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Thread: Help. Air Handler dripping water into secondary drip pan...

  1. #1
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    Help. Air Handler dripping water into secondary drip pan...

    I have a Bosch AC/Heatpump unit outside and a Bosch air handler in the attic. We live in the North East and just had a bad heat wave. When I got home last night the upstair AC was not running. So I went up into the attic and
    checked the secondary drip pan. Sure enough there was water in it and the safety switch tripped and shut the unit off. I opened the panel to the air handler and the bottom inside insulation was soaked. I was not happy.
    So I called the HVAC company and they came out this morning and spent some time here. Here is what was tried.

    1. Poured about 3 gallons of water in the drip pan inside of the unit to make sure the drain was not clogged. That worked fine with no issues.
    2. Checked the air filter to make sure it wasn't dirty. I am religious about changing it so I knew that would not be a problem.
    2. Tested the refrigorant in the outside unit. That was completely fine
    3. Tested the air flow in the air handler for something called negative pressure? Wasn't really sure what that meant but that was fine.
    4. This is also a Hydro-Air unit so checked the heating coil and pipes to make sure that wasn't the issue. Those were all fine.

    So at this point nobody is sure what is happening. So we left the panels off the unit so the inside could dry out. The only thing he can think of is that
    if there is a crack somewhere in the main drip pan in the unit. But since it was already soaked inside he couldn't tell when we poured the 3 gallons
    of water in it if water was getting through. So they are going to come back next week after everything is dry and pour a bunch of water in the main
    pan again to see if it makes the inside wet. Then he will know that is the cause.

    But if that does not work, does anyone have any idea what else can be tried. The outdoor and indoor unit are only 2 years old. I am now worried about a bunch
    of mold growing in the air handler and my family breathing it in.

    Thanks for any help,
    Derek

  2. #2
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    Is there a spot where they may have accidentally double-trapped it? The drain could be airlocking, while the blower is on it can't overcome the pressure and drain until the blower shuts off. Is there a vent on it? If so, is it capped? The drain line doesn't reduce in size anywhere does it?
    Good? Bad? I'm the guy with the gun.

    Statements made by me are strictly my opinions and do not reflect the opinions of my employer. I am not authorized to make any official statements on behalf of my employer.
    Any technical advice offered by me is for educational purposes only, all HVAC related repairs should only be attempted by qualified personnel.

  3. #3
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    I'm not sure exactly what you mean by double-trapped? But the way it is set up is that the PVC pipe comes out of the air handler and goes into a 90 degree fitting to send it out of the house. After the 90 degree fitting it goes into a P-trap. Right before the P-trap there is a screw fitting that you can unscrew to clean out the trap and put in water/antifreeze,etc if need into the trap. That screw fitting was on tightly. Right after the P-trap there is a piece of PVC connected vertically that is open to the air. Does that makes sense? The tech said that was put in place so a vacuum couldn't be formed when the handler was running and it allows the water to run freely.

    But I have the same exact theory as you do that while the handler is running the drain can't over come the pressure and drain. How is this proven? He checked the static pressure and said it was spot on.

    I was also wondering if that while the blower is runnig if it was sucking water off of the coil and into the handler. So I have wireless security cameras around my house. We actually put one inside of the handler and let it run for 20 minutes or so. I could see the water coming off of the coil and dripping down into the pan. It was not getting sucked into the handler. And when we pulled the panel off of the handler the blower motor casing did not have any water on it. So there goes that theory. But the only thing is that is was much less hot and humid the day the tech came. We had 6 days of 90-100 degree heat in our area, which is unusual.

    I am at a loss at this point. Any help is appreciated.

  4. #4
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    Did they measure static pressure? What air filter are you using and what size is it? If you have a 3M Filterete, I encourage you to try a simple 1" fiberglass filter which has a much lower pressure drop.
    Can you post a few pictures of the unit from 5' away, or a link to pictures?
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  5. #5
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    Here is what was on the paperwork about static pressure:

    Measured .4inwc static pressure and 8 degrees of sub cooling at compressor

    I don't know if the static pressure was measured with the filter in place or taken out. I was not there when he measured it. Should the filter be in place when this is measured?

    And the unit was installed with a 20x25x5 filter compartment. I was using GeneralAir MERV 11 pleated filters as that is what the original filter was on the install. I just ordered some MERV8 filters that I am going to switch to. In case the MERV 11 was too restrictive? I won't be home until Sunday night. So I can post pictures on Monday.

  6. #6
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    .4" WC static pressure sounds okay. Take note that I have seen techs measure the supply and return ducts without measuring after the filter to get the true static pressure. I hope yours measured correctly.

    You may be onto something with changing the filter. I have successfully reduced static pressure by using a MERV 8 instead of a MERV 11 filter. The complaint was noise and the filter change plus blower speed adjustment solved the problem.
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  7. #7
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    I am almost positive that he took the static pressure reading on the return side of the air handler, but after the filter. That is the correct way right?

  8. #8
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    Quote Originally Posted by db_9 View Post
    I am almost positive that he took the static pressure reading on the return side of the air handler, but after the filter. That is the correct way right?
    Yes
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  9. #9
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    Quote Originally Posted by db_9 View Post
    I am almost positive that he took the static pressure reading on the return side of the air handler, but after the filter. That is the correct way right?
    Define after?
    Is the probe between the filter and the blower?

  10. #10
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    Yes. The probe was between the filter and blower motor. Is that the correct spot?

  11. #11
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    Quote Originally Posted by db_9 View Post
    Yes. The probe was between the filter and blower motor. Is that the correct spot?
    Yes.
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  12. #12
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    Anyone know how to add a picture to this? Someone had asked if I could post a picture. I took some but don't know how to add them? I see the add picture button but it wants you to put in a URL link?

  13. #13
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    Quote Originally Posted by db_9 View Post
    Anyone know how to add a picture to this? Someone had asked if I could post a picture. I took some but don't know how to add them? I see the add picture button but it wants you to put in a URL link?
    It may be easiest to put pictures on a hosting website and just post a link here.
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  14. #14
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    Let me know if you can see this picture if you cut and paste this URL into a browser. I wasn't sure how to make this link clickable.

    https://photos.google.com/share/AF1Q...Y1T0Z6SDR1OTBR

  15. #15
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    Quote Originally Posted by db_9 View Post
    Let me know if you can see this picture if you cut and paste this URL into a browser. I wasn't sure how to make this link clickable.

    https://photos.google.com/share/AF1Q...Y1T0Z6SDR1OTBR
    I can’t tell much from that picture.
    But I will state that the supply trunk should be sized according to the outlet (probably 11x17) rather than the size of the air handler. Additionally, I hope there are turning vane in the Tee of the trunk.
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  16. #16
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    I highly doubt there is a turning vane in the T of the trunk. I had to google what that was. I am sure the original installers 22 years ago did not put one of those in. I guess the guys that swapped out the air
    handler 2 years ago should have.

    But the service manager is coming out tomorrow to look at what is going on and I will ask him about that. I let the panel doors open like in the picture for 5 days. In the heat of the day
    the attic gets over 100 degrees. The inside of the air handler is still very wet.

    Any advice on how to maybe dry it out faster?

  17. #17
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    Quote Originally Posted by db_9 View Post
    I highly doubt there is a turning vane in the T of the trunk. I had to google what that was. I am sure the original installers 22 years ago did not put one of those in. I guess the guys that swapped out the air
    handler 2 years ago should have.

    But the service manager is coming out tomorrow to look at what is going on and I will ask him about that. I let the panel doors open like in the picture for 5 days. In the heat of the day
    the attic gets over 100 degrees. The inside of the air handler is still very wet.

    Any advice on how to maybe dry it out faster?
    The attic air is humid. Perhaps a hair dryer or heat gun.
    *********
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