Suggestions in re: These Ventilation Cartoons?

[Ted Brown]

I've seen one too and couldn't find it either.

I agree the winter air doesn't intrude but it does move through the back part. The difference being how slow it moves. Woods calls it "wafting gently", if I remember correctly - the air in the front section and along the floor of the back section is cold, like outside. The chickens breath out warm air, which rises. As it rises, it cools. As it cools, it sinks but it can't sink down on the chickens because they have continued to breath more warm air. So it wafts down the slope of the front roof. The warm air rising (and the cooling air sinking) pull (and push) fresh air in along the bottom of the open front)

This is not my understanding and I do not recall reading this in Woods' book. I have read descriptions of an "air cushion", although I think those were in threads on BYC. Also recall reading of holding a ribbon (or candle?) while in the back section as a test to illustrate the lack of air movement.

If the air were to move in the manner you describe the birds would be roosting in a draft albeit not a strong one. Also can say from personal experience that I have never felt movement of air while in the back section even on a windy winter day.

 

[Ted Brown]

@Ted Brown Does this look right for winter?

View attachment 3154806

I would have the circular movement go further back to encompass all of the lower front section.

 

[3KillerBs]

I would have the circular movement go further back to encompass all of the lower front section.

OK. that's easy to fix.

 

[saysfaa]

"With this construction there need be no fear of "trapping" the warm moist air back of monitor windows, which seems to worry some theorists" page 117
...
Fowls do not sweat, they lose very little heat thru the skin because the feathers are almost perfect insulation. The urine of fowls contains very little moisture. The fowl gets rid of excess moisture and body heat thru the exhaled breath. If this moisture-laden air has an opportunity to condense on cold ceiling, walls or windows, instead of being carried off by good circulation of fresh-air thru an open front, it may be seen as dampness or frost.
...
Thru many seasons I have carefully tested the circulation of air in Woods houses under different conditions, in calm weather, in driving rain and snow storms, and great gales, with the house empty, and with fowls working in litter, or at night with them at rest on the roost. Smoke was used to test the air currents in various parts of the house. During storms the average extreme penetration of the wind was tested, marking the point where it could be felt upon face or moistened finger. Always the actual penetration of either snow or rain was very much less, seldom more than a few inches back of the wire. In Fig. 53, the upper diagram shows end elevation of house and path of circulation of air indicated by arrows. It will be noted that the cold out-door air enters all along the open front except close up near roof, that it is deflected toward the floor and curves upward just past center of house. If no dropping board is used, it flows up above the roosts, curves toward the monitor and down under the low front roof passing out at top of open front. There are variations due to outside conditions and movement of fowls or attendant in the house, but the air current is fairly constant as shown. Where a dropping board is used the direction of air current is about the same except that the exchange of air under the board is slower, but by day is kept agitated by fowls constantly running in and out. Dropping board and air current below, shown in dotted lines. Of course, when monitor windows are opened there is a strong air current up and out thru these windows. This is not a draft. (See discussion of drafts in Chapter 1.)"
page 120

Diagram two posts down. I don't know how to get a picture onto the post from the main computer. I'll edit again if I can figure it out.... editing on the phone worked.

Adding second, semi-related picture, while I have them found.

 

[saysfaa]

You are right Ted, in not feeling it in the back. The author didn't either because it is too slow to feel it even with a moistened finger. But the smoke showed it.

 

[3KillerBs]

Unfortunately, the picture won't open.

 

[saysfaa]

Does it now? I tried something else.

 

[3KillerBs]

Does it now? I tried something else.

Yes. So it looks like a very gentle, soft circulation without noticeable drafts.

I will edit the diagram again.

 

[3KillerBs]

 

[Ted Brown]

@saysfaa I stand corrected, thank you for the clarification.

@3KillerBs Your revised diagram assumes that no dropping board is used. In my coop I have about drop board width of 42". Obviously that will affect air flow significantly. Not trying to complicate your life...