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  1. #1

    1470 Square Foot not cool from day one

    I know you guys are busy, so I'll try to give you the essentials.

    Scenario:

    • 8 year old home - I'm original owner
    • 3 ton, 10 seer York with 80,000 BTU furnace with 1200 cfm blower
    • 9000 BTU of supplemental cooling in hottest bedroom
    • 1470 Sq Ft of main level above completely below grade basement - no shade
    • 700 Sq. Ft. of space with Cathedral ceilings from 8' to 14.5' all with soffit vents, ridge vents, and baffles - R-19 insulation
    • 770 Sq. Ft. of 8 Ft. Ceiling with soffit and roof vents - R30 insulation
    • About 80 sq. ft of windows on SW side
    • About 80 sq ft of windows on NE side
    • All exterior walls are 4.5" with 1/2 siding, 1/2 gypsum, and R-11 fiberglass
    • AC checked three times with no problems found - condenser, evaporator, and filter clean - 20 degree drop across coil
    • At 100 outside, 80 inside - cools great at night - aluminum on all SW window exteriors with no daytime cooking to maintain temp.
    • No Manual J performed - nobody willing to do it - rule of thumb techs only


    Where do I go next? I see lots of great advice here. Please point me in the right direction.

  2. #2
    Join Date
    Jul 2008
    Location
    Rydal,Ga
    Posts
    84

    Find you a HERS Rater !!!

    How much gas are you using during the cooling months ???

    How dusty is your home ???

    Where is the T-Stat and returns ??

    Do you have a ERV ???

    How long does it cycle or does it run all day long???

    Where are the Ducts and Air Handler located ???

    Where are you located????

    Find you a "HERS Rater" and have a Full Analysis done !!! (BlowerDoor, DuctBlaster and IR)

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,774
    Follow the advice above.
    You also need your duct work checked to see how many CFM your blower is moving. I doubt its moving 1200 CFM.
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  4. #4
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,467

    No Manual J - No CFM checks - rule of thumb techs only

    No Manual J performed - nobody willing to do it - rule of thumb techs only.
    Instead of constantly raising the SEER level of air-conditioners' maybe we need a building & HVAC Code requiring that every home have a documented manual J, & the CFM delivery of the blower/duct system with those documents available at all times.

    If we are going to get serious about Energy Conservation, there ought to be some government help in these areas at the county & township levels. The government & the energy provider's should all be actively involved in authentic Energy Conservation programs & actions!

    As beenthere stated, I also doubt you are getting near the 1200-CFM rating of the air handler. - Darrell

  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by udarrell View Post
    Instead of constantly raising the SEER level of air-conditioners' maybe we need a building & HVAC Code requiring that every home have a documented manual J, & the CFM delivery of the blower/duct system with those documents available at all times.

    If we are going to get serious about Energy Conservation, there ought to be some government help in these areas at the county & township levels. The government & the energy provider's should all be actively involved in authentic Energy Conservation programs & actions!

    As beenthere stated, I also doubt you are getting near the 1200-CFM rating of the air handler. - Darrell
    Florida code requires Man. J and D ,for new homes.Hasn't helped much,though they must be submitted ,they are not checked for accuracy.Checking them would require the dept to do it over again,which would be costly,plus the dept could be in error.

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Could be one or more of many things,some are;

    Undersized ducts
    Missing insulation,maybe the kneewalls
    Duct leakage
    Improper refrigerant charge
    Wrong fan speed

    You really need a Pro to check it all.


    For duct leaks ,try this;

    With the system running,all exhaust fans and clothes dryer off,crack the door to the garage,use a candle to see if air is flowing in or out of the home,if it is ,you have duct leaks.

    Same test for the door to the basement.

  7. #7
    Join Date
    Jul 2008
    Location
    Rydal,Ga
    Posts
    84

    Its been Code.... IEEC for years... It SHALL be posted now BUT????

    Quote Originally Posted by udarrell View Post
    Instead of constantly raising the SEER level of air-conditioners' maybe we need a building & HVAC Code requiring that every home have a documented manual J, & the CFM delivery of the blower/duct system with those documents available at all times.

    If we are going to get serious about Energy Conservation, there ought to be some government help in these areas at the county & township levels. The government & the energy provider's should all be actively involved in authentic Energy Conservation programs & actions!

    As beenthere stated, I also doubt you are getting near the 1200-CFM rating of the air handler. - Darrell
    It has been mandatory since 2001 IEEC.... the HVAC Industry dosen't recognize the IEEC code

    Here in Ga you "SHALL" post R's U's BTU's SHGC, HL, SL, LL, SEER, % CFM.... I am personally the only one that is abiding to this code in 10 counties surrounding me that I know of....

    Hey thats ok when the lawyers get done with the class action suites... I will be the only one left

    Great passion UD... don't worry the trail lawyers will take care of that soon as they get done with the "Sub-Prime Scandal"

  8. #8
    It was late when I posted, so let me get to some things I missed.

    Quote Originally Posted by kenny mac View Post
    How much gas are you using during the cooling months ???
    Not much. I'm on par or slightly lower than my neighbors. Unit cycles 2-3 times per hour on the coldest days.

    How dusty is your home ???
    We have animals and kids combined with some minor remodeling to fix other builder mistakes. So, its hard to say what dust is related to inadequate air turnover. If your asking to see if air is being cycled, any dust clears quickly when the unit is set to cycle. If your checking because of filters, they are MERV8, 5 inch media in side filter box that are changed every 2-3 months. Also the evaporator and condenser have been cleaned several times in the past 8 years. As recently as last month.

    Where is the T-Stat and returns ??
    T-Stat is on an interior wall of the living room with no direct exposure to sunlight. There is an 8 x 32 (6 x 29 of actual louvers) in the living slightly above and to the right of the T-Stat. Each of 3 bedrooms has an 8 x 16 return. All returns are at about 7' off the floor.

    Do you have a ERV ???
    Had to look that one up. No.

    How long does it cycle or does it run all day long???
    Normal cycle time if the outside temp is below 80, is 13-15 minutes. Between 80-90, cycle times increase. Anything above 90 puts the unit running all day if we try to hit 73 inside. At 100, 79-81 is all we can hit with the AC running non-stop. This is with blinds and/or curtains on all windows and aluminum foil on the exterior of all 75 sq. ft of windows on the SW side. As I write this, the outside temp is 79 and the inside is 72 with AC cycling at 10-12 minutes on and 10 minutes off. That means its running almost 50% of the time to drop 7 degrees.

    Where are the Ducts and Air Handler located ???
    Ducts are in the floor. Living room, dining room, kitchen, and small foyer are all under the same vault. LR has 2-4x12 on exterior wall below windows. DR has 2-4x10 on two separate exterior walls. Kitchen has 1-4x10, and foyer has 1-4x10. Each of 3 bedrooms has 1-4x10 on exterior wall below a window. Each of 2 bathrooms has 1-4x10 and 1 vent in a walk-in closet.
    Air handler/furnace is in the basement central to the vaulted upstairs space.
    There are also two ducts on the ceiling of the basement, but they are partially closed off because the basement stays around 69-70 all the time (year round).

    Where are you located????
    Lawrence, KS in a treeless and shadeless subdivision.

    Find you a "HERS Rater" and have a Full Analysis done !!! (BlowerDoor, DuctBlaster and IR)
    I have one scheduled for Sept. 2, because it was recently suggested by the last HVAC guy that came out.

    He inspected and cleaned the unit and listened to my problem. He inspected the ducts stating that they were sized to accommodate as much as 1400 cfm - all ducting is in the basement. He stated the returns were enough to do 4-5 tons. Both return air and supply ducts have been taped at every joint and around the plenum. He also looked at the position on the control module(?) to check fan speed. He showed me that the heat and cool leads that control the fan are jumper-ed together, placing the fan on its highest speed during cooling. No one has ever verified the fan speed or flow, only that my drop across the coil is within the normal range (18-20 degrees). One guy put a piece of paper on the returns to see if they were indeed drawing air and placed his hands over the vents. Refrigerant was checked 2 years ago and 7 years ago by separate techs because we were fighting the same problem back then. Both stated the levels looked good, basing their statement on their gauges connected during run cycle. When running, the line-set is hot and cold and the evaporator is removing humidity because the condensate line is constantly dripping. On that note, inside humidity is 45-47%.

    Sorry to be so wordy, but I just want to cover everything I can think of that may help narrow down the problem.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,774
    Can you measure the size of your supply trunk at the plenum, and the size of your return duct, when you get home tonight, and post it.

    Its not common for an installation company to put in duct work larger then needed.
    So, I find it hard to believe they pit in duct work sized for 5 tons, on a 3 ton system.
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  10. #10
    Join Date
    Feb 2007
    Location
    out in the country
    Posts
    633
    Do you have a chase for your return air? I have found return chases with no ceilings in them and the units would be drawing in attic air.
    I never let schooling interfere with my education... Mark Twain

  11. #11
    Join Date
    Jul 2008
    Location
    Rydal,Ga
    Posts
    84

    Wow.... Bull doz it down heheheh just kiding

    T-Stat is on an interior wall of the living room with no direct exposure to sunlight. There is an 8 x 32 (6 x 29 of actual louvers) in the living slightly above and to the right of the T-Stat. Each of 3 bedrooms has an 8 x 16 return. All returns are at about 7' off the floor.

    Just for piece of mind try what DASH recommended..... turn all off except the airhandler.... close all interior doors..... map off your home... and go to each closed room and note direction of air flow...
    Then open up the interior doors as lived in... go to the exterior openings and note air flow direction...
    Supply Duct Leakage "SUX"
    Return Duct Leakage "BLOWS"

    Attach (post) the map on here..... There is some really sharp guys on here that can pick up on a balance or flow problem...
    Sounding more like a thermal bypass / lack of insulation


    Ducts are in the floor. Living room, dining room, kitchen, and small foyer are all under the same vault. LR has 2-4x12 on exterior wall below windows. DR has 2-4x10 on two separate exterior walls. Kitchen has 1-4x10, and foyer has 1-4x10. Each of 3 bedrooms has 1-4x10 on exterior wall below a window. Each of 2 bathrooms has 1-4x10 and 1 vent in a walk-in closet.
    Air handler/furnace is in the basement central to the vaulted upstairs space.

    Supplies literally inside ext walls ????

    There are also two ducts on the ceiling of the basement, but they are partially closed off because the basement stays around 69-70 all the time (year round).

    Get your guy to open them back up and equally return that air if the mass walls are insulated.... if they aint insulated them



    I have one scheduled for Sept. 2, because it was recently suggested by the last HVAC guy that came out.

    He also looked at the position on the control module(?) to check fan speed. He showed me that the heat and cool leads that control the fan are jumper-ed together, placing the fan on its highest speed during cooling.

    Too much!! Too fast is bad !!!! Has any of your guys suggested that ???... you could be moving too much CFM to fast over the coil having a reverse effect..... how noisy is it ???
    Get them to slow it down

    Keep us posted on the HERS Rating... PM me Please.... I may forget about this by sept....

  12. #12
    Measurements of supply and return - all metal, all strapped to the bottom of the basement ceiling, all with four sides.

    Plenum - 16.5 x 21 w/ large supply connected to front and small supply on back.

    Supply #1 - 10 x 16 (runs about 30 feet w/ 11 round ducts shooting off to feed rooms, one of which is in the basement and partially closed.)

    Supply #2 - 8 x 10 (runs about 10 feet w/ 4 round ducts shooting off to feed rooms, one of which is in the basement and partially closed.)

    Return - 10 x18 running horizontally to reach return registers throughout house with an additional 3.5 x 36 in-wall cavity tied in immediately above the final vertical drop to the filter box attached to the furnace.

  13. #13
    Quote Originally Posted by kenny mac View Post

    Supplies literally inside ext walls ????

    [/B][/I]
    No, not literally. In the floor about 3" off exterior walls.

    I'll address your statement about lack of insulation. All flat, 8' ceilings are insulated with blow-in fiberglass at about R-30. Apprimately 770 square feet of ceiling. The vaults used to not be ventilated because it was "overlooked" in the build. The builder installed soffit vents and 3 exhaust vents for aesthetics and inspections, but they were doing nothing. Last summer, thinking that I found the solution, I ripped out all sheet rock in the vaults, added baffles on the underside of sheathing, added 1" of owens corning pink insulation board between the rafters and the sheetrock to provide additional insulation beyond the R-19 that was installed and to provide a thermal break, cut in 18 additional soffit vents to facilitate venting the entire length of the roof line, and installed a ridge vent at the peak where vaults are. There was improvement, but not the gains I expected. I dropped 5 degrees on the hottest days and reduced the humidity by 10-15% depending on how much we cook and shower. We were at 58-60%, we can now do 43-48%.

    I'll do the candle test and see what I get.

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