DRAIN

[doneinnc]

would it be wrong to connect pan drain to the unit drain, if the drain pipe is oversized?

[stuntryder]

I try to pipe secondary drains independently whenever possible,or not pipe them and install a wet switch.Every secondary pan that I install or have under contract gets a float switch or a wet switch installed.

[doneinnc]

it has a switch just wondered why the guy did it that way, my other house had two seperate drains

[totaleclipse]

I prefer a switch over secondary drain. Reason being if the sec. pan is filling up with water, you have a problem. If a switch is installed, you know about the problem sooner and you can get it fixed sooner. You dont have to worry about the pan being out of level, rusted, having pin hole leak, etc.
Just the other day I had a customer call about a water leak, the installing contractor, not us, piped the sec. drain according to code, but the pan had a small hole and distroyed his ceiling, and possibly his dryer. And the house is 2 or 3 years old.
Just my two cents worth.

[duct dr]

In most cases, running the primary and secondary drain together is against the rules. The secondary drain should be run by itself to a location that can be seen if there's a problem, I.E. over a window. I use the SS1 and SS2 safety switches. They have a threaded fitting that screws right to the overflow drain on the coil, with a float switch that wires like any other float switch. But these aren't IN the pan, so if there's a problem the switch will kill the system before any water can reach the pan. i still run a secondary drain from the pan to a good location.

http://www.smdresearch.com/index.shtml?products/SafeTSwitch/safetswitchss2.shtml~mainFrame