I'm selling a house where the indoor airhandler for the heat pump has a
vertical condensate drain that runs thru the floor into the crawl space. It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because it is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's right
or not.
Pro AC tech opinion requested ( since I dare not ask this question on their
newgroup).

Curmudgeon wrote:
I'm selling a house where the indoor airhandler for the heat pump has a
vertical condensate drain that runs thru the floor into the crawl space.
It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because it
is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's right
or not.
Pro AC tech opinion requested ( since I dare not ask this question on
their
newgroup).

If it connects to a sanitary sewer, it needs a trap. That prevents
sewer gasses from coming back in through it.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

That I know...

So why do horizontal condensate drain lines from AC units have a trap bend?
They connect to nothing but air.
The only thing I can figure is to keep insects and the like from crawling
into the unit.
But again, a trap bend in a vertical line connected to nothing would make no
sense...for either gas or insects.






co"Joseph Meehan" wrote in message
...
Curmudgeon wrote:
I'm selling a house where the indoor airhandler for the heat pump has a
vertical condensate drain that runs thru the floor into the crawl space.
It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because it
is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's
right
or not.
Pro AC tech opinion requested ( since I dare not ask this question on
their
newgroup).

If it connects to a sanitary sewer, it needs a trap. That prevents
sewer gasses from coming back in through it.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

I found with my unit, that the condensate drain is on the pressurized side
of the fan, this caused air to blow through the drain line, which in turn
caused the liquid to be blown through the pipe. I put on a small trap to
hold some water and it allowed the water to slowly drip through the tube.


"Curmudgeon" wrote in message
...
That I know...

So why do horizontal condensate drain lines from AC units have a trap
bend?
They connect to nothing but air.
The only thing I can figure is to keep insects and the like from crawling
into the unit.
But again, a trap bend in a vertical line connected to nothing would make
no
sense...for either gas or insects.






co"Joseph Meehan" wrote in message
...
Curmudgeon wrote:
I'm selling a house where the indoor airhandler for the heat pump has
a
vertical condensate drain that runs thru the floor into the crawl
space.
It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because
it
is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's
right
or not.
Pro AC tech opinion requested ( since I dare not ask this question on
their
newgroup).

If it connects to a sanitary sewer, it needs a trap. That prevents
sewer gasses from coming back in through it.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

"Curmudgeon" wrote in message
...
That I know...

So why do horizontal condensate drain lines from AC units have a trap
bend?
They connect to nothing but air.
The only thing I can figure is to keep insects and the like from crawling
into the unit.
But again, a trap bend in a vertical line connected to nothing would make
no
sense...for either gas or insects.


Its because there is negative pressure inside the air handler as opposed to
atmospheric, due to air pressure drop through the cooling coil.

Without a trap, the drain simply sucks air into the unit, and so then the
condensate collects all over inside the unit, overflows the drain pan and
generally makes one hell of a mess whenever the fan shuts down.

The trap seals against this occurance and allows draining because it traps a
water column of sufficient mass and at a low enough elevation such that this
negative pressure cannot overcome and lift water out of the trap--remember
vaccuum is often measured as "Water column".......together, this all allows
the condensate to drain to the outside of the cabinet under
gravity..........

--

SVL

"PrecisionMachinisT" wrote in message
...

"Curmudgeon" wrote in message
...
That I know...

So why do horizontal condensate drain lines from AC units have a trap
bend?
They connect to nothing but air.
The only thing I can figure is to keep insects and the like from
crawling
into the unit.
But again, a trap bend in a vertical line connected to nothing would
make
no
sense...for either gas or insects.


Its because there is negative pressure inside the air handler as opposed
to
atmospheric, due to air pressure drop through the cooling coil.

Without a trap, the drain simply sucks air into the unit, and so then the
condensate collects all over inside the unit, overflows the drain pan and
generally makes one hell of a mess whenever the fan shuts down.

The trap seals against this occurance and allows draining because it traps
a
water column of sufficient mass and at a low enough elevation such that
this
negative pressure cannot overcome and lift water out of the trap--remember
vaccuum is often measured as "Water column".......together, this all
allows
the condensate to drain to the outside of the cabinet under
gravity..........

--

SVL

When I posted a question asking why my a/c condensate pan was overflowing I
never got a satisfactory answer that I could use. I think you just hit the
nail on the head. I am off to build a better trap (but not for mice)

Charlie

Curmudgeon writes:

So why do horizontal condensate drain lines from AC units have a trap
bend?

(1) Keeps air from moving through it, which is inefficient in itself.

(2) Air flowing through the pipe deposits dust and fosters clogging through
microbial growth.

A "trap" in this case is a simple U bend somewhere in the run, usually at
the air handler. Not a more elaborate trap fixture like on a sink.

Hi Curmudgeon, hope you are having a nice day

On 10-Aug-04 At About 01:39:46, Curmudgeon wrote to All
Subject: condensate drain

C From: "Curmudgeon"

C That I know...

C So why do horizontal condensate drain lines from AC units have a trap
C bend? They connect to nothing but air. The only thing I can figure
C is to keep insects and the like from crawling into the unit. But
C again, a trap bend in a vertical line connected to nothing would
C make no sense...for either gas or insects.

They are trapped if they are on the negative side of the air stream. if you
didn't the water would never drain due to the air being pulled through the
pipe.


-= HvacTech2 =-


... "If you can't hear me it's because I'm in parentheses." - s.w.

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Hi Joseph, hope you are having a nice day

On 10-Aug-04 At About 08:36:56, Joseph Meehan wrote to All
Subject: condensate drain

JM From: "Joseph Meehan"

JM Curmudgeon wrote:
I'm selling a house where the indoor airhandler for the heat pump has
a vertical condensate drain that runs thru the floor into the crawl
space.
JM It
was installed that way new. Now, an inspector for the buyer lists
that drain as a "fault" because it
JM is
not trapped. Does a vertical drain need to be trapped. I'm not going
to replace it, but now I'm curious if the inspector's right or not.
Pro AC tech opinion requested ( since I dare not ask this question
on
JM their
newgroup).

JM If it connects to a sanitary sewer, it needs a trap. That prevents
JM sewer gasses from coming back in through it.

Actually no it doesn't if you think carefully about it. I have changed many
drains due to the fact they dry out in winter and cause a bad smell when in
heating mode. you should never run a condensate drain to a stack or sanitary
pipe.

-= HvacTech2 =-


... "Its hard for me to buy clothes because I'm not my size."- s.w.

___ TagDude 0.92á+[DM]
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++
spam protection measure, Please remove the 33 to send e-mail

Curmudgeon wrote:
I'm selling a house where the indoor airhandler for the heat pump has
a vertical condensate drain that runs thru the floor into the crawl
space. It was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because
it is not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's
right or not.
Pro AC tech opinion requested ( since I dare not ask this question on
their newgroup).


Most residential air handler manufacturers require traps.

Code usually says something like this:
"Condensate drains shall be trapped as required
by the equipment or appliance manufacturer."

"Curmudgeon" wrote in message
...
I'm selling a house where the indoor airhandler for the heat pump has a
vertical condensate drain that runs thru the floor into the crawl space.
It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because it
is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's right
or not.

It needs to be trapped. Most heat pump air handlers have the coil on the
negative side of the blower. As indicated by other responses, air will flow
from out to in and many times causes problems draining as well as the
efficiency side effects.

Pro AC tech opinion requested ( since I dare not ask this question on
their
newgroup).

We thank you for posting in the appropriate forum since many of us also read
this NG for the very purpose of trying to help homeowners.

- Robert

Thanks all for the replies. Sometimes logic just isn't enough.
But it's been draining fine for nearly 20 years....the new buyer will just
have to live with it working OK.
:-)



"American Mechanical" wrote in message
m...

"Curmudgeon" wrote in message
...
I'm selling a house where the indoor airhandler for the heat pump has a
vertical condensate drain that runs thru the floor into the crawl space.
It
was installed that way new.
Now, an inspector for the buyer lists that drain as a "fault" because it
is
not trapped.
Does a vertical drain need to be trapped.
I'm not going to replace it, but now I'm curious if the inspector's
right
or not.

It needs to be trapped. Most heat pump air handlers have the coil on the
negative side of the blower. As indicated by other responses, air will
flow
from out to in and many times causes problems draining as well as the
efficiency side effects.

Pro AC tech opinion requested ( since I dare not ask this question on
their
newgroup).

We thank you for posting in the appropriate forum since many of us also
read
this NG for the very purpose of trying to help homeowners.

- Robert