A/C secondary drain line

[Gary Mohel]

Does the IRC state that a secondary drain line has to terminate at a conspicuous location and if so where do I find it?

[Rick Cantrell]

From the 2006 IRC
"

M1411.3.1 Auxiliary and secondary drain systems. In
addition to the requirements of Section M1411.3, a secondary
drain or auxiliary drain pan shall be required for each
cooling or evaporator coil where damage to any building
components will occur as a result of overflow from the
equipment drain pan or stoppage in the condensate drain
piping. Such piping shall maintain a minimum horizontal
slope in the direction of discharge of not less than 1/8 unit
vertical in 12 units horizontal (1-percent slope). Drain piping
shall be a minimum of 3/4-inch (19 mm) nominal pipe
size. One of the following methods shall be used:
1. An auxiliary drain pan with a separate drain shall be
installed under the coils on which condensation will
occur. The auxiliary pan drain shall discharge to a
conspicuous point of disposal to alert occupants in the
event of a stoppage of the primary drain. The pan shall
have a minimum depth of 1.5 inches (38 mm), shall
not be less than 3 inches (76 mm) larger than the unit
or the coil dimensions in width and length and shall be
constructed of corrosion-resistant material. Metallic
pans shall have a minimum thickness of not less than
0.0276-inch (0.7 mm) galvanized sheet metal. Nonmetallic
pans shall have a minimum thickness of not
less than 0.0625 inch (1.6 mm).
2. A separate overflow drain line shall be connected to
the drain pan provided with the equipment. This overflow
drain shall discharge to a conspicuous point of
disposal to alert occupants in the event of a stoppage
of the primary drain. The overflow drain line shall
connect to the drain pan at a higher level than the primary
drain connection.
3. An auxiliary drain pan without a separate drain line
shall be installed under the coils on which condensate
will occur. This pan shall be equipped with a water
level detection device conforming to UL 508 that will
shut off the equipment served prior to overflow of the
pan. The auxiliary drain pan shall be constructed in
accordance with Item 1 of this section.
4. A water level detection device conforming to UL 508
shall be provided that will shut off the equipment
served in the event that the primary drain is blocked.
The device shall be installed in the primary drain line,
the overflow drain line or the equipment-supplied
drain pan, located at a point higher than the primary
drain line connection and below the overflow rim of
such pan."

[stanley frost]

It's time to replace my water heater. I've read some responses about tankless water heaters. Does anyone have any experience with external mounted tankless water heaters? I live in South Texas so weather isn't a concern.

[Rick Hurst]

Stanley,

If your looking to install a tankless gas water heater, your probably looking at having to update your gas service line to a larger size.

If not, a gas tankless is not going to work efficiently.

rick

[Richard Stanley]

I would not install it outside in your corrosive environment. It will rust before you put away the tools.
My next one will be tankless (electric).

[imported_John Smith]

Im interested why you want the tankless water heaters. In Houston, our cold water generally runs ~78F (except for our month of winter). I dont see the cost of heating water in the tank being that great as compared to the cost of the tankless systems. Just wondering what your motivation was.

[Gunnar Alquist]

I have always wondered why a trap is required in the primary condensate drain from the A/C. The secondary drain does not have one. Is this only necessary when the primary drain is connected to the household sewer piping, or is it always required. And, if required, why not the secondary drain? When the furnace or air conditioner is operating, the coil box is under positive pressure and heated or cooled air will escape out of the secondary drain pipe.

[Jerry Peck]

I have always wondered why a trap is required in the primary condensate drain from the A/C. The secondary drain does not have one.

Because that drawing from that manufacturer is one of the only ones not to specify that the secondary condensate line be trapped too - to keep the units from sucking air in or blowing air out through the condensate lines.

Now, as to what THAT manufacturer does not show the secondary being trapped ... that is beyond me. I would call them and ask them to explain that to me, and if the secondary drain does need to be trapped (as one would think it would) would they kindly send me a revised drawing showing it. :) I've done that with various appliances and manufacturers over the years and you would be surprised how often the engineering department goes ... 'Ummm ... I don't know why that is drawn/stated like that, it certainly should not be.', followed by some more discussion and 'I will fax/email the revised installation instructions to you as soon as we have them revised, you might get them later today or tomorrow, we will start working on it right away.', and they do.

[Gunnar Alquist]

Thanks JP. Apparently, I will now have to update my diagram for my reports. Does anyone have a correct diagram with the proper traps?

[imported_John Smith]

I did a home this weekend that was a new install. HVAC contractor was miffed because I called it out in my report. Copied the info off the evaporator coil and pulled up the install instructions off the internet. Cant hardly argue when the manufacturer calls for it.

See page 4 of the attachment.

[Jerry Peck]

See page 4 of the attachment.

From that page 4: note the plural aspect of the requirement (bold is mine)


9. Make sure that outlet of each trap is below its connection to condensate pan to prevent condensate from overflowing drain pan. Prime all traps, test for leaks, and insulate traps and lines if located above a living area. Consult local codes for additional restrictions or precautions.

Note, however, that the drawing on page 4 shows a "running trap", which is not allowed. Sometimes all you can do is wonder about the engineers and technical writers who write and draw those installation instructions.

From a Rheem/Rudd installation instructions - see attached.

[imported_John Smith]

I agree Jerry, but, I recall several references in IRC stating "or manufacturers instructions", probably not verbatim, but along the same lines.

[Jerry Peck]

I agree Jerry, but, I recall several references in IRC stating "or manufacturers instructions", probably not verbatim, but along the same lines.


"or manufacturers instructions"

Close ... but no cigar. ;) (see bold red text below)

- CHAPTER 14
- - HEATING AND COOLING EQUIPMENT
- - - SECTION M1401
- - - - GENERAL
- - - - - M1401.1 Installation. Heating and cooling equipment and appliances shall be installed in accordance with the manufacturer’s installation instructions and the requirements of this code.

Of course, though, the code then says:
- M1411.3 Condensate disposal. Condensate from all cooling coils or evaporators shall be conveyed from the drain pan outlet to an approved place of disposal. Condensate shall not discharge into a street, alley or other areas where it would cause a nuisance.
- - M1411.3.1 Auxiliary and secondary drain systems. In addition to the requirements of Section M1411.3, a secondary drain or auxiliary drain pan shall be required for each cooling or evaporator coil where damage to any building components will occur as a result of overflow from the equipment drain pan or stoppage in the condensate drain piping. Such piping shall maintain a minimum horizontal slope in the direction of discharge of not less than 1/8 unit vertical in 12 units horizontal (1-percent slope). Drain piping shall be a minimum of 3/4-inch (19 mm) nominal pipe size. One of the following methods shall be used:
- - - (then lists 4 methods)

Thus, when specified by the manufacturer, *it shall be done*, and when specified by the code, *it shall be done*... i.e., when specified by either one, *it shall be done*. :)

In the drawing Gunnar posted, it was not shown in the manufacturer's drawing, but - was it stated in the text of the installation instructions? If so, it was required, if no, that particular manufacturer did not require it, but ... if you call them and question them on it, I am sure it was an unintentional slight and that they will fix it.

Here is an example of an intentional slight I ran across in the Virginia Uniform Building Code today:

There is a section requiring door viewers in door entrance doors, unless there is view panels in the door, and the code stated that the *minimum*, yes, the *minimum* angle of viewing is ... drum roll ... 180 degrees.

Now, I don't know about any one else, but "180 degrees" is just what it says, and *I* cannot look out a glass door and see "180 degrees", much less any type of viewer I have ever seen. Try this - stand at your window and look out, can you see "180 degrees"?

The only way to see "180 degrees" is to bump the window out so it projects out past the wall the window is mounted in. Try that with a door view panel, much less a door viewer - even those wide angle viewers. :D

Technically, the super duper pooper scooper 200 degree wide angle door viewers are rated at that, but put them in a door and the jambs block the view to each side, unless, again, the door is projecting out from the adjacent wall.

[Darrel Hood]

I am beginning to frequently see moisture sensors installed in the primary condensate drain so they turn off the equipment if they sense moisture elevation. No secondary drain line is installed. I don't trust them and have not been able to find anything that allows this configuration. Am I missing something as usual?

Darrel Hood
DILIGENT PROPERTY SERVICES

[stanley frost]

darrel
IRC 2006 check M1411.3.1 Auxiliary and secondary drain systems, #3and #4

[Markus Keller]

Hmmm, so I guess I should include the 3/4" pvc condensate drain from the AC cemented into the basement cement floor from yesterday in my report. picky picky:D
House also had a great ventilation feature. I could stand in the basement and see the outside through the running foundation wall crack. I guess that eliminates the need for an xfan in the basement bath.
This report is going to be sooo long. :( Taking a quick break from it right now.

[RobertSmith]

Are secondary lines required to be insulated, either by code or manufacturer?

[Dom D'Agostino]

Are secondary lines required to be insulated, either by code or manufacturer?


The secondary isn't mentioned in Florida Code:

FBC 307.2.5 Pipe insulation. All horizontal primary condensate drains within unconditioned areas shall be insulated to prevent condensation from forming on the exterior of the drain pipe.

However, I've read AHU install guides that state "Insulate the drain lines where sweating can cause water damage." They don't differentiate between primary and secondary in the text.

I don't know about the IRC.

Dom.

[kenny martin]

The secondary isn't mentioned in Florida Code:

FBC 307.2.5 Pipe insulation. All horizontal primary condensate drains within unconditioned areas shall be insulated to prevent condensation from forming on the exterior of the drain pipe.

However, I've read AHU install guides that state "Insulate the drain lines where sweating can cause water damage." They don't differentiate between primary and secondary in the text.

I don't know about the IRC.

Dom.
Jerry,

Around here they only trap condensate with the draw through units and not the blow through.. running traps are only used with heat pumps.. soooooooooo??? I have never questioned, should I? what is the consequence? Thanks!

[Jerry Peck]

Jerry,

Around here they only trap condensate with the draw through units and not the blow through.. running traps are only used with heat pumps.. soooooooooo??? I have never questioned, should I? what is the consequence? Thanks!

Kenny,

Running traps are not allowed (unless a running trap is specifically referenced as being allowed/required in the installation instructions).

Some of the 'blow through' units do specifically state that a condensate trap is not required ... then the installation instructions hedge for wiggle room by adding: 'however, not installing a condensate trap will lead to a loss of efficiency" ... so why spend the extra money to buy a high efficiency unit and then blow all that savings out the condensate drain piping?

Those don't need a trap, except that they do to maintain their efficiency rating ... ? Huh? Does not make much, if any, sense, does it?

[kenny martin]

Kenny,

Running traps are not allowed (unless a running trap is specifically referenced as being allowed/required in the installation instructions).

Some of the 'blow through' units do specifically state that a condensate trap is not required ... then the installation instructions hedge for wiggle room by adding: 'however, not installing a condensate trap will lead to a loss of efficiency" ... so why spend the extra money to buy a high efficiency unit and then blow all that savings out the condensate drain piping?

Those don't need a trap, except that they do to maintain their efficiency rating ... ? Huh? Does not make much, if any, sense, does it?

?? I hate code writers!! And some manufacturers especially when things aren't written to be fully understood unless you are already an experienced pro! :tsk: Makes me head hurt!!! :frusty: