|I purchased my model 5814 heated pitot/static tube from
another RV builder. The pitot tube did not come with any
information so I didn't know what size wire to run or what amount of
current it would draw. I also plan on using either heated seats or
heated vests so I want to be sure I know all the amperage
The chart below represents the current flow (in seconds) for the pitot tube over an approximate 10 minute period. The temperature of the probe after that period of time was 425 degrees and slowly climbing. The initial spike of almost 20 amps occurred as I connected the ammeter to the pitot tube. I should have connected the test to a toggle switch but I didn't have one handy. The rate of current draw decrease, corresponded with a decrease in the rate of heat increase at the pitot tube. At the end of almost 10 minutes, the rate of current draw stabilized at approximately 9 amps.
I don't know what the ultimate temperature of the pitot tube is suppose to be, but 425 degrees seems excessive. I have to think that the airflow over the pitot tube in flight would keep this temperature down but without a thermocouple on the pitot tube in flight, I'll probably never know. I will re-run this test and document the pitot temperature vs. time later this week.
It was brought to my attention that during actual operation the airflow in flight would tend to cool the pitot tube and might change these readings. Maybe the test should be completed with the pitot tube submerged in water. Maybe I'll do this test another time.
Click on this link to see the actual data values that correspond with the chart. The data values clearly show the current draw trend as it stabilizes as time increases.
I'd be interested to know anyone else's interpretation of the data.