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Condensation in AC ducts first cold day of season ?

Ron Jr._3Ron Jr._3 Member Posts: 589
edited November 22 in THE MAIN WALL
This issue has happened twice in 2 years.

Installed an AC air handler and all new flex duct in an attic in a single floor home that previously had no central air.
Last year around this time , customer called to say water was coming out of the registers. Went back and found ALOT of water in the flexible return duct and alot of supply ducts. Obviously the customer was not happy and wanted all new equipment. We obliged.

Fast forward a year almost to the week , same thing happens again. Only difference is ......... Customer said they sealed the return with cardboard where the filter goes and closed all the supply registers a few weeks prior to this happening again I know it's not a true positive shut on them , but they tried it anyway.

Anyone ever hear of this happening ? And how was it solved ? Customer says they don't run humidifiers. The have a single bathroom without a working vent. And the attic gets super cold in winter. . Of course .

Thanks in advance for any help

Comments

  • ChrisJChrisJ Member Posts: 10,222
    edited November 22
    Was all of the insulation and flex duct R8?
    I assume this is all in a vented attic?


    The bathroom and cooking product plenty of humidity.
    Hell, even breathing produces a good amount. Any cold metal will condense it.


    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
  • acwagneracwagner Member Posts: 336
    What kind of climate is this house located in?
    Burnham IN5PVNI Boiler, Single Pipe with 290 EDR
    18 Ounce per Square Inch Gauge
    Time Delay Relay in Series with Thermostat
    Operating Pressure 0.3-0.5 Ounce per Square Inch

  • ChrisJChrisJ Member Posts: 10,222
    acwagner said:

    What kind of climate is this house located in?

    I assume Long Island NY.
    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
  • acwagneracwagner Member Posts: 336
    In addition to the insulation question, are the ducts air sealed?

    Was the client heating the home at the time?
    Burnham IN5PVNI Boiler, Single Pipe with 290 EDR
    18 Ounce per Square Inch Gauge
    Time Delay Relay in Series with Thermostat
    Operating Pressure 0.3-0.5 Ounce per Square Inch

  • Ron Jr._3Ron Jr._3 Member Posts: 589
    edited November 22
    Yep , the install is in mid Long Island . They replaced it with a new unit , new supply trunk and new flex ducting to everything when I wasn't there. I'd assume it's R-8. Ducts are all connected with zip ties on the inner and outer transitions and they are sealed to insulated supply trunk. The only thing that's not insulated is the return box at the ceiling and unit. But there's condensation in all the flexible supply ducts also.

    I understand how condensation can get into the ductwork when it's cold out. Was wondering if anyone ever came across it in such a severe case like this ?

    We change out dozens of attic units a year and have hundreds of them in our customer base. Never had an issue like this till now ..........

    Very perplexing !
  • mattmia2mattmia2 Member Posts: 357
    Is there a ton of moisture coming through the basement/crawlspace/slab? It seems even if there is that it would be condensing everywhere. Is it an unusually tight house that is superinsulated so that it doesn't condense and it doesn't have the normal infiltration to get rid of moisture?

    Maybe something with unbalanced attic ventilation such that there is a lot more exhaust than intake so it it pulling a lot of air in to the attic through what leaks there are in the AC system?
  • pecmsgpecmsg Member Posts: 942
    Warm moist air migrating to a cool dry environment.
    You have to run the fan on low from time to time.
  • ChrisJChrisJ Member Posts: 10,222
    > @pecmsg said:
    > Warm moist air migrating to a cool dry environment.
    > You have to run the fan on low from time to time.

    I have all of my duct work in an unvented attic and I never run the fan all winter long. I've never seen any condensation anywhere.

    I don't close anything either.

    @Ron Jr._3 Is there a diffuser / supply in the bathroom (s)?
    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
  • EdTheHeaterManEdTheHeaterMan Member Posts: 236
    I had a similar problem in Southern NJ near the Atlantic Coast. House was less than 1/2 mile from inter-coastal waterway. The customer purchased system with ECM variable speed fan. We set the thermostat to fan circulate (Not Fan On) and this did not noticeably increase the electric bill.

    The heating was a one pipe steam system. My guess was there was at least one steam vent that was passing steam so there was a unlimited amount of humidity thru the winter. I suggested replacing all the vents, both main and radiator. Im not sure if they ever did it.



  • FredFred Member Posts: 8,095
    You say this happens around this time of the year, both times. Do they run the heat and leave the A/C on during the shoulder season or the air handler fan running to better circulate the heat drawing moisture into the ductwork?
  • pecmsgpecmsg Member Posts: 942
    ChrisJ said:

    > @pecmsg said:

    > Warm moist air migrating to a cool dry environment.

    > You have to run the fan on low from time to time.



    I have all of my duct work in an unvented attic and I never run the fan all winter long. I've never seen any condensation anywhere.



    I don't close anything either.



    @Ron Jr._3 Is there a diffuser / supply in the bathroom (s)?

    Every home is unique. Have you opened the flex duct and inspected? I see it more on Fun with Flex jobs the solid ducts!
  • acwagneracwagner Member Posts: 336
    Is the attic insulated with spray foam or blown-in/batt insulation?
    Burnham IN5PVNI Boiler, Single Pipe with 290 EDR
    18 Ounce per Square Inch Gauge
    Time Delay Relay in Series with Thermostat
    Operating Pressure 0.3-0.5 Ounce per Square Inch

  • HVACNUTHVACNUT Member Posts: 2,619
    edited November 23
    I'm going way out on a limb here, but I'm thinking the system might be oversized, poor air sealing in the conditioned space causing increased humidity in summer rather than removing it. The condensate gets thrown into the ducts and sits there throughout the cooling season.
    Then Mom and Pop go into the attic to retrieve the holiday stuff, moving flex to get what they need and sending water down through the registers.
    Or maybe it's the "Deep State". I'm a sucker for conspiracy theories.
    Has the insulation in the blower compartment been checked for water?
  • Ron Jr._3Ron Jr._3 Member Posts: 589
    edited November 24
    Thanks everyone for your input.

    There is a bathroom vent that is piped to the outside , but currently not working.

    System is sized right. First thing we confirmed after the initial problems. Flex ducting , supply trunk and return size are all spot on.

    Basement is finished . No drops to the basement for ac though. Not sure what they're doing down there for humidity control.

    Attic floor is insulated with standard batts. No subfloor. No insulation running up the roof.

    Like I said , we replace dozens of attic units a year. Install maybe 20 new systems a year. And have hundreds of these systems in our customer base. Never had an issue like this. No less an issue like this in the same house with all different equipment.

    We should just bite the bullet and change the equipment to heat pump at this point .......... :(
  • ratioratio Member Posts: 2,131
    The water has to be coming from somewhere. What's the indoor humidity like? Any ventless fireplace, etc.?

    We've got a customer with high (90+) humidity all summer long (engineer oversized the cooling, no mater what he says), but it must be built on a spring, there's no other way for that much moisture to be getting inside the envelope.

  • wz25wz25 Member Posts: 10
    Indoor humidity exacerbated by lack of working bathroom vent fan + insulated attic floor (but otherwise unconditioned attic space) creating large temperature differential in attic --> condensation?

    Does this article help?

    https://www.achrnews.com/articles/97293-the-case-of-the-water-filled-ducts
  • ChrisJChrisJ Member Posts: 10,222
    > @wz25 said:
    > Indoor humidity exacerbated by lack of working bathroom vent fan + insulated attic floor (but otherwise unconditioned attic space) creating large temperature differential in attic --> condensation?
    >
    > Does this article help?
    >
    > https://www.achrnews.com/articles/97293-the-case-of-the-water-filled-ducts

    Agreed.
    This is why I asked if there was a supply in the bathroom. I could imagine hot damp air going right up that supply when the system is off.
    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
  • clammyclammy Member Posts: 2,345
    edited November 26
    Any chance you can leave a couple of small data loggers even a simple extech temp/humidity logger there pretty cheap . Just asking return box externally wrapped ? What type of wrap ? Plastic or foil insulation on the flex ? For the cost of replacing a system on the arm I de pick up 2 or 3 extech units and place one in the air handler ,attic and living area may help you pin point a issue . Maybe a blower door test for leakage gotta be some thing aside from equipment ,do they run the fan on constant ? Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • GordyGordy Member Posts: 9,341
    wz25 said:

    Indoor humidity exacerbated by lack of working bathroom vent fan + insulated attic floor (but otherwise unconditioned attic space) creating large temperature differential in attic --> condensation?

    Does this article help?

    https://www.achrnews.com/articles/97293-the-case-of-the-water-filled-ducts


    Nailed it!
  • Ron Jr._3Ron Jr._3 Member Posts: 589
    > @Gordy said:
    > (Quote)
    >
    > Nailed it!

    Thanks Gordy ! That article explains exactly what's happening. The solution kinda sucks. But at least we can forward something to the customer that says in layman's terms what's going on in their home. Thanks again !
  • ChrisJChrisJ Member Posts: 10,222
    > @Ron Jr._3 said:
    > > @Gordy said:
    > > (Quote)
    > >
    > > Nailed it!
    >
    > Thanks Gordy ! That article explains exactly what's happening. The solution kinda sucks. But at least we can forward something to the customer that says in layman's terms what's going on in their home. Thanks again !

    This is another reason I've put off doing anything to my attic. It's not vented and a lot isn't insulated but it keeps the duct work warmer in the winter.

    Ultimately I want to insulate the rafters and not the attic floor.
    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
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