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Vans or CiES Fuel Senders

Everwild

Well Known Member
Working on the tanks for a -10 and debating whether to use the Vans resistive float sensors or upgrade to CiES units.

The CiES units are reported to be very accurate and reliable, but they are $605 each vs $46.

Any PIREPs on the accuracy of the Vans units? Any regrets after installing one or the other?

Thanks!
 
On my -8, I plan on using the Vans sensors, but mounting a second in the rear baffle at the outboard bay, then wiring them in series. I’m happy with my vans gauges in the -4 I have.. I can’t justify the CIES price..
 
On my 10 I used the Vans gauges [typo! Should have said senders], but I ran the analog data thru the GRT EFIS and calibrated then in 5 gal increments. They’re incredibly accurate. Only negative is that they can’t tell the difference between 25 gal or 30 gal, due to the wing dihedral.
 
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Might be hard to justify the cost, but the CiES senders have a much higher MTBF (listed at 90,000 hours) and are much more accurate. There is a reason these senders are being used on many certified airplanes today.

Whether or not it's worth it to you is something only you can answer.
 
I'm usually happy to spend a few bucks on something shiny but this one did not make the cut. I'm a techie and love well designed technology. I have a full G3X setup and putting one in the other plane now too. I have every cool doodad in existence that improves safety, accuracy, etc.

The Vans floats work extremely well and in 900 flight hours over ~4 years I have never once thought "the other brand would have been nice." Ever. Don't waste your money :)
 
I don't understand the current craze with installing CiES fuel senders because they are "more accurate". At 12 Xs the price.? Who is relying on a fuel gauge indication so much that they need that level of accuracy? With the engine instrumentation we all have, and fuel flow readouts, and known fuel burn rates, is one still going to look at the fuel gauge and say nope, "I'm good".? I don't get it.
 
How much fuel do I have...?

I don't understand the current craze with installing CiES fuel senders because they are "more accurate". At 12 Xs the price.? Who is relying on a fuel gauge indication so much that they need that level of accuracy? With the engine instrumentation we all have, and fuel flow readouts, and known fuel burn rates, is one still going to look at the fuel gauge and say nope, "I'm good".? I don't get it.

+1 agreed. Dip your tanks during preflight so you know actual fuel on board. I overestimate my fuel flow to have a buffer during cruise. I leave at least a 45 minute safety fuel on board at destination. I also have a 2-2.5 hour butt so that is easily made. :) My knee board has time on tank L/R and estimated fuel remaining. I look at the fuel gauges to see if they agree with my stopwatch and calculations, not for confirmation of how much fuel I have. Don't trust 'em. Look nice in the panel, though....;) My senders are Vans. Good enough for 1200+ hours so far.... The left tank sender is screwing up so I will be replacing it this Winter. And probably the right as well, while I am in the ProSeal goop phase..... Bought my replacements years ago......for $25 each, as I recall....:)
 
Low fuel warning sensors?

Thanks for all of the replies so far!

I'm transitioning from the high wing world and getting used to low wing tank changes every 30 minutes and calculating "estimating" fuel burn. To me, the process seems like an accurate guess as to how much fuel is remaining in each wing. Especially in the Piper Warrior I'm currently flying with less than modern systems. Anytime I'm near a calculated or indicated 5 gallons or so remaining in each tank, range anxiety really starts to set in due to the inexactness of it all.

I'm surprised that pilots generally can't or don't trust their fuel senders. Isn't that an inherent problem?

Having a fuel totalizer will be a huge improvement and will show with a high degree of accuracy TOTAL fuel onboard. But you still risk the chance of emptying a tank with inattention or bad math. Or getting low and possibly unporting a tank during critical phases of flight at the end of a mission.

I'm kinda talking myself into the CiES senders as I think this is a pretty important consideration. Doesn't mean that I would stop doing the calculations but would know with a much higher degree of confidence that my math checks with the gauges.

Biggest downside is definitely the cost. But maybe accurate fuel measurement is more important than some other option I had planned.

Another option I discovered are low fuel optic sensors. Anyone have experience with these or something similar?

https://www.aircraftextras.com/FuelSensor1.htm

If they work, they would also give you that extra layer of insurance that the math isn't suspect. And they are a significant cost savings over the CiES senders.

Choices, choices.
 
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Thanks for all of the replies so far!

I'm transitioning from the high wing world and getting used to low wing tank changes every 30 minutes and calculating "estimating" fuel burn. To me, the process seems like an accurate guess as to how much fuel is remaining in each wing. Especially in the Piper Warrior I'm currently flying with less than modern systems. Anytime I'm near a calculated or indicated 5 gallons or so remaining in each tank, range anxiety really starts to set in due to the inexactness of it all.

I'm surprised that pilots generally can't or don't trust their fuel senders. Isn't that an inherent problem?

Having a fuel totalizer will be a huge improvement and will show with a high degree of accuracy TOTAL fuel onboard. But you still risk the chance of emptying a tank with inattention or bad math. Or getting low and possibly unporting a tank during critical phases of flight at the end of a mission.

I'm kinda talking myself into the CiES senders as I think this is a pretty important consideration. Doesn't mean that I would stop doing the calculations but would know with a much higher degree of confidence that my math checks with the gauges.

Biggest downside is definitely the cost. But maybe accurate fuel measurement is more important than some other option I had planned.

Another option I discovered are low fuel optic sensors. Anyone have experience with these or something similar?

https://www.aircraftextras.com/FuelSensor1.htm

If they work, they would also give you that extra layer of insurance that the math isn't suspect. And they are a significant cost savings over the CiES senders.

Choices, choices.
You don’t have to flip tanks every 30 minutes.. I use my totalizer and flip tanks at a whole number.. keeps the math simple. For example, my -4 has 16 Gallon tanks for 32 total. I start on one, fly and after using 5 gallons (27 remaining on my totalizer) I switch to the other one. I’ll run that as long as I want, knowing that when my totalizer gets to 21, it’ll be empty (5+16), then me first tank has 11 remaining (16- the first 5)
 
Thanks Tom for the insight! Makes perfect sense.

I currently don't really have an "accurate" fuel burn in the Warrior outside of the POH, or the probably not so accurate fuel burn needle. I was taught to switch every 30 mins and do the math.

Your method is way easier and makes more sense frankly. Using the totalizer, burn whatever amount keeps the imbalance under control and is easy to calculate.

Anyone know if a G3X can alert you at gallons remaining or a gallons burned setting?
 
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On my -8, I plan on using the Vans sensors, but mounting a second in the rear baffle at the outboard bay, then wiring them in series. I’m happy with my vans gauges in the -4 I have.. I can’t justify the CIES price..

Wiring two float sender resistors on series? I’m lost as to what it is you are trying to do, but as stated this will not work.

There is no reason to think standard Van’s float sender will not work perfectly for decades.

Carl
 
I have Vans senders connected to a Dynon EFIS in my RV7A. During Phase 1 testing, I repeatedly checked the senders vs. Dynon fuel flow sensor vs. actual fuel consumed a purchased at the fuel pump. I found agreement within 1 gallon.

A caveat is that anything above about 16 gallons in the tank maxes out the sensor.

David
 
Wiring two float sender resistors on series? I’m lost as to what it is you are trying to do, but as stated this will not work.

There is no reason to think standard Van’s float sender will not work perfectly for decades.

Carl

It’s my understanding that wiring two float senders in series, (one in the stock location, the other in the rear baffle to read the end bay, similar to the way Vans shown the optional “Flop Tube” tank, but outboard.) will allow the fuel gauges to read all the fuel. Starting from full, as soon as the level drops, the outboard float starts moving, and you’ll get continual resistance changes throughout the entire fuel tank range. I believe other manufacturers (Beech) do it this way. Like others said, I tend to use the totalizer anyway, but while I’m building, why not try to make something better? The only risk is an additional leak potential if not sealed correctly..

Who stated that this would not work? Perhaps you thought I was going to install both senders in the same location? You’re right, that wouldn’t accomplish anything.
 
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It’s my understanding that wiring two float senders in series, (one in the stock location, the other in the rear baffle to read the end bay) will allow the fuel gauges to read all the fuel. Starting from full, as soon as the level drops, the outboard float starts moving, and you’ll get continual resistance changes throughout the entire fuel tank range. I believe other manufacturers (Beech) do it this way. Like others said, I tend to use the totalizer anyway, but while I’m building, why not try to make something better? The only risk is an additional leak potential if not sealed correctly..

The problem with the two sensor approach is that you are introducing a second potential failure point. Wired in series, if either sensor fails, then the reading will be wrong. These sensors, although they do seem to work fine for them most part, are not invulnerable to failure.

And this risk is incurred only to read the top 4 gallons - which are the least important gallons to know about. My tanks hold 21 gallons. My read-out shows 17 gallons when the tanks are full, and stays at 17 gallons until the level drops below 17 gallons. If I'm flying and the display shows 17 gallons, I know I have at least 17 gallons. Whether I have 17, 18, 19, 20 ? I really don't care.
 
It’s my understanding that wiring two float senders in series, (one in the stock location, the other in the rear baffle to read the end bay, similar to the way Vans shown the optional “Flop Tube” tank, but outboard.) will allow the fuel gauges to read all the fuel. Starting from full, as soon as the level drops, the outboard float starts moving, and you’ll get continual resistance changes throughout the entire fuel tank range. I believe other manufacturers (Beech) do it this way. Like others said, I tend to use the totalizer anyway, but while I’m building, why not try to make something better? The only risk is an additional leak potential if not sealed correctly..

Who stated that this would not work? Perhaps you thought I was going to install both senders in the same location? You’re right, that wouldn’t accomplish anything.

But - most EMS systems assume a linear change in resistance with the change in fuel level. This two in series will not be linear at all. Back in the Grand Rapids engine monitor days you had to create the high school line equation (Y=MX+B) to set the slope and the like offset for the line (M and B). For newer systems the EFIS computer does the math for you.

So before creating this solution verify your EMS can operate with non linear inputs. You may go through a lot of trouble with little to no gain. Whatever you do make sure the indication is accurate when fuel is at half full and below.

Carl
 
But - most EMS systems assume a linear change in resistance with the change in fuel level. This two in series will not be linear at all. Back in the Grand Rapids engine monitor days you had to create the high school line equation (Y=MX+B) to set the slope and the like offset for the line (M and B). For newer systems the EFIS computer does the math for you.

So before creating this solution verify your EMS can operate with non linear inputs. You may go through a lot of trouble with little to no gain. Whatever you do make sure the indication is accurate when fuel is at half full and below.

Carl

Good point. I was under the assumption that most fuel calibration setups was done by adding a set amount of fuel, then telling the efis what you added, then adding another calibrated amount..ect..until full.
 
Good point. I was under the assumption that most fuel calibration setups was done by adding a set amount of fuel, then telling the efis what you added, then adding another calibrated amount..ect..until full.

They are calibrated as you list - but still assume a straight line between calibration points (at least the ones I’m familiar with).

Carl
 
This is really a non-issue. You can even set your G3X to give you a message ever X gallons or XX minutes to remind you to switch tanks. The Vans floats are more than sufficient for you to use to figure out how much fuel is in the tanks without the totalizer, mine have never been off by a noticeable amount.

If you really want to spend the money, I'm sure the fancy floats are very pretty, but functionally they don't really get you anything.
 
CIES lover

I had my Vans sender fail on my 12 after 7 hours of flight. This was the second Stewart Warner sensor I have replaced. Replaced one in my 7. I was the 12 Guinea Pig. I hope to never have to replace a sender again. For me it is worth the cost. But yes I only need one on the 12.
 
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