Ductwork - clean vs replace

We moved in back in Oct so really never needed to flip the air on til this year.

About June I started noticing a moisture type smell in my entryway and dining room.
Its not an earthy moisture smell like wet wood or dirt, but you can tell it's moisture.

The SO claimed he could never smell it and that I was crazy. Fast forward to a couple weeks ago the smell is now stronger and he claims he can now smell it as well.

We went under the house this weekend and took a look at the unit.
Before we moved in the inspector peeled back the shoddy duct taped wall of the housing unit for the cooling coil. It was sitting in water.
We requested the homeowner fix the problem and clean the coil.
She said they did and when we did our 2nd viewing we saw a pump installed and the duct taped wall had been reapplied. Not wanting to cause any problems to the tape we didn't open it up to see if the coil had been cleaned.

While under the house we pulled back the duct taped wall and sure enough the coil is sitting in water, again.
The coil is filthy with all kinds of mildew and possibly mold.
The SO poured water in the pump and it was working properly but the housing box is unleveled causing all the water to fall to the wrong side (of course).

Sunday we called our home warranty people and they sent a company out today.
The man said it was not good news, we have a lot of problems going on down there. He said the coil had not been cleaned in what looks like years and the warranty company will not cover routine maintenance. That costs $250 for the cleaning, which they just leave the coil in place.

He said the insulation on the duct leading to the dining room is torn and sweating, which aside from the moisture in the coil, is also adding to the smell. We saw the tear in the insulation while down there, it's right where it comes of the housing unit and is torn about 2 foot (really it looks like where someone was straddling it to get to the unit and ripped it off.)

He said the housing unit and the coil are not level and they will need to be leveled.


I asked him if the sweating duct and coil would cause mold on the inside of the duct work and he said it probably could and is.
He then said, having these problems I would replace all the duct work in the house. I asked him how much that usually runs and he said about $10k (1800sqft house w/ 4 returns).
I asked him about cleaning duct work he said they don't have the machines to do that but he wouldn't suggest doing that.

So now Im having to wait to see what my warranty company will cover.
Im hoping the leveling of the housing unit and coil and possibly cleaning the coil.


But my question is, once the cooling coil and its housing unit is leveled, dried out, cleaned and we wrap the torn ductwork do I really need to replace the ductwork??
That sounds rather extreme to me..

Can I just have it cleaned or should it just be fine?

As for your air handler,,,, you don't want it perfectly level,,,, it has to be slightly angled so it will drain to the condensate pump from the drain pan,,,, the drain pan is probably full of mold and junk,,,, same with the a coil,,,, I don't know if your husband, boyfriend is mechanicly inclined but he could attempt to clean them,,,, would be difficult under the house,,,,really no telling on the ductwork,,,, maybe call a duct cleaning Co and get an estimate,,,, see what they say,,,,I'd say it is probably to extreme to replace the ductwork but the cleaning guys can inspect it for you,,,,

$10,000 to replace ducts. Run from that contractor. You could have a new unit AND ducts for that kind of money. If it were me I'd change them. Mold is not good. I know a reputable contractor in your area. Shoot me a pm if you'd like his contact

How old is the AC unit? If it has been abused like that in the past and only has duct tape holding the panels on, you are going to have more problems.

But 10 grand for duct work is crazy. I put in new ducting in the crawlspace and attic with 1 3ton gas unit downstairs and 1 .5 heat pump split unit upstairs for $12K about 4 years ago.

Unless your unit has a lot of warranty left I would get a price on a new system.

I've got a feeling the contractor didn't want to do that particular job, but if he did, he was going to make a killing on it if you went with him. Jmo.

I would start with cleaning the coil and drain pan. The pan probably isn't draining correctly. I've seen mold in the air handler, near the coil and near a cold air register/grill in a hot room. I'm not so sure about the duct work between the two being moldy.

I'm not sure how replacing/cleaning the duct would keep the problem from returning if you don't replace the old air handler. Maybe even then it might still return without prevention.

The evaporator coil is always wet in the summertime. The drain pan as well to a certain extent. With commercial units little drain tablets are used to control algae to keep the drain open.

The modern way is UV lights. I was surprised at how well those lights keep mold & algae from growing on or near an A/C coil. If I was going to go to the trouble to clean my duct, I'd want to install one of those lights.

Look and inspect some of the other register/grills in your house. I wouldn't clean the whole duct system in only one was showing mold. It might not have originated at the air handler. It could just be in a humid room. Then maybe clean the air handler and the duct leaving the air handler to include the distribution box.

I have seen water from a stopped up evaporator go into the air handler and even into the return duct. That would require drying out and cleaning.

It could be the crawl space itself is too damp and may need better ventilation. I'd love to have one of those encapsulated crawl spaces that looks nice and clean.

Cmp1 said:

As for your air handler,,,, you don't want it perfectly level,,,, it has to be slightly angled so it will drain to the condensate pump from the drain pan,,,, the drain pan is probably full of mold and junk,,,, same with the a coil,,,, I don't know if your husband, boyfriend is mechanicly inclined but he could attempt to clean them,,,, would be difficult under the house,,,,really no telling on the ductwork,,,, maybe call a duct cleaning Co and get an estimate,,,, see what they say,,,,I'd say it is probably to extreme to replace the ductwork but the cleaning guys can inspect it for you,,,,

Click to expand...

Just last night I opened up my air handler and dumped a half gallon of bleach in the drain pan to clear out algae build up in the condensate line. If the line gets backed up it will cause the unit to sling water where it's not meant to be.

Mold needs moisture, cold air off the evaporator coil has been stripped of moisture, and it goes in the catch pan. Insulation may dry, but mold spores will remain, however they should be exterior of the ductwork, not on the interior.
Unit should be level, or IF out of level, lower to the drain side so the water can run out.
Cleaning the coil and relevelling the unit can be a DIY job, it ain't rocket surgery..
Google HVAC parts or Appliance repair sales and call and ask for coil cleaner, it's not regulated and will be available over the counter.
Turn off the power, open unit, spray the cleaner and wait the time period on the label, then hose it off. If it's really bad, shop vac that rascal before spraying cleaner on.
Even 2-3 applications should only take 45 minutes or so.
grab a handful of cheap ceramic 6x6 tile from the big box DIY place, and use to shim the unit to drain properly.
Cleaning the coil will have an immediate effect on smells, and make unit more efficient.

Artfuldodger said:

I would start with cleaning the coil and drain pan. The pan probably isn't draining correctly. I've seen mold in the air handler, near the coil and near a cold air register/grill in a hot room. I'm not so sure about the duct work between the two being moldy.

I'm not sure how replacing/cleaning the duct would keep the problem from returning if you don't replace the old air handler. Maybe even then it might still return without prevention.

The evaporator coil is always wet in the summertime. The drain pan as well to a certain extent. With commercial units little drain tablets are used to control algae to keep the drain open.

The modern way is UV lights. I was surprised at how well those lights keep mold & algae from growing on or near an A/C coil. If I was going to go to the trouble to clean my duct, I'd want to install one of those lights.

Look and inspect some of the other register/grills in your house. I wouldn't clean the whole duct system in only one was showing mold. It might not have originated at the air handler. It could just be in a humid room. Then maybe clean the air handler and the duct leaving the air handler to include the distribution box.

I have seen water from a stopped up evaporator go into the air handler and even into the return duct. That would require drying out and cleaning.

It could be the crawl space itself is too damp and may need better ventilation. I'd love to have one of those encapsulated crawl spaces that looks nice and clean.

Click to expand...

This^^^, only I prefer the GPS over the UV lights.

https://gpshvac.com/

hobbs27 said:

This^^^, only I prefer the GPS over the UV lights.

https://gpshvac.com/

Click to expand...

Interesting technology, I'll have to look into that.

Also check with your real estate agent , you may have recourse against the seller because the repair was not done correctly, it would have been better if you had an inspector or heating/air company come back and inspect after the repairs were done before buying the house, I would also get a couple more estimates from reputable heating/ac companies in the area, having more than one opinion is a good thing.

We won't be allowing this company to do any work other than what the warranty covers..

There are no signs of mold on the exterior of the insulation, he just said there *could* be mold in the interior ductwork and he'd tear it out and start new.

I don't smell mold within the moisture smell. It just smells like moisture. No earthy smells, no pungent smells, its not a great smell that I enjoy, but it's one you know you're not supposed to be smelling.

We went under there last night and put bricks under the low side.
The pump immediately filled twice while we were still down there.
As of this morning the smell of the moisture has significantly decreased, but I'm going to wait till the hottest part of the day to be hopeful on that.

I have the air set on a timer to kick up to 78 at 5am so it won't turn back in til later today. I have it set to gradually start dropping around 4pm to 76 settling at 72 at 9. I guess I'll see if the smell starts back up then

Like the other guys have said,,,, you could try to clean the a coil,,,, it's probably pretty nasty,,,, AC removes the humidity first before cooling,,,, if the a coil is nasty it won't remove the humidity as well,,,,, I think I would probably call a reputable tech out and have an inspection done,,,, might be worth the service call cost,,,,

contact your power company. Most of them have energy experts that can advise you.

Cleaning coils is part of standard maintenance for AC units. Needs to be done regardless.

JohnK said:

Cleaning coils is part of standard maintenance for AC units. Needs to be done regardless.

Click to expand...

Not really,,,, at least not here,,,, I would clean off the condenser coils with a hose but no way the a coil without an extra charge,,,, just to get access is difficult,,,,

Everything on an A/C unit should be cleaned as possible. It works by transferring heat from one place to another. Built up crud interferes with the efficiency of it's operation. Duct work should be cleaned if it is blocked or restricted. It's purpose is to allow air to be moved and any restrictions hampers it's doing it's job. The decision to clean or replace should be based on ease of access. And ease of removing and replacing a duct will decide which to do. Also determined by overall cost.

i'm thinking about a ductless system. they run around $800 in home depot.

maybe one in the main living area..another in the master bedroom..?

biggsteve said:

i'm thinking about a ductless system. they run around $800 in home depot.

maybe one in the main living area..another in the master bedroom..?

Click to expand...

Go with a Mitsubishi unit ductless,,,,

If you go the ductless route make sure service is available. Mom bought one of the early ones, many years ago. Company quit the business and parts are no longer available and there is no help available for the tech.

It did do the job and she liked it.

It's not the best way to do a whole house. But they are great to do parts. Controlling temp in individual rooms or a section of rooms works great. Found it was superior to a window unit by orders of magnitude.

It is basically a mini heat pump system.