Wet Lennox ....WHY???

[R12rules]

I was invited to inspect a new Lennox this morning. It is recently installed and leaking water.

Model # CB29M-41-2G
Serial # 5804M01466

Location is Austin, TX.
Application, school classroom.

I read the instructions and found everything to be in order. This system is being operated in horizontal position, right hand blow. It comes from factory to be installed as is. (according to instructions).

I checked for the diverter plate over the coil and it is oriented correctly.

hmmmmm....

I pulled the cover, found small amount of water in plastic pan underneath coil.
Fan sucking air in correct direction. (these are 480V units)
Drain line running free.
I set my level on system and found she is leaning towards the drain pipe itself, ever so slightly.


So tell me, how is water getting onto the floor?

It is showing up on the floor BEFORE the air filter!!!

When I pulled the filter, it was dry inside.

The system has a large secondary pan underneath the forsed air unit itself. And this water is showing up outside of the pan. While the pan itself has minor amount of water inside.


I dont usually investigate water related issues in these systems... this is a unique problem. Several guys have already looked at it and nothing has come from it.


Thanks for the help, in advance.

[Edited by R12rules on 05-25-2005 at 07:44 PM]

[bku46]

Did you install a trap?? Is it possible the water is comming from somewhere else, leaking above on the duct work. whats abouve unit??

[icemeister]

Situations like this are often caused by water that should drain off the coil into the pan but instead gets blown into the cabinet. Although I haven't tried it, I had a contractor friend recommend putting a clear plexiglas panel on the air handler in place of the standard panel so you can observe what's going on in there.

Just a thought.

[R12rules]

Gentlemen, but sugestions are taken. There is a trap. And the clear window is about to be employed as this situation is taking place in several units on the project.


Thanks for the advice.

[airworx]

not enough return air will cause fan to pull the water out of the pan, also on pull through coils which is what you have there must be a ptrap installed in the drein line.

[Shophound]

Is this thing above ceiling tile and leaking onto it, staining the tile?

A few things come to mind:

P-trap vented downstream of trap vs. upstream, especially on pull-through coil. Common installer mistake to vent trap upstream. Makes trap useless.

Secondary drain installed and trapped? Some pull-through handlers can also pull through the secondaries. I had a few Lennox air handlers in my building doing that until I fixed them. Were big time leakers until that was repaired.

Suction lines and TXV's insulated right up to the air handler cabinet? Just a little exposed copper in a plenum space above ceiling tile can make for a lot of dripping onto the tile. No rubatex split anywhere on lineset, exposing copper?

All drain lines leaving air handlers sloping downhill? P-trap not too shallow?

How's the return, supply, and external static pressures? Within OEM spec? Blower speed sufficient?

[flange]

does the drain line run in the direction of the leak and could it be sweating at startup until WB temp drops in the space?

[denis]

Quick spray with coil cleaner will eliminate oil on coil ,however attained, aeresols or from factory. I've seen water leap from the top of a evap coil and splash where it ain't supposed to through a small peep crack in door panel with flashlight. this rare situation humbled me several times.

[DeltaT]

Not totally undersanding the installation (wish you could show some pictures) I would strongly suspect that the drain is somewhat empty which causes air sucked back into the unit which allows the coil moisture to get blasted in and around the inside of the unit.

Either the drain is dry, partially dry which compounds the problem, or the drain is not deep enough to maintain a solid column of water to block the inrush of air.

My bet is the drain. This comes from lots of this kind of experiences.

Someone did a study of the speed at which inrushing air enters the inside of an air handler when the drain is on the negative side of the fan and it is empty. The speed was very high.

The enterering air can and will keep the coil from draining plus propel the coil water all over the inside of the air handler and even down into the discharge side of the duct sometimes.

[chilbrig]

All of the above. Also check and make sure something isn't touching the coil like a piece of insulation that may be wicking the condensate away from the coil.

[jel]

Please post what you find out about this...I may be having the same problem...I have a 2.5 ton Heil split heat pump unit...the air handler is under the house...a week after it was installed, I smelled a moldy odor which I am highly sensitive to. The air in the house also felt humid. I checked the drain and it did not seem to be putting out much water. This was during the summer time. It had a standard...not running...trap on it. I looked at the owner's manuel and it recommended a deeper trap. So I called the installer to come check it and the sales rep. They checked the air handler and said there was no blown water towards the blower motor wall so the trap was fine. However, I noticed there were alot of condensation beads under the plastic drain pan...it is sloped...and some water in the insulation underneath it. They said this was normal and would dry out. They also checked the static pressure, drain line, returns, ducts, and freon. I am still having the problem.

[LGM]

Several things could be the problem. First, as Airworx said, too high a negative static could pull water out of the pan.

The second thing I've seen is the CFM is too high. If the velocity of the air across the coil is greater than 550 to 600 FPM it will pull the water off the coil.

The last thing is, if there is an air leak at the under the bottom of the coil, the air that leaks out on the leaving air side is at a very high velocity (regardless of face velocity) and will spit water out into the unit and leak everywhere.

Hope this helps.

[R12rules]

Ok folks, I believe we are onto something here.

These systems being replaced are all new equipment, but the majority of the pre-existing ductwork is remaining in place.
The company has manufactured transitions and such in order to tie into the old ductwork.

And we dont have any idea of which systems were "problem childs" prior to our envolvement.


Hmmmm.... sounds like the school hoped they would get rid of their troubles with all new equipment ....

Possibly there are issues with the ductwork itself. I havent seen anyone bring airflow measurement insturements onto this project.
That would certainly tell us what we need to know here.


Too much airflow across the coil will bring water right off the coil and into the ductwork ..... hmmmm.....


For my sake and for that of those here who are not air balance experts .... would someone please explain in simple terms, what is necessary in tools etc., in order to check out this system I am working on?
Thank you in advance.



And thanks for the great responces thus far.

[LGM]

I play one on TV!

No, really, a simple velometer will do the job. The best thing is to do what's called a transverse measurement. If the coil is 20" wide X 15" tall, take readings 3 across the top by 3 down for a total of 9 readings. Add together and divide by 9 to get the average. You will probably find that certain areas of the coil will have a higher velocity than others.

To get the duct velocity use the same method. Once you get that, multiply the average FPM times the square foot fo the duct for the CFM.

[spike]

Lennox air handlers have an OEM TXV. I'd drop the blower speed to M or even L, regardless. This will increase your latent removal and may address condensate pulling off the evap, if that's the prob. Kill 2 birds w/ one stone...

GL

[R12rules]

The only tool I own, presently, for measuring airflow is the Fieldpiece atachment.

Will that do me any good?

[service guy]

Is this a TXV system or does it have a orfice at the coil?

[R12rules]

Originally posted by service guy
Is this a TXV system or does it have a orfice at the coil?

TXV.

[Dowadudda]

I had a situation about 5 years ago that kicked my a$$ for about a week. It kicked a lot of other companies a$$ before I ever took a shot at it. Now. It would be prudent to do all your air side diagnostics as a first process of elimination. But I will share with you this.

I had an RTU at a bagel sandwich shop. Return was a straight drop down to some egg crates. About right where the customers stand to place their sandwich order. Did exactly what you are describing. It was a 2 year old ten ton carrier HVAC RTU. I got a hold of a very renowned carrier service rep who takes care of MI. Great guy. Smartest guy I have met yet, hvac speaking. I give him the details. I had my airflows, my CFM's. All in line. He says to me. "Wash the coil with some powdered dishwasher detergent". I thought he was nuts. But as I said. When Mr Carrier says something, you listen. So I did.

Problem fixed. The smoothness of the tubing and fins was so slick from manufacturer that the surface was letting condensate slide right off. The detergent etched the surface a bit. Worked like a charm. Every time I run into him we have a good chuckle about it.

To this day, that coil never wept again.

[R12rules]

Dow, your talking about the kind of detergent used in automatic dishwashers?
That stuff would take the hide off an elephant!!!

Using that stuff on a coil would be risky at best.


Yea I guess it would ETCH the surfaces a bit!



I will try it.

[Dowadudda]

Well, Hold on Cowboy.

I made it real clear you need to go through the diagnostics first. CFM's and Such. Once this is accomplished and no trouble found. Then this is an idea to try.

But I can assure you I did not make that up. And the guy who advised me to do this wierd thing has been an outstanding service representative for many years at Carrier here in Michigan.

[R12rules]

I hear ya.

[service guy]

OH it's a TXV well I'll share my story anyway, I once had a york 5 ton split kept blowing water into duct work. could not figure it out for the life of me, after giving the system a good inspection I came up blank then I looked at the length of the line set and size of piping and found my orfice was not changed (fixed metering device) changed to proper orfice and problem solved. The orfice that was in there was to large causing a pressure drop and the evap was not completely filling with refrigerant this caused dry spots on the face of coil and when condensate ran down coil it hit the dry spot and blew off into the duct!!!

[DeltaT]

So, R12, what's the verdict? We are all in suspenders here!

[R12rules]

Originally posted by DeltaT
So, R12, what's the verdict? We are all in suspenders here!

Well Folks .. I do not have the answers as of today.

From a conversation with the foreman and another pipe fitter ... it may be something as simple as the drain pan being split.

These areas all have hard piped drain lines which attach to the plastic pans inside the FAU.
Stepping on and over the lines can split the plastic in the pan causing a leak.


I have not seen any split pans, but what this one guy said does make sense to me.

Eventually it will be figured out.

If it were up to me, I would have been digging in and seeing what is up.
But since I am trying to keep my job and not so much concerned about how I want to investigate every issue ... I have to keep myself restrained a little.

[mopar440man]

is the drain line on the supply or return side
if it is on the return side u need a trap