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The Critical Eye!

Michael Leavitt’s professional inspection related blog.

Michael's Inspection Tip - A/C Cutoff Switch

Michael's Inspection Tip - A/C Cutoff Switch

On a recent 2013 home I found the furnace located in a closet on the second floor of the home. It was a combination forced air furnace with air conditioning coils installed below the furnace. The issue was that there was no safety pan installed under the furnace and no A/C condensate cutoff switch installed. Here is a photo...


Here is what I reported...

REPAIRS ARE NEEDED -I recommend further evaluation/repair by a licensed HVAC air conditioning specialist.

"The unit located on second floor does not have the recommended overflow drip pan.  This pan protects the home from any condensate leaking or overfilling = Consider either adding the recommended overflow pan and drain line or the A/C emergency condensate cut-off switch."

This is a very straight forward repair and an issue that is quite often overlooked. The guidance comes directly from the International Residential Code. So as not to be scoffed as a brand new requirement, let me share the 2006 IRC verbiage. The bluew, red and brown highlights help add some clarity.  For the second floor installations that can cause condensate overflow damage to the structure below there are 4 viable options...

2006 Internation Residential Code

M1411.3 Condensate disposal.
Condensate from all cooling coils or evaporators shall be conveyed from the drain pan outlet to an approved place of disposal. Condensate shall not discharge into a street, alley or other areas where it would cause a nuisance.
M1411.3.1 Auxiliary and secondary drain systems.
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 ¾-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.
M1411.3.1.1 Water level monitoring devices.
On down-flow units and all other coils that have no secondary drain and no means to install an auxiliary drain pan, a water-level monitoring device shall be installed inside the primary drain pan. This device shall shut off the equipment served in the event that the primary drain becomes restricted. Externally installed devices and devices installed in the drain line shall not be permitted

REAL LIFE SCENARIOMatthew-Flinders-UtahMatthew Flinders

Matthew Flinders is the agent involved in this situation and he sent me a photo by text message earlier today that read, "Michael, they installed this. Would your unnofficial position be that this may be correct? I am curious because I don't know what it is supposed to look like."

 Take a look at the photo and ponder the following...

  • 1) Look at the water staining in the top middle of the photo from prior leaking.
  • 2) They cut the cut the drain line and installed an A/C condensate cut-off switch.

Here is the photo...


I looked at the photo and then responded with the following email...

I am still giggling at the installation. I am assuming that the homeowner probably installed this and not a licensed HVAC.  I cannot see where the black wires go in the left of the photo. Is it installed so that it will cut off the unit when the drain line backs up? If so, then they got it part right. If there is a clog or blockage to the remaining 12” of PVC pipe, then the unit will shut down and we can rename this a A/C drain line cut-off switch.  This is a low voltage float switch designed to cut off if the water raises above the half way point in the pipe. If it were installed at the appropriate location it would be at the elevation of the red plug so that if the condensate pan is about to overfill the float is raised and the A/C unit is shut off. Unfortunately it is installed so low that it will only protect the water level from the switch to the drain and not prevent overfilling of the condensate pan up at the red drain plug.

YOUTUBE VIDEO - Here is a U-tube link featuring this product if you are still confused about this switch, it’s purpose, how to install, and why your configuration does not address its purpose…

NOTE:Your configuration protects from pipe blockage at the very end, but not blockage of the condensate pan.
I have attached 3 pictures of another unit (This is not the AC in the Springville home). You can see the AC coils with the cover removed and another photo of the pan with the rust and slight debris that happens in the pan and occasionally will block the drain pipe hole.


SOLUTION - Install the AC cut-off switch, per the manufacturer’s instructions, in the appropriate location and elevation. Was this work done by a licensed HVAC? If so, then share with them my observations and let’s come to a meeting of the minds. If it was the homeowner, then I refuse to invest my consulting time educating them as to why it is wrong and convincing them how to do it right. I always recommend this work be done by a licensed professional so that there is the assurance that they have done it before and that there is some warranty coverage for my clients if there are issues with the installation in the future.

IN SUMMARY- I have tried my best to find instructions and justifications that would allow this installation, but I do not see any in my current online searches at the manufacturer’s website. I understand the switch mechanism’s design, purpose, and theory, and your current configuration is close, but in my opinion it will offer no real protection as currently installed.
Respectfully, Michael Leavitt

Matthew Flinders brings up a good question when he admits that he doesn't know what these a/C water level cut-off switches even look like. Here are several photos pf real life installations...


CALL TO ACTION - If you have central air conditioning, then take a look at your furnace and A/C. If your condensate pan overfills, will it damage interior finishes? Is there a safety pan installed below the unit?... Probably not. Is there an A/C cutoff safety switch installed?... Probably not. Many homes are built and systems installed overlooking this requirement. But don't freak out because the majority of the homes I inspect have the furnace installed in the basement on the concrete slab with a floor drain nearby. In this situation is it usually not necessary to have anything other than the condensate drain line routed to the nearby floor drain.

NOTE - WARM WEATHER LOCATIONS: If you are not is cold snow country, then you might see a second drain line that gets routed to the exterior of the home in a conspicuous location where dripping would alert the homeowner to issues.

If you have questions or concerns, then schedule a routine heating A/C tune-up with a licensed HVAC and ask them to evaluate the condensate drain and overflow situation. A good HVAC will not try to upsell an unneeded item. If there recommendation is in harmony with what I have addressed in this blog entry, then get the needed condensate improvements installed and prevent future damages to the finishes below the unit.

Make it a great day!

Michael Leavitt - Orem, Utah -

What are your thoughts?

Hang In There... And Never Give Up!
Matthew Flinders - ENDORSEMENT by Michael Leavitt


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