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  1. #27
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by joe 40
    They still say a 3 ton is good for my house and not too big.
    I hate to keep asking this, but HOW DO THEY KNOW? Did they perform a heat gain calculation?

  2. #28
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,243

    Question Nearly Impossible

    IMO, the vagueness of this whole thread makes it near impossible to progress toward a reasonable conclusion.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  3. #29
    Join Date
    Jul 2005
    Posts
    21
    Originally posted by joe 40
    It's 99degrees outside and I have the unit set at 78degrees. The vents air is marking 70degrees!! And of course, the tech hasn't come! This system is a 3ton and I should be freezing my butt off. If this system is oversized it should be turning on and off constantly and it doesn't.

    Ducting is not leaking, so they say!

    Presures are 270 high, 82 low .
    So at least based on the low pressure, that puts the refrigerant at 49 deg, the evaporator at 59deg, and the air off at 69 deg. So that falls close to your 70 degrees.

    Why is the suction pressure so high, since its not like your house heat load on it is excessive. So based on the very limited info:

    1. Open return duct.
    2. Blower door on furnace is not secure/sealed well(if in attic).
    3. Too small of an orfice was used.

    Superheat and subcooling with pressures will tell a lot here.

  4. #30
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by joe 40
    Thanks for replying but I'll just wait for the a/c tech if he ever gets here. Wife is getting inpatient cause she wants cold air out of the vents!

    Joe,

    If you want to resolve this,you need to do a few things to get the advice you need.

    1.Post all model numbers involved,then we will know if it's a properly matched system,or not,and that could be part of the problem.

    2.Tell us how the ducts are run,and what they are made of,not just"in the attic".Where is the indoor unit?Where is the return run,down a wall,in ceiling,etc..

    3.Measure the temerature of the air going in and out of the indoor unit.

    Have the tech check to be sure the electric heaters aren't on, if so equiped.

  5. #31
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    Presures are 270 high, 82 low .

    It's 99degrees outside and I have the unit set at 78degrees. The vents air is marking 70degrees!!
    So at least based on the low pressure, that puts the refrigerant at 49 deg, the evaporator at 59deg, and the air off at 69 deg. So that falls close to your 70 degrees.
    Ductwork, airflow, or charge.

    Or a combination of any of the above.

    New unit? Could be overcharged. Not uncommon.

    This does not strike me as a "I want my money back" problem. Rather, it's a "installer, make this thing work right" problem. At three tons you can either be oversized at design conditions for your size house or be dead on, depending on how tight your house is built and what kind of solar exposure it has. I have a 1,500 square foot house with 3 1/4 tons with good insulation in the attic and at design conditions it will keep the house at a comfy 74 degrees.
    It is a little oversized for lower heat demand, however.

    (sort of off topic but related) All this talk about SEER when I think every new resi system that goes in should have some form of capacity control. You want to save energy? You want great comfort? Install a system that meets demand more precisely under both design and less than design conditions. Single stage to me is getting to be dinosaur technology for resi applications. If enough systems with capacity control were going out the door the price point would drop and the payback and comfort satisfaction of homeowners would go up.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #32
    Join Date
    Aug 2005
    Posts
    18

    Angry

    Tech(yeah, right!!) They finally came down and still no answers. Guess what, this idiot(tech)wants to install a 3 1/2 ton unit in my house. O.k. everyone has been getting on my case saying a 3 ton isn't slightly oversized but severely!! They checked pressures outside and amps.
    Pressures 250high, 90 low. They(there's two on them) said it needed freon!

    I don't know what to believe anymore. They are sure because its a 14seer I get low differential.

    Home: 1300sq ft.
    Family: 4
    Pets:none
    Windows: double pane, tint
    Insulation: what the contractor put? attic blown in.
    Air handler in attic and ducting(round tubes 7in. mostly)
    Intake in hallway(20x20)centralized.
    Outside unit 3 ton: Goodman CLQ36-1
    Air handler: ARUF-42

    Hope I answered everyone questions! Need help or these idiots will put me a 3 1/2 ton. What energy would I be saving there!!

    Please hurry, they'll be back!! Went to get r-22 and ladder.(I know, I'm an idiot too!!)

  7. #33
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by travisfl
    Did they perform a heat gain calculation?
    Well, is that how they came up with the 3 1/2 ton?

  8. #34
    Join Date
    Jun 2005
    Posts
    169
    It's 99degrees outside and I have the unit set at 78degrees. The vents air is marking 70degrees!! And of course, the tech hasn't come! This system is a 3ton and I should be freezing my butt off. If this system is oversized it should be turning on and off constantly and it doesn't.

    Ducting is not leaking, so they say!

    Presures are 270 high, 82 low .
    ________________

    Joe

    With a high suction. It seems to me that the system is overcharged. What is the subcooling temp. It should not be
    more than 20 deg F.

    Kelvin

  9. #35
    Join Date
    Feb 2005
    Posts
    19
    Sounds like the return may be slightly undersized for a 3 ton. It is definitely undersized if it is a fliter grille. Sounds to me like there is some sort of return leak. I also know that sometimes a powered attic ventilator can actually make the cooling capacity on a home much higher because it speeds up the natural breathing pattern of a home. We never recommend a PAV on homes because it puts such a negative pressure on the attic. We always recommend natural ventilation. I am not saying that is why you are experiencing such a low split. But it could be why your bills are a little high.

    Have you calculated your duct BTU loss/gain??

    We recently put in a new Lennox XC21 for a customer and he couldn't pull the house down to temp. We checked, checked, and rechecked everything. We sealed all of the supplies and returns with mastic and we knew the system was tight. Finally we ran a duct BTU loss/gain and found out he was gaining 8 degrees in his duct system in the attic because his attic was so hot and his duct system was subpar. Sold him a full duct job and reduced the duct heat gain from 8 to less than 2. Now he is happy as a lark.

  10. #36
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    631
    Originally posted by joe 40
    Tech(yeah, right!!) They finally came down and still no answers. Guess what, this idiot(tech)wants to install a 3 1/2 ton unit in my house. O.k. everyone has been getting on my case saying a 3 ton isn't slightly oversized but severely!! They checked pressures outside and amps.
    Pressures 250high, 90 low. They(there's two on them) said it needed freon!

    I don't know what to believe anymore. They are sure because its a 14seer I get low differential.


    Please hurry, they'll be back!! Went to get r-22 and ladder.(I know, I'm an idiot too!!)
    Sounds like they have a serious problem.
    1. Don't make thier problem your problem. Let them run around and figure it out
    2. Remember, they are to provide you a service, not you provide them with answers. You're the customer.
    3. You are not the idiot here.
    4. They should have performed a manual J on your house, now they are scrambling around trying to fix what you paid for.
    5. Call a lawyer. They can come in handy when you or they get into a pinch.
    Happiness is the only good. The time to be happy is now. The place to be happy is here. The way to be happy is to make others so.
    -Robert Green Ingersoll

  11. #37
    Join Date
    Aug 2005
    Posts
    18

    Frown

    I know I shouldn't worry but if these techs don't know what they're doing I must find out what's wrong.

    Techs left and guess what? They left pressures at
    95-290. They also added extra freon. O.k. I know I'm no
    a/c genious but aren't you suppose to vacuum the system a few hours before? Surprise, they didn't!! I also found out from another source(a/c tech) that there is a good chance they could have messed up the compressor. He told me to ask for a new system but I don't think they will give me one. I personally want my money back!! It's been three weeks, and system still not working properly.

    Personally, I think these tech aren't certified or licensed! Wife says they were still wet from crossing the river!!(Rio Grande River)

    Temp set at 75degrees, but vents only 66degrees. 9 to 10 degrees difference. Please anyone think this is normal?

  12. #38
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,750
    The temp needs to be checked at the coil.

    May be you should call another contractor, and see what he says.
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    How many times must one fix something before it is fixed?

  13. #39
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    631
    Originally posted by joe 40
    I know I shouldn't worry but if these techs don't know what they're doing I must find out what's wrong.

    Techs left and guess what? They left pressures at
    95-290. They also added extra freon. O.k. I know I'm no
    a/c genious but aren't you suppose to vacuum the system a few hours before? Surprise, they didn't!! I also found out from another source(a/c tech) that there is a good chance they could have messed up the compressor. He told me to ask for a new system but I don't think they will give me one. I personally want my money back!! It's been three weeks, and system still not working properly.

    Personally, I think these tech aren't certified or licensed! Wife says they were still wet from crossing the river!!(Rio Grande River)

    Temp set at 75degrees, but vents only 66degrees. 9 to 10 degrees difference. Please anyone think this is normal?
    95-290 is high, but what is the condenser air temp, wet bulb, suction press?

    It seems as if there is an obstruction in the A/H or you're pulling air from the attic or the blower is spinning the wrong way.

    Adding a charge? With those pressures, they may be damaging your a/c more than helping you get cool.

    I can't see superheat or subcooling telling you to add with pressures that high.

    As far as a vacuum, residential systems only require that you pull and hold 500 microns for 10-30 minutes, whatever your flavor happens to be. In installs, it comes quick. As soon as I reach 3-400 microns, I close my valves and start cleaning up. Check it a few times, and by the time I'm done, usually 20-30 minutes later, I break the vacuum with whatever charge the weight in my lineset and evap need, open the valves and let the system run 20-30 minutes to stabalize. I finish cleaning up and then I'm ready to do a superheat or subcooling.

    The part where you're frustrated, it's not working and you start looking at your check book to see how much you paid is where a laywer comes in quite handy as motivation for the company to fix their problem.

    Also, I know it's a long shot. If they used flex duct, what r value did that duct have? I know up here it does matter in really hot attic, and r-8 is code, at least up here. That may also be adding to your problem.

    [Edited by atufano on 08-23-2005 at 07:56 PM]
    Happiness is the only good. The time to be happy is now. The place to be happy is here. The way to be happy is to make others so.
    -Robert Green Ingersoll

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