Edit:
The same guy came back, apologized and immediately got to work putting the drain back and running the line back where it goes. No fuss about it which was shocking.
I asked about getting a mold test as well as getting us a dehumidifier for down there while the crawl space dries out and he said he’d talk to his boss.
I got a call from the owner shortly after the guy left and they’re gonna get us a mold test and cover any remediation, and refunded what they initially charged me to get a dehumidifier.
I was ready for the run around. If I could name the company without doxxing myself I would in a heart beat.
Okay good folks of lemmy, I’m a bit out of my wheel house with HVAC, and I want to see if two things are connected or not.
Long story short, a few months ago I had a plumbing/hvac company come out to just repair an old washer drain that was still be used for our AC/Furnace condensation line. The old pipe was fully cracked. For some reason, and I feel like an idiot now for not questioning it at the time, the guy just capped the old drain pipe where it was cracked and put the condensation line hanging in the crawl space. So we’ve had water just pouring into the crawlspace in our basement for months.
We just moved into this house a couple weeks before, I was running through electrical and carpentry projects that my wife wanted done as soon as we moved in (and I’m still working on that list) and I just hadn’t thought about it, didn’t check, it seemed like an easy job and I liked the guy. I just noticed today because I was planning on replacing a run of knob and tube that went through that crawlspace.
I called today and there’s apparently a 1 year warranty and they’re sending someone out tomorrow to take a look, the entire 20x20 crawl space is soaked, there’s puddles in there.
So tonight I went down to clean up a bit since the basement has been pretty much abandoned for months and boxes kept getting piled when I felt a drop of water hit me on the head. Our HVAC ducts are just covered with condensation, pretty much all of them all the way through.
My question: Could the condensation on the ducts be related to the pool of water sitting in the crawl space? Is it like a closed loop circuit where air gets pulled form inside the house, cooled and pushed back, so the humidity from the crawl space is causing the AC air to be extra humid?
This is the first place I’ve ever lived with central AC or really working heat, so I have no clue how it works. But I’d hate to assume it’s unrelated if this a bigger issue caused by something this company did.
I’m not looking to blame these guys for every little thing to do with the the AC, just want to be sure.
We did also just go through that insane heatwave and had the air sitting on 70 for the past 4 days.
Thanks in advance.
Excess moisture in the crawlspace can absolutely cause condensation on the HVAC ducts when the AC is running. Especially if the ducts are uninsulated or poorly insulated, as is often the case in older homes.
Get a dehumidifier and dry it out. If needed, you could run the dehumidifier in the basement and put a fan in the crawlspace opening to circulate air.
The dehumidifier may be necessary even after the crawl space is dried out. We always have to run one in our basement in the summer.
That said, there are zero reasons why the condensate line should have been terminated in the crawl space. Dealing with incompetent contractors sucks.
Yes, extra high humidity in the crawlspace will cause condensation on the ducting. And once you solve that, it should stop/lessen.
For some reason, and I feel like an idiot now for not questioning it at the time, the guy just capped the old drain pipe where it was cracked and put the condensation line hanging in the crawl space.
Do you mean like…hanging with free discharge of the condensation dripping into the crawl space, where it is now accumulating? That’s fucking wild.
Is it like a closed loop circuit where air gets pulled form inside the house, cooled and pushed back, so the humidity from the crawl space is causing the AC air to be extra humid?
I don’t really understand when you say the “AC air” is extra humid. Is the condensation on the outside of the ducts, inside or both? Are the ducts with the condensation the supply or the return?
Can you put a bucket under the condensation line and see how much is coming out? Is it possible the puddle is from condensation on the duct that is dripping to the floor and pooling?
Behold, the most important HVAC chart (or so I’m told, I’m a chemical engineer who works with HVAC guys not an HVAC guy): https://www.flycarpet.net/en/psyonline
Basically, relative humidity is how much water is in the air relative to the max amount of can carry at that temp.
Air at 20 c (dry bulb) and 70% RH has 10.256 g water/kg dry air. If you increase the temp to 30 c, the same 70% RH means that air now has 18.873 g water/kg dry air.
The dew point of this more saturated air is 23.9 c. So if you take that same 30 c and 70% RH air and chill it down to 23.9 c, you will get condensation starting to form as the air can no longer hold that water.
If you can grab some of these cheap gauges you can measure the temp and humidity in different places:
If the air in the crawl space is colder than the basement and condensation is on the outside of the ducts then the condensation might just be the humid summer air condensing and pooling water. I worked on a site with brand new underground tunnels that streamed with water along the walls in the summer because it was so much colder than the rest of the building and they didn’t account for that in the HVAC design. It was so crazy.
If the air in the crawl space is warmer than the rest of the basement and the condensation line is dripping (confirmed by bucket) it could be adding humidity to the air. If the vapour pressure is less than the saturation vapour pressure then water will evaporate. These are parameters you can figure out with the temp and humidity. The hot air will also rise, which could be how it’s moving up and out of the crawlspace and contacting the ducts.
I can’t think of what could be causing condensation inside the ducts unless is on the return side (hot air before it is cooled by the AC). If the basement is much cooler than the air in the duct, it’s possible the duct itself is colder than the dew point of the air inside it so water in the air is condensing on it.
It doesn’t mean the water in the crawl space isn’t the root cause of the humid air. You could be recycling the condensate as follows: hot air enters AC, humidity condenses, leaves via condensate line, condensate line drips into crawl space, water evaporates into hot air, hot air moves up wards, hot air gets sucked into the return register, return duct is in cold basement and causes condensation, condenser on drains out into condensate line…ad infinitum.
You probably need a dehumidifier somewhere in the system or even just in your house. I know my basement is humid in the summer just because it’s colder than the rest of the house. The same air circulating through it will condense on cold surfaces (like concrete) and the RH is much higher.
Good luck!
Yea, what a useless ass. If that’s the kind of people they employ I wouldn’t want that shitty company back in my house.
The condensate drain needs to be drained out of the house, like any other drain.
There are condensate pumps (very small, like a large aquarium pump) for moving condensate up high enough to reach a proper drain (such as the one for your washing machine).
Simply capping off the existing drain is simple laziness. Fuck that guy.
Yeah I honestly can’t tell you what the thought process was there, would it really have been much more work to fix the drain?
At this point I’m hoping they show up and offer to fix the drain and put the condensation line back where it was. Then offer to pay for mold testing and remediation because I’m sure there spores growing in there now. That’s a fucking pipe dream, but wouldn’t that be nice.
Not an HVAC guy but I’m confused by your house, you have a basement and a crawlspace? Are they connected somehow? If the puddles in the crawlspace could be seeping into the basement then I’d say yes. Basements are known for being damp though, has there been a ton of rain?
Also your HVAC guy was really a jackass if he directed the condensation line into your crawlspace.
In the short term, fix the condensation line and maybe get a dehumidifier going in the basement. Those boxes will get moldy fast.
Yeah its the basement and then there just a hole in the wall that leads to the crawlspace. I assume at some point they wanted laundry upstairs so they put an addition on and that’s what’s above the crawlspace
We haven’t gotten too much rain, and before we moved in we had the previous owner do mold remediation down there which included repainting the exterior walls with some special paint to keep moisture out.
I did put a small humidifier down there which was all we had. I’m hoping they’ll handle it right tomorrow, but assuming not I ordered a much bigger one.
I’d also strongly consider getting some sensors going in the basement and crawlspace to monitor the humidity and temp. You’d have real data and you can set an alarm level.
If that crawl space is a dirt floor and not concrete, that soil is going to continually provide a moisture source.
I’d seal that opening with some plastic to create a vapor barrier (tape it around the ducts and to the wall or framework). Anything more solid will generate noise from the ductwork vibrating against it.
I actually had exactly that. I did a shit job and it looked like it was my first time using tape so I took it down when I went to go in there and planned on putting it back up a little nicer.
There’s another crawl space that’s the same thing but no ducts running through so I was able to fully enclose it with plastic and built a nice little door for it.
