Condensate Drain Trap

This furnace removes both sensible and latent heat from the products of combustion. Removal of the latent heat results in condensation of the water vapor. The condensate is removed from the furnace through the drains in the plastic transition and the vent fitting. The drains connect to the factory installed internally mounted condensate drain trap on the left or right side of the furnace.

The startup of a new furnace will involve a cycle or two of the furnace to properly prime the condensate trap with water. Until the trap is fully primed, some condensate will be pulled into the combustion blower. The furnace may cycle on the pressure switch connected to the plastic transition box due to condensate buildup. After the trap is primed, the condensate will start draining from the furnace. The combustion blower will clear out any remaining condensate in the blower housing through the vent fitting downstream of the blower. Note that the condensate trap can also be primed by pouring water into the 1/2″ (12.7mm) drain hose. Remove the1/2″ (12.7mm) ID drain hose from either the gutter or the white PVC tee trap. Using a funnel pour eight (8) ounces (30 ml) of water into 1/2″ (12.7mm) ID drain hose. Water will flow through the drain hose and into the condensate drain trap. This will prime both the vent and the transition sides of the trap. Reconnect the 1/2″ (12.7mm) ID drain hose to the original component, either the gutter or the PVC tee trap.

The condensate drain trap supplied with the furnace MUST be used. The drain connection on the condensate drain trap is sized for 3/4″ (19.1mm) PVC or CPVC pipe, however alternate 1/2″ (12.7mm) CPVC [nominal 5/8″ (15.9mm) O.D.] or vinyl tubing with a minimum inner diameter (I.D.) of 5/8″ (15.9mm) may also be used, as allowed by local codes. Alternate drain pipes and hoses may be used as allowed by local codes.

The drain line must maintain a 1/4″ (6.4mm) per foot (304.8mm) downward slope toward the drain. 1/4″ (6.4mm) per foot (304.8mm) is recommended. Installation of an overflow line is recommended when the 1/4″ (6.4mm) per foot (304.8mm) slope to the condensate drain cannot be maintained. A drain tube clip is included in the furnace to prevent kinking/buckling of the drain tube. The clip should remain in the furnace (between the door switch plate and the blower shelf, Fig. 10) during operation. See Fig. 20 for proper routing and installation of the overflow.

Drain Tube

Clip

Blower

ShelfDoor

Switch

Representative drawing only, some models may vary in appearance.

A07705

Fig. 10 - Drain Tube Clip Location

DO NOT trap the drain line in any other location than at the condensate drain trap supplied with the furnace.

If possible, DO NOT route the drain line where it may freeze. The drain line must terminate at an inside drain to prevent freezing of the condensate and possible property damage.

1.A condensate sump pump MUST be used if required by local codes, or if no indoor floor drain is available. The condensate pump must be approved for use with acidic condensate.

2.A plugged condensate drain line or a failed condensate pump will allow condensate to spill. If the furnace is installed where a condensate spill could cause damage, it is recommended that an auxiliary safety switch be installed to prevent operation of the equipment in the event of pump failure or plugged drain line. If used, an auxiliary safety switch should be installed in the R circuit (low voltage) ONLY.

3.If the auxiliary switch in the condensate pump is used, the furnace may shut down due to a blocked condensate line or failed pump. To prevent frozen water pipes see the “Frozen Water Pipe Hazard” section of this manual.

!CAUTION

FROZEN AND BURST WATER PIPE HAZARD

Failure to follow this caution may result in property damage.

If a condensate pump is installed, a plugged condensate drain or a failed pump may cause the furnace to shut down. Do not leave the home unattended during freezing weather without turning off water supply and draining water pipes or otherwise protecting against the risk of frozen pipes.