Performed preferred customer furnace start up. Checked over the furnace installation. Found that the 90 degree elbow on th exhaust is leaking water. The pipe is 2 1/2†pipe. Office to call to schedule an appointment for an installer to come repair the leak. Cycled the furnace. Set the furnace gas pressure. Took a temperature rise and set the fan speed. Performed furnace combustion test. The furnace is running normally at this time.