Arrived on site for no heat call. Was informed by supervisor that the four furnace needed to be quoted to convert to run on LP instead of natural gas. Went to roof and found all four units on lock out for flame roll out which happens when trying to run LP in a furnace that has not been converted. Took pics of all data tags and gas valves and will submit quotes to have conversion kits and orifices ordered for all four York furnaces. Please bill install for this call.