Horizontal air handler condensate issue

pecmsg

I believe Supply house.com carries them!

icy78

Ill bet the goodman is derated for horizontal.
Many are.
Trane ,AS, will be at 4ton airflow in horizontal config, if i remember correctly.

ChrisJ

> @icy78 said:
> Ill bet the goodman is derated for horizontal.
> Many are.
> Trane ,AS, will be at 4ton airflow in horizontal config, if i remember correctly.

There's no mention on that in the documents.
Why would that cause this issue?

ratio

Derate the coil on horizontal (left,right) applications in such a way as to lower the air velocity through the coil.

Some if these li'l details are exceedingly hard to find in the mfgr's paperworks. No to say that yours is. One would think that something like that would be at least in the IOM, but it might be that you're Just Supposed To Know™.

ChrisJ

> @ratio said:
> Derate the coil on horizontal (left,right) applications in such a way as to lower the air velocity through the coil.
>
> Some if these li'l details are exceedingly hard to find in the mfgr's paperworks. No to say that yours is. One would think that something like that would be at least in the IOM, but it might be that you're Just Supposed To Know™.

The AHU is their high seer version so the thing is already huge. It uses a much bigger coil and a large blower running slower than the standard one.

I would think the velocity through it would also be much lower than the standard version.

The AVPTC36 is the standard, This is the 37.

@ratio do you have an example of this rule printed anywhere?

ratio

No, I don't. I was just explaining what (I believe) is the purpose of derating a coil for horizontal use.

I don't know that your coil needs to be derated for horiz. use, just that I believe any derating would be to alleviate the very problem you're experiencing; and that sometimes critical information, such as this, isn't as readily available as one might expect.

I've come across more than a number of instances where necessary information isn't published. It's known by the factory startup guy & (presumably) covered by the factory training but isn't explained in any kind of detail in any readily-found documents. (NB: this is somewhat specialized commercial equipment, but there are a good number of competitors so the assumption of a lock-in by a mfgr is flawed.)

ChrisJ

A plexiglass door isn't going to work IMO because it's not bad enough for that.

On the hottest days of the year, it slowly soaks the insulation on the bottom. It takes days of it running almost nonstop. I'm talking 90+ degrees and 50+% humidity. Guys down south stop laughing.

Best I can tell, it's an occasional drip that just misses the bottom evap and instead hits the plastic that is pitched towards the blower compartment.

I'm looking at it now and see no signs of water hitting the blower housing and it actually seems like it's only at the front corner, the back shows no real signs either.

I'm thinking a simple 4" x 18" aluminum pan siliconed in with a lot of pitch back into the evap across the bottom.

I hate the fact this is in a place that becomes off limits by the time I really need it. If I ever build a house all of the equipment goes in the basement.

pecmsg

Any chance it not carryover but condensation forming in the cold chamber?

ChrisJ

> @pecmsg said:
> Any chance it not carryover but condensation forming in the cold chamber?


I've wondered if it's the plastic above and maybe below condensating sand dripping but I have no way of knowing.

You make a good point, maybe aluminum isn't the best material for me to use either. That could cause the same issue

SuperTech

Maybe you could use the leftover plexiglass that you will have after making a see through air handler access panel.

pecmsg

3/4" Plywood between the cabinet and uni-strut!

It will stiffen the cabinet as well

GW

I had the same issue with a Unico and thankfully Unico sent us a drip rail kit of some sort and that fixed the problem. The key was figuring where the drips were coming from.

clammy

I may have to agree w the unistut n plywood . We usually take a little more consideration when I hang a air handler if rafters are sized and can handle the load I use rod deep strut and 3/4 plywood if I don’t use a gorilla pan and go w plastic or have a metal pan made iusuually sit the pan on the plywood and then get a sheet of 2 blue board and set my unit on that .theres a few pluses to this method one your pan doesn’t have to be totally filled to shut off pan switch or set wet alarm off and it help support the air handler being some manafactures units are tin foil also if u do have a coil get frozen the cabinet doesn’t get bend and warped from the weight and the issue w drainage and warped housing is a true hassle . If rafter are on the light side we build a plywood base w 2 x6 and some 3/4 plywood and do the pan w blue board or gorilla pans . I don’t seee any other doing it but I not in any race to the bottom and there’s always somebody cheaper and I hate doin shortcuts to get a job I just won’t do it being every little thing i do shoddy always bites in the butt so I refuse to do hackystuff w my name on it as a sub I could less what ever u want the cheaper the better they say . Also I try to run my versa bar length wise so removing blower or coils are not a pia and it stiffes the air handler . This is just me and I know I’m not the rule but when I’m the one who has to deal w the issue related to a install at least I can take just a few things off the issue list like tweaked cabinets Have u filled the pan capped the condensate line to ensure the pan is not cracked it happens . Have u checked u pressure drop across ur air cleaner Peace and good luck clammy

ChrisJ

I have the unit sitting on two pieces of unistrut running longways that sit on top of the supporting unistrut on the ends.

You can't really see it in the picture, but that's why there's a gap between the end pieces and the unit.

I found the AHU was so flimsy I couldn't removed the panels so I did that.

ChrisJ

If I didn't mention it before, I'm running a 25x20x5" MERV 8 AirBear filter that I believe is rated something like .15" drop @ 1200 CFM.

It was the biggest filter I could fit.

It amazes me all of the MERV 10 and 13 1" filters I see for sale....... I have no idea what people are using them in but they wouldn't work for me.

pecmsg

ChrisJ said:

It amazes me all of the MERV 10 and 13 1" filters I see for sale....... I have no idea what people are using them in but they wouldn't work for me.

AKA Furnace Killers.

DZoro

You had mentioned that it was happening on the really hot days. I'm not sure if you added insulation on the cabinet itself. I have insulated some cabinets with 2" Styrofoam cut and glued completely around the cabinets. Just a thought if maybe more of a high humidity/air condensation issue than condensate off the a-coil itself issue.
Just a thought.
D

pecmsg

1 or 2" Styrofoam is more then enough. With the cradle you built just lay the cabinet on it!

clammy

I hate all flimsy doors especially in a 140 attic sometimes it’s the worse part of the whole job get the service doors on after it’s all tweaked even when u handle it w kid gloves . Some are better the others . I think the trane tam units are pretty tough w there air tight doors . I kinda feel trane residential air handlers are up on the top tier as for not tweaking and if it does u must have been working on it . As for the rest cheese cake have to say unico are nice ah too I have to say but doesn’t this only occur on hi ambient I know excaltly how much work it would be to reinsulare the inside of the cabinet using closed cell armoflex 1/2 thickness . If u install the outside u may be forming a vapor boundary which may let condensate form on the cabinet and rot it just a thought I know unico are insulated in such a manor for approve in California wish they all would be insulated in such manor instead of the foil crappola peace and good luck clammy

ChrisJ

The AHU only sweats on the bottom not the top or sides.

ChrisJ

Found a doodle of my return setup.



And here's a rendering of the Unistrut setup. This is to scale but obviously not 1:1.

Tinman

I did not read every post so this has probably been covered.

Most of my conventional system, horizontal A type coils have been Trane/American Standard. On those, there is a metal air diverter on the outlet side of the coil that is installed at an upward angle away from the bottom of the coil. The bottom of metal diverter drops into the drain pan so any water that is blown off the coil, drains back into the pan.

It always worked. If yours doesn't have that, i would suggest going that route assuming everything else checks out.

ChrisJ

Steve Minnich said:

I did not read every post so this has probably been covered.

Most of my conventional system, horizontal A type coils have been Trane/American Standard. On those, there is a metal air diverter on the outlet side of the coil that is installed at an upward angle away from the bottom of the coil. The bottom of metal diverter drops into the drain pan so any water that is blown off the coil, drains back into the pan.

It always worked. If yours doesn't have that, i would suggest going that route assuming everything else checks out.

Hi Steve,

Are those coils mounted backwards like mine, with the wide part facing the blower?

pecmsg

Whats the Model # of that air handler?

ChrisJ

pecmsg said:

Whats the Model # of that air handler?

AVPTC37D

Tinman

@ChrisJ - No, they’re not.

ChrisJ

The proposed ABS or CPVC pan.




Please excuse the crudity of this model as I didn't have time to build it to scale or to paint it.

icy78

Iz> @ChrisJ said:
> The proposed ABS or CPVC pan.
>
>
>
>
> Please excuse the crudity of this model as I didn't have time to build it to scale or to paint it.

Man that is a crude piece of work. WTH!

No no, just kidding.🙂 Nice work👍

ChrisJ

This is what I get to do on my way off.....

Bleh.

ChrisJ

It's not anywhere near as fancy as I wanted but I don't have time time to do it.

Quickly done with snips and hand tools.

Hopefully this will get the job done. It's aluminum.

ChrisJ

So I ended up ripping this modification out yesterday.

It was causing a howling sound I could really hear through the returns. So I went up into the attic and it was actually making the air handler vibrate enough it was vibrating the rafters through the threaded rod.


The howl \ noise was at around 150Hz.


I tried pulling the aluminum down in the center by taping the bottom all the way across, no improvement. The vibration also appeared to be knocking a ton of water off of the upper half of the evaporator, making the problem far worse than before.


I don't know what happened, but I do wonder if that piece was causing the upper blower wheel to move more air than the bottom one and cause some sort of imbalance / oscillation.

Really not sure what to do now. I never imagined such a small change could totally screw it up. It's so quiet normally and that made it awful.

A video I took with my phone up near the main return grill.
That howl / ringing is completely gone now without my little "shelf". You can hear it kind of fade louder and quieter in the video.

https://youtu.be/b_IBZyXa-38

clammy

Not for nothing that was a multi pose ah did you reverse the coil usually the open part of your coil is towards the blower not the way I see urs .we switch Bryant and carrier units all the time I ve never seen a coil that was not reversed drain properly . I don’t really do Goodman’s so I can’t tell u but I would chk w manafactures .i do remember a pan extension but I believe that was from the single slant carrier coils not a or n coils. Peace and good luck clammy

ChrisJ

clammy said:

Not for nothing that was a multi pose ah did you reverse the coil usually the open part of your coil is towards the blower not the way I see urs .we switch Bryant and carrier units all the time I ve never seen a coil that was not reversed drain properly . I don’t really do Goodman’s so I can’t tell u but I would chk w manafactures .i do remember a pan extension but I believe that was from the single slant carrier coils not a or n coils. Peace and good luck clammy

Hi Clammy,
My first post in this thread shows a snip from the installation manual. It shows the coil exactly as I have it and I did have to flip it. It's just bass-ackwards from normal. I guess that's a Goodman thing, I don't know.

pecmsg

The air outlet...…….Is there or was there 20 - 36" of straight duct, no takeoffs or bends to let the air flow settle down?

ChrisJ

pecmsg said:

The air outlet...…….Is there or was there 20 - 36" of straight duct, no takeoffs or bends to let the air flow settle down?

The supply duct?
No, there's a plenum right on the end that splits into two 14" round ducts, one on each side. I forget it's dimensions off the top of my head.

That's on the other side of the blower as this is a draw through evap.

Why do you ask?

pecmsg

Several units require a straight run of duct too allow the air turbulence to settle into a smooth straight run.

Amp the fan motor with several raps on the probe and see if the amperage is steady of bouncing.
Steady the air flow is smooth and fan speed is content. (rarely seen)
Bouncing a lot and the speed is changing due to the blower wheel slipping or Surging!

ChrisJ

pecmsg said:

Several units require a straight run of duct too allow the air turbulence to settle into a smooth straight run.

Amp the fan motor with several raps on the probe and see if the amperage is steady of bouncing.
Steady the air flow is smooth and fan speed is content. (rarely seen)
Bouncing a lot and the speed is changing due to the blower wheel slipping or Surging!

Unless I missed it, they made no mention of this requirement in the documentation.

I haven't metered it out, but I can tell you my 0 - 1" Magnehelic moves around when it's running. The total static pressure varies up and down by about 0.04" or so. I always assumed this was normal, but really have no idea.

Leonard

Might drill a hole and install a camera to watch how water sheds off things. Someone showed me a camera ~ 1/4 inch diameter on ~ 25 ft of USB cable that shipped from China for ~ $7, was new. Add a 50 watt 12V light bulb

150 hz howling...likely vortex shedding off the edge of your added sheetmetal, (turbulence). (Honeywell made a velocity meter for liquids that translated that frequency into flow speed, )

Might try changing angle of your added sheet metal or add trailing edge to it so it approximates side of a delave nossel (hourglass shape). don't know if that will work, but it should smooth the air flow, if get curve right. with smooth curves more likely to get laminar flow rather than turbulence.

Lot of talk of DIFFERENTIAL pressures along air path. I assume you already did it but I'll just say it in case condensate pan is spilling. Try putting a hole into plenum down stream of coils and use U-tube water manometer to measure pressure between inside and outside of unit. Compare that to U tube height on your condensate drain, make sure you have enough height on that U-tube drain.

I'm not a HVAC installer , I'm mechanical engineer with some experience with tenant screw ups on roof HVAC (mostly just drains) and have reconditioned window AC units.

To cool attic in summer so can work in it how about couple water sprinklers on roof to keep it cool and some fans in attic vents

BillM

One other thing to look for is air leakage from the attic into the return of the unit. Extreme hot and humid air can produce so much moisture that it overwhelms the coil's ability to runoff the water. It can also cause condensation on any cold metal part. We have actually had to add additional insulation to the cabinets to avoid condensation on some attic jobs

ChrisJ

This nightmare is still continuing.

Right now, my plan is to fabricate a plastic pan for the blower side of the evaporator to catch what comes off of it on hot humid days. I'd use either poly carbonate or PVC and solvent weld it.

My little baffle idea failed horribly so I want to make this pan the full dimensions of the compartment to keep it out of the air stream.

I'd run a bead of silicone on the evaporator side to make sure any drippings make it into the pan and not behind it.