The few rotary kilns I have seen have a sight glass or some type of camera to see the flame. The bluer the flame the better. Check also the exhaust gases to see if their is any extra oxygen out the stack.
lucino , Boy or buy - I can see you have an issue...
Let me try to help you out.....
1. Any chance of installing a meter - if cost is the issue, some meters are pretty cheap.
2. Have you tried the furnace vendor for his assistance?
3. Does your furnace vary in heat input /output - if not...
do you have a gage on the lpg tank. You should be able to know by the gage the usage of lpg per day, week etc or if no gage is there, ask the supplier to advise how much he adds when he fills it.
