Originally Posted by Biancoblu
My Interstate Ext 2014.5 has a way excessive LPG consumption rate. As per manual on full load should not be over 0,58 gal per hour; however just with AC on, it goes well beyond 1,75 gal per hour.
The dealer checked for any leak and none was found. They say it could be normal. I don't buy it!
Any advise? It is frankly very annoying to look for a LPG station every 12 hrs which is what last the tank.
Thanks in advance
My manuals don't give a 0.58 gallons/hour figure. May I ask where that number came from? Did that 1.78 gallons per hour figure come from comparing the amount of propane in your last fill-up to the engine hours on the generator?
Anyway, you may be suffering from a misconception. When the tank monitor shows
"Empty" that just means the tank is less than 1/3 full, not that it's actually empty. Just as when it shows 1/3 full that lust means it's somewhere between 1/3 and 2/3 full. The only time the monitor will ever show the tank as "Full" is if you fill it in cold weather, and leave it until warm weather; expansion can just barely get the liquid propane level up to where the monitor will show full. At least, that's how it works on mine.
The on-board tank holds 14 gallons at 78% full, according to my 2012 Airstream Interstate manual. If you could
fill the tank brim full, it would hold 18 gallons. Of course the OPD valve prevents that. But the point is, 1/3 full on the tank monitor is 6 gallons, 2/3 full is 12 gallons.
So, assuming you're refilling as soon as the tank monitor shows
"Empty" and not when all the propane-fueled appliances shut off due to a truly empty tank, you're refilling when you've got somewhere between 0 and 5 gallons left (somewhere less than 1/3 full), and you should be getting somewhere between 9 and 14 gallons of propane per fill-up. Last time you filled the tank, how much propane did you pay for?
Since I have consumption figures for the generator, but not for the furnace, water heater, or stove burners, let's use the generator for illustration purposes. A 2.5kW Onan generator uses 1.0 pounds per hour at no load, 1.5 pounds per hour at half load, and 2.5 pounds per hour at full load. Pounds, not gallons.
Propane weighs 4.24 pounds per gallon at 60°F and 4.09 pounds per gallon at 80°F, which is about the lowest temperature that most people would turn on the AC. At 90°F, it weighs right at 4.0 pounds per gallon, and you'd be running your AC a lot. So let's use that figure.
At 90°F, 14 gallons weighs 56 pounds. At full load, you'd use up your propane in (56÷2.5=) 22.4 hours. BUT, your tank monitor would show empty when you've got about 5 gallons left, so at that point you'd actually have only used 9 gallons, or 36 pounds. At full load, you'd run the generator (36÷2.5=) 14.4 hours before the tank monitor showed
empty. But you'd still have another 8 hours of runtime left.
Now, if you were also running the water heater on propane at the same time to keep from overloading your generator by running the water heater on electicity, it's not at all unreasonable for a tank of propane to show that it needs to be refilled in just 12 hours, though you might have a full 18 hours of tank capacity.
Does that help at all, or did I just confuse you more?