Mold in air handler?

DeltaFox

My wife complained that the HVAC has feels moist and the house smells "musty". I flushed the drain line and cleaned the condenser. I also change the filter regularly. No obvious signs of trouble there. I opened up the air handler unit today and discovered obvious signs of moisture. 

How f***ed am I?

*Scheduled technician for inspection tomorrow AM.

ChrisJ

It's an air conditioner.
It runs with a relative humidity of close to 100% if not 100% on the outlet of the evaporator.

Of course there's signs of moisture.
Give it all a decent cleaning and clean the evaporator with a foaming cleaner designed for aluminum coils.


Make sure the condensate pan is nice and clean as is the drain for it.

I don't see anything terrible there honestly.

But I am confused as to why the warmer return side has any signs of moisture at all? And why that much dust? Did someone put the filter on the wrong side of the system?

ChrisJ

Besides something seeming weird, I'd recommend trying to get that liquid line insulated if that's in an attic. Insulating the condensate drain may also be warranted.

mattmia2

The return side may get cold enough from the conditioned return air that hot, humid attic air infiltrating in after the blower shuts off condenses on it or it could be hot humid indoor air condensing on the cold parts in the attic in the winter.

ChrisJ

@pecmsg

kevink1955

Why would you want to insulate the liquid line, it's not a Mini Split

HVACNUT

Something looks very wrong about that air handler setup. 
It looks like it's backwards. 

ChrisJ

kevink1955 said:

Why would you want to insulate the liquid line, it's not a Mini Split

Well, the condenser worked hard to get that liquid down to 90-110F.  Do you really want to warm it up running through copper tubing that's in a 130-140f attic?

A liquid line will literally feel cold in a hot attic especially on higher efficiency units like 16-18 seer.

ChrisJ

HVACNUT said:

Something looks very wrong about that air handler setup. 
It looks like it's backwards. 

I know American standard / trane made some positive pressure air handlers and I have no idea what brand this one is but the signs of moisture and dust on the blower side confuses me.  

Maybe @Ma@mattmia2 's right, I dunno.

pecmsg

ChrisJ said:

@pecmsg

Oversized equipment on undersized ducts. 

Where is this located!
size of the house!
size of the equipment?

ChrisJ

pecmsg said:

ChrisJ said:

@pecmsg

Oversized equipment on undersized ducts. 

Where is this located!
size of the house!
size of the equipment?

That looks like an awfully small evaporator.

pecmsg

ChrisJ said:

pecmsg said:

ChrisJ said:

@pecmsg

Oversized equipment on undersized ducts. 

Where is this located!
size of the house!
size of the equipment?

That looks like an awfully small evaporator.

2-Tons if you read the tag!

ChrisJ

pecmsg said:

ChrisJ said:

pecmsg said:

ChrisJ said:

@pecmsg

Oversized equipment on undersized ducts. 

Where is this located!
size of the house!
size of the equipment?

That looks like an awfully small evaporator.

2-Tons if you read the tag!

I didn't even notice that.

So it is a TAM9 and it is positive pressure on the evap side.


2 tons is the smallest you can get these days isn't it?

EBEBRATT-Ed

Something doesn't look right with that configuration.

The air flow looks like it's right to left based on the filter and the fan but the coil is on is on the discharge??. Or is the filter on the wrong side of the unit?? Usually with an ahu your draw through the coil to get more even air flow through the coil although this is not true with a furnace

pecmsg

The coil can be positive pressure. 

HVACNUT

ChrisJ said:

HVACNUT said:

Something looks very wrong about that air handler setup. 
It looks like it's backwards. 

I know American standard / trane made some positive pressure air handlers and I have no idea what brand this one is but the signs of moisture and dust on the blower side confuses me.  

Maybe @Ma@mattmia2 's right, I dunno.

Ok, thanks. I've never seen that setup for strictly an air handler. I figured it was aTrane with the plastic blower housing. 

The line volt has to travel through the evap section to get to the motor and board.
The low volt access is in the evap cabinet. This is a weird air handler. 

Dave Carpentier

I was told once by a mechanic to turn off my truck a/c and just run blower on full for the last few miles of the trip, to help get some of the 'wet' out.
Are home a/c units ever set up for a "post" airflow period to help dry things out ?

mattmia2

Dave Carpentier said:

I was told once by a mechanic to turn off my truck a/c and just run blower on full for the last few miles of the trip, to help get some of the 'wet' out.
Are home a/c units ever set up for a "post" airflow period to help dry things out ?

In dry climates there is sometimes a post purge to cool a bit more air by bringing the evaporator up to ambient. In wet climates there usually is no post purge to minimize re-evaporation of the condensate. Many thermostats can be set to keep the blower on for post purge.

ChrisJ

Dave Carpentier said:

I was told once by a mechanic to turn off my truck a/c and just run blower on full for the last few miles of the trip, to help get some of the 'wet' out.
Are home a/c units ever set up for a "post" airflow period to help dry things out ?

Mine as well as most newer ones are set for a 1 minute run after the outdoor unit shuts off.
But this is to gain efficiency not dry anything. I think mine runs at 50% of normal speed, or whatever the slowest and shortest length I could get was.

Generally running the blower with the compressor off tends to raise indoor humidity levels which is bad.

Basically, evaporators stay soaking wet most of their life when in use, it's just the way it is.


I've heard some mechanics claim that with air conditioning as well.
I've never bothered to do it. A combination of not wanting to feel hot humid air and laziness I suppose.

mattmia2

ChrisJ said:

I've heard some mechanics claim that with air conditioning as well.
I've never bothered to do it. A combination of not wanting to feel hot humid air and laziness I suppose.

It also tends to fog up the windows which is problematic.

pecmsg

mattmia2 said:

I've heard some mechanics claim that with air conditioning as well. I've never bothered to do it. A combination of not wanting to feel hot humid air and laziness I suppose.

It also tends to fog up the windows which is problematic.

???

mattmia2

pecmsg said:

mattmia2 said:

ChrisJ said:

I've heard some mechanics claim that with air conditioning as well.
I've never bothered to do it. A combination of not wanting to feel hot humid air and laziness I suppose.

It also tends to fog up the windows which is problematic.

???

The moisture evaporating off the evaporator after you shut the ac off tends to condense on the windows inside the car if you turn the ac off and leave the blower running, at least in michigan's humid climate.

pecmsg

mattmia2 said:

mattmia2 said:

I've heard some mechanics claim that with air conditioning as well. I've never bothered to do it. A combination of not wanting to feel hot humid air and laziness I suppose.

It also tends to fog up the windows which is problematic.

???

The moisture evaporating off the evaporator after you shut the ac off tends to condense on the windows inside the car if you turn the ac off and leave the blower running, at least in michigan's humid climate.

In  a caR OK

Dave Carpentier

Ya, I guess blowing the accumulated moisture inside the AH back into the house wouldnt be the best plan.. lol.
How about a UV light inside, to kill off (some/most) potential mold spores ?

ChrisJ

Dave Carpentier said:

Ya, I guess blowing the accumulated moisture inside the AH back into the house wouldnt be the best plan.. lol. How about a UV light inside, to kill off (some/most) potential mold spores ?

 Only works on areas the light can "see".  So usually it takes multiple bulbs which are far from cheap and residential air handlers generally aren't setup for a configuration that actually works.  

It's also not great on plastic parts.

EBEBRATT-Ed

Can't see how re evaporating some condensate will change the humidity that much.

What are we talking a coffee cup full of water on the wet coil??

ChrisJ

EBEBRATT-Ed said:

Can't see how re evaporating some condensate will change the humidity that much. What are we talking a coffee cup full of water on the wet coil??

No idea other than I was able to measure a difference in my house.

Maybe because it's between every cycle, I don't know.

mattmia2

I guess the first question is ow much water vapor is mixed in the volume of air in a house. It seems like the dehumidifier only produces a cup or 2 of water per cycle as it decreases the rh 5% or so. It certainly doesn't produce enough water to run the condensate pump every time the dehumidifier runs.

ChrisJ

mattmia2 said:

I guess the first question is ow much water vapor is mixed in the volume of air in a house. It seems like the dehumidifier only produces a cup or 2 of water per cycle as it decreases the rh 5% or so. It certainly doesn't produce enough water to run the condensate pump every time the dehumidifier runs.

That depends on way too much.

It's going to remove far more water with a dew point of 70f than with one of 50f