Dear Mr. Hagan:
Sorry about the critters. I see them destroy heaters in 10 million dollar homes all the time. You will see ice if the heater is running at night or the temperature is below 55 degrees outside. The main thing I care about is that the air coming out the top of the heater is 5 to 10 degrees colder than the outside air. If the heater is icing when it is 70 out then we need to call for service.
360 568 3718