Horizontal air handler condensate issue

icy78

Try the citrus juice first.

1- lemon or lime may be in your fridge
2- cheap
3 -easy
4-proven
5-bio-degradable

However, if your 0.5" pressure drop is across the coil only , it's the wrong coil or way too much air or the RH may be too high, (long shot)

Is this by chance an ADP evap coil? If so, I'm not surprised at the high DELTA P.

ChrisJ

pecmsg said:

According to Fig 5 it blows thru.

Draw thru Must have a trap. A running trap may not have enough water weight to hold back the incoming air. with .5 SP i would like to see at least 1" of water in the trap.

Those arrows indicate the direction of the blower rotation. Supply connects to the right side, return to the left side.

JUGHNE

Looking at Fig 5, those arrows on the blower housing might show rotation of the wheel or maybe they shouldn't even be there.
The air filter frame (cheesy as it is) is on the left.
The breakers and elements (if any) are on the right.
I would call it negative pressure coil.
And I agree the running trap just isn't deep enough.
If water is not freely draining the pan level will come up possibly giving more water available to sling away.

ChrisJ

> @icy78 said:
> Try the citrus juice first.
>
> 1- lemon or lime may be in your fridge
> 2- cheap
> 3 -easy
> 4-proven
> 5-bio-degradable
>
> However, if your 0.5" pressure drop is across the coil only , it's the wrong coil or way too much air or the RH may be too high, (long shot)
>
> Is this by chance an ADP evap coil? If so, I'm not surprised at the high DELTA P.

no sir, .5 is total drop across ductwork both supply and return and filter. I've never measured the drop across the coil it self.

McGee

> @ChrisJ said:
> Gentlemen,
>
> @McGee, @GW
> You're looking at the adjustable flag on the magnehlic, that's not the pressure. In that picture the gauge wasn't even hooked up yet, the red needle was at 0.
>
> The pressure runs at 0.5" WC in high stage, that's the highest it's been. When I dropped speed to under 1100 CFM it was around 0.4". Low stage runs around 0.2".
>
> Pressure is taken from the AirBear filter housing on the air handler side, and from the supply plenum before it splits into two trunks. This shows the total static load on the air handler.
>
> I had considered plumbing it into the suction side of the blower just after the evaporator as it would also show a dirty evaporator then, but I decided not to as I didn't want to put holes in the air handler.
>
> I'll see if I can get some videos when I pull the cover off but it's going to be a while. Air handler is a variable speed ECM setup.

McGee

I now see your static psi, lol, can’t see much of anything without reading glasses. Process of elimination, wash that coil and for from there. These things definately can be frustrating but when solved you’ll always remember this one.

GW

ChrisJ said:

Gentlemen,

The pressure runs at 0.5" WC in high stage, that's the highest it's been. When I dropped speed to under 1100 CFM it was around 0.4". Low stage runs around 0.2".

Pressure is taken from the AirBear filter housing on the air handler side, and from the supply plenum before it splits into two trunks. This shows the total static load on the air handler.

I so badly hate it when people split hairs with me, but, where at the Air Bear? I'm curious where you're getting a reading on the air bear cabinet.

So, that means-- you are getting a drop across the coil of .5" right? If I'm not too terribly mistaken, i thought these ahu's were designed for .2". I understand many people get confused on this. Furnaces are designed for .5 (no ac coil on a furnace), and AHU's are designed WITH the coil, hence a lower number.

ChrisJ

> @GW said:
> Gentlemen,
>
> The pressure runs at 0.5" WC in high stage, that's the highest it's been. When I dropped speed to under 1100 CFM it was around 0.4". Low stage runs around 0.2".
>
> Pressure is taken from the AirBear filter housing on the air handler side, and from the supply plenum before it splits into two trunks. This shows the total static load on the air handler.
>
>
>
> I so badly hate it when people split hairs with me, but, where at the Air Bear? I'm curious where you're getting a reading on the air bear cabinet.
>
> So, that means-- you are getting a drop across the coil of .5" right? If I'm not too terribly mistaken, i thought these ahu's were designed for .2". I understand many people get confused on this. Furnaces are designed for .5 (no ac coil on a furnace), and AHU's are designed WITH the coil, hence a lower number.

I'm plumbed in right after the filter right by where it's screwed to the ahu.

No, this is rated for 0.5". How could you get .2" when most pleated filters are that brand new alone?

ChrisJ

give me a bit and I'll post a diagram and some pics

GW

yes, i've been a static pressure dude for a long time; where to stick the tip, all that fun stuff. If we are talking just ahu, then we are not including the air bear. Poking holes is quite simple, you can get a drop on the filter, a drop on the ahu itself (the coil), a reading on the return ducts, and a reading on the supply.

ChrisJ

> @GW said:
> yes, i've been a static pressure dude for a long time; where to stick the tip, all that fun stuff. If we are talking just ahu, then we are not including the air bear. Poking holes is quite simple, you can get a drop on the filter, a drop on the ahu itself (the coil), a reading on the return ducts, and a reading on the supply.

Oh no, it measures the Airbear's pressure drop. The only thing it doesn't measure is the evaporator's drop.

Here's a drawing I did showing everything.

GW

very nice drawings Chris. if you have the energy please shoot some pix on where you're getting your static pressure readings. Not too close please, 3 or 4 feet back

ChrisJ

GW said:

very nice drawings Chris. if you have the energy please shoot some pix on where you're getting your static pressure readings. Not too close please, 3 or 4 feet back

It's in an attic.......3 or 4 feet back? Come on now.. It's also covered with insulation so you can't see much.

The return side is plumbed right in front (air handler side) of the air filter, and the supply side is plumbed into the supply plenum before it splits in half. It

The setup was Brad White approved.

GW

Ok wasn't trying to bust your chops- didn't know it was buried up there. I'd post a pic of my attic ahu job but you may curse me. I thought someone else asked for a drop across the coil and you said, 'don't have a drop across the coil'. It sure seems like you do. If you're on the inlet side of the ahu and the outlet side of the ahu, that's the coil drop you're reading.

ChrisJ

GW said:

Ok wasn't trying to bust your chops- didn't know it was buried up there. I'd post a pic of my attic ahu job but you may curse me. I thought someone else asked for a drop across the coil and you said, 'don't have a drop across the coil'. It sure seems like you do. If you're on the inlet side of the ahu and the outlet side of the ahu, that's the coil drop you're reading.

No need to apologize, you're here spending time helping me, I appreciate it.

I think you may be mistaken though.

I'm reading the suction from the blower after the evaporator, so I'm seeing pressure drop from the ductwork and filter on the return side.

On the supply side, I'm reading after the blower, but before the trunks so I should be seeing only the supply ductwork pressure drop.

In order to see the pressure drop of the coil, I would need my return line plumbed in between the blower and evaporator. No?

GW

I may be off, I can't think when i don't have an appliance in front of me. The Coil drop is B and C. The AHU TESP is B and D. My mistake. You're at B and D?

ChrisJ

> @GW said:
> I may be off, I can't think when i don't have an appliance in front of me. The Coil drop is B and C. The AHU TESP is B and D. My mistake. You're at B and D?

Correct B and D

GW

and the unit is rated for .5"? then that settles it, you're good!

McGee

If you have heatstrips even though it isn’t a lot it should actually be taken upstream of the strips.

ChrisJ

Well,
Last summer I had the same issue, condensate soaking the insulation in the bottom of the blower compartment. It didn't happen right away, it waited until it was too hot to do anything about it. I went up there a few times when it was over 130F in the attic to check on it.

Right now I'm convinced it's a bad design and that coil should've never been installed in that direction regardless of what the instructions say can be done.

I'm planning on making a small pan to catch hopefully all of the water and run it back into the evaporator. I hope.

I'm thinking some 6061 aluminum bent into a tiny pan with a lip on the end and install it using a thick bead of RTV on each end glueing it to the PVC border around the evaporator.

I hope it works, the last thing I want to even think about is evacuating the system and having to flip the entire air handler over and re-install everything.

This sucks.

pecmsg

T E S P

clammy

Chris I would install a deep trap and see how it goes As much as many will argue it’s unneeded look at the installation manual they show one no . I also have seeen the issue your having it’s usually in the ducting I always design my install for .75 on supply and .50 o return and never have a issue all my units are installed dead level and after over 30 years of installation work I have yet to have any issues . I sub for others who insist on putting crazy pitch on the air handler to wear they look like crap because I believe they don’t understand but I completely have given up trying teach them I just do what’ ever they want it’s not me going to the service call and not my name on it so it not my concern I’m there to toss it in for $ not for my brain peace and good luck clammy

ratio

That's pretty much the profile of the plates I've seen included with coils. I think you're spot on with it. (Bet this layout worked just fine on the engineers' desk…)

I forget, how many CFM are you flowing at high? Is there a table that shows face velocity for various CFMs? The ECM self-adaption stuff changes things, but with a PSC blower I'd expect face velocity to drop as TESP increases.

The only time I can recall that I've come across this issue the face velocity of the coil was like 40% over spec because of low ( below 0.2 IN WC) TESP.

ChrisJ

@pecmsg my total static is 0.4 in high stage with new filter. Towards the end of the season is up around 0.5.

@clammy I decided to install a new drain going a different route last spring and I used a deep trap hoping the problem would go away.

@ratio This is an ECM blower. I should be just over 1200 CFM according to their chart. No velocity chart that I can remember. I tried dropping it to just under 1100 CFM and it still had the issue.

This is 3 ton in high stage.

ChrisJ

Here's the new drain and trap setup we did last spring.
This goes out the side of the house and straight down only a few feet away.

The air handler perfectly level.

DZoro

I have seen condensate come off of the High side manifold piping and not going into the pan. Re-routing piping, and some insulation tape worked.

Low side is already insulated but check it out also.

Don't know the brand, but Goodman does want certain sloping of the horizontal units front-back, and left-right. Some also need a baffle.
D

icy78

Get a piece of plexi glass the size of your coil cover. Watch the action of the water.

Some units are cfm derated in horizontal config.
Some need the coil fins treated with a simple cleaner. I cant recall what it is. Maybe @pecmsg can chime in on that.

The ecm is killing you on this. It would be good to know the actual cfm, not the ecm calculated cfm.

pecmsg

icy78 said:

Get a piece of plexi glass the size of your coil cover. Watch the action of the water.



Some units are cfm derated in horizontal config.

Some need the coil fins treated with a simple cleaner. I cant recall what it is. Maybe @pecmsg can chime in on that.



The ecm is killing you on this. It would be good to know the actual cfm, not the ecm calculated cfm.

I just use Foam coil cleaner and rinse.

I agree you need an accurate CFM reading not calculated.

SuperTech

I really like the idea of using the plexiglass to provide the ability to view the system during operation. Maybe set up something in the attic to record the operation of the system so you don't have to be in the 130 degree attic watching condensate formation.

clammy

Do u have a transition piece between your a h and your air cleaner . I usually have a 12 inch or so transition between them I feel it gives more even air flow across the coil and the same applies to air cleaner . I see where they just screw air cleaner to the air handler and put a piece of patch onto the air cleaner and a collor and flex same w the return boxes . There usually all sorts of issues with that type of set up including condensate . Have u tryed removing your heap filter and try a cheapie and see if you still have a issue .usually on a 3 ton I usually use a 16 return flex at a minimum and usually I install returns in bedrooms . Just a though peace and good luck clammy

ChrisJ

@icy78 @pecmsg

I used a foaming cleaner last spring.

I'm sorry to sound ignorant, but why would the exact CFM have an effect on this? The AHU is sold to be used on 2.5 to 3.5 ton and I'm using it's on 3 ton. I would think it should do fine lower than I think I am as well as higher than I think I am.

This is a Goodman AVPTC37D I believe.

Im using profile C.

pecmsg

The ECM motor may be attempting to move 1200 CFM's but the duct work in, out or both can be restricting it!

Lower the fan speed too B and see if the carry over stops, if the coil doesn't freeze up you may be good.

DZoro

FYI It was on a Goodman that needed the piping re-sloped and insulated. That along with sloping the air handler both directions. But the slope wasn't the issue the internal piping was.
D

ChrisJ

> @pecmsg said:
> The ECM motor may be attempting to move 1200 CFM's but the duct work in, out or both can be restricting it!
>
> Lower the fan speed too B and see if the carry over stops, if the coil doesn't freeze up you may be good.

I tried B, it still continued.

I sized the duct work both return and supplies. They were sized for 0.05" rather than the typical 0.1" drop.

ChrisJ

> @DZoro said:
> FYI It was on a Goodman that needed the piping re-sloped and insulated. That along with sloping the air handler both directions. But the slope wasn't the issue the internal piping was.
> D

The pan drains good. I also made sure anything that sweats was inside the pan. That was my first suspect.

pecmsg

Have you measured the Actual air flow?

DZoro

If you have a go pro camera, you could mount it inside the air handler.
D

ChrisJ

> @pecmsg said:
> Have you measured the Actual air flow?

No, only the Magnehelic that I have permanently installed showing total static. It's plumbed into the return side of the AHU and the supply plenum.

I've never checked velocity.

My duct work is oversized by normal standards so I never suspected it.

There's a drawing on the previous page showing it as well as the Magnehelic plumbing.

EBEBRATT-Ed

With the oversized ductwork the fan may be moving more air than designed for. The velocity through the coil is the concern in most cases.

I like the plexi glass idea

pecmsg

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