I bet the flow switch will only allow 8 gpm, plate on the side will also say 8 gpm unless they have just changed it. Coil is 1/2 which means higher pressure, but more pressure loss over the 250 ft (approx 200- 220 psi if I remember the chart approx). Only other thing I partially given up on is there thermostat, standard one gives up once a year, got tired of dealing with this issue.
Specs that should be asked or displayed I think on every hotbox ad should be
Coil size + length, heat rise, which temp limit thermostat+high limit switch is used (There are about 3 versions of thermostat's, 2 high limits that all look the same), burner brand (wayne/beckett) and which model is being used, and last but not least an option to get the exhaust conversion extension on the horizontal burner to connect to a standard chimney pipe.
Specs plus options for these if you are interested.
http://www.gcalargo.com/hot-boxes.php
The prices are good, and I even have one myself, just don't agree with all the marketing material out there. The frame, coil, burner assembly, fuel tank is still running 3.5 years later. Just about everything else has been replaced for more volume or reliability (broke too many times).
I got a new burner/hotbox about a month ago for a new truck, went farley instead. Bigger unit, larger diameter coil, 1 inch flow switch capable of more then 8 gpm, and did my own thermostat to avoid the wide band standard one that fails yearly, and a 40g stainless fuel tank.
