AC Secondary Pan

[Jack Tam]

Hello,

I tried searching this topic and couldn't find what I was looking for, maybe someone here could help.

I had an inspection done to my home and in the report it says that the condensation pan is too small and must be more than 3 inches from the perimeter.

The object in question is my coil case. It has the manufacturer's drain pan installed. It appears sufficient, is this something I can argue?

Thank you.

[Tom Rees]

Picture would help. 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.

[Chuck Melocco]

I believe the secondary drain pan is only need if evaporator is located in an attic' Although I recommend if evaporator is located on a wood floor. This pan needs to drained. or a water senor be installed to shut off unit if water is detected.

[Jerry Peck]

From the IRC: (underlining is mine)
- M1411.3.1 Auxilliary and secondary drain systems. - - In addition to the requirements of Section M2422.2, a secondary or auxilliary 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. (blah, blah, blah follows that)
- - - (then it lists four options)

An air handler unit anywhere inside the house can potentially meet the above conditions "as a result of" blah, blah, blah.

An air handler unit in the garage or basement ... maybe even ones installed there.

Obviously, an air handler in an attic can cause damage "as a result of" blah, blah, blah - but it is not limited to air handler units (coils) in attics.

[Dave Borowski]

Hello,

I tried searching this topic and couldn't find what I was looking for, maybe someone here could help.

I had an inspection done to my home and in the report it says that the condensation pan is too small and must be more than 3 inches from the perimeter.

The object in question is my coil case. It has the manufacturer's drain pan installed. It appears sufficient, is this something I can argue?

Thank you.


The Primary (OEM / factory) drain pan is not in this equation. The code defect is failing to provide a field installed secondary pan that can be seperatly plumbed or sealed and contain a float switch. Some municipalities will have some degree of interpretation but universally if the product is above the living plane - it needs a aux pan. For the record the living plane is the FLOOR.

[Jerry Peck]

... but universally if the product is above the living plane - it needs a aux pan. For the record the living plane is the FLOOR.

... or one of the four (4) code stated options (if the applicable code is the IRC or based on the IRC).

[Markus Keller]

My guess is you are probably talking about a secondary drain pan under the furnace rather than the actual manufacturer A coil pan. It would be very odd for an HI to call out the manufacturer's pan. The HI could be nuts but you are probably mentioning the wrong item.
If the HI is saying the pan is too small (obviously I haven't seen the report so I don't know the actual wording) then tell the Buyer you want their HI to verify 'based on what standard'. If he can't prove his sizing comment and dimensions based on a recognized industry standard ... well then.

[Frank Adame]

According an ASHI article from 2009 "They should extend beyond the air handler or coil box by 3 inches or more on all sides." I always write up the aux pan being too small. I don't see them too often though. I don't trust a pan where I cannot even fit my fingers in between the pan walls and the coil box. I have seen at least one of these where the condensate quickly overflowed to the attic floor. I like the larger, wider ones which are the ones I see almost every time.

I did have a seller call me up asking about my comment on the smaller pan. He said his a/c guy said the pan came with the equipment. I told the seller I will not argue with the tech or the manufacturer. I am just making a recommendation. I also always recommend a pan float switch. In Texas of course, the seller doesn't have to make repairs of any kind. Just say no.

I would quickly tell a buyer or seller that some things that I call out may not be code. My recommendations come from experience and what accidents I've seen.

Like someone said: "...a floor to work up from."

[Jerry Peck]

Regardless of what an ASHI article says, the codes say that the pan is to be 3 inches larger than the unit, which means that if the pan was centered under the unit the pan would be 1-1/2 larger than the unit all the way around the unit ... if the pan was centered ...

... and there is no requirement for the pan to be centered.

The pan could basically be lined up with one side of the unit as long as it catches all dripage from the unit.

[Tom Rees]

Like Jerry said, you could also use one of the other methods below (bold is mine).


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.

*I often see the 4th choice but I always recommend that this option be used only if this is not the only heating source in case the device shuts off the system when heat is required and pipes could freeze.

[Jerry Peck]

(bold is mine)

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.

*I often see the 4th choice but I always recommend that this option be used only if this is not the only heating source in case the device shuts off the system when heat is required and pipes could freeze.

There are four main problems with option four:
- 1) The code approves it. :)
- 2) Many are installed at a point below the primary drain line (in the primary drain line and downstream and downhill from the drain line opening) ... the installers were apparently not the brightest bulbs in the box.
- 3) When the coil ices up, then the unit shuts down ... all that ice WILL melt ... and all that water HAS to go someplace ... and there IS NO PLACE for that water to go. See 4) below.
- 4) See 3) above, a freeze switch needs to be ... versus "required to be" ... "needs" to be installed on the coil to shut the system down BEFORE the coil freezes up.

[Tom Rees]

All good points Jerry. I would estimate, from what I see at the houses I inspect, 90% of the installations that call for one of these 4 options are installed wrong.

[Frank Adame]

In the attic, I just saw three rusted baking pans directly underneath a coil box which had an undersized secondary pan. Proof of past overflow. The a/c tech's solution was to hang a larger secondary pan underneath the original smaller pan. So: undersized original pan, new larger hanging pan and 3 baking pans on the attic floor. That should take care of overflows.

[Dave Borowski]

In the attic, I just saw three rusted baking pans directly underneath a coil box which had an undersized secondary pan. Proof of past overflow. The a/c tech's solution was to hang a larger secondary pan underneath the original smaller pan. So: undersized original pan, new larger hanging pan and 3 baking pans on the attic floor. That should take care of overflows.

32970 And it just gets better...

[Jerry Peck]

32970 And it just gets better...

Dave,

That must be one of those newfangled 'quiet' traps - those traps are so quiet ... you can walk right up on one and not even notice the trap because its sneaking around. :thumb:

Or ... 'Honey, have you seen my old sneakers? I haven't seen both of them for a while now, not since ... you remember when we the ac in the attic worked on - not since back about that same time.'

[Tom Rees]

Wondering what your thinking was on installing a SAFE-T-SWITCH® at secondary condensate drain line where there is only one furnace and you are in a northern climate where there is the possibility the switch could shut off heat.

[Jerry Peck]

Wondering what your thinking was on installing a SAFE-T-SWITCH® at secondary condensate drain line where there is only one furnace and you are in a northern climate where there is the possibility the switch could shut off heat.

About all you can do is point out that code does not address common sense, or the lack thereof ... and that common sense would obviously point that out as a potential loss of heat and that the common sense solution is to install a secondary drain - and that same common sense would point out that such drain needs to be protected from freezing.

But that is just common sense speculating ...

[Tom Rees]

Jerry, My thoughts exactly.

[Dave Borowski]

Jerry, My thoughts exactly.

Perhaps the greater takeaway here is a better understanding of not only ALL OEM installation guidelines & most all mechanical codes across N America, the general wording is all products that could cause water damage (HVAC, humidifiers, WH, Dehumidifiers, Condensate pumps, etc.) must have field installed emergency pans installed IF the product is above the living plane. For clarification, the living plane is the FLOOR - so Yes, even vertical air handlers installed in a closet on the 1st floor require emergency pans. The draining of the pans and or the float switch option varies from code to code but norms are in play IE: you can't tie secondary & primary drains together.

[Jerry Peck]

Perhaps the greater takeaway here is a better understanding of not only ALL OEM installation guidelines & most all mechanical codes across N America, the general wording is all products that could cause water damage (HVAC, humidifiers, WH, Dehumidifiers, Condensate pumps, etc.) must have field installed emergency pans installed IF the product is above the living plane.

(bold is mine)
"must have field installed emergency pans installed IF the product is above the living plane"

That would be nice, but that is not a code requirement.

Perhaps the greater takeaway here is a better understanding of the codes and what the code requires, and the code requirements are minimum requirements.

It would be nice, really nice, if all contractors EXCEEDED the code's minimum requirements, but that is not required. The code requires certain things, the manufacturer's require certain things, the most restrictive between the two is what establishes the minimum requirements ... and unless any given manufacturer requires an auxiliary pan under the equipment, it is just wishful thinking that an auxiliary pan is required ... an auxiliary pan IS NOT "required" ... the code offers four (4) choices and ANY ONE of those four (4) choices IS ALLOWED.

Common sense to allow not installing an auxiliary pan? Not really, but the code is not a collection of common sense dos and don'ts - thus one should not go around stating (bold is mine): "must have field installed emergency pans installed IF the product is above the living plane" as that is incorrect.

[Frank Adame]

Today's air handler in the attic didn't even have a secondary pan at all. Instead a 5 gallon bucket was placed under.

[Tom Rees]

Today's air handler in the attic didn't even have a secondary pan at all. Instead a 5 gallon bucket was placed under.

Frank, Did the 5 gallon bucket have a drain line??
We should have a special forum for all the crazy stuff we've seen.