1

I recently had my a/c system replaced with a heat pump system (Less than 2 weeks ago). The original was a 2.5-ton a/c. The new system is a 3-ton heat pump. I'm now having all sorts of drainage issues with the air handler and would like to confirm if the installation is incorrect. I don't have experience in HVAC, but after some research I can tell that it was done very poorly. I would like to better communicate the issues to the next crew that I hire to fix the issues.

The home only has 1 giant return duct, on the second floor in the hallway. The air handler is above the return, in the attic - mounted horizontally. A few days after the install, I noticed water dripping out of the return duct from the ceiling. Went up into the attic, and the secondary drain pan was dry. Opened up the air handler and saw that it's flooded with water. I called the installer back, only to have them bandaid the real issues with some slight modifications (explained below).

With the unit running, I stuck my head into the return to watch for water and can see that the blower is sucking up water out of the drain pan, and there are droplets of water that seem to be falling directly onto the blower housing - missing the drain pan.

I noticed the following things when I looked over their work (some of which I'm not sure are valid issues):

  1. The V-shaped evaporator looks like it's installed backwards or upside-down, but I'm not 100% sure. Most photos I see of this same config, has the pointy end of the evaporator towards the blower motor. Looks like the side door was cut where the drain holes are to accomodate the upside-down evaporator. The diagram in the installation manual is also showing the pointy end of the V towards the blower (see photos).
  2. The P-trap (or lack of). It looks more like a V-trap (?). I think that this issue along with the backwards evaporator are the main culprits.
  3. Several of the PVC lines are not cemented, but don't seem to be leaking.
  4. The secondary drain is piped into the primary drain pvc, shouldn't it run separately?
  5. No overflow safety switch.
  6. Their bandaid fix was: to raise the drain pan about 1/4" with some wood spacers, and add a piece of insulation to cover the open gap between the evaporator and the blower. The drain hole on the primary pan that they connected to initially seemed correct (lower hole). But after the band-aid visit, they switched to the higher hole and plugged the lower one... seems strange to me.

Attached are photos of the install. Would appreciate any comments and advice on the above. The P-trap would be a pretty simple fix, but I'm really curious about the potentially backwards evaporator. Should I only focus on fixing the P-trap and not worry about the orientation of the evaporator? Thank you

Model numbers of the equipment for reference (AirTemp 3-ton system): Air Handler: AirTemp B6BMM042K-B Heat Pump: AirTemp VSH1BE4M1SP36K

Air Handler layout: Air flow from left to right in photo (return is on the left).

Air Handler layout. Air flow from left to right (return is on the left).

Original Drain setup

Bandaid drain setup

Install manual orientation

Update on the situation: I cut out and removed their entire “trap” assembly. I installed a proper p-trap in the lower outlet of the primary drain pan. Then installed a safety switch into the overflow outlet of the primary drain pan. I have not yet replaced the secondary drain pan (it’s very rusted), but when I do, I plan to add a water sensor switch on the pan and wire it in series with the overflow safety switch.

Unfortunately my changes to the P-trap didn’t fix the main issue:

  • The blower motor is still sucking water out of the edge of the primary drain pan, and onto the unit bottom insulation… flooding the unit and leaking water into the return vent and onto the ceiling drywall.
  • This negative pressure seems to still be preventing drainage while the motor runs.
  • I can’t figure out if this caused by the gaps that allow air to bypass the evaporator right near the drain hole area, or if it’s caused by an abnormally high negative pressure. I am running the system with no filter at the moment, to rule that out as being a cause of too high negative pressure.
  • The unit bottom insulation is completely soaked. Will it need to be replaced? What material can I replace it with?

Thanks for any further suggestions.

5
  • A trap must be installed to prevent air being sucked in the drain which prevents drawing while unit is running. Also if the single return is not adequately sized or has a restrictive filter negative pressure inside the AH WILL BE TO GREAT TO ALLOW DRAINING
    – Kris
    Oct 5 '21 at 3:25
  • youtube.com/watch?v=s1ZWHgoYTNA.
    – Kris
    Oct 5 '21 at 3:32
  • Can yiu show the diagram for horizontal left?
    – Kris
    Oct 5 '21 at 4:17
  • 1
    Hold payment until they resolve it, you may have to go through your bank or credit card company. Also complain to the local licencing authority and your inspectors. It appears the installer(s) are shade tree mechanics, not HVAC professionals which you paid for. If you make enough noise to the appropriate authorities it will get fixed especially if you hold money out, but I would guess they demanded that up front. The insulation etc should all be new. If you have a BB or equivalent complain to them as well.
    – Gil
    Oct 5 '21 at 4:47
  • I don't think there's anything inherently wrong with the V-trap instead of a nice, curvy P-trap. However, only the line to the right goes through the trap. The line on the left will be exposed to any sewer gas, direct outside air, etc, because there is no trap between it and the exit. Also, it does look like some of those joints in the trap area aren't glued. There will likely be enough evaporation through the unglued joints to let the trap dry out, even if it doesn't directly leak.
    – FreeMan
    Oct 5 '21 at 14:27
1

So, yea, there are a few things wrong here, and the giant burn mark on the front panel is the first indication of this being a bad install. I don't care if you do get some soot on a panel while soldering/brazing - clean it off! Anyway...

  1. I'm actually not sure what the implications of this is, but the return air is coming from the wrong direction based on the diagram, so we will call this wrong. I'm pretty sure installing it in this orientation will allow condensation to get sucked into the fan quite easily.

  2. Any fitting in the condensate line is a place for mold/trash/whatever to build up and form a clog. P traps should be smooth to help prevent that. Way to many fittings here.

  3. Everything should be glued except for a cap on top of a cleanout. Vibration of the unit can work unglued fittings apart if they aren't leaking already.

  4. The secondary drain should be totally separate from the primary. In cases where you cannot feasibly run a secondary (a good reason, not just being lazy), you absolutely must have a float switch in the pan that will cut power to the unit (red wire is best). Sometimes a switch is installed on the primary drain to cut power if that backs up, but in the case where water starts leaking from somewhere else, a overflow pan mounted switch is better.

  5. Covered in #4, should absolutely have a switch on the overflow pan.

  6. As you mentioned, there are two drain outlets on the side of the AC and one is mounted higher than the other. The higher mounted hole is for a secondary drain and they have used it for the primary. The unit will hold too much water, leading to problems down the line.

As for the blower sucking water out of the drain, there are different air handler configurations, but if the drain is under negative pressure, this must be accounted for when running the drain. Sounds like they messed that up as well.

2
  • Updated details in question.. I cut out and removed their entire “trap” assembly. I installed a proper p-trap in the lower outlet of the primary drain pan. Then installed a safety switch into the overflow outlet of the primary drain pan. I have not yet replaced the secondary drain pan (it’s very rusted), but when I do, I plan to add a water sensor switch on the pan and wire it in series with the overflow safety switch. Unfortunately my changes to the P-trap didn’t fix the main issue: The blower motor is still sucking water out of the edge of the primary drain pan, and flooding the unit. Oct 10 '21 at 3:55
  • Sounds like you’ve done a lot of good work, but that coil being installed backwards seems like the biggest issue, and one that will require the unit to be discharged to fix.
    – JPhi1618
    Oct 10 '21 at 4:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.