G

gofast

Member
Quick question. I have been enjoying my dual screen G3X Touch in my RV7. Yesterday, I powered the system to update the databases. While it was completing, I finished my pre-flight. When I came to remove the pitot cover, I discovered my pitot heat was on...it works! However, it was 85' in my hangar. After I came back from flying in 80' F air, the pitot probe was still really hot. I'm 7 states away from my installer. What should I troubleshoot first? Any ideas?

Thanks!
 
What is the question? Do you believe you have a faulty on-off switch?
If the heat is always on this sounds normal to me.
 
heat

If it didn't melt the cover and you could touch it without leaving skin behind it was doing it's job, regulating heat.
 
There is no on/off switch in a regulated probe install. Why would the thing be hot/heated on an 80' day?
 
heat

It's probably at it's lowest setting. Ask garmin instead of here G3X guy is very responsive.
 
control.

If you have a heat element installed that you do not have control of and it stays on all the time. My question would be, Why? I don't think I would put any electric item on the down stream side of the buss that I could not shut off. We most often put up with the battery leads to the starter post and then the line that feeds the buss from there as being unprotected, but from the buss out you have a choice. Hope this helps. Yours as always R.E.A. III #80888
 
cb

It is supposed to have a circuit breaker according to Garmin manual.
My point is instead of incurring speculation on this forum contact the manufacturer if unsure of proper operation.
 
Page 4-4 of the G3X installation manual shows a 15 amp breaker and switch in the heater circuit.
 
I would think you would want a switch. If I remember correctly the heater uses a max of 12 amps so I wouldn't want to be running it all the time if not needed. I plan to have a switch for mine.
 
I'd put a switch in too.
But to answer your question:
The temperature sensor is, of necessity, inside the probe. But what matters is the temperature outside the probe. So some engineer has calculated that to keep the outside, tip of the probe at 40 F when it's 5 F air temperature, and that air is moving past at 200 mph, then the sensor has to be at, say, 150F, due to the temperature gradient between the sensor and the outside of the tube. So when you are not moving at all, the outside will be closer to 150F.
 
You going to get a fault message if you turn off with a switch?
Does anyone know or are you all just making guesses?
If anyone bothered to look at the wiring diagram a cb is called out but no switch.
Contact Garmin.
 
Last edited:
paul mosher said:
You going to get a fault message if you turn off with a switch?
Does anyone know or are you all just making guesses?
If anyone bothered to look at the wiring diagram a cb is called out but no switch.
Contact Garmin.
Click to expand...

I bothered to look at the wiring diagram and it does show a switch. The wirirng diagram actually shows a fuse and a switch. The installation manual also describes the operation of the discrete logic circuit on page 4-5, paragraph 4.5.4
 
I stand corrected.
I would like to know why he's getting a hot probe on the ground then.
 
There is no provision for weight on wheel switching in the logic circuit, when there is power to the probe it will heat up. Would be cool to have some sort of reliable WOW switch set up for RVs.
 
Regulation good?

I wouldn't think regulated pitot heat would offer and advantage, so please tell me if I'm missing something... It seems overly complex for such a simple thing as pitot heat (i.e. the old way of "turn on" if you need it, "turn off" if you don't).

-If the regulated version also has to be turned "on" to function, then what's the benefit of the regulated version over the non-regulated?
-It seems like if you turned the regulated one "on" for every flight, then perhaps the benefit is "set it and forget it," but what if the internal thermostat fails?
-If you hit icing conditions, doesn't it happen suddenly? Wouldn't you want the pitot heat on full bore, so that if you encountered ice, it would already have a "head start" so to speak in melting it, instead of trying to go from zero (luke warm) to hero upon encountering the icing conditions?
-The non-regulated version is $150 cheaper (Garmin anyway), so please somebody tell me why regulated is better..
 
Many advantages. Much less likely to melt the pitot cover to the probe when accidentally turned on during maintenance. Much less chance of severe burn injury since it only try's to maintain a temperature that is a little more than 25c. Less current draw, the two elements are regulated and only maintain the set temperature. Discrete output that provides inputs for CAS messages on the EFIS for status of pitot heat. Much less chance of leaving pitot heat turned on while on the ground and burning out the heater elements which happens a lot in other GA aircraft.
 
You must log in or register to reply here.