Section 307.1/Condensate Disposal
IMC 307 covers condensate pump and drain requirements for cooling equipment including drain pipe sizing, point of discharge, and secondary overflow protection to prevent water damage.
All equipment that produces condensate (cooling coils, evaporators, condensing furnaces) must have provisions to collect and dispose of condensate to an approved location. Section 307.2 requires condensate drains to be sized based on the equipment capacity, with the minimum drain pipe matching the drain connection size on the equipment. Drains must slope at least 1/8 inch per foot toward the discharge point. Condensate must discharge to an approved location: a floor drain, an indirect waste receptor, the building exterior (where permitted by local code), or a dry well. Section 307.2.3 requires auxiliary (secondary) overflow protection where equipment is located above finished ceilings, above areas where water damage could occur, or in concealed spaces. Secondary protection options include: an auxiliary drain pan with a separate drain, a water-level detection device that shuts off the cooling equipment, or a secondary drain connection on the equipment.
Why this section exists
A typical residential air conditioner produces 5 to 20 gallons of condensate per day. Commercial equipment produces significantly more. When a primary condensate drain clogs, water overflows the drain pan and causes damage to ceilings, walls, flooring, and contents below the equipment. In concealed spaces above occupied areas, a clogged drain can cause extensive water damage before the overflow is discovered. The secondary drain or shutoff device requirement provides a backup that either diverts the water to a visible location (alerting occupants to the problem) or shuts off the equipment to stop condensate production.
What plan reviewers look for
Plan reviewers check the mechanical drawings for condensate drain routing from every cooling coil and condensing appliance to an approved discharge point. They verify drain pipe sizes match the equipment connections and that the routing shows adequate slope. For equipment above finished ceilings or occupied spaces, they check for secondary overflow protection: either a secondary drain pan shown on the equipment detail, a float switch noted in the control sequence, or a secondary drain connection. They verify the point of discharge is to an approved receptor, not to a location that creates a tripping hazard, moisture problem, or unsanitary condition. For equipment in service clearance areas, they confirm the condensate routing does not obstruct maintenance access.