Attic HVAC Drain Pan
 

Where do installers here usually route the drain pan emergency pipe? Is there a code requirement? From what I've seen, most installers run it outside to the soffit where it outlets directly outside a window so a homeowner can see it drip if there's a backup in the primary drain.

Is this typically an installers job to run this pipe, or a plumbers or a handyman?

this should be done by the installer of the hvac co. However when pulling permits many towns want a licened plumber for this part of the install. I pull the permit for my work and install the drains and have the homeowner deal with the plumbing permit. Some times the homeowner write in on the permit that they themselvs done the work and simply pay the fee and have it inspected. It is a real pain in the *ss

drip, drip
 

Depends on the contract--The HVAC co. often includes it in their bid, sometimes the plumming cont.. As an HVAC Cont., I prefer to include it in our scope of work. Plummers don't always know exactly where to "rough-in" the secondary drain (or the primary drain for that matter) when running their pipes to or from the coil location.

So where do you guys usually run the secondary drain? Is it per code? I've heard where some people run the secondary to the primary, which defeats the purpose because the homeowner wouldn't be the wiser if there is a problem.

Typically over a window, onto a deck--the shorter the run the better. But always per code. If you have your doubts, could be the inspectors wrong--good luck proving it. There is a device available that allows you to eliminate the secondary line altogether.

Is there a real code requirement?

My experience is with this outside a window.

I also have a float shutoff switch for the air handler on my pan, which is probably what you are referring to.