Lennox International Inc Merit CBX25UH Series Duct System and Filters, Sloping the Drain

IMPORTANT

A field-fabricated secondary drain pan, with a drain pipe to the outside of the building, is required in all installa­ tions over a finished living space or in any area that may be damaged by overflow from the main drain pan. In some localities, local codes may require a secondary drain pan for any horizontal installation.

The air handler is provided with ¾” NPT condensate drain connections.

SLOPING THE DRAIN

Make sure the unit is sloped (similar to the slope shown in figure 10) (horizontal or upflow) so that the drain pan will empty completely without water standing in the pan.

THIS CORNER SHOULD BE 5/8” (+/- 1/8”) HIGHER

THAN DRAIN CORNER

THIS CORNER SHOULD BE 5/8” (+/- 1/8”) HIGHER THAN DRAIN CORNER

DRAIN CORNER

Figure 10. Sloping the Drain

INSTALL CONDENSATE DRAIN

1.Remove the appropriate drain knockouts. If necessary, remove the indoor coil assembly from the cabinet.

2.Connect primary drain line connection to the primary drain pan connection. The primary drain connection is flush with the bottom of the inside of the pan. Secondary connection is raised above the bottom of the inside of the pan.

NOTE — When making drain fitting connections to the drain pan, hand tighten the fitting and use a thread sealant. Over-tightening the fittings can split connections on the drain pan.

3.If the auxiliary drain line is to be used, remove the plug and route the drain line so that water draining from the outlet will be easily noticed by the homeowner. The auxiliary drain line does not require venting or a trap. Refer to local codes.

4.After removal of drain pan plugs, check the drain port to see if holes have been drilled. If not drilled, use a 19/32” bit to drill out the primary drain hole; use a 3/8” drill bit for the secondary drain hole. Remove all drill shavings.

5.Make sure drain ports and drain pan are free of all debris.

6.Plug and check any unused drain pan openings for tightness. Torque plugs to 30 in. lb. to prevent water leaks or seepage from the drain pan.

7.Install a 2” trap in the primary drain lines as close to the unit as practical (see figure 9). Make sure the top of the trap is below the connection to the drain pan to allow complete drainage of the pan.

NOTE — Horizontal runs must have an anti-siphon air vent (standpipe) installed ahead of the horizontal run (See figure 9). An extremely long horizontal run may require an oversized drain line to eliminate air trapping.

NOTE — Do not operate air handler without a drain trap. The condensate drain is on the negative pressure side of the blower; therefore, air being pulled through the condensate line will prevent positive drainage without a proper trap.

8.Route the drain line to the outside or to an appropriate drain. Drain lines must be installed so they do not block service access to the front of the air handler. A 24” clearance is required for filter, coil, or blower removal and service access.

NOTE — Check local codes before connecting the drain line to an existing drainage system.

Insulate the drain lines where sweating could cause water damage.

TEST CONDENSATE DRAIN

Test the drain pan and drain line after installation:

1.Pour several quarts of water into drain pan, enough to fill drain trap and line.

2.Check to make sure the drain pan is draining completely, no leaks are found in drain line fittings, and water is draining from the end of the primary drain line.

3.Correct any leaks found.

Duct System and Filters

DUCT SYSTEM

The air handler is provided with flanges for the connection of the plenum and ducts. The air handler is equipped with flanges that can form a filter rack for the installation of the air filter, or the filter may be installed as part of the return air duct system.

Supply and return duct system must be adequately sized to meet the system's air requirements and static pressure capabilities. The duct system should be insulated with a minimum of 1” thick insulation with a vapor barrier in conditioned areas or 2” minimum in unconditioned areas.

Table 1. Unit Air Filter Size Chart

Model	Filter Size	Actual Minimum
		Filter Size
-018	12” x 20” x 1	11.50” x 19.50” x .75”
-024 and -030	15” x 20” x 1	14.50” x 19.50” x .75”
-036	18” x 20” x 1	17.50” x 19.50” x .75”
-042, -048 and -060	18” x 24” x 1	17.50” x 23.50” x .75”

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CBX25UH SERIES