Arkansas HVACR NewsMagazine May 2023

HVACR NewsMagazine May 2023

Tech News

Traps & Vents

But that excerpt really isn't talking about condensate drains when read in context. Some municipalities do require that horizontal portions of the drain inside the structure be insulated to prevent condensation, and this standard makes sense to me. In Florida, we always insulate horizontal portions of the drain because we would have consistent growth and water damage issues due to the high dew points if we didn't.

The IMC states that condensate drains should be trapped according to manufacturers' specs. HOWEVER, new wording was added in IMC 307.2.4.1 that states that ductless systems must either have a check valve or a trap in the condensate line. While most manufacturers don't specify this on gravity ductless drains, it is something to look out for. Venting after the trap (shown in both examples above) is an excellent idea in most applications because it helps prevent airlocks that can occur due to double traps and shared drains. It also prevents siphoning. This vent is AFTER the trap and must remain open to be effective. The vent opening should always rise above the trip level of the condensate overflow switch when it is in the primary drain line or pan or above the secondary/aux overflow port on the primary drain pan. That helps ensure that the water properly trips the switch instead of overflowing out of the vent if a backup occurs. While venting is a common best practice, it isn't required by the IMC. Drain Insulation The IMC doesn't directly state that the drain line must be insulated. Many will point to where the ICC energy efficiency code states: N1103.3 Mechanical system piping insulation. Mechanical system piping capable of carrying fluids above 105°F (40°C), or below 55°F (13°C) shall be insulated to a minimum of R-2.

Condensate Switches IMC 307.2.3 states that all HVAC equipment that produces condensate must have either a secondary drain line or a condensate overflow switch, a secondary drain pan with a secondary drain line, a condensate switch, or some combination of these installations should be used to prevent overflow if the primary drain line blocks. This code includes rooftop units, ductless units, and downflow units, but the code does allow for the overflow prevention switch to be placed in the primary drain pan in these cases but NOT the primary drain line, according to 307.2.3.1