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06-04-2007, 06:38 AM
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Join Date: Mar 2007
Location: Roswell, GA
Posts: 55
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Traps on Primary Condensate lines
I found several threads dealing with this but I didn't find any definitive answer to the question of whether primary condensate lines need traps. If they do, why? I somehow remember someone telling me that it was required only of Heat Pumps. But again, if so, why? Hoping you guys can set me straight. Thanks.
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Scott Dana
Dana Home Inspections, Inc.
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06-04-2007, 06:45 AM
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Join Date: Mar 2007
Location: Spring Hill (Nashville), TN
Posts: 1,751
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Re: Traps on Primary Condensate lines
Originally Posted by Scott Dana
I found several threads dealing with this but I didn't find any definitive answer to the question of whether primary condensate lines need traps. If they do, why? I somehow remember someone telling me that it was required only of Heat Pumps. But again, if so, why? Hoping you guys can set me straight. Thanks.
Yes, they are required. By code and the manufacturers.
The trap will help keep air and other stuff from being sucked into the evaporator. |
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06-04-2007, 07:51 AM
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Re: Traps on Primary Condensate lines
Required only for Heat Pumps? That's almost always where I see them.
And how could something be sucked into the evaporator coil? I just want to have the answer when some asks "Why" after I call this out in a report. Thanks.
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Scott Dana
Dana Home Inspections, Inc.
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06-04-2007, 08:37 AM
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Location: Philadelphia PA
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Re: Traps on Primary Condensate lines
Not sucked inside the coil line itself with the refrigerant, but sucked into the air handler where the evaporator coil sits. So, for instance, if the condensate line discharges somewhere smelly, nasty odors could be sucked into the air handler and distributed throughout the house.
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06-04-2007, 08:40 AM
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Join Date: Mar 2007
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Re: Traps on Primary Condensate lines
OK, sounds unlikely but I get the point. But can someone please site what these traps are needed on? Heat Pumps only? Is there a code reference that can be sited? Thanks.
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Scott Dana
Dana Home Inspections, Inc.
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06-04-2007, 10:00 AM
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Re: Traps on Primary Condensate lines
I can't think of any reason why it would be heat pumps only. The difference between a heat pump being run in AC mode, and an AC unit being run in AC mode has nothing to do with condensate removal.
I don't have a code reference. Try looking up some manufacturer's installation guides on the web?
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06-04-2007, 11:13 AM
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Re: Traps on Primary Condensate lines
if the condensate drain line is under negative pressure e.g. upstream of the blower (behind the blower) a condensate drain is needed. the way in understand this is if air is being "pulled" through the A coil it requires a trap, if air is being pushed through the coil, it does not.
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06-04-2007, 11:16 AM
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Re: Traps on Primary Condensate lines
OK, I spoke to a local HVAC guy and here is what he said. A trap is needed on any system that does not have a flue. I'm not sure I understood completely why as he was telling me this from within a hot attic, but it was something about how the air handler pulls air in instead of pushing air out. Something along those lines. But basically if it has a flue, it would NOT need a trap. If anyone can clarify that would be great.
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Scott Dana
Dana Home Inspections, Inc.
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06-04-2007, 11:56 AM
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Re: Traps on Primary Condensate lines
I found this by searching the archive.
M304.8.2 SEAL. The condensate drain system shall provide a seal that
prevents ingestion of air or other gas, through the condensate drip pan
drain and overflow connections, from all outside sources, including the
condensate disposal place, during all operating conditions.
Source Standard Mechanical Code 1994
M304.8.2 SEAL. The condensate drain system shall provide a seal that
prevents ingestion of air or other gas, through the condensate drip pan
drain and overflow connections, from all outside sources, including the
condensate disposal place.
Source Standard Mechanical Code 1997
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06-04-2007, 12:27 PM
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Location: Dallas, Texas
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Re: Traps on Primary Condensate lines
Scott, basically the trap seal prevents air from moving through the drain line. If you don't have a trap, then you can move conditioned air out of the system (bad for energy use) or dirty air into the system (bad for your health).
All openings in the ductwork should be sealed to prevent energy loss. You would not think of leaving a 3/4 inch hole in a duct un-sealed. Why would a 3/4 inch hole in the drain pipe be different?
While this is a general standard, I don't think it would be much of a stretch to use
IRC 2003 section
N1102.1.10 Air leakage All joints, seams, penetrations; site-built windows, doors, and skylights; openings between window and door assemblies and their respective jambs and framing; and other sources of air leakage (infiltration and exfiltration) through the building thermal envelope shall be caulked, gasketed, weather stripped, wrapped , or otherwise sealed to limit incontrolled air movement.
Jim
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Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002
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06-04-2007, 02:09 PM
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Location: Ormond Beach, Florida
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Re: Traps on Primary Condensate lines
Originally Posted by Rick Yerger
if the condensate drain line is under negative pressure e.g. upstream of the blower (behind the blower) a condensate drain is needed. the way in understand this is if air is being "pulled" through the A coil it requires a trap, if air is being pushed through the coil, it does not.
Almost right ...
BOTH require traps.
Not only do you NOT want to suck unconditioned air in through the condensate line, but you DO NOT want to blow conditioned air out through the condensate line. |
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06-04-2007, 02:12 PM
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Join Date: Mar 2007
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Re: Traps on Primary Condensate lines
Originally Posted by Scott Dana
OK, I spoke to a local HVAC guy and here is what he said. A trap is needed on any system that does not have a flue.
He is (I presume) assuming that any system which does not have a flue has a coil, however, many systems have both a coil and a flue.
If you have a coil through which refrigerant runs, you will need a trap. |
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06-08-2007, 09:10 AM
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Re: Traps on Primary Condensate lines
Originally Posted by Jerry Peck
Almost right ...
BOTH require traps.
Not only do you NOT want to suck unconditioned air in through the condensate line, but you DO NOT want to blow conditioned air out through the condensate line.
How does air blow through a condensate drain if it is located behind the blower?, The key words are under negative pressure, if the system is running air could not blow out of a condensate drain because air is traveling, under pressure, the oposite direction. |
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06-08-2007, 09:37 AM
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Location: Agoura Hills, CA
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Re: Traps on Primary Condensate lines
This fella removed the trap and vent. Maybe this hairy knuckle-dragger thought the condensate would drain faster.
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06-08-2007, 11:05 AM
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Re: Traps on Primary Condensate lines
Rick, I won't presume to speak for Jerry, but I think the point is that negative or positive air flow through a line is not right; air leakage is air leakage. There are both types of systems out there, the coil on the upstream or downstream.
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Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002
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06-08-2007, 11:32 AM
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Re: Traps on Primary Condensate lines
The biggest culprit I find is with high efficiency units. The manufacture instructions require (in most cases I would say but haven't found one so far that hasn't required it) that the cooling condensate line be trapped before it reaches the heating condensate line if they drain to a common pipe. Generally (check unit specifics) the heat condensate is internally trapped (usually visible internally right before the condensate line protrudes through the housing). Most installers do not trap the cooling condensate line prior to reaching the common drian union.
Now, do not ask me why, I have read the reasons but went over my head. (or through it, or around it)
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06-08-2007, 11:45 AM
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Re: Traps on Primary Condensate lines
Originally Posted by Jim Luttrall
Rick, I won't presume to speak for Jerry, but I think the point is that negative or positive air flow through a line is not right; air leakage is air leakage. There are both types of systems out there, the coil on the upstream or downstream.
Precisely.
EITHER will cause air flow through the condensate line.
One causes air flow to flow into the unit unfiltered and bringing with it whatever was in the air wherever it came from.
One causes air to flow out of the unit, losing air which has already been conditioned, thereby wasting that energy.
That is why BOTH types require traps. On BOTH primary and secondary condensate lines. |
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06-08-2007, 11:49 AM
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Re: Traps on Primary Condensate lines
Even though it is not as apparent, the air leakage into the air stream is also a net loss of energy. This will cause pressurization of the building envelope and tiny losses at each door, window or other penetration.
Leakage should be controlled at every point in the system.
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Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002
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06-08-2007, 05:54 PM
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Re: Traps on Primary Condensate lines
Originally Posted by Jerry Peck
Precisely.
EITHER will cause air flow through the condensate line.
One causes air flow to flow into the unit unfiltered and bringing with it whatever was in the air wherever it came from.
One causes air to flow out of the unit, losing air which has already been conditioned, thereby wasting that energy.
That is why BOTH types require traps. On BOTH primary and secondary condensate lines.
I See your points, I'm thinking of a split system a/c with the coil borrowing the blower of the furnace. I can see with a heat pump system a trap is essential for the reason mentioned. |
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06-08-2007, 07:06 PM
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Join Date: May 2007
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Posts: 478
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Re: Traps on Primary Condensate lines
Don't all split systems share the same blower?
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06-08-2007, 08:12 PM
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