Also, I have readings from the tach where there is no paint dot???...... White paint dots don’t always work… you should be using a strip of proper tachometer ‘reflective tape’. It’s cheap and readily available. The other problem is that when you put it on a location where other blades pass by the laser, it’s possible to get false readings. Is there someplace you can put the reflective tape where it doesn’t also cross the other blades. Can you get access to the end panels of the impeller or a rotational part of the motor.?
Pulling down gently on the front of the unit distorts the wall bracket ..... My goodness, that’s not much of a factor of safety, is it?
I have always heard using flex duct is not good for flow..... No kidding. I looked at the pictures and it does not look like a good set up at all. The idea is to test and not change the conditions by adding any system resistance. It’s always better to test on the inlet side of a unit due to the fact there is less turbulence than after the unit. However, that can be a problem if there isn’t any available space.
Doing a second flow survey the numbers dropped and the air cooled???....... Yup… not easily to test a moving target.
I’ve not given up yet, still looking at obtaining the RPM of the fan.
Seeing a few readings that look like possible RPM?? 256??
Reading the manual, why not? I believe that I can run FAN ONLY at fixed three speeds could work, but the defrost still overrides that function.
Looking at your link to ziehl-abegg.com, the lowest speed listed for Size 100 was around 600 RPM???
Also, a nice explanation of CROSS FLOW FANS, THANK YOU.
Looking for something repeatable, I marked each of the available divisions of the fan, maybe 1 mm wide, on the continuous rim.
Not an easy view, through the auto louver, The horizontal diverter, and a heavy wire grille(structural?) about five inches back the fan.
While standing on a ladder. Similar to a cheap circus act.
NEXT: attempting a larger paint spot on a blade. You mentioned the reflective tape, I have it in stock!, but it did not adhere well to the blower for my boiler, and that one I could get my fingers on.
I ordered a non-contact amprobe that claims 1 milliamp resolution, AC or DC non-contact clamp, and microamps using the probes.
Uses the Hall effect, cool stuff.
And hopefully with a few known RPM points...
If nothing else we have a $$$ gift toaster that takes forever, with this meter I may be able to see if it is working or if the bread is simply getting stale as I wait.
I did a couple of surveys of the return flow to calculate the mean (average)...
Then I remembered this:
“Beware of averages. The average person has one breast and one testicle.”
— Dixie Lee Ray a sharp old girl.
Thank you for your help.