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    Clarification of M 307.2.3

    Clarification of M 307.2.3

    New postby bigdog on Fri Mar 11, 2016 8:49 pm

    M 307.2.3 is confusing to me.

    I can't figure out whether or not an emergency pan is required under an air handler in a second or 3rd floor location. Common sense would dictate yes but the code........

    It states an auxiliary method of protection is required and then lists 4 options of which 3 are pans and the 4th one goes back to a float switch in the primary drain. Where is the protection when the pan cracks or leaks?....or the coil freezes up and then melts all over the floor.

    David
    bigdog
     
    Posts: 51
    Joined: Thu Apr 12, 2012 10:54 pm

    Re: Clarification of M 307.2.3

    New postby Jerry Peck - Codeman on Fri Mar 11, 2016 10:11 pm

    bigdog wrote:M 307.2.3 is confusing to me.

    I can't figure out whether or not an emergency pan is required under an air handler in a second or 3rd floor location. Common sense would dictate yes but the code........

    It states an auxiliary method of protection is required and then lists 4 options of which 3 are pans and the 4th one goes back to a float switch in the primary drain. Where is the protection when the pan cracks or leaks?....or the coil freezes up and then melts all over the floor.

    David


    That's one of the flaws of the way the code is worded - it leaves out a crucial aspect - the coil freezing up.

    The code should say to the effect of the auxiliary pan not being required 'when an anti-freeze switch is installed' - with an anti-freeze switch, a sensor in placed on the coil and when the coil is colder than 35 degrees (the typical setting of the anti-freeze sensor) the sensor shuts a switch off and the system shuts down ... no ice build-up on the coil as it is not cold enough to make ice (which requires 32 degrees or colder).

    The 2014 FBC-Residential says: (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:
    - - - - (Jerry's note to the above: "a secondary drain or auxiliary drain pan shall be required" ... then it says "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).
    - - - - - (Jerry's note to the above: auxiliary drain pan - which is one of the two stated choices)
    - - - - 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.
    - - - - - (Jerry's note to the above: separate overflow drain - which is one of the two stated choices)
    - - - - 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.
    - - - - - (Jerry's note to the above: auxiliary drain pan - which is one of the two stated choices)
    - - - - 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.
    - - - - - (Jerry's note to the above: water level detection device??? - this IS NOT one of the two stated choices ... BUT is it one of the items following the "One of the following methods shall be used" statement. This means that M1411.3.1 says "a secondary drain or auxiliary drain pan shall be required" ... then provides another option which is not a secondary drain or auxiliary drain pan - got to love those code writers.)
    - - - M1411.3.1.1 Water-level monitoring devices.
    - - - - On down-flow units and all other coils that have no 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.
    - - - - - (Jerry's note to the above: "down-flow ... most are up-flow ... and ... "that have no secondary drain or provision to install a secondary or auxiliary drain pan" ... all modern units I have seen have a provision for a secondary drain connection, which can go to an auxiliary drain pan. Using this section, M1411.3.1.1, one could state that, on units other than down-flow units and which have a secondary drain provision, a water-level device is not permitted, thus option 4, a water level detection device is not a code permitted option - try to get an AHJ to understand what the code is actually saying there ... not going to happen ... unfortunately.)
    - - - M1411.3.2 Drain pipe materials and sizes.
    - - - - Components of the condensate disposal system shall be cast iron, galvanized steel, copper, polybutylene, polyethylene, ABS, CPVC or PVC pipe or tubing. All components shall be selected for the pressure and temperature rating of the installation. Joints and connections shall be made in accordance with the materials specified in Chapter 30. Condensate waste and drain line size shall be not less than 3/4-inch (19 mm) internal diameter and shall not decrease in size from the drain pan connection to the place of condensate disposal. Where the drain pipes from more than one unit are manifolded together for condensate drainage, the pipe or tubing shall be sized in accordance with an approved method.
    - - - M1411.3.3 Appliances, equipment and insulation in pans.
    - - - - Where appliances, equipment or insulation are subject to water damage when auxiliary drain pans fill, those portions of the appliances, equipment and insulation shall be installed above the flood level rim of the pan. Supports located inside of the pan to support the appliance or equipment shall be water resistant and approved.
    - M1411.4 Auxiliary drain pan.
    - - Category IV condensing appliances shall have an auxiliary drain pan where damage to any building component will occur as a result of stoppage in the condensate drainage system. These pans shall be installed in accordance with the applicable provisions of Section M1411.3.
    - - - Exception: Fuel-fired appliances that automatically shut down operation in the event of a stoppage in the condensate drainage system.

    Who suffers because of the cheap mechanical contractor who was to cheap to do it properly? The homeowner. Too bad that homeowner is not the building official who allowed that installation - that is about the only way to get their attention on things like that ... things which they think a 'no big deal because it is not life safety' - it isn't 'life safety' in that aspect, just 'unjustly costly for no reason' to the homeowner, and, it could be 'life safety' if the overflow went on long enough and created a mold problem with an occupant who was allergic to that mold.
    Jerry Peck - CodeMan
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    Re: Clarification of M 307.2.3

    New postby bigdog on Mon Mar 14, 2016 12:28 pm

    Thanks Jerry.....I fell a little better now. This goes into the same file that allows washing machines on 2nd and 3rd floors with out a pan of some kind.
    bigdog
     
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