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Hot air panels - one installed - photos
By Dave B, Section Heat Posted on Tue Feb 24, 2009 at 02:49:29 AM MST
One installed one to go

I moved this project over to "heat". It's been a couple weeks of waiting on the weather and finally today Dave and I got this first hot air panel installed. One more now to get down here and installed and then it's time to work on the control, fan(s) etc. to dial these in.
The dual pane glass is not reflective coated, it's just a bit of the evening light playing neat tricks with the photo. It's been quite a project so far and not quite as simple as I had first thought but that's what makes it fun. More updates to follow and plenty of data logging in the near future also. Dave B.

Hot air panels - one installed - photos | 24 comments (24 topical)

Re: Hot air panels - one installed - photos (3.00 / 0) (#1)
by wdyasq on Mon Feb 23, 2009 at 07:56:39 PM MST

Are you selling heat back to the utilities yet?

OOPS.... that is another form of energy ... Looks good,

Ron

Adventure is just bad planning." -- Roald Amundsen

Re: Hot air panels - one installed - photos (3.00 / 0) (#2)
by dnix71 on Mon Feb 23, 2009 at 08:26:45 PM MST

That looks nice. I guess if you get a lot of snow it has to be mounted where it won't be covered. Does it face south or west?

Re: Hot air panels - one installed - photos (3.00 / 0) (#3)
by Dave B on Tue Feb 24, 2009 at 12:35:27 AM MST

Thanks for the comments. Plenty of snow and cold this year for sure and I've got these raised up a bit for a couple other reasons besides. Well out of the way of mowing if and when that finally happens and also it's giving me many more years before thinking about having to cut a few trees out back. This wall is facing due South. The upper hot air inlets are at the upper course of logs just below the ceiling on the first floor so this also works out well. It will be interesting for sure data logging the temperatures. Dave B.

[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#4)
by Jon Miller on Tue Feb 24, 2009 at 03:00:04 AM MST

Hi Dave,

will you be measuring solar input as well as temperature?
Jon M

www.otherpower.co.uk "I am certainly not a perfectionist, the thing is to know where you can take short c
[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#5)
by tecker on Tue Feb 24, 2009 at 04:21:36 AM MST

That's a nice looking install should be perfect for spring is that all going in one room .What sized fan did you end up using

Re: Hot air panels - one installed - photos (3.00 / 0) (#6)
by paborralho on Tue Feb 24, 2009 at 08:04:16 AM MST

Great!
I hope you'll have sunny days soon to test it.
It really looks cold out there.

Re: Hot air panels - one installed - photos (3.00 / 0) (#7)
by Dave B on Tue Feb 24, 2009 at 11:38:20 AM MST

Thanks all for the comments. I will soon be using my Davis Weather Wizard 3 to log the temperature, right now that sensor is logging my hot water temp in my 50 gallon pre-heat tank my 16' axial machine is heating. (just as a side note, the other day was the best full 24 hours monitored. 12 MPH + average with peaks over 30 rose 75 gallons of water from 60 degrees F to 90 degrees F in 24 hours.)

The installed panel is currently venting into 1 room and the other will have options of one room and or down the hall into the main area. I have not worked out the fan details or control yet but hope to experiment soon. Our main focus will be to get the other one down here and installed first.

We have had some intermittent sun today and just as a convective unit I can't believe the amount of heat rolling out of the vent. I'll get some rough data soon and post that. Let the sun shine and the wind blow, this is really great stuff. Dave B.

Re: Hot air panels - one installed - photos (3.00 / 0) (#8)
by carlb23 on Wed Feb 25, 2009 at 01:49:35 PM MST

I have two hot air panels on my home that I built a few years ago and they work quite well. I use simple snap disk switches available form grainger or mcmaster for less then 10 dollars. They have various on/off temperatures available i use ones rated at 120F on 90F off. Just place them at your outlet duct and let them turn the blowers on and off. Simple reliable and cheap.

I don't know what size panel but if I remember correctly the blower CFM should be around 3to4 cfm per sq/ft.

I run a 165CFM blower on my small panel and a 425cfm panel on my large panel.

I am sure when you get these finished you will be amazed and the amount of heat they produce.

Carl

[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#9)
by ghurd on Wed Feb 25, 2009 at 02:14:54 PM MST

Guessing the air line is ~4.3" OD.

How were the holes cut to the interior?

G-

Re: Hot air panels - one installed - photos (3.00 / 0) (#10)
by Dave B on Wed Feb 25, 2009 at 11:12:30 PM MST

Thanks for the information and replies. The vent holes were drilled with a 4" hole saw and right angle drill. When you build with logs you end up with some serious tools. I had to stop every couple inches to chisle out the relief of the hole cause the hole saw itself before botttoming out is only maybe 2 1/2" deep and those are 6" walls. Through from the outside in until the pilot bit just came through the inside wall then back out through from the inside out to finish the hole.

I have to credit Dave for figuring the key to the alignment. We brought both panels down here (there is an A and B) before installing the glass and set each one on the brackets then drilled through the panel vent holes with the hole saw directly marking the wall. With the panel as the template we knew after the glass was installed and the wall holes were drilled that the vent pipes should slide right in from inside the house and with this first one it went perfect.

Today I moved my temp. sensor from my preheat tank to the hot air exaust so I can log temperatures with my Davis Weather Wizard 3. The specs. indicate 145 degrees F max. for the outdoor temp. Well, I'm not sure how accurate it is after 145 F but just convecting in decent sun today I measured 181 degrees F air at the vent output (not even inside the panel or pipe !) Pretty obvious the fans and controls will make these units very effective hot air movers, I am amazed so far at what I have observed.

I'll have more photos and graphs to post as we move forward with installing the other panel as well as the fans and controls. Dave B.

[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#11)
by MattM on Sat Feb 28, 2009 at 01:34:58 AM MST

I figured it was a false facade on the cabin, but those are real logs! That's a real pita to drill through them without the proper tool. They make a 16" deep bit for those types of jobs that runs about $130 apiece. You can probably find some old fashioned auger bits that can do the same job for a lesser price. They were made for hand drills so it just takes a little adaption for power drills.
----------------------------- Go Huskers!
[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#12)
by Airstream on Sat Feb 28, 2009 at 08:27:57 AM MST

I'd be so into going through the concrete foundation, no matter the 'cost', instead of violating those logs..

Re: Hot air panels - First Data (3.00 / 0) (#13)
by Dave B on Sun Mar 01, 2009 at 12:51:25 PM MST

I recently installed a muffin fan and adjustable snap disk thermostat. We had a clear day yesterday with no shade on the panel all day, max. 25 degrees outside, perfect for logging the temperature.

The graph tells the story and I am very impressed. I look forward to tweaking the fan and thermostat as I learn more of the response times and air flow etc.

The speed at which the panel heated up to 120F degrees is amazing and even at the sun angle of 9:30 AM. (these are mounted vertical flat against the South wall) The fan kicked on at 120F and off at 100F. The hot air out rose to 159F degrees even with the fan continously running. This was an unusual day in that there was never any shading all day.

The yellow line is room temperature and the bumps are my furnace cycling indicating about 1/2 degree F fluxuation. This is due to the air escaping around the closed off room vents. The panel held and actually upped the room temperature over 2 degrees from 72 to over 74F for 12 hours. The outdoor temperature range was 16F - 25F max.

The fan is 120 VAC 20 watts Max. and 65 CFM. Learning from the data I'll be playing with the fan size and thermostat etc. but for now it's a great start. About 2 cents of grid power to heat my 12x16 room 72-74 degrees F as well as spill off into the adjoining room by leaving the door open. Actually is was easily free, my 16' wind generator more than made up for that heating my water yesterday besides. More graphs and updates to follow, I can't wait to get the other one mounted and running as well. Dave B.

Re: Hot air panels - First Data (3.00 / 0) (#14)
by heynow999 on Mon Mar 02, 2009 at 07:33:56 PM MST

Looks nice. I want to install some of these on my house but I don't have a good place to put them. I was looking at some manufactured ones. Heres the link for the technical data, maybe you could get some info from it.

http://enerconcept.com/documents/SLK-Flyer.pdf

Those panels use a 70 cfm fan for a panel about your size. It looks like you could use a bigger fan as the temperature seems to keep rising steadily after the fan comes on.

Nice work!

[ Parent ]

Re: Hot air panels - First Data (3.00 / 0) (#15)
by Dave B on Tue Mar 03, 2009 at 12:30:53 AM MST

Thank you for the comment and information. I have adjusted down the range of the thermostat to turn on at 110 degrees F and off at 90 F. The graph shown was for a completely clear sky all day, very unusual for here but a great referrence as posibly the max. potential for that particular day of the year and outdoor temperature.

A more typical day here today cycled the fan several times and the maximum temperature out today was 129 degrees F. It's all a give and take and I know at first glance possibly moving more air at a lower average temperature could be more efficient. Around here I favor the temperature being able to overrun the fan volume to a maximum as this will only happen on rare occasions. The greater percentage of time will be running in a very responsive heat range more like today when it is clear but partly cloudy.

Looking at the specs. of the panels you provided the information for proves out that I am close to these numbers. I have slightly less volume and a slightly lower rated fan CFM also. Earlier I had help figuring maximum and minimum BTU's for my panel and it's amazing how they compare. Just a rough average output temperature of 130 degrees F indicates it to be equivelent to approx. 1200 watts of heat.

What a great thing to be using that star power out there. More data to follow. Dave B.

[ Parent ]

Re: Hot air panels - First Data (3.00 / 0) (#17)
by Gordy on Tue Mar 03, 2009 at 01:18:24 PM MST

Dave,

You are getting the heat for basically nothing, so it's fine as is. But a number of sites recommend keeping the collector temp about 20* above room temp. As the higher the temp difference between the inside of the collector and outside temp, the more heat is lost through the glazing and insulation. This would be most important to those who can't afford another collector, or don't have room to put another one up.

Can't help but wonder how to rig up a temp control unit to run a 2 or 3 speed fan. Or put a Y or T on the output. So you could mount 2 fans with the snap switch's set at different temp's, and a lite plastic damper over one fan to keep the other fan from sucking air through it when not in use.

Gordy

[ Parent ]

Re: Hot air panels - one installed - photos (3.00 / 0) (#16)
by ghurd on Tue Mar 03, 2009 at 07:31:12 AM MST

"What if..." from the PV questions.
A horizontal mirror reflector a foot wide was fastened to the lower end?
Wouldn't it add the equivelent of about a foot more panel?
Only need one of those long narrow $10 plastic wally-world mirrors to try it.

What I think is cool is 2 panels, the same, with temp data logging.
Great to test what helps and what does not.
G-

Re: Hot air panels - Both installed update (3.00 / 0) (#18)
by Dave B on Fri Mar 06, 2009 at 05:31:25 PM MST

Well, we finally got the time and weather to install my other solar panel. It went up just as slick as the 1st one and now I can wire up the fan and thermostat.

I have a couple different fans that I will experiment with that push more CFM than the current one I am using. The snap disk thermostat I have is adjustable too so I think I'll be able to tweak these in to be even more efficient.

Looking at the graphs I think moving a bit more air at lower temperatures could be even better than what it is now. I am already impressed with the output as is. Updates to follow. Dave B.

Re: Hot air panels - Both installed update (3.00 / 0) (#19)
by jclaudii on Thu Mar 19, 2009 at 08:23:19 PM MST

So...Whats your data look like so far? Those are nice, I bet you have been showing them off to anyone that will come over and listen to you huh?

[ Parent ]

Re: Hot air panels - Both installed update (3.00 / 0) (#20)
by divemaster1963 on Thu Mar 19, 2009 at 09:05:01 PM MST

hey I was wondering if I could use a small solar panel to power a 12volt fan that i got from a aux power supply from a cable company. it could power my homemade air panel during the daylight to heat my rear bath. the heating system does not keep that room warm during the winter months. I live in the southeast so my unit is quiet small.

[ Parent ]

Re: Hot air panels - Both installed update (3.00 / 0) (#24)
by tmcmurran on Wed May 06, 2009 at 05:25:02 PM MST

You should be able to hook a small fan direct. I have a small fan running direct from a 15watt pannel that only needs to run if enough sun hits it to move a little air. Works so far so good.

[ Parent ]

Re: Hot air panels - Both installed update (3.00 / 0) (#21)
by Dave B on Mon Mar 23, 2009 at 12:27:03 PM MST

It's been a couple weeks now and my panels are on "automatic". I only need to design the backdraft dampers over the fan assemblies and make things look neat. I have both panels running off a single snap disk thermostat that is set at 110 degrees F on and off at 90F.

At high noon on a clear day this Winter the hot air may rise to 120 F but on average while running with no clouds it seems to run at 115 F with outdoor temperatures even as cold as 15 F. A 40-50 degree differential between input and output seems to be right where they run.

I have installed a higher CFM fan in each unit and this has improved the efficiency greatly moving a higher volume of air at lower temperatures. I am impressed to say the least and this project has been well worth the effort and extremely satisfying pouring 3000 watts of heat into the house from star power alone.

I plan to post more data in the near future. Right now it's 37 degrees F outside and over 72 in the house and rising. Log homes make a great heat sink, I doubt my furnace will kick on even throughout the night. Dave B.

[ Parent ]

Re: Hot air panels - Both installed update (3.00 / 0) (#22)
by ubud on Sun Apr 05, 2009 at 08:01:30 AM MST

can you give us more info. on the SNAP SWITCH THERMOSTAT?
I am in the planing stage of a water collector, and want to control Max. Collector
Temp. (want to keep below 200 Deg. far.)
Frank
CIWIH (cause its what i had)
[ Parent ]

Re: Hot air panels - Both installed update (3.00 / 0) (#23)
by Dave B on Sun Apr 05, 2009 at 10:37:57 AM MST

Here is a link to a company that provides all kinds of temperature control sensors. http://www.thermodisc.com/defaultpage.asp?PageID=8 Dave B.

[ Parent ]

Hot air panels - one installed - photos | 24 comments (24 topical)

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