air is .24Btus/lb so with a 25 degree rise in temperature you are capturing a whopping 900 Btu/hr or the equivalent of about 264 Watts. To put that in perspective, you would get as much heat in your house from three 75W light bulbs, a laptop computer, or a TV set. At $.15/kWhr that's "THEORETICALLY" about 4 cents of energy per hour of operation. Lets say you can get this for an average of 4 hours a day, about 60 days a year, (again, an extremely optimistic estimate for Oregon), you COULD save $9.5/year so that's more like a 5-6 year pay back. And this doesn't even take into account the heat you will lose by compromising the air tight integrity of your window which would likely make this a net energy loss from your building envelope.
I am a huge proponent of solar energy applications, especially homegrown applications, but this is little more than a fun experiment with no practical value.
Capt. Carter, www.shipofimagination.com
Great follow up! Now could you do another followup theis winter.. temps outside in the 30's? thanks!
If aluminum is a great heat conductor . Couldn't you save money by just using aluminum cans or any other recyclable material?
Your taking the temp of the electric motor
4:21 It's about the same temp inside as it is outside.
Thanks!
Did I hear correctly "1 year to pay for itself" at cost of $50?
Did i miss something? You said you turned off the electricity but how'd you power the fan?
Thanks
Now all you need to do is put the collector at about a 23 degree angle.
Hi . It won't allow me to view your video on the solar furnace for 50. Is there another place/site I might view it ? Have you used tested this in the winter ? Thanks -:)
Could you check out the design in the video linked to below? I'm wondering about how much those heat the big screens might produce relative to your dryer vent piping or the can method. What are your thoughts about this design in general? ua-cam.com/video/OxCroNxU9eM/v-deo.html
Still too cold for my taste XD