What's the pressure to the heater? It should be a minimum of 11 to 13 water column inches. Also, make sure that your heater is in fact a propane fueled heater. Don't go by whats on the box it came in. Look at the manufacturer's tag(s) on the heater. It may be a Natural Gas unit instead of Propane unit. I've seen this happen before. In which case it won't work and can not be converted.