"By the way, I cannot understand why you van guys don't get a Webasto Ailrtop heater. Installation and costs, including a 2500W inverter, all hidden nice in compartment of sleeper, was appr. $1800. Turn on the switch/temp. setting, and heat pours out in two minutes. I stay warm in 63" sleeper, and fuel cost is negligible. Stock truck with 3 batteries, and I added a fourth. In the summer, turn on a rotating fan, get a roof fan, etc. If 90 and muggy, then I run the motor."
I am very satisfied with the Webasto, and I'm certain the Espar is of comparable quality. I just got the Airtop and didn't bother pricing the Espar.