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Horizontal panels wt drain back

Tim_34
Tim_34 Member Posts: 56
Those 4 x 10 panels in that picture are not designed like a typical flat plate collector. The headers run in the same direction as the 10 foot side of the panel. The risers come off the header in the 4 foot direction.

Although I have never done it, I guess you could pipe a standard 4 x 10 in a horizontal position but you'd have to give it a healthy slope (at least 1/2" per foot) and use a reverse return to gang the collectors together.

Comments

  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    I've been reading the

    thread on solar tubes vs flat panels with great interest. Paul posted some pictures of some nice looking jobs where the panels are horizontal and drainback. How does this work? I was reading Tom Lanes book on solar lessons and he gave all sorts of rules of slant to make sure the system would drain properly when the pump turns off. As I lay waiting for my approval from my neighborhood architectural committee to install my solar system I am questioning my design ideas to go vertical flat panels and now am wondering about going horizontal. I like the looks of the horizontal but was going to go with 4- 4 x 10 water panels lined up vertical on the roof. If I went horizontal I don't know if I can get all 4 because of existing skylights. I like the fact that to tilt a horizontal more for heating you dont have to raise the top as high off the roof. How would you pipe it so the slant is good enough? WW

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  • caution will robinson, CAUTION......

    Wayne, If you do decide to do that, either use antifreeze (cheap insurance), or find a internal solder plug. If you let water accumulate in the capped off header, it WILL come back to bite you.... (Been there, done that, got scorch marks on my arms from soldering the repairs...)

    On most solar collectors I've worked with, you can pull up on the outlet header and get even more drain back pitch. Just make sure you firmly lock it in place.

    Some Euro collectors are serpentine and as such can NOT be used with drain back. The Germans looked at me like I was crazy when I explained the principles of operation for a drain back solar system..."We NEVER do anything but closed loop" was the response I got. I think it probably has to do with the high head, high watt pumps necessary to over come the system height. A simple time delay circuit, or other means could be used to time in a much smaller, lower watt pump once siphon has been established. Or program a Stratos to do it for you... (You listening ST? :-)

    Happy Solar Hydronicing!

    ME
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    The solar contractor

    I'm trading services with uses AET flat panels. On the Website they have both vertical and horizontal. I'm just having trouble picturing how to slope everything. The chapter in Tom Lanes book on drainback slope has my head spinning. Yeah, Yeah I get it. Be sure it can drain. Now I'm concerned to death. WW

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  • hot_rod
    hot_rod Member Posts: 21,793
    another horizontal panel idea

    the boys at Cedar Mountain have 2X10 panels built for flat roof applications to lessen the roofline "look". Although these pictured look like 4X8's. Steep angle might indicate a system "slanted" to heating loads.

    While this is not a drainback installation it could certainly be adjusted to be one. This is also considered a sawtooth mount where the distance is calculated so sun's rays are never blocked by the panel in front.

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Good seeing you last week HR..

    Sorry we couldn't have spent more time together. Maybe next time we can make a run to the mountains.

    So, how is your new life as a "Solar Powered Road Warrior"?

    Got lots of positive feedback from your presentations.

    ME
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,226
    After tax credits...

    ...went away, I inherited a bunch of orphan systems to maintain. Panels installed with only a little slope froze because of the slight dip that can happen with the tubes running between headers. But really, the thing that has frozen more panels around here than anything is sticky air vents. Design without them if possible.

    Yours, Larry
  • Tim_34
    Tim_34 Member Posts: 56
    2 x 8 panels

    hr

    If the panels in your photo are 2 x 8's does it follow that the guys standing near the panels are 3 and a half feet tall?

    Maybe I have been out in the sun too long. ;-)
  • Mike Dunn
    Mike Dunn Member Posts: 189
    I noticed

    this too. Maybe there off to the yellow brick road.
  • hot_rod
    hot_rod Member Posts: 21,793
    They're hobbits!

    actually I noted those in the picture look like 4x8 in that post above.

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 21,793
    the correct 2X10 pic

    from the Cedar Mountain install.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • CC.Rob_4
    CC.Rob_4 Member Posts: 37
    two questions

    1) if this is a sawtooth-type mount, what latitude is this installation? Spacing seems tight, or I'm misled by the angle of the collectors and the photo.

    2) what is the overall system performance penalty, if any, that comes with these smaller panels?

    Thanks.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    I was just re-reading the chapter

    in the Tom Lane book on drainback systems. He sez plain as day in one section never use horizontal on South facing roofs. He says there's too much cahnce for a sag in the lines for water to pool and not drain back from. Too bad. I like the look of the horizontal. WW

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This discussion has been closed.