Hello everyone! I am glad I found this site! I have been using a tankless Richmond / Reheem LP 7.4 gpm now for 2 years. Every November I have to take out the burner and clean it good or I will get code 11 failures. Installed in 09 and I love the unit but wondering if anyone else has this yearly dirty duty issue. Everything is installed to exact specs too.. It's not a big deal now as I have good practice at it, I may even be able to assist someone else having this code, it always runs with no issues until the 1 year mark in November then..... failures start. Otherwise, switching to tankless was the best thing I have ever did, my 2 years data show a solid reduction of 1/2 the propane that I used to use. I heat the house with corn so the only propane user is the water heater. I went from 1 to 1.2 gallons per day to .6 gallons per day and it has repeated this range for 2 years!