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Thread: Had a Tech Out

  1. #1
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    Had a Tech Out

    I had posted an earlier thread about what to expect with a service call for the A/C not cooling properly. I had a tech come out and look at the system a little while ago, and here is what he said:

    - I asked him about static pressure, and told him the numbers I had gotten from an energy audit: He said
    * 0.35" W.C. across a clean blue fiberglass filter was fine (shouldn't it be more like 0.05" - 0.10" if the system is designed properly?).
    * static depended on the system and house, not the 0.5" W.C. allowable on the name plate
    * said high static was common
    * he didn't have the tool with him to measure static pressure, and he said that they don't do that for residential, only commercial.

    - I told him about lowering the fan from High to Med/Hi (see other thread). He said he never would have checked if I hadn't mentioned it

    - I asked about face velocities and asked him if the return drop might be too small. He said that that's way over his head (exactly what the last tech said).

    - He originally set the blower speed for heat to medium low, which is definitely not enough air flow for the 80K output furnace. I asked him why, and he said you couldn't have the heat and cool on the same blower tap (I don't see why, because you would just splice the wires). I asked him about the heat exchanger cracking, and he said that there were plenty of "safeties" in place to prevent that from happening. I said I didn't want it tripping on the high limit, and he just said yeah. He just left the blower lead for heat unplugged.

    - He said the system was a little low on freon, and he said he added a little under a pound. He said there was a 21 degree difference at the outside unit, and super heat was 12 degrees. I have no clue if that's good or bad, but he sounded like it was good.

    - I asked him about it taking longer to cool the house down with the much reduced airflow. He said that would cool the house down faster.

    It's been over 45 minutes since he left, and the temperature hasn't even cooled down 0.1 *F inside (it's 75.3 inside currently) - it's only 82 *F outside. What should I be doing now? I'm afraid you all are going to say get another tech. I don't have $+ to shell out on every visit trying techs until I find one that knows what he's doing (not a slam on the members of this forum at all... I wish one of you was in my area for sure ).
    Last edited by beenthere; 07-06-2009 at 05:03 PM. Reason: Removed price reference

  2. #2
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    I didn't put the actual price on there, it was a guess as I haven't even got the bill yet. But if you feel that guesses need to be edited, then that's fine, BT.

  3. #3
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    No HVAC prices. Not even guesses.
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  4. #4
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    The tech that came out isn't the type of tech you want.
    You may need to cal a company that is involved with air balancing. To get the kind of check out you want.
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  5. #5
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    Most techs in our area wouldn't have a clue what you are talking about. Mine do but only because I train them to know.

    As Been said ask when you call about the type of questions you have. Ask if they can check static pressure and check duct sizes. You would think that most techs should be able to do this but the truth is most can't.
    Its a good Life!

  6. #6
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    I would hope he would have at least caught the obvious red flags, if there were any. Does it sound like the current system is just undersized, or what?

  7. #7
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    Could be undercharged.
    could be overcharged.
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  8. #8
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    Quote Originally Posted by beenthere View Post
    Could be undercharged.
    could be overcharged.
    I assume that's what he checked when he decided it needed freon and then added some.

  9. #9
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    Quote Originally Posted by skizot View Post
    I would hope he would have at least caught the obvious red flags, if there were any. Does it sound like the current system is just undersized, or what?
    We in this business are just like any other professional business, there are certain Doctors that perform heart surgery and then some that are regular MD's. The average service tech is not a professional air balancer or probably has never seen manometer or a healic gauge, then again I would love to see an air balancer or static pressure dude working on a 40 ton Chiller, I could probably close my eyes and fix it faster than him.

  10. #10
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    Quote Originally Posted by skizot View Post
    I assume that's what he checked when he decided it needed freon and then added some.
    He nay have overcharged it, or it could be undercharged still.

    A 21° coil delta, doesn't tell us much, because we don't know what CFM is going acroos the coil.
    Apparently, he didn't check that either.
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  11. #11
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    Quote Originally Posted by MW TMC View Post
    We in this business are just like any other professional business, there are certain Doctors that perform heart surgery and then some that are regular MD's. The average service tech is not a professional air balancer or probably has never seen manometer or a healic gauge, then again I would love to see an air balancer or static pressure dude working on a 40 ton Chiller, I could probably close my eyes and fix it faster than him.
    I understand. However, I don't see how measuring static pressure isn't part of their job though. How can you set a non-variable speed blower without knowing the static pressure? You'd just be guessing at the amount of air you're moving at the air handler. The blower charts that come with each unit tell you how much air it's moving at a given static pressure. You can assume the system is operating at 0.5" W.C. and make your adjustments based on that. However, not all systems are designed correctly (mine being one of them), so it's just a guess.

  12. #12
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    Quote Originally Posted by beenthere View Post
    He nay have overcharged it, or it could be undercharged still.

    A 21° coil delta, doesn't tell us much, because we don't know what CFM is going acroos the coil.
    Apparently, he didn't check that either.
    Given the static pressure with the blower set on medium (which it is now for cooling), the mfr. blower chart shows about 1375 CFM.

  13. #13
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    Quote Originally Posted by skizot View Post
    Given the static pressure with the blower set on medium (which it is now for cooling), the mfr. blower chart shows about 1375 CFM.
    I thought you said he didn't measure the static.

    If its really moving 1375CFM with a 21°delta. Then its removing 31,185BTUs of sensible heat.
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