What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Avionics fans

B

bob888

Well Known Member
A seemingly trivial question: Like many, I am installing computer type fans in the glare shield. My question is whether to wire them to a separate switch or just run them through the avionics master. In other words, is there ever a time when you would want them off?
 
bob888 said:
A seemingly trivial question: Like many, I am installing computer type fans in the glare shield. My question is whether to wire them to a separate switch or just run them through the avionics master. In other words, is there ever a time when you would want them off?
Click to expand...
If you had an alternator failure or some type of electrical failure you might want to shed non-essential loads. You might want to be able to manually switch these fans off in such a situation.
 
My question is, do you even need these fans?

Many RV's are flying without them.

If you are worried, cut some nice looking vent holes in the top of the glair shield and let the heat rise on its own.

(Why add the weight and complexity?)
 
There is no correct answer to your question. I installed mine on a switch, but they are on about 80% of the time. Having them on all the time doesn't hurt anything, unless you have an alternator failure and want to start shedding devices.

They are needed for us RV-10 folk up north. They also function as a defroster.
 
Last edited:
N941WR said:
My question is, do you even need these fans?

Many RV's are flying without them.

If you are worried, cut some nice looking vent holes in the top of the glair shield and let the heat rise on its own.

(Why add the weight and complexity?)
Click to expand...
Actually a better solution to the problem is this:
http://vansaircraft.com/cgi-bin/store.cgi?ident=1442822538-132-612&browse=heatvent&product=air-routing-devices
Weight penalty = 'little to none'
Complexity of installation = 'dirt simple'
Power demand = 0
reliability = 100%

I can testify these have been working flawlessly for me for the past 5 years now.
 
RVbySDI said:
Actually a better solution to the problem is this:
http://vansaircraft.com/cgi-bin/store.cgi?ident=1442822538-132-612&browse=heatvent&product=air-routing-devices
Weight penalty = 'little to none'
Complexity of installation = 'dirt simple'
Power demand = 0
reliability = 100%

I can testify these have been working flawlessly for me for the past 5 years now.
Click to expand...

Steve, do you fly in the rain? Back in the 70's Cessna used something similar. What they got was rusted and corodded avionics, and a SB to disconnect direct outside air cooling.

It's well known that heat is not good for electronics, but how much or where the threshold is is hard to say. I figure a couple of computer fans are cheap insurance. Mine are not switched but do run thru a pullable CB for emergency shutdown.
 
BobTurner said:
Steve, do you fly in the rain? Back in the 70's Cessna used something similar. What they got was rusted and corodded avionics, and a SB to disconnect direct outside air cooling.

It's well known that heat is not good for electronics, but how much or where the threshold is is hard to say. I figure a couple of computer fans are cheap insurance. Mine are not switched but do run thru a pullable CB for emergency shutdown.
Click to expand...
No, I do not fly in rain. I had my dual EFIS screens going black on a handful of occasions early on in my flying before these were installed. I installed these air diverters and have had no issues since. I can, however, see where if you did fly through rain on a regular basis this could be an issue but for VFR conditions you cannot beat the simplicity and low maintenance of this as a solution for getting cooling air to the electronics behind the panel.
 
mosture and thermal switch

I worked for Cessna Avionics at the time of moisture problems. At the time they were taking air from the outside scope and directing it directly to the avionics. They then took air from the cabin which did not have the moisture, problem solved. A automatic thermal switch might be the ans.
 
redbaron said:
...A automatic thermal switch might be the ans.
Click to expand...

I ask again, does the RV-10 need the added complexity?

Modern EFIS displays, radios, etc.put out a LOT less heat than comparable items did even 10 years ago.
 
Last edited:
Hardly Complex

2 avionics fan installed in the glare shield are hardly considered added complexity.

Like many others, I have 2 that are wired to the master and stay on at all times.
Can't beat the added defrost function and simplicity if those fans.
As an added bonus, the light humming sound when the engine is turned off reminds you to kill the master when you leave the airplane.

BTW Modern EFIS dynon for example have built in avionics fans but cannot remove heat from the compartment behind the instrument panel but merely
circulate warm air around.
 
I am installing 2 fans in my RV9A in parallel. The manufacturer of the fans calls for an external 4.7 uf capacitor to avoid unstable power.
I could use input from the brain trust,
Do I need to install the capacitors and if so do I just wire them from the power side of the fan to ground?
 
You must log in or register to reply here.
Back
Top