I too have a pulse 21, circa 1996, and have a condensation problem. Coughing and constantly sputtering. My unit is located in a very tight crawl space and I can't get the installer to service it. It would be nice to have a diagram or tech lit on how to flush it out before I get under the house. I don't find anything of the sort, any help out there?
About the noise. After mine was in for a few days I complained about the noise and my installer put 2 sets of mufflers on the exhause pipe. Just in case anyone didn't know they are available. It helped alot but I just can't stand the sputtering.