AC Infinity Controller 67 accuracy (or not)

I've had a controller 67 for a year or so. Its a nice upgrade from the standard controller and has worked like a charm thus far.
I recently noticed its readings and a Inkbird 608T differed by 8-9 % RH, A bag of cheap digital mini hydrometers were also reading far lower than the AC probe.

I figured the cheaper ones were wrong but decided to test against some other sensors I have.

Unconvinced, I wired up three different sensors to a raspberry pi, a BME280, an ATH20, and a SCD30. I let them run and logged data for a few days. All three are within a few % RH of one another. More importantly, all three are 8-9% lower than the AC probe.

There's a provision in the AC controller to enter an offset so its an easy fix.

I write this primarily because 8-9% is far enough off to be problematic; e.g. 70% night humidity is risky, 61% is fine.

In the advanced setting the humidity calibration has a + - 8% offset for you.

enjoy.

I mentioned that

When you toggle thorough the settings, it’s along the same area as the on and off . Adv, then toggle the other buttons to select what your after.

oh I am sorry, thought you were asking. Will read better

No worries

Frankly I'm still surprised the "Swiss made sensor" in the AC probe is so far off.

it looks like all the new fans also mimic the controller . Perhaps this is the weaker link rather than the probe.

Nah, the controller simply displays the output from the sensor.

Your just under the belief that Swiss should be more accurate that’s all.

The AC documentation touted the "Swiss-made sensor'. Any hygrometer should be better than +9 % RH.

10/12 cheapo digital hygrometers were closer than the AC Infinity readings

I tested mine along with the inkbird, my Wifi, and a bunch of the little ones I put in jars then adjusted them all accordingly. The AC Infinity one was within about 1-2% for me. A ziploc bag, some salt and water, etc. and it took a day to sort. Probably worth doing. a few times a year just to make sure. I always figure this stuff is really 'ballpark' no matter what.

Billy the Mountain said:

The AC documentation touted the "Swiss-made sensor'. Any hygrometer should be better than +9 % RH.

10/12 cheapo digital hygrometers were closer than the AC Infinity readings

Click to expand...

Did you contact AC Infinity?

I sandwiched three sensors between two 62% Boveda packs in their little ziplock. The AC Infinity read 1% low, Inkbird was 3% high and the ecowitt wi-fi gateway was 4% high. I had previously entered a 7% correction in the Inkbird based on comparison to several other devices, now that correction is 3%.
The next test will be running them all together in the real world.

I tried the salt but it was too slow, things would stabilize in something like an hour with the Boveda packs.

No, the max -8% offset in the settings compensates. The readings now mirror the other sensors. I don't recall if I ever tried the salt slurry 75% RH test with the AC probe. I do it with the cheapo tiny ones and write the difference on a piece of tape.

Billy the Mountain said:

No, the max -8% offset in the settings compensates. The readings now mirror the other sensors. I don't recall if I ever tried the salt slurry 75% RH test with the AC probe. I do it with the cheapo tiny ones and write the difference on a piece of tape.

Click to expand...

One day when I was remote working here at home, I set up a couple salt calibration stations, did one that had my AC Infinity probe, my Inkbird and my wifi/bt temp/hygro then a second that had all my mini's. I actually have a bunch of boost packs so I certainly could try that method too.

Of course, with only one calibration point you're really only sure that you're accurate at 75% or at 62% and probably the further away you get from that, the more wonky things will be.