Thread: No drain pan in attic

Hi, my name is Ricky and I am new to the site and I have a question maybe someone can answer. Inspected a home this morning, built in 2008. The air handler in the attic main condensation drain line was connected and also the auxiliary drain line. However there was no drain pan installed. Is a drain pan still required eve if there is an auxiliary drain line.

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These are the requirements for Virginia - from the 2012 Virginia Residential Code: (underlining is mine)
- 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. 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). 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 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. Galvanized sheet steel pans shall have a minimum thickness of not less than 0.0236-inch (0.6010 mm) (No. 24 Gage). 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 installed 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 condensation 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 pan shall be equipped with a fitting to allow for drainage. 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 installed 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.

Which all that means:
- Yes, an auxiliary drain pan is required (it says so): "secondary drain or auxiliary drain pan shall be required"
- Well, sort of, ((it kinda says that): "One of the following methods shall be used" ... and not all of the following methods include an auxiliary drain pan - how consistent is that???
- No, because you have other choices (it says so) - options 1 and 3 include an auxiliary drain pan, options 2 and 4 do not.

Thanks for the reply Jerry. Been doing inspections a little over three years and this was the first time I had no seen a drip pan under an air handler in the attic. I was informed that because the auxiliary drain line was connected a drain pan was not needed. Which I did not believe. Informed the client and the agent to have a HVAC technician evaluate further.

Ricky,

Even though there are options which allow to not have an auxiliary drain pan ... I always recommended one anyway - that way, when there was a backup and overflow (there will be, at some point) *I* recommended an auxiliary drain pan (i.e., call the HVAC guy, *not me* because I recommended a pan anyway.

There is one common scenario where the options for no auxiliary drain pan fail to protect the structure - when the coil freezes up and ices up, the shut-off switches in the other devices shut the unit down ... that block of ice melts (the coil) ... and there is no pan to hold that water.

An additional recommendation (not required by code) is to install an anti-freeze up coil sensor and cut-off switch - when the coil gets down to around 34 degrees F (I don't recall the exact temperature, but it is above the 32 degrees F freezing point of water), there is a problem (typically limited or restricted air flow is what allows the coil to freeze up) and the cut-off switch shuts the unit down before it can even freeze up ... gosh ... one would think that HVAC guys would install one on every unit, wouldn't you, but they don't.

Such a simple device to eliminate an overflow problem. When no auxiliary drain pan is installed, an anti-freeze up switch is a necessity (but still not code required) - oh well, we don't write the code here ... we just see the after effects of what the code allows to happen.