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Thread: Drain Pan

  1. #1
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    Default Drain Pan

    Shouldn't there be a catch pan underneath both cooling or evaporator coil units ?

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  2. #2
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    Default Re: Drain Pan

    Sam,

    That's pretty funny.

    "No no, the one on the right is guaranteed to not leak".



    Just for clarification... Yes, both should have pans.


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  3. #3
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    Default Re: Drain Pan

    That's what happens when you only have one left on the truck that day.


  4. #4
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    Default Re: Drain Pan

    Sized "on accordance with an approved method " ... means what?

    'Approved" means as approved by the building official - which means a visit to the building official to find out if he/she "approves" two units into one condensate drain.

    And, if so, do they approve 3, 4, 5, or how many into one 3/4" condensate drain pipe.

    The answer to about 2 units into 1 drain pipe will likely be "yes" without thinking about it, by following it with a question about 3, 4, 5, etc ... will likely cause them to pause and think about it

    Hmmm ... screenshot phone image didn't show - will have to go to my computer later. Fixed it on my phone ... found thay the image was just over the 1200 limit.

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    Last edited by Jerry Peck; 11-01-2022 at 06:41 AM.
    Jerry Peck
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  5. #5
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    Default Re: Drain Pan

    I didn't notice the sensor there. I don't know what the regulation for sensors is. It seems to me that the coil box could still leak (I see leaking coil boxes fairly frequently), so it seems to me that a pan would be required whether or not a sensor was present.

    Typically, the coil box is located over a drip pan and both the coil box and the pan have drains. When done correctly, there is a primary drain connected directly to the coil box and a secondary drain that is connected to the pan. In very rare instances (in my area), the coil box will have a drain, the drip pan won't have a secondary drain but will have a sensor.

    Can anyone give me code or industry references for the sensors? I don't see them much and have not ever noticed one in the secondary drain from a coil box.


    Last edited by Gunnar Alquist; 11-01-2022 at 09:23 AM. Reason: Spelling & Clarification
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  6. #6
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    Default Re: Drain Pan

    From the IRC: (bold and underlining are mine)

    M1411.3 Condensate disposal.
    - Condensate from cooling coils and 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 not less than 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 be not 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.
    - M1411.3.1.1 Water-level monitoring devices.
    - - On down-flow units and other coils that do not have secondary drain or provisions to install a secondary or 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. Devices shall not be installed in the drain line.

    That cut-off switch in the secondary drain outlet in the equipment drain pan is allowed by M1411.3.1 Auxiliary and secondary drain systems, 4. A water level detection device ... HOWEVER ...

    This statement I just made above "That cut-off switch in the secondary drain outlet in the equipment drain pan" is an incorrect statement because of one word: "that".

    THAT cut-off switch in the PRIMARY drain outlet in the equipment drain pan, NOT the SECONDARY drain outlet.

    Notice the cut-off switch is in the drain hole in the bottom corner - that is the lowest drain outlet, not the higher drain outlet.

    When that unit is installed horizontally, the drain outlet you see above and to the left of the bottom corner drain outlet is the secondary, higher, drain outlet.

    When installed vertically, as shown in the photo, the bottom corner drain outlet is still the lower, primary, drain outlet, with the drain outlet to the right (where the primary drain line is installed) is higher than the drain outlet in the corner - which means that will not work as intended, nor does it comply with the code requirement of "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".

    Jerry Peck
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  7. #7
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    Default Re: Drain Pan

    Hmmm... I'll have to take your word for it that the sensor is in the primary drain outlet. It looks like it's higher, but that might just be the angle of the pic. All of the coil boxes that I have seen are as you described, with the primary drain closest to the corner, which would indeed make that sensor in the wrong location.

    From what I read in your post, the pan is required whether or not the secondary drains or is fitted with a sensor.

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  8. #8
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    Default Re: Drain Pan

    Quote Originally Posted by Jerry Peck View Post
    M1411.3.1 Auxiliary and secondary drain systems.
    - In addition to the requirements of Section M1411.3, a secondary drain or auxiliary drain pan ...
    .
    .
    One
    of the following methods shall be used
    :
    .
    .
    .
    - - 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.
    Quote Originally Posted by Gunnar Alquist View Post
    From what I read in your post, the pan is required whether or not the secondary drains or is fitted with a sensor.
    No. This "M1411.3.1 Auxiliary and secondary drain systems." covers to distinct and different systems: a) auxiliary; b) secondary ... drain systems, and requires that "One of the following methods shall be used:".

    "4. A water level detection device" is one of those methods ... if done correctly.

    That was not done correctly from what I remember, and, from what I looked up. I looked up various air handler units to confirm what I remember, and I found there were two methods for equipment drain pan drains: 1) two separate drain pan drain openings, one for horizontal and one for vertical installation, each with a primary and a secondary drain opening; 2) one combination drain pan drain opening which contained one primary drain opening in the corner, and two secondary drain openings to either side.

    The air handler (fan coil) in the photo shows the one combination drain pan opening with the one primary and two secondary openings.

    Yes, a photo from a different angle would clear that presumption up.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
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  9. #9
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    Default Re: Drain Pan

    Here is some more pictures
    Quote Originally Posted by Jerry Peck View Post
    No. This "M1411.3.1 Auxiliary and secondary drain systems." covers to distinct and different systems: a) auxiliary; b) secondary ... drain systems, and requires that "One of the following methods shall be used:".

    "4. A water level detection device" is one of those methods ... if done correctly.

    That was not done correctly from what I remember, and, from what I looked up. I looked up various air handler units to confirm what I remember, and I found there were two methods for equipment drain pan drains: 1) two separate drain pan drain openings, one for horizontal and one for vertical installation, each with a primary and a secondary drain opening; 2) one combination drain pan drain opening which contained one primary drain opening in the corner, and two secondary drain openings to either side.

    The air handler (fan coil) in the photo shows the one combination drain pan opening with the one primary and two secondary openings.

    Yes, a photo from a different angle would clear that presumption up.


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  10. #10
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    Default Re: Drain Pan

    I still can't tell from the photos - do you have the manufacturer and model number?

    The installation instructions would answer the question.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
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  11. #11
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    Default Re: Drain Pan

    California does not use the IRC for mechanical, plumbing, or electrical. Only the building portion is used (frustrating).

    I will need to look that up in the California Mechanical Code (mostly the UMC) to see what the wording is there. Usually, they coincide, but on occasion they diverge.

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  12. #12
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    Default Re: Drain Pan

    I had a thought today - why not look at the two air handlers in our garage to see what they have as random examples of what might be out there, and ... mine are representative of two types:

    - First one has the primary condensate drain connection in the corner when the unit is installed vertically or horizontally, with the secondary drain connection higher off to each side.

    - Second one has the primary drain connection not in the corner when the unit is installed vertically, but looks like the primary drain connection would be in the corner when the unit is installed horizontally.

    With the end result being - if you can't tell by looking at it (or don't have a photo which shows it well), always refer to the installation instructions for that manufacturer and model (I looked it up by searching the manufacturer's name and air handler of the second one above and it showed it like the first one I described above, then I refined my search with the model number and it showed as I described the second one above. So it may not even be consist throughout a given manufacturers models).

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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