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A really weird leaky air conditioner problem

A couple years ago, I had a brand new furnace and air conditioner installed as well as new duct work since my house never had any kind of central forced air heating / cooling solution. Overall, the system seemed to work fine and we haven't had any problems. Last week, we were running our air conditioning and I walked into the basement where the unit sits and there is water all over the floor. Obviously, the first estimate would be clogged drain line. I did find a little debris in the drain line, got that all cleaned out, wiped up water in the pan and on the floor etc. Turn the AC back on, let it run for awhile, starts leaking again. So, I decide that maybe the unit has settled a little bit since being installed, so I shim the back and left side of the drain pan to make sure everything is draining to the drain line on the front right side. Ok that's all good, test again, still leaking. Here is where it gets weird, when I run the unit, I get a slow drip out of the proper drain, but it is not fast enough to keep up with the humidity being pulled from the house unless....I open the bottom drawer where the filter goes. When the drawer is shut, the drain drip is super slow. When it is open, it drains fairly quickly. So that leads me to believe that there is not enough return air getting to the unit leading to too much vacuum in the unit slowing the drain water, but it cools the house fine and how the heck did I not have any problems the past two years? What changed? And now what do I do? Should I just cut in a few more returns or something? Or is that even the problem? Any ideas?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,989
    It does sound like it't in a vacuum. Are all return air air dampers (f you have any, not likely) open?. No registers blocked, filter clean??.

    How is the drain piped ....Pictures. It should have a trap and a vent after the trap. Some don't install a trap on a furnace but it should have one.

    Try this test. Run the ac hard for a while and while looking at the drain shut the indoor fan off. If it drains a lot when you shut the fan down it's in a vacuum. The right trap and piping will fix this.
  • Prevch
    Prevch Member Posts: 50
    Thanks for the response. The returns are open. Not all supply registers are open but most of the main floor and all upstairs, none in the basement are open.

    I just shut the unit off and it drained like crazy.


  • dopey27177
    dopey27177 Member Posts: 873
    Do you have a trap on the discharge of the pan?

    The trap should look something like this.

    See Enclosure


    Jake

  • pecmsg
    pecmsg Member Posts: 2,881
    edited July 2021
    your static pressure is too high pulling water off the coil. 
    You need a p-trap and a proper drain. 


    SuperTech
  • ratio
    ratio Member Posts: 3,173
    If the coil (& therefore drain) is on the suck side of the blower, you're going to need a trap on it. There's a way to measure & math up how deep the trap needs to be, but I'd probably just use a pre-formed PVC p-trap (say that six times fast!) & be done with it. Make sure you don't obstruct filter access & be aware of what has to come apart &| move for service.
  • Prevch
    Prevch Member Posts: 50
    edited July 2021

    Do you have a trap on the discharge of the pan?

    The trap should look something like this.

    See Enclosure


    Jake

    Thank you very much. I had no idea. Any idea why I would just start having this problem now? Also, should my drain pan have any standing water in it when the unit is shut off?
  • ChrisJ
    ChrisJ Member Posts: 12,827
    Prevch said:

    Thanks for the response. The returns are open. Not all supply registers are open but most of the main floor and all upstairs, none in the basement are open.

    I just shut the unit off and it drained like crazy.


    That being reduced in size isn't helping either.
    But as others have said it needs a trap of some sort.

    You could build one from 3/4" PVC from homer / lowes.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Prevch
    Prevch Member Posts: 50
    Some additional pics 
  • ChrisJ
    ChrisJ Member Posts: 12,827
    This is a horrible doodle but if you build this with some sch40 3/4" PVC and fittings it'll fix your problem.


    You can add tees to make cleaning it easier.
    You could even build the trap from elbows or tees if need be.

    Make sure you prime and glue the PVC.

    Honestly, if the pipe dips far enough into the pump it would even work without the trap. 
     Almost anything will work better than me what you have.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 9,756
    What I have done for air handlers like this is put a 3/4" male pipe thread by male garden hose adaptor.
    Then with a good grade of rubber garden hose connect to that fitting and form a large deep trap with the hose. Then it would go into the pump you have.

    I would secure the hose with 2 screw 3/4" PVC conduit straps and use only 1 screw for each clamp. To remove the hose you just bend the strap back.

    The home owner was then instructed to remove that hose at the end of the cooling season and connect it to his water heater tank drain and run water out of it down the drain. Then put the hose back just the way it was.
    The hose would get cleared every year and the WH would get flushed.

    Most of my customers (rural area) understood the reasoning for all this.

    Did have one call because his filter was getting wet, he was embarrassed when I asked him about replacing the hose as it was....he just let it lay on the floor.

    You want to use full size hose and if you do this use 2 wrenches to remove that brass barbed fitting from the other part.
  • Prevch
    Prevch Member Posts: 50
    JUGHNE said:
    What I have done for air handlers like this is put a 3/4" male pipe thread by male garden hose adaptor. Then with a good grade of rubber garden hose connect to that fitting and form a large deep trap with the hose. Then it would go into the pump you have. I would secure the hose with 2 screw 3/4" PVC conduit straps and use only 1 screw for each clamp. To remove the hose you just bend the strap back. The home owner was then instructed to remove that hose at the end of the cooling season and connect it to his water heater tank drain and run water out of it down the drain. Then put the hose back just the way it was. The hose would get cleared every year and the WH would get flushed. Most of my customers (rural area) understood the reasoning for all this. Did have one call because his filter was getting wet, he was embarrassed when I asked him about replacing the hose as it was....he just let it lay on the floor. You want to use full size hose and if you do this use 2 wrenches to remove that brass barbed fitting from the other part.
    Thats a cool idea thanks for sharing!
  • mattmia2
    mattmia2 Member Posts: 5,510
    Was the drain previously in the condensate pump tank and under the water level in the tank?
  • HVACNUT
    HVACNUT Member Posts: 4,590
    Pipe it all in 3/4 PVC and use an EZ-Trap.
    Also get a bottle of pan treatment tabs and always have a clean air filter. 
    SuperTech
  • neilc
    neilc Member Posts: 1,804
    so like everyone has said, you need that trap,
    but, and you asked, what changed?
    so back to you,
    did you upgrade to a better, thicker, more restrictive filter ?
    I'm guessing this hasn't been leaking from day one, and a more restrictive filter is having affect there
    known to beat dead horses
  • pecmsg
    pecmsg Member Posts: 2,881
    Why now after so many years?

    The installing contractor didn't follow the install instructions but got lucky. The equipment is probably oversized on undersized ducts but again the installing contractor got lucky. Were in an extremely humid month, as such more condensate is being generated, your equipment is running longer and the poor install practices of the past are showing up.
    SuperTech
  • JUGHNE
    JUGHNE Member Posts: 9,756
    Glue, cleaner, fittings, cleanouts, brushes.
    Glue it all together and maybe have to cut it apart if plugged.
    Put some pressure on the entire PVC assembly and maybe crack the pan.

    What is wrong with the hose method?
    Clean the hose every year and maybe change the hose every 5 years or more.

    I have used this method on rooftops as well, only used clear hose.
    It will freeze and stretch the hose but not crack any fittings.
    I have seen all sorts of traps on rooftops what should be drained for winter or are cracked come spring.

    I'm just a kid from the country where you try to do things simple. :)

    Now for gas furnaces, positive pressure on the coil drain, I use a short threaded PVC nipple, a maybe 4" section of clear vinyl hose that fits over the top of 3/4", secure with hose clamps. Then to a clean out tee, and pipe down to pump or floor drain.
    The entire assembly can be removed by removing the clear tube, take outside and shoot the garden hose thru it.
    Replace the hose when crappy.
    The hose lets you see the cond water drainage at a glance.
    Also the slight curve of the, if you rotate is such, hose corrects the sometimes uphill drain pipe connected to the pan.
    IMO, this does not look any more "hokey" than all the tubing on some condensing furnaces.

    But any drain glued solid together has been a pain to clean and often neglected.

  • Prevch
    Prevch Member Posts: 50
    mattmia2 said:
    Was the drain previously in the condensate pump tank and under the water level in the tank?
    Nope
  • Prevch
    Prevch Member Posts: 50
    neilc said:
    so like everyone has said, you need that trap, but, and you asked, what changed? so back to you, did you upgrade to a better, thicker, more restrictive filter ? I'm guessing this hasn't been leaking from day one, and a more restrictive filter is having affect there
     I think it's been the same? I could be wrong about that.
  • Prevch
    Prevch Member Posts: 50
    edited July 2021
    HVACNUT said:

    Pipe it all in 3/4 PVC and use an EZ-Trap.
    Also get a bottle of pan treatment tabs and always have a clean air filter. 

    This looks like a really cool product. I found it on supply house and it looks like the drop is 1". According to my manual, I need a 2" drop between the bottom of the side exit of the lower t and the bottom of the tube (lowest point of u curve) would the EZ trap do that with a 1 inch drop?

    UPDATE: Nevermind! I just found the diagram on supply house, and yes, it will work in case anyone else is wondering. Just ordered!
    SuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,989
    As far as a trap goes make it as deep as you want. Deeper is better than too shallow and won't hurt a thing.

    As i mentioned above a unit that gushes water when the fan is shut down is a classic sign of a trap that is too small or no trap.

    The drain pan should hold almost no water. I like to install traps with a PVC union on the inlet and outlet makes it easy to take the trap out to clean it. on the outlet side of the trap put an open tee at the high point to act as a vent so the trap won't syphon
    SuperTech
  • dopey27177
    dopey27177 Member Posts: 873
    Additionally:

    Every 6 months pour clorox down the drain line. The clorox will kill any algae or mold or mildew that may form in the piping. Also flush out the drain line at least twice a year. Do this after 1 month of the clorox pour.

    This what I do to my 20 year old a/c Unit besides filter changes every month.

    Jake
  • neilc
    neilc Member Posts: 1,804
    the drop on that easy trap is 4 - 6 inches, or more,
    the drop is measured from the pan outlet to the top of the bottom of the trap loop,
    the one inch you're seeing is the pan outlet, and the trap outlet, different things,
    that trap should fix your issue,
    or I'm liking the clear hose loop others mention,
    hell, you could get a longer length of the tubing your using now, loop it, and that should work also
    the smaller tube diameter would be more prone to blockage,
    but you know what to do bout that.
    known to beat dead horses
  • Prevch
    Prevch Member Posts: 50

    As far as a trap goes make it as deep as you want. Deeper is better than too shallow and won't hurt a thing.

    As i mentioned above a unit that gushes water when the fan is shut down is a classic sign of a trap that is too small or no trap.

    The drain pan should hold almost no water. I like to install traps with a PVC union on the inlet and outlet makes it easy to take the trap out to clean it. on the outlet side of the trap put an open tee at the high point to act as a vent so the trap won't syphon

    Thanks for that info. Like Is aid above, I did have to pitch my drain pan a little to make it drain a bit better. It does not drain completely, but I would say like 80-90% or so of water drains off. I assume that is fine, right? The trouble is, when the unit was installed, they did not pitch it correctly in the first place.
  • mattmia2
    mattmia2 Member Posts: 5,510
    That bushing will raise the bottom of the opening above the bottom of the pan. If you are going to reduce the size of the pipe/tubing, you should make a turn downward with a 90 and make the reduction in a vertical section of pipe so the reduction won't hold water.
  • ChrisJ
    ChrisJ Member Posts: 12,827
    mattmia2 said:
    That bushing will raise the bottom of the opening above the bottom of the pan. If you are going to reduce the size of the pipe/tubing, you should make a turn downward with a 90 and make the reduction in a vertical section of pipe so the reduction won't hold water.

    Agreed.
    But any reduction is a place likely to clog and what's the reason to reduce something that's only 2 feet long?

    3/4" pvc is probably the most common size out there.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 9,756
    edited July 2021
    They do make 3/4" garden hose also.... ;)
    Also you could make the hose drain out of clear vinyl tubing and watch everything that happens.

    But like they said above the first horizontal connection needs to be full size or the water will back up to the bottom of any fitting smaller.
  • Prevch
    Prevch Member Posts: 50
    JUGHNE said:

    They do make 3/4" garden hose also.... ;)
    Also you could make the hose drain out of clear vinyl tubing and watch everything that happens.

    But like they said above the first horizontal connection needs to be full size or the water will back up to the bottom of any fitting smaller.

    How do you make sure the horizontal connection is full size? a standard 3/4" pvc male threaded should work fine, correct?
  • JUGHNE
    JUGHNE Member Posts: 9,756
    3/4" pvc would be full size of the drain port.
    I actually get schedule 80 pvc nipples and cut them half, they are a little smaller inside diameter but not enough to make a difference.

    But all parts of the horizontal drain have to be that full size.

    If you then turn down or at a 45 angle you can reduce a little if you want to go for the "hokey" hose method I use .
  • Prevch
    Prevch Member Posts: 50
    JUGHNE said:

    3/4" pvc would be full size of the drain port.
    I actually get schedule 80 pvc nipples and cut them half, they are a little smaller inside diameter but not enough to make a difference.

    But all parts of the horizontal drain have to be that full size.

    If you then turn down or at a 45 angle you can reduce a little if you want to go for the "hokey" hose method I use .

    Awesome thank you. I plan on picking up parts today.
  • Prevch
    Prevch Member Posts: 50
    Wow! You guys must be pretty smart! I did the recommended items everyone referred to above (improving drainage from pan, adding pan tablets to clean up the pan, and adding the drain trap using an EZ trap, which is awesome) and voila! It appears to be fixed. Here is a picture of the new system. Thank you everyone for your help!
  • ratio
    ratio Member Posts: 3,173
    The two Sta-Kon terminals to the left of the LEDs are for a high-water shutdown switch. They open if the pump reservoir overfull. I usually use them to break the red wire going to the thermostat.
    mattmia2
  • Prevch
    Prevch Member Posts: 50
    ratio said:

    The two Sta-Kon terminals to the left of the LEDs are for a high-water shutdown switch. They open if the pump reservoir overfull. I usually use them to break the red wire going to the thermostat.

    Interesting thanks
  • Lance
    Lance Member Posts: 209
    remove the funnel and pipe directly into the 1" hole in the condensate pump. If you want to use a reducer keep in mind it should only be on the vertical and it is a restriction that will clog or make cleaning hard to do. Putting a reducer on the coil drain also raises the water level in the coil pan. The only time it makes any sense to not trap a condensate drain is when it is on the pressure side of the blower and can freely dump into a drain with an air gap inside the conditioned space. But if this drains outside, it must have trap to stop the air leak. Drains into sewer pipes especially on heat pumps, (suction side of blower), can suck in sewer gas. It has odor and can be a flammable vapor danger as well.
    SuperTech
  • Mike M
    Mike M Member Posts: 33
    Its hard for me to believe anyone in the hvac industry installed this. If so, never let them touch anything in your system, they dont have elementry beginers understanding of hvac equipment, or the ability to read an install manual. What change, well it could have been several things. You may have cleaned the pump tank or moved it or the hose to the point , the water seal that was made by sticking the drain hose below the water level in the tank. You may have switched the thermostat from auto to on. When the fan is in auto, the condensate pan would empty into the pump container. When the fan is on (without a trap) and the blower is downstream, it sucks air through the drainline preventing water to drain out in the opposite direction. The barbed fitting is the kicker, ive never seen even a novice try that one. Like hvacnut said, the EZ trap is the way to go, theyre under $20, and you can see everything happening, and it comes with a cleanout brush to be used in all directions...
  • Prevch
    Prevch Member Posts: 50
    edited August 2021
    Mike M said:

    Its hard for me to believe anyone in the hvac industry installed this. If so, never let them touch anything in your system, they dont have elementry beginers understanding of hvac equipment, or the ability to read an install manual. What change, well it could have been several things. You may have cleaned the pump tank or moved it or the hose to the point , the water seal that was made by sticking the drain hose below the water level in the tank. You may have switched the thermostat from auto to on. When the fan is in auto, the condensate pan would empty into the pump container. When the fan is on (without a trap) and the blower is downstream, it sucks air through the drainline preventing water to drain out in the opposite direction. The barbed fitting is the kicker, ive never seen even a novice try that one. Like hvacnut said, the EZ trap is the way to go, theyre under $20, and you can see everything happening, and it comes with a cleanout brush to be used in all directions...

    I know it is hard to believe, but yes an HVAC professional did install it. Where I live, you would not even remotely believe how common these types of issues are with our contractors....that is if you can even get one to show up.

    The good news is that I fixed it with your guys' help and it works great now.
    SuperTech
  • Prevch
    Prevch Member Posts: 50
    Lance said:

    remove the funnel and pipe directly into the 1" hole in the condensate pump. If you want to use a reducer keep in mind it should only be on the vertical and it is a restriction that will clog or make cleaning hard to do. Putting a reducer on the coil drain also raises the water level in the coil pan. The only time it makes any sense to not trap a condensate drain is when it is on the pressure side of the blower and can freely dump into a drain with an air gap inside the conditioned space. But if this drains outside, it must have trap to stop the air leak. Drains into sewer pipes especially on heat pumps, (suction side of blower), can suck in sewer gas. It has odor and can be a flammable vapor danger as well.

    That picture is the working version. Works great now.