Welcome to the Solar Collector
Brainstorming and Development Page!


 

Home

Hot Air Collector

Hot Water Project 1

Hot Water & Space Heating

Solar Electric

Solar Construction 101

FAQs

Best Collectors

Simply Solar
Sign up Latest Topics
 
 
 


Reply
  Author   Comment   Page 1 of 2      1   2   Next
defer12

Registered:
Posts: 10
Reply with quote  #1 
so I just dove in and did this.  so many things going on, and far from perfect.  today was my first day running it.  I was pretty excited.  I got a 35 degree temp difference at the output, this was my max.  

stats:
-4x8 3-screen collector. 
-1" poly iso on sides and back.  
-$150 EC motor i got on amazon - terraboom
-had the fan on the lowest speed the whole time
-when i'd turn it up the temp would go down
-the interior screen absorber doesn't cover the entire width or length of the box.  the box sits horizontal.  the absorber is about 1/2" short on the height, so I thought maybe air is sneaking by there and that's why I'm getting the low temps?

current issues:

1. outputting only 81 degrees at its peak, and it was 46.  
2. the perimeter of the glazing is not airtight.
3. duct run needs to be cut down (will do this eventually)
4. screen absorber not snug in the insulated box.  air can move around the sides of it in a few places...is this that big of deal?!

Here is all the pictures I just took:

https://photos.app.goo.gl/BnUxMZUbfRwWkEoM7

Any thoughts on getting higher temps?!  hit me up!

gbwillson

Avatar / Picture

Super Moderator
Registered:
Posts: 2,461
Reply with quote  #2 
Hi Defer-

Nice looking unit! A 35˚F temperature rise isn't far from where you want the output to be. Because if you were using 60˚F air from inside the house instead of cool outdoor air, your output temp would be 95˚F. You don't mention the CFM of the output air, but for now, it's as low as your CFM will be without some modifications, and with adjustments, you will likely be turning up the fan's CFM's to maximize the BTU output.

Assuming you are blowing the air into the collector box, you may be able to feel the air leaks, especially if you partially block the exhaust opening. And yes, some air may be bypassing the screens since air will take the path of least resistance. 

From looking at the photos, was the sun shining brightly when you were taking the temps? And it looks like the collector face is fairly upright, and not perpendicular to the sun. Both of these can have a dramatic effect on output. 

Keep in mind that once you make a few very minor changes you will see better results, but that your heater is now producing heat.  You will have plenty of time before next winter to tweak your heater for optimal output BTU's. Let us know once you have made any adjustments so we can hear your updated output results!

Greg in MN

PS:Make sure to prime and paint any exposed foam as the UV rays from the sun will quickly turn the foam to dust.

jjackstone

Registered:
Posts: 118
Reply with quote  #3 
You can also use a spray bottle of soapy water to check for leaks. That's what I do on inner tubes for the bicycles.
__________________
JJ
defer12

Registered:
Posts: 10
Reply with quote  #4 
Hi Guys

Thanks for the replies.  Pix to come, but for now, here's where I'm at.

1. I'm getting about a 30 degree bump in temps outside to inside.  
2. With 8" ducts, as soon as I bump the speed of the fan above its lowest setting, the output temp goes down.  
3. I need to get one of those snap switches, it's a pain in the butt to constantly monitor the temp outside, and then turn things on and off based on the output temp.  
4. how are people keeping their ducts covered that run into the house?  are you building enclosures?
5. I see some people have the collectors mounted on the sides of their houses...this means they are not nearly as efficient cuz they don't have the right angle and azimuth to the sun, right?  
6. I used a black 100 percent silicone to airseal the perimeter of the collector.  worked well.  still a few more spots to do where my two pieces of glazing come together.
7. the fan I got was 150 bucks.  wow. expensive.  the one a guy on here suggested was 50, but it was single speed, and noisy as heck, and vibrated.  do you guys seriously use fans like that?  am i missing something here?  yes i know, it's a lot more money, but the alternative stinks.  

that's all for now.  i hope to get pix and video up soon.
defer12

Registered:
Posts: 10
Reply with quote  #5 
I've made four videos of the process so far.  not hollywood quality, but it's something:







gbwillson

Avatar / Picture

Super Moderator
Registered:
Posts: 2,461
Reply with quote  #6 

Hi defer-

 For the size of your collector using 8” ducts may be a bit overkill. Bu if you should upgrade the size of your collector you should be all set. The duct size is unlikely to ever be a problem.

Snap switches, especially preset ones are cheap. They can be had for less than $10.

I use flexible ducting, which can come surrounded by an insulation sleeve that can be removed and solid ducts can be slipped inside if so desired. I thought I noticed insulated flex ducts in the photos you posted earlier.

Collectors mounted directly to the side of the house eliminate heat loss from the ducting and can simplify installation. Yes, there can be some loss due to the angle of the sun, however tests show that a blanket of snow, mylar, and even mirrors can more than offset this loss. Another possible advantage is that as the sun rises hight in the spring, less heat is needed, and at some point, very little heat will be collected, possibly eliminating the need for a cover. 

I’m not a fan of the corrugated polycarbonate, especially if the ribs are horizontal. But it may be the only polycarbonate available in your area without special ordering. The ribs collect rain, snow and dust, which can degrade the clarity over time. The ribs are also much tougher to seal tightly compared to single or twin wall polycarbonate. 

Spending $150 may be overkill. But if it’s quiet and has the features you need or want, then it is the right choice. the high cost will increase the time it takes to experience actual savings from you heater. Personally, all of my fans were either free or very cheap, as in less than $20. Old furnace fans and discarded range hood fans work very well and can be found with multiple CFM’s and adjustable speeds. Even if the fan has but a single speed, an electronic fan speed control can dial down the fan from just above a whisper to the maximum. this versatility allow the system to be adjusted as changes are made for maximum efficiency.

 Greg in MN

 

PS:Your previous link that showed photos is no longer working. Would you see if you could fix the link? The photos were good in that they showed clearly as you work on your collector.

gbwillson

Avatar / Picture

Super Moderator
Registered:
Posts: 2,461
Reply with quote  #7 
Very nice job on the videos. I'd like to see a planning video where you considered the size and type of collector you finally decided upon. I hope you continue the series, although the weather and angle of the sun might delay practical results until the weather turns cold again. 

Greg in MN
defer12

Registered:
Posts: 10
Reply with quote  #8 
Thanks for the comments Greg.  Could not have had near the success without you and this forum.  

Here's another video.



Also, I ended up taking down those pictures and delteing them.  But I was thinking of doing another video with some more close up shots of stuff and talking about my reflections on the project.  

few remaining issues:

1. Ducting is expensive, IMO, and it looks like i may need to buy another 25 ft piece so my supply can come from my house, not the ambient air outside.  shoot!  more money.  any creative ideas?

2. I still have not gotten the snap switch yet.  with the fan i currently have, it has 6 levels and is controlled by a remote control.  would a snap switch work for a three pronged electrical chord that is used to bring power to my fan?

3. my ducting looks like trash.  pretty sure i have decreased my home value by 5k.  how are people making it looks nice?  buildling a box for it?  it's gotta get out of the elements (rain, snow, sleet, and sun).  am i looking at more money, time, and materials to build something to house it in as it runs from the collector to the house?  looks like yes.....  [frown]

4. moisutre on the back side of the glazing....help?

Thx!
gbwillson

Avatar / Picture

Super Moderator
Registered:
Posts: 2,461
Reply with quote  #9 

From the amount of excess ducting, it looks like you should be able to connect both ends of the collector to the house from the single 25' piece. I’d hate for you to have to purchase a 2nd 25’ piece of flex duct.

Yes, you can use a snap switch, but it needs to interrupt the power to the fan. A cheap 3-prong extension cord can be used for this splice. you could also consider something like this:
https://www.amazon.com/Inkbird-Max-1200W-Temperature-Controller-Greenhouse/dp/B01HXM5UAC/ref=sr_1_1?crid=29YR22N4BWV8V&dchild=1&keywords=temperature+controller&qid=1587148134&sprefix=temperature+contr%2Caps%2C234&sr=8-1

or this:
https://www.amazon.com/Inkbird-All-Purpose-Temperature-Controller-ITC-1000/dp/B00OXPE8U6/ref=sr_1_5?dchild=1&keywords=temperature+controller&qid=1587148218&sr=8-5

The shiny mylar duct cover is a bit loud to say the least. Some brands cover the duct with black plastic, which is far less noticeable. I ended up covering my shiny mylar with black plastic. I did this for a few reasons. It covers the shiny mylar, and will protect the mylar from UV, wear and tear and helps protect the ducting from moisture. And being black it will help melt snow that lands on it. For a cheap cover, use large thin black plastic garbage bags. Cut off the sides but leave the bottom intact. Open the bag so that the top of the bag is now at either end. You should have a large piece roughly 2’ x 7’ which can be used to wrap around the flex duct. Simply overlap the pieces and tape into place. Cut new covers next season. These covers will make the flex ducting and cover last for years!

The moisture on the underside of the glazing is common, even if you use twin wall glazing. It can be reduced by making sure you have a back flow device of some sort for the ducting. The back flow device will also prevent warm basement air from being drawn out of the basement and called down via convection. There are several ideas you can search for on the website using back flow as your search perimeter. 

I would also consider moving the fan inside the house. Ideally, intake air should come off your basement floor where the air is coldest, so you replace it with the warmest. A board the size of the broken window and foam could be used for added security.

 Greg in MN

defer12

Registered:
Posts: 10
Reply with quote  #10 
few more videos:



Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.

 

web statistics