HVAC condensate drain

[MeDesignEng]

I recently design an AHU above ceiling unit with a condensate pump located in the emergency drip/overflow pan. The contracter left me a comment stating that whenever possible the condenstation from the HVAC equipment should be a gravity flow drain and not rely on mechanical means for discharge. He recommended using a hub drain with a trap primer under a near by sink instead. I see know that this may be a better option but I wanted to get a second opinion, or see if anybody else had a better option.

 

[atlas06]

In general, most utility companies will not let you connect condensate drain to sanitary piping unless they have a combined sewer. Check IPC under definitions for "condensate drain". You need to connect to a storm line or spill on grade into a splash block. Connecting to the sink as you describe is a code violation.
The rational being that any non-metered water cannot connect to the sewage treatment plant.

PS: Not a good idea to locate a condensate pump inside a drain pan, you are not likely to get positive drainage from the coil. How would you handle water form the drain pan with the pump inside the pan? Locate your condensate pump outside the drain pan and below the unit.
The utility company may let you connect the emergency drain pan to the sink. Check it out.

 

[RossABQ]

Atlas, around here it isn't allowed to connect any process drain (incl. cond. drains) to a storm drain system. This is doubly true if the airhandler has a chilled water or heating water coil, as the CHW/HW is chemically treated and (potentially) contains heavy metals that would go to storm drain if the coil leaks. A storm drain system doesn't have any treatment capability. Condensate drains go to process drains (acid waste) if available or to sanitary, both of which are monitored and have treatment processes. Spilling to the ground (with a CHW/HW coil involved) is likewise verboten.

 

[atlas06]

RossABQ
Agree with CHW/HW/CW that they should not connect to the storm for they contain chemicals. CHW/HW/CW are also all METERED water and therefore can go back to their originating point, while Condensate from the air is not metered and is not contaminated with chemicals.
IMC 307 calls for connection to an approved place of disposal, IMC's way of dumping the responsibility on the local authority and the Engineer.

That is the way we handle it over here, and any time we connect cooling coil condensate to the sanitary, we get a code review comment.

Overflow from secondary drain pan: Yes, Condensate from Cooling coil: No.
You can have a secondary drain pan without a drain pipe if you have a water level detection device conforming to UL 508 (IMC 307.2.3.)

 

[lilliput1]

We typically run condensate drains to discharge at the mop sink in the janitor closet.

 

[RossABQ]

We do, too, when they are available. Note this is a sanitary system connection.

 

[trashcanman]

The 2003 IMC, 307.2.1 states that condensate shall be piped to an approved place of disposal. That could be sanitary or storm, depending on the local authority having jurisdiction. Check with local code official to be sure.

 

[MeDesignEng]

Thanks for all the responses so far. Do anyone have comments on which is better, a condensate pump or gravity drain. And if the gravity drain is better, what is the best way to set one up?

 

[NCDesign]

I would guess that the contractors rational is that by using a gravity drain there is not another point of mechanical failure. As others have pointed out how you can dispose of the condensate is ultimately up to the local jurisdiction. However, how you get it there should depend on the conditions of the install. My point being, on some installs gravity may be better and on some a pump may be the only way. I always prefer to utilize gravity as much as possible on condensate drainage for the same reason I think your contractor is recommending it.
To specifically answer your question on how to set it up. Make sure you have sufficient space and clearance to maintain the necessary slope and that it is trapped properly. The termination will be determined by the AHJ.