re: AC drain question

quote:

---

bigger risk of using bleach might be if the solution flows back to the coil and makes contact.

---

its really this. Even fumes of bleach is corrosive. With modern coil tubing wall thickness being paper thin to achieve efficiently standards, I don't want anything that would expedite a leak.

Most air handlers are set up with the blower being after the coil. This puts the drain under a vacuum that could suck bleach fumes into the coil cabinet. Never mind the decent chance someone can overfill the trap with bleach and push it back up into the coil pan.

One of the best ways to keep the drain clear is to keep dirt off the coil in the first place. This requires a good filter and making sure all ducts to the return are sealed. But a high-merv filter also causes high static (tesp) so you need a large filter or even multiple filters to increase the surface area. Obviously all that isn't easy to accomplish on an existing setup.

Easiest thing to check is that there are no leaks in the return duct that would allow air to bypass the filter.