Barometric Pressure Sensor Location

There are some threads on this issue, both for the 830 as for, unfortunately, other Edges. But ley me summarise:

Firstly: de sensor (most likely a Bosch) is mounted on the printed circuit board of the Edge (there is only one PCB), just as all the other components, except the display and the buzzer.

The innerside of the Edge and so the snesor needs to be connected to the atmosphere to enable the p-sensor to work. The cover of the USB-port is fixed to the edge by a kind of rubber stem, which is held in its place by a small thin metal fork like plate, which in its turn is fastened by a small screw.

If you unscrew it and remove the lid and the stem, you can peek in that hole and at the end you can see a very tiny hole, white.

This is the 'entrance' to the Edge inner side. Most likely, the white stuff you see is an expanded PTFE (aka 'Teflon') membrane that should prevent liquid water coming in.

If you read the application notes of the Bosch sensor, you can see that Edge's construction is principally fault: the membrane size is too small and the membrane cannot be cleaned. The resistance to changing air pressure is so too big. Further is the inner volume of the Edge "too big" and all kind of temperature effects, even the sun yes or not shining on the Edge, does that large volume of air expand or shrink. By the limited size of the membrane, temperature changes so do change the air pressure in the Edge and so the recorded elevation. Proof for this assumption is for example the case that when I leave home and the Edge is at room temperature, say 20 °C and outside it is considerably colder, I see when starting my ride that the apparent elevation increases like ***, this while the start of my ride is essentially flat. This by the fact the cooling and shrinking air in the Edge cannot be replenished fast enough by outside air entering the Edge, so the pressure of the trapped air decreases and so apparent altitude increases. (Of course all depending measures as grade and cumulative elevation gain/drop are so faulty as well). Bosch describes that the 'dead volume' between the membrane and sensor opening must be as small as possible by a dedicated channel to the outside, which is not the case for the Edge.

So when rain or sweat enters the hole, mixed with dirt and salt, the membrane gets clogged and this cannot be removed easily. What I tried is cleaning the membrane with demi water (just some drops; you can use condensed steam from your kettle) and then repeatedly heat the Edge to 40 - 50 °C with a hair dryer to forcefully expand the air in it and so push any water outside. This with varying success, and sometimes only time will resolve it partially.

As far as I know Garmin has not made principle design improvements to this aspect in later series (At least to the 1030, 840), let alone you can not open the unit any more, as it is now glued instead of screwed.

Disappointingly, there has never been any reaction of Garmin, admitting that their design is faulty or I am wrong.