Joined Primary and Secondary and Float switch

Can the secondary (pan drain) be joined in with the primary (obviously not ducted to a ‘conspicuous location’) if they’ve also installed a float switch?

All in an air handler in the attic above framing.

I know I’d ***like ***to see them separated, but is it okay this way? :roll:





17 views, nothing yet…:smiley:

Are you going to make me search the code book Michael?

The float switch essentially negates the necessity for a “conspicuous” secondary. There’s nothing more “conspicuous” than your system shutting down :wink:

I know Jeff, I just dislike the heck outta this install.

I’ve seen other production builders (Centex to be specific) install the pan drain where it exits above a kitchen sink window… now that’s conspicuous!

They also have the float switch to disable them as well (I tell people it’s really a tertiary safety as you should observe the dripping secondary prior to the float be actuated).

My issue with the float switch in-lieu-of a conspicuous secondary is that it doesn’t always “shut off” the system - it’ll still ‘blow’ just not as cool… and the pan is now FULL of water…

Here’s another joined I saw today as well in a different builder’s town home… through this is easier to ‘fix’…


No, I know what it says; I’m just looking for someone else to validate my thoughts that this is certainly not (as Big Will says) Best Building Practice…:mrgreen:

And maybe some thoughts on how to ‘recommend’ something different.

If your jurisdiction follows the IRC, here’s the reference. . .

M1411.3.1 Auxiliary and secondary drain systems.

. . . The auxiliary pan drain shall discharge to a conspicuous point of disposal to alert occupants in the event of a stoppage of the primary drain. . .

Regardless of any float switch or other system.

Thanks Jeff…

I pretty much said it was okay, but not the best possible design… we’ll see what we see…

At least I’ve perfected the double lugged neutral call out! :mrgreen:

You can add a float switch as backup to a separate secondary drain, as long as the secondary drain discharge is to a clearly visible (“conspicuous”) location. But there shouldn’t be a concealed secondary drain discharge with a float switch.

If the secondary drain discharge is not clearly visible (e.g. both connected together and/or discharging into say a gutter or waste line), and there is a problem with system, nobody will even know there is a problem … unless the secondary line clogs and the pan fills up to activate the float switch. It might work, but it’s not ideal or the way it should be done.

Also note that IRC Section M1411.3.1 states that … “One of the following methods shall be used” which then continues with the three options of: pan with visible secondary drain; high visible secondary drain; or pan with float switch. A pan with a concealed secondary drain and a float switch isn’t one of the options.


Since the float switch meets one of the three options by itself the secondary drain would not be required and in this case is in addtion to the requirement IMHO.

Actually, the IRC does not allow a secondary drain line if the float switch option is used.

Now if you use a pan that has a secondary drain line to a clearly visible location that would meet one of the options, and then if you add the float switch that would be supplementary.

The point is that a pan with a concealed secondary drain and a float switch isn’t one of the options, and doesn’t meet the IRC provisions.


If it is as you say, then the fix would simply be to plug the secondary drain line in this case. :wink:

Since that seems ridiculous on its face (because it decreases protection), the IRC should probaly be re-written for clarification. JMO

Actually the correct fix would be to route the secondary drain line to a visible location. The float switch could stay as an optional back-up in case the secondary drain clogs.

The IRC restrictions make sense to me as the intent is if there’s a problem with the primary drain which starts overflowing the owners should be aware of that (visible condensate flowing or the unit shuts down). Otherwise if there is a primary drain problem, it could be overflowing for quite some time before it’s noticed, which can damage the equipment and/or pans, as well as the building.

I know of at least one case locally where the secondary drain discharge was not visible, and the primary drain clogged (it happens). Over time it damaged the unit and pan, which then started leaking onto a ceiling below. The unit and pan, as well as a section of the ceiling, insulation, and floor below had to be replaced.

Why? If a secondary drain is not required, then one could simply plug the secondary drain line in this example and rely on the float switch as the second means of protection from flooding. It would then meet the requirements as stated in the IRC. No re-routing to a visible location necessary. It’s like the seconddary drain line wasn’t even there.:shock: This installation goes above the minimum requirments of the IRC. Though non-standard, it is not wrong.

IRC is mininum standards.


Per the IRC it wouldn’t be wrong to just plug the secondary drain and rely on the pan float switch. But the drain line is already installed, so IMO the correct fix would be to reroute the discharge to a visible location (stub outside, slop sink, etc), which also provides better protection.

The minimum standards are met if you remove the drain line on the secondary pan completely. Nuff said.

Feel free to recommend what you are comfortable with.

It violates common sense. I often say this:

“The auxiliary condensate drain discharges into the primary condensate drain pipe. Should the primary drain pipe ever clog, water may overflow the drain pan and damage the ceilings below. Service by a licensed HVAC contractor is recommended.”

To drive the point across and better CYA you may want to add

“The auxiliary condensate drain discharges into the primary condensate drain pipe. Should the primary drain pipe ever clog, water may overflow the drain pan and potentially damage the service floor, insulation, ceiling joist/plaster/sheetrock, and furnishings or flooring below. Service by a licensed HVAC contractor is highly recommended.”
but I did like the intent of the original, Thanks!