Products works perfect out of the box. I installed it outside, with the duct going inside via a windows. Additional I placed another duct that sucks the air from the heated room to the heater to have a closed circulation.
The heater is advertised as 8kW. The heater is not delivering 8kW, as it replaced a 3kW gas heater which I can do a direct compare with. I guess it is maximum 5kW (or less at it looses a significant amount of heat via the exhaust). I have no means to measure the exhaust heat exactly.
The heater regulates itself: you have setting 1 to 6 and you hear it regulating on the exhaust temperature. The pumppulses decline or increase and keep the exhaust temperature on for example at 210 degree Celsius.
I have runned it now for 2 weeks, every day for 2-3 hours and it worked flawless.
Assembly quality is okay, it used white diesel lines, found no assembly failures (I disassembled it to verify construction).
One drawback is that I sometimes smell Diesel, which is coming from the air intake. The housing is not fully airtight between the housing and the heater itself and the wind can cause that the exhaust fumes are sucked into inlet due to these openings (despite that I recirculate the air). Isolating this with some rubber fixed it.
During operation I see no visual smoke, running at output 3-6 I do not smell the diesel output.
Running in output 1, I smell a little bit Diesel, probably because it is generating not enough heat.
Heat output out of the duct is hot, and when installed outside the sound is acceptable for a garage shop.
Conclusion: I should buy this heater again.
David 
