Horizontal air handler condensate issue

ratio

Most split systems require drilling holes in various places to take pressures. It's pretty tedious to drill into a coil to get to the right spot. At least some mfgrs want one pressure taken from in between the slabs of the coil, which means you've got to drill into the front, while missing all the cap tubes, suction line, etc. inside there.

And after it's all done, you've got holes drilled in your brand-new equipment!

<sigh>

JUGHNE

Old Lennox units from the 60's were predrilled with snap in plugs installed. Such that you could go in between the coil slabs without removing any panels. Also up stream and down stream.
I doubt if many were ever used....just git er done.

ChrisJ

> @JUGHNE said:
> Old Lennox units from the 60's were predrilled with snap in plugs installed. Such that you could go in between the coil slabs without removing any panels. Also up stream and down stream.
> I doubt if many were ever used....just git er done.

That's also back when equipment typically lasted 20-30 years no?

JUGHNE

A small church here build in 1969. 2 horizontal Lennox gas/AC in attic.
Wet ceiling, my guess was rusted out drain pans.
Had to add additional attic access holes to get to coil doors.
When I was younger I could climb over the tops of the units, but I was younger 40 years ago.
Pans look great. Long galv pipe drain was plugged.
Plugged coil drains with rubber plugs and they held water for at least 2 days.
Coil tubing is all 1/2" OD, something you could solder on if needed.....fed by that unique Lennox 1/4" coil of copper that you do not shorten.

Since I first serviced these they have replaced one compressor, some run caps, belts, inside motors and little else in 40 years.
Still the same T-couples in the NG furnaces for 40 years.
Have not had to relight a pilot.

51 years is almost unheard of for any horizontal gas furnace....but they are in a dry attic with good sized pilot flame 24/7/365/51 years.

Twice a week they bring temp up from 55 to 75, that seems drastic for heat exchangers to handle in a cold attic....but that pilot light is there.

ChrisJ

What do we have here?

This isn't mine and it's not connected to my ductwork and its not in an attic.

ChrisJ

So after a good test yesterday I went up into the attic to check my modified ahu at home and for the first time (on a high load day) since I installed it in 2017 the entire bottom of the air handler was dry and warm. No cold or sweating and we had a reasonably high dew point. Dew point was 70F.

Also, the drain for the blower side pan even had water in it.


I guess I'll be making a pan for the one at work too.

JUGHNE

Looking at the last picture you posted....not your coil....should that A coil be flipped with the point of the A pointing at the suction of the fan. Might not pull as much water off the coil??

ChrisJ

> @JUGHNE said:
> Looking at the last picture you posted....not your coil....should that A coil be flipped with the point of the A pointing at the suction of the fan. Might not pull as much water off the coil??

That's the entire issue.
For horizontal right which I need in both applications this is how they tell you to install it. It's a bad design and I guess is rarely used.

Im sure in horizontal left it works just fine.


It's happening because the water is fighting the air on the top section and not draining.

JUGHNE

A couple got a double wide with the typical "trailer house" ductwork.
The counter flow gas furnace was 1st floor hallway closet.
A coil sitting up right under furnace.
They noticed water dripping out of the basement ductwork.
You have to keep the blower on high speed to hammer the air thru the maybe 5 X 16 supply duct. It resembles an aluminium pillow case. Someone told me it comes in a roll and they inflate it up like an air mattress?? So thin it is almost impossible to install a take off. I just cut small registers for the basement.

I simply sprayed the coil with liquid soap mixture.....it worked.
It makes "wetter water"....like fire fighter foam, makes water cling to the surface to prevent re-ignition.
Maybe you need "Dawn soap spray injectors", set on run timer

I wonder how many double wides had this problem and it went unnoticed as few were sat on basements.

jwigginton

I just installed a Goodman ASPT49D14 (4 ton unit). Its in the garage. I had to install horizontal right also. I live in FL, so its crazy humidity and hot. I'm see the unit sweat and insulation is soaked and leaking out of the cabinet. I think i may be having the same issue you are having. I noticed the sweating is only on the right blower side of the unit.

Suggestions? Is your DIY blower side drain pan working for you? Not sure what else I could try. I thought it could be something with the drain pain not draining correctly and it overflowing to that side. But ran across this thread and might be same issue.

ChrisJ

jwigginton said:

I just installed a Goodman ASPT49D14 (4 ton unit). Its in the garage. I had to install horizontal right also. I live in FL, so its crazy humidity and hot. I'm see the unit sweat and insulation is soaked and leaking out of the cabinet. I think i may be having the same issue you are having. I noticed the sweating is only on the right blower side of the unit. Suggestions? Is your DIY blower side drain pan working for you? Not sure what else I could try. I thought it could be something with the drain pain not draining correctly and it overflowing to that side. But ran across this thread and might be same issue.



How long has the unit been in use?

Not sure on how much the pan is helping.
I say that because I've yet to get any actual condensate out of the drain on that pan and the bottom was sweating a little the last time I was up there. It's still not perfect but it seemed 90% better.  The sweating was not minor especially in a 120 degree attic.

I also sealed the covers with tape because it seemed to be having big issues with leakage as well.

That said, I installed a 5 ton unit where I work also horizontal right and for a while the amount of water that came from the blower side when you shut it off was unreal.   And then.... It stopped.  Or at least got good enough it's bit l not leaking out.  I suspect oil on the evap was either causing it, or making it a lot worse.

If it's only been a few days I'd wait another week or so.  Or try washing the evaporator.

Do you have a good trap on it?

ratio

@ChrisJ, is your unit condensing on just one side of the box as well? That sounds like an airflow issue, too much cold air blowing on one side & overcooling it. @jwigginton, look inside & see of there's a reason the air is favoring one side over the other. Blower canted slightly, ductwork turns too soon after leaving the unit, etc.

ChrisJ

ratio said:

@ChrisJ, is your unit condensing on just one side of the box as well? That sounds like an airflow issue, too much cold air blowing on one side & overcooling it. @jwigginton, look inside & see of there's a reason the air is favoring one side over the other. Blower canted slightly, ductwork turns too soon after leaving the unit, etc.

Well, yes.
The bottom side, where the water lays. The air isn't favoring it.


The one at work was dumping water out any time we shut of it off. It wasn't really sweating because it was in the conditioned space.

The last time I checked mine and it seemed like it was 90% better, I'm thinking there's a chance either very little water was laying in an area for whatever reason, or, it's an area the insulation is pushed down some from the way it's built and it's just not enough in a hot humid attic. I'm ok with that. The pan under the unit catches any minor sweating during extreme conditions.

Wil_F

New guy here. I'm not an installation professional but by vocation I am trained as an engineer in my former life. Interesting problem in this post, and is the same problem as what I'm seeing in my (hot climate) SC home, this time it's a Goodman ARUF31B14AA ....also horizontal/right discharge, and also "hot-attic" located. Forgive my ignorance, but can we review some basics?... I thought I had these systems pretty well understood and now something seems strange. With the blower located to the right of the evaporator, this makes the unit (at least the evaporator section), operate under negative pressure, and therefore also requires the MAIN drain under the evaporator, to have a "U" trap in the drain line. I understand the need....The "U" trap then allows a continuous drain that would be blocked otherwise by incoming air being sucked-in. Without a trap, water levels can build up under the evaporator,and only drain as a "dump" when the unit is shut. Can also overflow, etc, etc. Anyway, ...in my situation, the SECONDARY (higher) drain connection, only has a PVC pipe installed that points down onto the large drip pan under the air handler. Completely open without a trap ( aside: the drip pan has a separate drain connection and piping the leads to the outside of the house).
The questions:
1.) Wouldn't the "open" secondary drain connection allow hot humid air to enter the air handler, and negate any "Sealing" that is done on the unit.....either at the access doors or sealing up penetrations, etc ???..and wouldn't this then create even more tendency to form liquid water (condense), inside the unit?
2.) In the case of the new pan built by Chris that he located under the blower.....we see from his pics that it also has a threaded PVC port for drain. Is this also "open" to the outside like the secondary drain?...and wouldn't this likewise allow hot/humid attic air to enter the air handler?
Help a guy out here......thanks......

ChrisJ

Wil_F said:

New guy here. I'm not an installation professional but by vocation I am trained as an engineer in my former life. Interesting problem in this post, and is the same problem as what I'm seeing in my (hot climate) SC home, this time it's a Goodman ARUF31B14AA ....also horizontal/right discharge, and also "hot-attic" located. Forgive my ignorance, but can we review some basics?... I thought I had these systems pretty well understood and now something seems strange. With the blower located to the right of the evaporator, this makes the unit (at least the evaporator section), operate under negative pressure, and therefore also requires the MAIN drain under the evaporator, to have a "U" trap in the drain line. I understand the need....The "U" trap then allows a continuous drain that would be blocked otherwise by incoming air being sucked-in. Without a trap, water levels can build up under the evaporator,and only drain as a "dump" when the unit is shut. Can also overflow, etc, etc. Anyway, ...in my situation, the SECONDARY (higher) drain connection, only has a PVC pipe installed that points down onto the large drip pan under the air handler. Completely open without a trap ( aside: the drip pan has a separate drain connection and piping the leads to the outside of the house).
The questions:
1.) Wouldn't the "open" secondary drain connection allow hot humid air to enter the air handler, and negate any "Sealing" that is done on the unit.....either at the access doors or sealing up penetrations, etc ???..and wouldn't this then create even more tendency to form liquid water inside the unit?
2.) In the case of the new pan built by Chris that he located under the blower.....we see from his pics that it also has a threaded PVC port for drain. Is this also "open" to the outside like the secondary drain?...and wouldn't this likewise allow hot/humid attic air to enter the air handler?
Help a guy out here......thanks......

The new pan I built also has a trap on it, actually two. It goes outside, and I have a shallow trap right by the unit, but because I knew that would run dry I installed a "waterless" trap outside at the bottom, basically a check valve with a very light spring.

The secondary drain also needs a trap, but obviously that will end up dry fast and (hopefully) never fill, so for that I'd also use a waterless trap or a simple float switch instead of a drain. The last thing I'd want is it pulling in attic air.


In my case, I'm not sure the new pan I made does much, if anything. I believe the main issue was attic air leaking in around the blower side door/cover. Even small amounts getting in after the evaporator will condense on anything cold, which on that side is pretty much everything.

It's an ugly fix, but I taped around most of the doors. No air leaks and the problem seems to have gone away. The blower side I sealed 100% and the evaporator side I sealed anything big, but tried to also make it so worse case, water would drip out into the secondary pan under the unit.

I'm pretty confident attic air getting in after the evaporator was the main issue.

Wil_F

Thank you kindly for your comments. From your experience, and this latest note of yours, and also seeing how I'm plumbed.....would you recommend these steps in my situation?--->

1.) adding a "hinged cover plate" ( aka "check valve"), on my secondary drain ( using a soft gasket material on the inside of the flapper-plate, aka "flapper-check-valve")... maybe to include a LIGHT spring to keep it closed? Better yet instead of a spring on the flapper....maybe instead have an elbow on this drain line, to discharge horizontally ( opening is a vertical plane, flapper-hinge on top), but angling the discharge SLIGHTLY up so the weight of the cover will try to keep it closed?....and
2.) taping everything up as you did? ....I don't relish building a second drip pan under the blower, especially if you think you are not getting the total benefit you were expecting.....

So...if this is the best I can do.....does that mean every time there is a service call....we'll be cutting the door tape and have to re-install new tape every time? Not great....but it seems acceptable and do-able.

Many thanks for engaging.......

Wil_F

As follow-up....in principle something like this---> https://www.parts.spearsmfg.com/ProductDetails.aspx?pid=316&prdID=14107, using just the weight of the flapper door to keep it closed, slightly angled from totally vertical plane.
Oh...lastly..... what about adding poly sheet insulation over the entire air handler "box" ?.... thanks.

ChrisJ

I wouldn't try to build a trap.

If I was going to try and use the secondary drain, which I originally did but gave up on it for a few reasons I'd use this :

https://www.supplyhouse.com/Rectorseal-97637-Safe-T-Switch-Model-SS2

Wire it in to shut off the system if it trips.
But if you insist on having a secondary drain, something along these lines will work.

https://www.supplyhouse.com/EZ-Trap-83180-EZT-180-Waterless-In-Line-MiniTrap-without-Brush?gclid=EAIaIQobChMIicms_qWk8gIVSFtyCh3ydwBnEAQYBSABEgLlFvD_BwE


The one I used on my added pan was a vertical design, but they stopped making it.

ChrisJ

Sorry I forgot to mention, the link you posted didn't work so I couldn't look at it.

Not sure about polysheet. Added insulation certainly couldn't hurt.

And yeah, any time I want to do anything, I get to cut the tape and re-tape everything. It stinks, but it could be a lot worse.

Wil_F

Really appreciate you staying engaged.

Let me help on some of the things I didn't say correctly or make clear. Thanks again .

The electrical shut-off you recommend on the secondary line is OK in principal, but looking at the link you provided and the picture of the device, it SEEMS the unit is not sealed and would allow intake of air. The flapper-check valve I suggest instead to be installed on a small tail-piece of PVC.....would be "closed" to attic air under normal running conditions, yet if it's only a flapper valve with no spring, ...and if oriented correctly...it should open with minimum "cracking" pressure, which is what we want, when it begins to fill with water. Maybe this picture link works....by the way....when I show links I too thought the link doesn't work, but actually this website we're on, interjects a bit and reminds you you are LEAVING the site...then you need to look at this web text again and look lower, ....find the link again....and then when you click on the link, it works. Maybe that's what is happening to you too? In any case, let's try again by illustration--->

https://www.parts.spearsmfg.com/ProductDetails.aspx?pid=316&prdID=14107

( no "period" at the end !!). Maybe cut-n-paste the link address and insert elsewhere in your browser?

OK on the tape needing to be cut during service and the response to adding insulation..... many thanks.

ChrisJ

The switch needs to be glued to the NPT fitting it comes with.
The switch it self fits snug into the housing but is removable. I doubt it leaks any amount of air that would ever matter and the little if any it does, goes before the evaporator.

Wil_F

The switch is a good idea....but I found an "Angled" check valve ( flapper door has hinge on-top, and the flapper sits against its "Seat" not with the flapper straight down, but at an angle so the flapper-door weight helps keep it closed...if you can envision this). I'll see if I can upload a pic here. Anyway, this way when the A/C is running, the slight vacuum pressure in the air-handler keeps the flapper shut. Also, when the A/C is "off", likewise, the flapper is shut....and when running.... and if needed to drain, it opens, even if only 1" of water column exists upstream of the flapper, .. it will open.

I like this over a switch as it's non-powered, meaning, one-less thing to malfunction. To be clear, I have it plumbed this way---> the secondary drain opening at the unit has a downward-directed elbow...followed by about 5-6" length of vertical, 3/4" dia PVC.....then an elbow attached at the bottom that exits horizontally.....which is the input to the horizontally-located check valve located very close to the surface of the "external" drip pan. (That's how my unit is plumbed....primary to the outside of the house with water "U" trap, this secondary drain originally open to atmosphere draining into the external pan....and the external-pan "wall" having a piped drain connection that exits over an external wall window.

This is odd. The air-handler is normally "Sealed" all over the place, yet this secondary drain... as originally installed .... allows hot/humid attic air to enter the unit. Seems like it defeats the whole idea of sealing the handler. Seems either my method or your switch should help "tighten -up" the handler.

ronbugg

Is the coil in backwards Wirenut 

Wil_F

No...in this case of "air-in" from left ( called "horizontal-right configuration" by Goodman)....that is how the Goodman unit is built and configured...yes, it is better for the A-frame design to be put in the other-way around, but that's not possible here. Look at a composite of all my earlier comments in my dialogue with ChrisJ....my solution has worked now for 2 seasons. The fix..... 1.) encapsulating the entire air handler unit with a good amount ( 1" or more thick) of poly foam-board insulation ( the silver 1/4" thick stuff inside is not adequate for units placed in hot attics....2.) adding a flapper-check valve in the high-level overflow PVC connection that normally is open to the external drain pan....this prevents "sucking-in" hot air when the unit operates under negative pressure and lessens the tendency for the unit to "sweat". See earlier comment showing this piece.

ChrisJ

Wil_F said:

No...in this case of "air-in" from left ( called "horizontal-right configuration" by Goodman)....that is how the Goodman unit is built and configured...yes, it is better for the A-frame design to be put in the other-way around, but that's not possible here. Look at a composite of all my earlier comments in my dialogue with ChrisJ....my solution has worked now for 2 seasons. The fix..... 1.) encapsulating the entire air handler unit with a good amount ( 1" or more thick) of poly foam-board insulation ( the silver 1/4" thick stuff inside is not adequate for units placed in hot attics....2.) adding a flapper-check valve in the high-level overflow PVC connection that normally is open to the external drain pan....this prevents "sucking-in" hot air when the unit operates under negative pressure and lessens the tendency for the unit to "sweat". See earlier comment showing this piece.

I don't think I've had any issues at all either since adding the pan under the blower, which, best I can tell does absolutely nothing, and taping the doors / covers closed to fix leakage issues.

Wil_F

The core issue....that I think we've both found....is that we have a cold "box" located in a "hot" attic....much like a cold iced-tea drink left on the table will "sweat" on the outside-surface, in a warm / humid environment. Yes....sealing the access door better, but also eliminating any other means of sucking-in hot attic air ( like my check valve on the overflow connection)...plus adding a pile of insulation around the whole unit....I think does the trick. For the record, before my mods there was a hellish amount of water pouring off the far-end ( right side in this same Goodman "right-side-exit" configuration) of my unit....that AT FIRST made me think of an internal pan solution as ChrisJ followed, because of the goofy backward evaporator coil design that can cause water carry-over internally. After some false starts it ended up working better for the 2 mods I mentioned. Lastly this.....if you dig deep into the Goodman manual....it says to add insulation around the unit if the air-handler is placed in a "hot location". I think they mention something like 1"-2" of fiberglass insulation but I think it would have been better to give some guidance instead on recommended R-values for certain conditions. In my case, the "local" atmosphere in the attic was about 120-125 degF and over 90 % humidity that caused my original problems.....

ChrisJ

Wil_F said:

The core issue....that I think we've both found....is that we have a cold "box" located in a "hot" attic....much like a cold iced-tea drink left on the table will "sweat" on the outside-surface, in a warm / humid environment. Yes....sealing the access door better, but also eliminating any other means of sucking-in hot attic air ( like my check valve on the overflow connection)...plus adding a pile of insulation around the whole unit....I think does the trick. For the record, before my mods there was a hellish amount of water pouring off the far-end ( right side in this same Goodman "right-side-exit" configuration) of my unit....that AT FIRST made me think of an internal pan solution as ChrisJ followed, because of the goofy backward evaporator coil design that can cause water carry-over internally. After some false starts it ended up working better for the 2 mods I mentioned. Lastly this.....if you dig deep into the Goodman manual....it says to add insulation around the unit if the air-handler is placed in a "hot location". I think they mention something like 1"-2" of fiberglass insulation but I think it would have been better to give some guidance instead on recommended R-values for certain conditions. In my case, the "local" atmosphere in the attic was about 120-125 degF and over 90 % humidity that caused my original problems.....

True,
But keep in mind lack of insulation would cause it to sweat outside, not inside the unit.
Infiltration causes the sweating inside.


I do have to ask though, how did you manage 125F @ 90% RH?
That's a dew point of 120F? I don't know if that even exists on earth naturally? Is something adding humidity to the attic?

Wil_F

True enough on the temp/humiduty pairing....these were separate day measurements for each characteristic...not concurrent. What I am saying is that it's not unusual to have 120-125 degF attic temps as one meanurement....it is also not unusual for our coastal SC climate to show high-ish humidities at outside-of-house 90-ish F ,ambient conditions. Good catch...
As to the other points.....at the time my unit was shedding heavy droplets of water on the outside / right-most surfaces.....I actually called in an AC guy who took off the doors and proclaimed the interior fairly dry ( all this before my mods were done). So I was left confused. I would offer that a steel air-handler casing with inadequate 1/8" foil type insulation inside...as we seem to find with modern AC units...can still transmit coldness to the outside surface to cause a bad case of sweating. No ? All I can say is I don't see the sweating now after my mods. No doubt sucking-in warm air via the high/high overflow pipe that I found open to the external drain-pan.... without a check valve..is a problem to fix.