I need a hand book or notes on how to design a radiative heating system.Does any one have any designs?

I am intending on using black tube type infrared gas burner heaters.

My attempts to contact via email have been answered as out of office.To date I have been reverse engineering a consultation/quote based on mounting them at 6metres height and at 45 degrees. I have used cosine law, Inverse Square and a knowledge of lighting design to work out the irradiances at different heights for a directly overhead arrangement.

However the problem is I have had to assume the original idea from the sales person was spot on. Whenever I contact them I get a rule of thumb type response. They are too far away to just pop in when I come across something different.I need enough info to check my figures basically. Also I want enough info to proceed with some confidence. I have had some issues with some so called heating engineers in the past and these people don’t seem to have the knowledge required. please don't suggest alternatives I am trying to heat a large well vented shed