# HVAC experts - Should I be concerned about this? (Dehumidifier related) **URL:** \ **Category:** Factual Questions\ **Created:** [February 14, 2017, 9:19pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849 "2017-02-14T21:19:06Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [February 14, 2017, 9:19pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/1 "2017-02-14T21:19:06Z")
We had a new furnace installed around a year ago. With it came a dehumidifier. With that came a little device that pumps the accumulated water through a clear plastic tube, up and across the basement terminating in the laundry tub. Just the other day I noticed that the clear tube is now black. So black that it looks like it’s full of ink. My only thought is that it is oil and something is malfunctioning terribly. I haven’t disassembled the pump itself but nothing looks amiss from the outside. There are no other signs of trouble aside from the black tubing. Is this normal? Something serious? Warranting a phone call to the seller/installer? Thanks! mmm ---
**Author:** ![PoppaSan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/poppasan/32/189_2.png) [@PoppaSan](https://boards.straightdope.com/u/PoppaSan)\ **Post date:** [February 14, 2017, 9:41pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/2 "2017-02-14T21:41:33Z")
I would tend to think it is mold that grew in the damp environment of the tube. Especially if the whole tube is black. I don’t recall much oil in the small pumps used and for those that did have oil, it is typically clear or honey colored. Grease in the gear head might be black but that doesn’t leak into the water stream especially in the first year. Ask the seller about it. Their might be a product to clean out the mold, if that is what it is. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 14, 2017, 9:50pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/3 "2017-02-14T21:50:59Z")
Probably mold. Dump some bleach in the pump until it turns on. Follow with some fresh water to clear the bleach out of the pump. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [February 15, 2017, 12:24am UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/4 "2017-02-15T00:24:12Z")
> [@MindsEye\_Watering](#): > > Probably mold. Dump some bleach in the pump until it turns on. Follow with some fresh water to clear the bleach out of the pump. I agree with this. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [February 15, 2017, 12:53am UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/5 "2017-02-15T00:53:39Z")
I agree that it’s mold, but before dumping bleach in it, I would check with the seller to make sure that it’s not going to damage the pump, seals or any other components. They may also recommend a dilute bleach solution rather than pure bleach. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [February 15, 2017, 12:46pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/6 "2017-02-15T12:46:01Z")
Thanks, everyone! mmm ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [February 15, 2017, 1:12pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/7 "2017-02-15T13:12:41Z")
Nah, don’t worry about it, it’s just mold. I get that too. Someone told me to use black tube. When I asked if that would stop the mold, he said ‘no, you just won’t see it anymore’. However, here’s the deal. The mold in the tube, in and of itself, isn’t (probably/shouldn’t) hurt you. But it can’t cause some issues. Eventually it will clog that tube to the point that water can’t pass through it. In the heating season, if water can’t drain, the furnace will shut down. If you have central air and the the evaporator is all plumbed into the same tube, it’ll continue to run, but it’ll overflow from somewhere. If you’ve only just noticeed it, you’re probably in the clear. But it doesn’t hurt to clean it from time to time, either pour some bleach down it or just replace it every few years. FTW, instead of pouring bleach in the condensate pump, I always (and I don’t know why) plumb in a little T near the top with an open end and pour it in there. Either way, if you just pour it into the pump, you’re not going to clean the part from the furnace to the trap. I’d also make sure to flush it a few gallons of water afterwards. You probably don’t want bleach sitting on the pump parts. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [February 15, 2017, 3:13pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/8 "2017-02-15T15:13:32Z")
It might be safe/worthwhile to toss a toilet sanitizing brick into the catch basin. That would provide a continual low level of bleachy/antifungal stuff for a couple of months. While mold in these kinds of slow drains is common, it’s something you may not want found, or spreading, come home-inspection time. Lots of people will run from a house that has MOOOOOOLLLLLLDDDDDDD! found in it. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [February 15, 2017, 5:15pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/9 "2017-02-15T17:15:06Z")
“I like to put a humidifier and a dehumidifier together in the same room and let them fight it out.” - Steven Wright ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [February 15, 2017, 6:02pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/10 "2017-02-15T18:02:08Z")
Bleach sounds like a fine idea, I’m not sure how exactly to get it done though. The pump, next to the furnace, sits on the basement floor. The tubing goes straight up to the basement ceiling, across the ceiling about 30 feet, then straight down into the laundry tub. I can’t exactly just pour bleach into it. So, pour bleach into the pump? I assume there is some reservoir within that holds the water before pumping it out? mmm ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [February 15, 2017, 7:30pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/11 "2017-02-15T19:30:11Z")
> [@Mean\_Mr.Mustard](#): > > Bleach sounds like a fine idea, I’m not sure how exactly to get it done though. > > The pump, next to the furnace, sits on the basement floor. The tubing goes straight up to the basement ceiling, across the ceiling about 30 feet, then straight down into the laundry tub. > > I can’t exactly just pour bleach into it. > > So, pour bleach into the pump? I assume there is some reservoir within that holds the water before pumping it out? > mmm There is a reservoir somewhere in the dehumidifier that likely has a float switch which turns on the pump. Find out where that is and dump a little (dilute) bleach in there. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 15, 2017, 8:05pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/12 "2017-02-15T20:05:35Z")
> [@Mean\_Mr.Mustard](#): > > Bleach sounds like a fine idea, I’m not sure how exactly to get it done though. > > The pump, next to the furnace, sits on the basement floor. The tubing goes straight up to the basement ceiling, across the ceiling about 30 feet, then straight down into the laundry tub. > > I can’t exactly just pour bleach into it. > > So, pour bleach into the pump? I assume there is some reservoir within that holds the water before pumping it out? > mmm [The condensate pump](https://www.amazon.com/Little-Giant-VCMA-15UL-horsepower-Condensate/dp/B000CCMUCM/ref=sr_1_2?ie=UTF8&qid=1487188720&sr=8-2&keywords=little+giant+condensate+pump) usually has two or three large holes into the reservoir for water to go into, and a small one (with a barbed fitting) that is for the water pumped out. The holes not occupied by the current drain line are covered with plastic plugs that simply pulls out of the housing. Dump the bleach into one of the large holes until the pump turns on. A funnel will help. After the bleach is pumped out, dump some clean water into the same hole to rinse the bits inside. I always use bleach straight out of the bottle, and I always run clean water through after. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 15, 2017, 8:38pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/13 "2017-02-15T20:38:36Z")
[Here’s an illustration.](http://i1202.photobucket.com/albums/bb377/MindsEyeWatering/Condensate%20Pump%20Illustration.jpg) One of the red “Into Pump” holes is occupied by the pipe coming out of your air handler. Pull the cap off one of the other red “Into Pump” holes and add bleach there. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [February 15, 2017, 11:29pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/14 "2017-02-15T23:29:01Z")
So, what can I expect? Will the tubing turn clear (ish) again? Or will it stay black? Thanks for all the help. mmm ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 15, 2017, 11:42pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/15 "2017-02-15T23:42:07Z")
> [@Mean\_Mr.Mustard](#): > > So, what can I expect? Will the tubing turn clear (ish) again? Or will it stay black? > > Thanks for all the help. > mmm Don’t know. The plastic may be permanently stained and probably won’t look new again. Stains won’t affect how the tubing works, though. If the discoloration still bothers you, that tubing is very cheap at Home Depot. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [March 14, 2017, 9:53am UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/16 "2017-03-14T09:53:33Z")
Quick update in case anyone else runs into this problem. The bleach worked like a charm. The tubing is now clear as glass. Thanks, all. mmm ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [March 14, 2017, 12:15pm UTC](https://boards.straightdope.com/t/hvac-experts-should-i-be-concerned-about-this-dehumidifier-related/779849/17 "2017-03-14T12:15:03Z")
> [@Mean\_Mr.Mustard](#): > > Quick update in case anyone else runs into this problem. > > The bleach worked like a charm. The tubing is now clear as glass. > > Thanks, all. > mmm One of the joys of home ownership. Just another thing to keep on top of. Make sure you periodically clean the tube that runs from the pump to where ever it exits as well as the the tube or tubes\* that run to the pump\*. What was someone elses problem when you rented is your problem now. Also, if you did it with bleach, only pour bleach directly into the poly tubing, I think I mentioned plumbing in a tee. Don’t attempt to pour it into the evaporator pan. That’s a good way to start rusting things. However, they do make evaporator tablets, but that’s a whole other thing. \*You have a line from your evaporator (AC) and you may or may not have a separate line coming from your furnace. I prefer clear ones so you can glance over at them from time to time and see if they need to be cleaned or replaced.