Of course, it depends on how much you idle for heat. If it will take 15 months of cold weather use for you, then you idle very little.
For those who idle all winter for heat, the typical (in many cases conservative) idle time is 8 hours a day, 5 days a week. Some as much as 12 hours a day. Teams will idle much less, of course. If you stay out over the weekends, sometimes sitting the whole time, your idle time becomes significant over the course of the colder months. Weekly idle times will be 60 or more, and if you idle 10 hours a day during the week, and then say, 24 more on the weekends, you're at 74 for some weeks. Many people will idle more than that.
But, if you idle 8 hours a day, 5 days a week, for 30 weeks, that's 1200 hours of idling. Assuming .8 gallon per hour burned, at $2.75 a gallon, that's $2640. That works out to $2.20 an hour.
For a 40 hour week of idling, that's $88. At that hour and fuel cost rate, the $1400 Espar costs out at 16 weeks. And that's really at a conservatively typical rate.
Each vehicle is different, of course, but most Ford and Chevy vans, for example, will burn a minimum of .8 gallon an hour, usually right at 1 gallon per. (This Sprinter burns only about a third per hour, tho.) But you see it all the time, where a van or truck (solo drivers, mainly) will run loaded for about 40 hours in a week, and the vast majority of the rest of the time they're idling. It's not uncommon at all for one of these vehicles to idle 60 hours during the week, and then another 30 or more over the weekend.
So, if you idle as much as 13 hours a day averaged over 7 days (91 hours a week), you wind up idling for 2730 hours. Even at .8 gal/hr, that's $200 a week. And at 1 gal/hr it's $250 a week.
At $200 a week, the Espar pays for itself in 7 weeks, and at $250 a week it's done in 5 1/2 weeks.
Of course, the heater will burn up .06 gal/hr, so that needs to be factored in. At the 91 hours a week it'll burn about $15 a week in fuel, and at the 40 hours it'll burn about $6.60 a week.
So, for most people, it'll pay for itself somewhere between 8 and 14 weeks. YMMV
But if you even take the most conservative numbers, say just 16 weeks of idling and idle 8 hours a day for 5 days, no idle on the weekends, then the numbers come out to 640 idle hours per winter. At $2.75 a gallon, and at .8 gal.hr, that's $1408 per year. That's the same cost as the heater. But the heater will burn about $105 in fuel during those same 640 hours.
So you'll spend $1500 for the heater and the fuel it burns for the first year, instead of spending $1408 on idling fuel. But the next year you'll only be spending the $105 or so for fuel, and the rest of it goes into your pocket.
It's a no-brainer.
