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Discussion Starter #1
There is an opening in the HVAC unit that is leaking cool air.
It is the opening around these PVC pipes.
I have included a full view to help get oriented. The PVC pipes are just behind the black foam insulation.
My first instinct was to glob around the PVC with some type of caulk.
But then I got to wondering if the leak was not somewhere further inside and air from that leak was filling the space behind the PVC and flowing out around the PVC. I say that because it seems odd that the installer would leave this opening wide open.


Any opinions?


Also when I purchased the house I had an inspection and the report included the line, "Repair: The temperature drop measured across the evaporator coil of the heat pump system is lower than typical. This usually indicates that servicing is needed. A qualified heating and cooling technician should be consulted to further evaluate this condition and the remedies available."

Note. This is not a heat pump according to the model number.
 

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Get some permagum or duct seal at your local big box hardware store. Tear off an appropriate amount and have at it.

For Example

Dough-like material
Helps seal conduit openings, gaps and holes against drafts, dust, moisture and noise
Easy to handle
Simple to install
Under normal conditions the material will not harden or form a skin
Non-conduction
Non-deteriorating
Non-toxic
Non-corrosive
Non-staining
Non-curable
Flash point is over 550°F
Temperature ranges between -20°F to 350°F
California residents see Prop 65 WARNINGS
 

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Discussion Starter #3
surferdude2, great idea. Better then the "glob" of sealer.
Except, I am not sure the problem isn't inside somewhere and stopping it here is not the right place.

I don't know enough about the configuration of this unit to understand that.
 

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I can assure you the problem is not inside. This is typical on air handlers so you're not being picked on. It's called sloppy installation and it's all too common. Too many installers never heard of Permagum or the duct seal I pictured in that example to you. :sad:

Best regards, SD2
 

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"Repair: The temperature drop measured across the evaporator coil of the heat pump system is lower than typical. This usually indicates that servicing is needed. A qualified heating and cooling technician should be consulted to further evaluate this condition and the remedies available.
What was the temperature drop?

A low drop can be normal if the return humidity was high when testing and or the blower speed is set too high for the size of a/c.

The latter is very easy to correct.

The installation looks pretty bad, the flex return is going straight into the cabinet -> no box.
 

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If you're still in home warranty period or full disclosure recourse, you really should get a qualified HVAC technician to check out that installation and do what is necessary to ensure that it's performing up to specifications.

Also, given that it's in your attic, have him correct the drain that appears to be hooked into the wrong outlet. You should insist on the main drain being connected to the lower drain outlet of the coil. Then the upper drain (overflow) should run down to a pan below that contains a float operated switch that will shut the compressor off when/if overflow drain ever starts running water. Without that protection, you can get extensive ceiling damage if the main drain ever plugs up (happens often). It's a cheap device ($10 ~ $15) and easily installed and wired (open run low voltage).
 

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Discussion Starter #7
What was the temperature drop?

A low drop can be normal if the return humidity was high when testing and or the blower speed is set too high for the size of a/c.

The latter is very easy to correct.

The installation looks pretty bad, the flex return is going straight into the cabinet -> no box.

It is always very humid in "middle Tennessee"....just being sarcastic about the weather here.
The report doesn't specify the actual temperature drop.
The report calls this a heat pump system which it is NOT. Do heat pump systems expect the same temperature drop as a standard HVAC or a different value?


I am trying to understand the temperature drop issue. If I remember right, the evaporator is cold and the air forced through it is hot. The air gets cooled by the evaporator and exits at a lower temperature. So if the blower speed is too high, the air doesn't stay in the evaporator to cool enough and thus the temperature drop is less then it should be. Did I get that right.

I hope to learn something every day.

Is it possible that this leak allows the air to flow faster and thus effect the temperature drop? Just guessing. It is strong enough to blow out a butane flame.
 

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Discussion Starter #8
If you're still in home warranty period or full disclosure recourse, you really should get a qualified HVAC technician to check out that installation and do what is necessary to ensure that it's performing up to specifications.

Also, given that it's in your attic, have him correct the drain that appears to be hooked into the wrong outlet. You should insist on the main drain being connected to the lower drain outlet of the coil. Then the upper drain (overflow) should run down to a pan below that contains a float operated switch that will shut the compressor off when/if overflow drain ever starts running water. Without that protection, you can get extensive ceiling damage if the main drain ever plugs up (happens often). It's a cheap device ($10 ~ $15) and easily installed and wired (open run low voltage).
Out of warranty and I accepted the house with full knowledge of the report. To me that means it is now my problem. Am I to honest?

I didn't include enough of the installation in my picture. There is a pan with a float switch.

I need to understand more about what you say about where the drain is connected before I bring someone in. There are a lot of less then "ideal" "experts" around here. There is so much construction that anybody that can spell "nail" is a carpenter.

I will go up there and try to understand the installation better. But that will have to wait because it is about 115F up there. We had a cool spell over the weekend so I had a chance to take the pictures. If I get up at the crack of dawn tomorrow it might be cool enough to venture up.
 

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It is always very humid in "middle Tennessee"....just being sarcastic about the weather here.
The report doesn't specify the actual temperature drop.
The report calls this a heat pump system which it is NOT. Do heat pump systems expect the same temperature drop as a standard HVAC or a different value?


I am trying to understand the temperature drop issue. If I remember right, the evaporator is cold and the air forced through it is hot. The air gets cooled by the evaporator and exits at a lower temperature. So if the blower speed is too high, the air doesn't stay in the evaporator to cool enough and thus the temperature drop is less then it should be. Did I get that right.

I hope to learn something every day.

Is it possible that this leak allows the air to flow faster and thus effect the temperature drop? Just guessing. It is strong enough to blow out a butane flame.
Yes - the air moves faster through the coil and every cubic foot gets cooled less. you still get the same amount if not more cooling -> less cooling per cubic foot of air but more cubic foot per minute.

Dehumidification isn't a good though with a higher than normal speed though.

Straight a/c cools the same as a heatpump.

Some leakage around the coil drain lines won't make much of a difference airflow rise. You should still stop the leakage.
 

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I didn't include enough of the installation in my picture. There is a pan with a float switch.
That's a break in your favor! Now all you have to do is hook the present drain to the lower drain outlet (if it isn't already, picture may be fooling me) and then add a drain line down to the pan from the upper.

The way it looks now, any overflow will run down on the heat exchanger and who knows where else before getting into the pan. Lots of damage possible to the furnace that way. Easy to fix now that the switch is already installed. That assumes they have it wired properly to disable the compressor.
 

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Discussion Starter #11
That's a break in your favor! Now all you have to do is hook the present drain to the lower drain outlet (if it isn't already, picture may be fooling me) and then add a drain line down to the pan from the upper.

The way it looks now, any overflow will run down on the heat exchanger and who knows where else before getting into the pan. Lots of damage possible to the furnace that way. Easy to fix now that the switch is already installed. That assumes they have it wired properly to disable the compressor.

(1) Now I am stumped. Where is the lower drain outlet you mention? Frankly I don't see anything I could call drain outlet.


(2) I used the permagum to cover that opening around the PVC. Works great. But there is still enough air flow to blow out a butane lighter. But it seems to be coming from out of the black foam insulation wrapping the PVC pipe.

(3) Also, if I lift up a little on the entire foam tube, the PVC screw fitting rotates. That would be the fitting with the blue cement on it. I sure hope that PVC is just protecting a metal Freon tube inside.
(4) As for the reported temperature drop. How would I measure that? Are there some "test points" on the return and exit ducts where I can insert some probes?
 

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(1) Now I am stumped. Where is the lower drain outlet you mention? Frankly I don't see anything I could call drain outlet.

That red pipe plug is a drain connection as is the one that your drain is now connected to that's adjacent ot it. The higher one of those two is the overflow drain.


(2) I used the permagum to cover that opening around the PVC. Works great. But there is still enough air flow to blow out a butane lighter. But it seems to be coming from out of the black foam insulation wrapping the PVC pipe. That drain line is obviously running through some area with a more positive pressure than your attic. Maybe even from outside air if your attic is negative.

(3) Also, if I lift up a little on the entire foam tube, the PVC screw fitting rotates. That would be the fitting with the blue cement on it. I sure hope that PVC is just protecting a metal Freon tube inside. That's your condensate drain line. No freon in it. Good that it is loose since you're probably need to switch it to the other port if it isn't on the lowest one.
(4) As for the reported temperature drop. How would I measure that? Are there some "test points" on the return and exit ducts where I can insert some probes? You have to make those holes yourself. One below the coil and one above it.
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You should construct the new primary drain line to have a trap in it and a plugged tee at the first turn for a clean out or as an alternate a short length of flexible hose that can be removed for cleaning the line when/if it clogs.

Also, be aware that tightening the drain fittings too tight risks breaking the drain pan so use some teflon paste thread dope and snug it up firmly but not extra tight.

Get it a little tighter than the original installer did on his best shot example and don't try to daub some pvc cement on it like he did to make up for his mistake.
 

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Discussion Starter #14
Wow, was I out in left field. I thought that PVC line with the blue cement had to do with refrigerant because it was wrapped in that black foam. WRONG, thanks for setting me straight.


So I decided to investigate the whole system to better understand what is happening. Outside I found two PVC pipes coming through the exterior brick wall and directed toward the ground.


Back upstairs I followed the PVC line with the blue cement into the black foam and found it snaked around the unit, then across the back and extended about 5 feet to the left of the unit. Then it turned coming back parallel to the left of the unit. After about 5 feet the black foam ended and it was just PVC all the way across the attic to the wall where the outside pipes were. Why did they wrap a drain line with black foam for, maybe 15 feet then stop the foam? I attached a pic



Then I took a closer look under the unit and found a second PVC line. You can see it in the picture showing the full front of the unit. It is just visible below where the return duct meets the unit. This is ridiculous. It just penetrates the wall of the pan and ends. As if, should the pan started to fill, the water would flow into that pipe. But, that pipe runs about 5 feet to the left then becomes parallel with the other (foamed) pipe. Well, it then runs about 25 feet to the wall and then becomes the second pipe I found outside. But there is noting to ensure that there is any pitch to this pipe. So water could just as easily overflow the pan as flow into and through the pipe.

Note (1), the two fittings, the blue cement one and the one with the red plug, are side-by-side. Both at the same level. I am going to find a manual for the unit to understand the intent of two side-by-side connections.


Note (2) Where I thought there was cool air coming out from the foam, I was wrong. It was coming from those vent wholes below the foam. I have taken the front door off the unit and can feel a little cool air coming from "somewhere" but I haven't where. But with the front on the air came out of the vents.
 

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That's all well and good. The drain from that pan is a secondary/backup drain in case the primary gets plugged. If the secondary/backup also gets plugged, the pan will fill and the safety switch will shut the compressor down. See to it that the secondary/backup is sloped to drain as best you can.

If the drain outlets from the pan are the same heights, then the manufacturer has built the overflow outlet feature into the drain pan inside where you can't see it so that it's above the primary drain level. Check the literature for the proper primary drain... hopefully you are already connected to it. I suspect the secondary/overflow drain has the red pipe plug in it. Remove that and run that down in PVC to the pan below so any overflow will go directly to the pan.
 

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Discussion Starter #16
Well I finally had a chance to climb up there a find a model number for the evaporator (from my old fridge days, I think that is a good name for it).


I have attached the appropriate pics. of the unit and the manual. The PDF was too large so I had to screen capture the necessary pages.
My interpretation is that both condensate drains are draining the same area. Would you concur?

If so, should I just add another short length from the plugged line to the pan below?
But that drain from the pan is useless. It has virtually no pitch across about a 20 foot run. It is just laying on a joist for the run then goes into a wall.
Maybe I should replace it with a line from the plugged outlet (which is 3 or 4 feet above the joists) with a pitch of about 3 or 4 feet across the 20 feet to where the far end of the pan drain line goes into a wall.
Or just rely on the switch on the pan. I tested it and it seemed to work.


Also, I was hoping to get some information about the recommended temperature drop but, no luck
 

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