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  1. #1

    HVAC Pros vs. Plumbers

    Hello!

    I am new to the forum so please be gentle

    We are in the process of buying a home that does not have central AC (yet). It's about 6000SF located in the Northeast.

    One of the issues I've had in the past was with a plumber that "installed AC systems". To my chagrin, this has resulted in mediocre performance of my AC system. At the end of the day, it takes forever to cool the house down because the "professional" didn't size my units properly (confirmed by others who've serviced my equipment).

    I've also been told there's a world of difference between HVAC pros and plumbers that install AC units.

    I'm looking for some help if finding people who are truly great at HVAC and can install and stand behind a 6000SF retrofit where the installation will be properly sized and calculated for the environment. Are there certain questions I should ask? Are there certain "red flag responses"? I'm all ears and thank you for taking the time to read this.

  2. #2
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    Quote Originally Posted by kingofbytes View Post
    Hello!

    I am new to the forum so please be gentle

    We are in the process of buying a home that does not have central AC (yet). It's about 6000SF located in the Northeast.

    One of the issues I've had in the past was with a plumber that "installed AC systems". To my chagrin, this has resulted in mediocre performance of my AC system. At the end of the day, it takes forever to cool the house down because the "professional" didn't size my units properly (confirmed by others who've serviced my equipment).

    I've also been told there's a world of difference between HVAC pros and plumbers that install AC units.

    I'm looking for some help if finding people who are truly great at HVAC and can install and stand behind a 6000SF retrofit where the installation will be properly sized and calculated for the environment. Are there certain questions I should ask? Are there certain "red flag responses"? I'm all ears and thank you for taking the time to read this.
    Find an HVAC company that will do a Manual J and D calculation. Post your location and check the contractor locator in the index on this site and perhaps someone will be in your area.

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
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    4,985

    Original A/C equipment may not be performing well &, may not be undersized

    We need to know a lot more about your situation.
    In the NE, what large city do you live near?

    Your A/C may not be undersized but rather it may not be performing near up to par.

    Simple easy anyone can do ways to check the performance of your central air conditioner so, if needed; you can call an Energy Efficiency HVAC Technician. Want to find out...?

    If U want us to run a ballpark analysis of how your system is performing in respect to its 'Nominal Rated Btuh' we need at least the following information & numbers:

    Performance Data Collection – Best Time to collect data is late afternoon around 4:30 pm, when attic is HOT; also when outdoor temps are around 85; 95; 105F or, anywhere in between.
    *All U need is a good thermometer (digital reading in tenths preferable) & and indoor Humidity Gauge

    1) Helpful; Tonnage & SEER of Unit &/or outdoor condenser model number: __________________

    2) TXV or, orifice metering device? _______. Only if U know…

    3) Outdoor condenser’s discharge-air-temperature ______-F
    Subtract Outdoor air temperature: _______
    Outdoor Condenser Air-Temp-Split _______

    4) Need the ‘Indoor’ percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___
    5) Indoor Return-Air Temperature ______
    Subtract Indoor Supply-Air Temperature ______ -F
    Indoor temperature-split _______-F

    If U can find a turn in the small liquid line insulate the temperature-probe; get its temperature for the subcooling analysis:
    Small liquid line temperature ____F

    To measure return air the wet bulb temp, wrap a small/thin, wet (not dripping) piece of cloth around the probe and put it into the Return Air grille & then close to the closest Supply Air diffuser near the air handler (need air movement). Wait until the temperature stabilizes - may take a little while.

    Return Air wet bulb ____F
    Supply Air Wet Bulb ____F

    Need the above information for troubleshooting & performance analysis.

    Example below:
    A Goodman 2-Ton 13-SEER condenser, 800-cfm indoor airflow; 80-F indoor dry bulb & 50% relative humidity; Indoor temp-split 18 to 19-F.
    @ 85-F outdoors; 103.9-F - 85-F outdoors or around an 18.9-F temp-split;
    @ Indoor 75-F, 63-wet bulb around 50% RH - condenser temp-split is only around 14.9-F.

  4. #4
    Join Date
    Oct 2004
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    So Cal
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    3,517
    Quote Originally Posted by kingofbytes View Post

    One of the issues I've had in the past was with a plumber that "installed AC systems". To my chagrin, this has resulted in mediocre performance of my AC system. At the end of the day, it takes forever to cool the house down because the "professional" didn't size my units properly (confirmed by others who've serviced my equipment).

    I've also been told there's a world of difference between HVAC pros and plumbers that install AC units.

    .
    Lets not lump all the plumbers into your s list.
    While I'm a licensed HVAC contractor- I'm also licensed separately in plumbing, fire sprinklers, landscaping, swimming pools, medical gasses, electrical, as well as a general contractor.
    There's plenty of hack HVAC contractors out there who don't perform Man J & D load calcs, so don't think your issues are exclusive to your guy. You could have easily got screwed by an a/c guy as well. Just read these forums for awhile & you'll see.

  5. #5
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    Quote Originally Posted by precision hvac View Post
    Lets not lump all the plumbers into your s list.
    While I'm a licensed HVAC contractor- I'm also licensed separately in plumbing, fire sprinklers, landscaping, swimming pools, medical gasses, electrical, as well as a general contractor.
    There's plenty of hack HVAC contractors out there who don't perform Man J & D load calcs, so don't think your issues are exclusive to your guy. You could have easily got screwed by an a/c guy as well. Just read these forums for awhile & you'll see.
    As hard as it is to find a company that is proficient at one discipline the chances are even rarer to find one that is diversified. There are a few but quite limmited

  6. #6
    Thanks all!

    The location would be closest to Manchester, NH. Would love recommendations of those who run Manual J and D calcs as a pre-req that are in my region.

  7. #7
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    Quote Originally Posted by kingofbytes View Post
    Thanks all!

    The location would be closest to Manchester, NH. Would love recommendations of those who run Manual J and D calcs as a pre-req that are in my region.
    Looking at the map there are several in that area. Start calling

  8. #8
    Quote Originally Posted by second opinion View Post
    Looking at the map there are several in that area. Start calling
    Thanks! I've put in some requests today. Looking forward to tomorrow. Thanks for taking the time to read my request and listen to what I was looking for and where I was coming from

  9. #9
    Join Date
    Jun 2005
    Location
    SW Wisconsin
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    Quote Originally Posted by kingofbytes View Post
    Thanks all!

    The location would be closest to Manchester, NH. Would love recommendations of those who run Manual J and D calcs as a pre-req that are in my region.
    The 2.5% summer design at Manchester is 88-F dry bulb & 71-F wet bulb or about 43% relative humidity. Doubt you'd have a lot of hot days up there...

    We are in the process of buying a home that does not have central AC (yet). It's about 6000SF located in the Northeast.

    One of the issues I've had in the past was with a plumber that "installed AC systems". To my chagrin, this has resulted in mediocre performance of my AC system. At the end of the day, it takes forever to cool the house down because the "professional" didn't size my units properly (confirmed by others who've serviced my equipment)
    Your present poor performing system is what you could collect the temperatures on for analysis...
    ----
    IMO, for more efficient performance you'll need at least two units for the future 6,000-sf home in NH.

    Are there two furnaces? Duct systems for heating are seldom sized large enough to work well for cooling.

    I'd definitely have a "Home Energy Efficiency Audit," performed on that home, that doesn't yet have central air; so work could be done to lower the heat-gain & heat-loss.

    Then after that work is done have the load calcs done.
    Yes, a Manual D for designing the duct system is also definitely called for.

  10. #10
    Thanks udarrell....the problem in the Northeast is worse that you might think. Not only do we have more hot days that you give us credit for, we also have VERY humid days such as the last 4 or 5 days just as a small example. I'm looking for AC to condition the air...not just cool it. Sticky 70 degree days are worse than dry 85 degree days imo.

    Is it standard for HVAC pros to do "Home Energy Efficiency Audits" done? If not, who does them? Approx cost?

    Thanks!

  11. #11
    Join Date
    Jun 2005
    Location
    SW Wisconsin
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    Quote Originally Posted by kingofbytes View Post
    Thanks udarrell....the problem in the Northeast is worse that you might think. Not only do we have more hot days than you give us credit for, we also have VERY humid days such as the last 4 or 5 days just as a small example. I'm looking for an AC to condition the air...not just cool it. Sticky 70 degree days are worse than dry 85 degree days imo.

    Is it standard for HVAC pros to do "Home Energy Efficiency Audits" done? If not, who does them? Approx cost? Thanks!
    It will become more standard in the future as they gear-up to the whole home concept along with "Testing the Actual Delivered Performance" of the equipment.

    Some utility companies will do them at no cost or for a lesser fee than other sources; so be sure to ask both the electrical & heating fuel companies.

    For mild high humidity days IMO, U need a slightly undersized A/C with a temperature differential SWING digital programmable thermostat. That allows U in milder weather to get longer-runtime cycles for increased dehumidification.

    I wouldn't go higher than a 14-SEER & I'd operate the indoor blower at 350-CFM per/ton of cooling, or even slightly less than 350-CFM. You want the evaporator coil operating at well under the dew point temperature of the air passing through it.

    The indoor coil must have a TXV metering device for safe operation at low CFM blower settings.

  12. #12
    Join Date
    Aug 2012
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    11
    Quote Originally Posted by kingofbytes View Post
    Is it standard for HVAC pros to do "Home Energy Efficiency Audits" done? If not, who does them? Approx cost?
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.
    Last edited by jpsmith1cm; 08-08-2012 at 04:02 PM. Reason: Non AOP member

  13. #13
    Agreed daveknapp, thanks for the insight!

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