Ash yourself why is these unit not sold by the company that has always sold them, and why has the one sold on e bay business to window cleaners changed there advert and not calling it a flaming hot anymore. I have one but its just a though I have had.
A different aseptic to gas water heaterr
On the other hand one needs to match the pumps liter flow rate with the heaters capacity to heat water. THis is why one has great success and the other has flow problems and the heater not igniting. IN my case I have a 7.2 liter per minute pump and a 8 liter heater.I also have thermometer meter on the heater.This helps to balance the heat to pressure ratio.