AAV Behavior Observations

[RRoller123]

I have a second AAV and have been wondering about its behavior over various temperatures and time. So today being well below zero and having nothing else to do, I thought I would look into this thing.

First quick observations:
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Soaked it at room temperature for a few hours (~72F).

Opening roughly a equilateral triangle. Pic below of a similar AAV (but not this actual one).



I put it outside for approximately an hour on the porch railing last night, before the cold front really hit us. (~32F).

Brought it inside, no change, still roughly an equilateral triangle opening.

Immediately put it into a preheated (~200F) oven for approximately an hour.

Took it out and it was completely closed, no daylight getting through at all.

SECOND SET OF OBSERVATIONS:
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How often do we get an opportunity to use a -11F temp chamber?

So this morning I put it out on the railing for about an hour. (~-11F, 25mph winds)

It fully opened, to the point where you could see a second sliver of light getting through up the side of the triangle.

This is the actual AAV:



Brought it inside and just let it sit on the table at ~72F (8:24 a.m.)

At just about 7 minutes, the sliver was almost gone and the opening was back to an equilateral triangle.

20 minutes later, the opening was still an equilateral triangle, and remained thus, even though the housing was still cold to the touch.

So it responded within about 8 minutes when going from very cold to room temperature. And it does not appear to be thermally linked to the housing very much, more so to the surrounding air temperature.

(bored yet?)

THIRD SET OF OBSERVATIONS:
====================

This time I tried to determine how quickly the opening would close, from cold state, by putting it in the oven (~170F this time) and removing it every 2 minutes to observe the opening.

Soaked it outside on the railing at ~5F for about an hour.

Brought it in (the opening was the ubiquitous triangle) and put it directly in the ~170F oven.

after 2 minutes: No change at all.
after 4 minutes: No change at all.
after 6 minutes: No change at all.

after 8 minutes: Slight decrease in the opening.

after 10 minutes: completely closed.

So. I am assuming that this thing is working properly. It appears to be. The conclusion I have is that the AAV, probably because of how the bimetallic is wound, has a sort of "mechanical delay" designed in, about 7 or 8 minutes or so, and probably only marginally needs the electrical input to change rapidly. If you get in and start driving, the engine warms up pretty quickly. (None of these observations were with the 12VDC electrical boost).

Once I get my car restarted after all the fooling around I have done with it this Winter, I will pull the existing AAV and see how it compares to this one.

I also am really curious to see if the electrical input causes the opening to close any more quickly, and if it is significant. I will report back when I experiment with doing that.

OK, go back to sleep, it is cold here and I clearly have too much free time on my hands today.

Pete

[RRoller123]

I did a little more investigation into how this little device does its job and have these further observations:

I started my Spider (~32F environment) yesterday morning, and immediately unplugged the connector from the mounted AAV and plugged it into my second AAV which I could hold in my hand and observe as the heater element in it did its job. Immediately also started the stopwatch.

For almost 4 minutes, there was no response at all, the opening remained approximately an equilateral triangle.

Then the housing started to feel warm to the touch, and the opening started to close. It took about 2 more minutes for it to fully close. So in about 6 minutes it was completely closed, using only the heater element to actuate it. It may close a little more quickly when mounted on the head as it would get more heat that way.

The heating element appears to be entirely contained inside the long spur that has the connector on the end, as that is the only part that felt warm. The large disc part of the AAV, that has the 2 airway tubes, remained cool to the touch.

I was somewhat surprised by two things. First, my Spider ran well and warmed up well without the connector attached to the mounted AAV.

Second, after unplugging the handheld AAV, it cooled down and opened back up fully, very quickly, like in a minute or two. The thermal mass of the AAV does not appear to be strongly thermally linked to the bimetallic actuator.

So my conclusion is that the heater element is far more important in helping keeping the disc closed once the engine warms up?

Pete

(on to something else to fool around with)

[lglade]

Thanks for the thoughtful post. I'm planning to remove mine and give it a good cleaning when the opportunity presents itself, so in the meantime I've been reading up on the AAV and have been wondering about some of these details. Anyway, thanks for filling in my knowledge gaps.