Furnace leak while running AC unit

lbartowski · 09-16-2009, 01:04 PM

My furnace has 2 threaded female-type hubs on it about 3 feet off the floor. One has a connector screwed into it that attaches to a plastic drain line hose that runs into the drain in the floor. The other has nothing in it...but is leaking water out of it when I run the AC. Why would it do that? Can I just plug the other hold with putty? Any advice is appreciated.

SKIP4661 · 09-16-2009, 05:05 PM

The drain pipe that is connected to the coil is plugged. Clear the drain and you should be ok.

fritzycat1 · 09-18-2009, 02:38 PM

I agree - the 'primary' condensate drain appears to be clogged.

It appears you are seeing water coming out of the secondary condensate drain - you will only see water coming out of there if the primary is clogged.

Your secondary condensate drain should probably be connected to ~something~. Either a secondary drain line or a float switch that will cut off your AC when the primary gets clogged.

DON'T plug it with putty - if you want to plug it, you should be able to get a threaded nipple from the hardware store for $0.39. If you do plug it, be aware that it will still cause flooding if the primary drain is clogged - the water will drip down inside the unit to the floor where it will be captured by the drain pan that your furnace is mounted on... Your furnace does have a drain pan, doesn't it??

If you can, please post a photo of your AC unit and condensate lines. It will help the forum members to make recommendations.

Here is a good article on the subject:
http://www.ashireporter.org/articles...s.aspx?id=1648

(Note: The other DIY Chatroom members that recently educated me in the ways of the condensate - you'll probably see some additional posts from them shortly.)

fritzycat1 · 09-18-2009, 02:46 PM

FYI, I found the following four options regarding the secondary drain on another forum. Your secondary drain should probably comply with one of these - although your local codes may differ.

The original post is found here: (http://www.inspectionnews.net/home_i...rain-line.html)

In addition to the requirements of Section M1411.3, a secondary drain or auxiliary drain pan shall be required for each cooling or evaporator coil where damage to any building components will occur as a result of overflow from the equipment drain pan or stoppage in the condensate drain piping. Such piping shall maintain a minimum horizontal slope in the direction of discharge of not less than 1/8 unit vertical in 12 units horizontal (1-percent slope). Drain piping shall be a minimum of 3/4-inch (19 mm) nominal pipe size. One of the following methods shall be used:

- - - 1. An auxiliary drain pan with a separate drain shall be installed under the coils on which condensation will occur. 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. The pan shall have a minimum depth of 1.5 inches (38 mm), shall not be less than 3 inches (76 mm) larger than the unit or the coil dimensions in width and length and shall be constructed of corrosion-resistant material. Metallic pans shall have a minimum thickness of not less than 0.0276-inch (0.7 mm) galvanized sheet metal. Nonmetallic pans shall have a minimum thickness of not less than 0.0625 inch (1.6 mm).
- - - 2. A separate overflow drain line shall be connected to the drain pan provided with the equipment. This overflow drain shall discharge to a conspicuous point of disposal to alert occupants in the event of a stoppage of the primary drain. The overflow drain line shall connect to the drain pan at a higher level than the primary drain connection.
- - - 3. An auxiliary drain pan without a separate drain line shall be installed under the coils on which condensate will occur. This pan shall be equipped with a water level detection device conforming to UL 508 that will shut off the equipment served prior to overflow of the pan. The auxiliary drain pan shall be constructed in accordance with Item 1 of this section.
- - - 4. A water level detection device conforming to UL 508 shall be provided that will shut off the equipment served in the event that the primary drain is blocked. The device shall be installed in the primary drain line, the overflow drain line or the equipment-supplied drain pan, located at a point higher than the primary drain line connection and below the overflow rim of such pan.