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  1. #1

    5 Ton York unit replacement options

    Hi all,

    I have a York H4DH060S06A 5-Ton unit installed in 2000
    that is 12 SEER and I'm starting to wonder if it is worth upgrading to
    a more efficient 18-21 SEER model out there.

    I just bought this home in Brea, CA in Sept 2011, and the temps will get up in the 100's in the summer. I'm just trying to pre think my plan if this unit croaks or try to save on power if upgrading to a 21 SEER unit is worth it.

    The house is a 2,900 Sqft multi-level home.

    If you had this unit would you consider upgrading, or just repair it if/when it
    breaks.

    I installed a NEST thermostat so I can track how much time my A/C is running, and I will soon have a TED 5000-C energy detective installed
    so I can see my power usage.

    Comments?

    -Aaron

  2. #2
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    If you expect to live there for a while, wouldn't be a bad idea to get a more efficient unit once this one breaks.

    The SEER 18 should use 67% the electricity of a SEER 12.
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  3. #3
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    19,289
    Quote Originally Posted by hcong View Post
    If you expect to live there for a while, wouldn't be a bad idea to get a more efficient unit once this one breaks.

    The SEER 18 should use 67% the electricity of a SEER 12.
    I wonder how many years one would have to own the unit to actually "save" any money. Think about it. Let's say a new unit costs "3X." By spending that amount, you hope to save "0.3X." Hmmm. I don't like that math.

    I would use the existing equipment as long as I could. It is a known quantity, and the "bugs" have all been worked out. If you have maintained it well, you are in a good position.

    I see too many new ideas that are "not ready for prime time."
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  4. #4
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    Quote Originally Posted by timebuilder View Post
    I wonder how many years one would have to own the unit to actually "save" any money. Think about it. Let's say a new unit costs "3X." By spending that amount, you hope to save "0.3X." Hmmm. I don't like that math.

    I would use the existing equipment as long as I could. It is a known quantity, and the "bugs" have all been worked out. If you have maintained it well, you are in a good position.

    I see too many new ideas that are "not ready for prime time."
    yep, hence the "living there for a while."
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  5. #5
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    California average electricity cost for residential is 15.7 cents per kWh (http://www.cpuc.ca.gov/PUC/energy/El...arts_elect.htm).

    Brea, CA is between CA climate zones 8, 9, & 10. The state predicts cooling is needed between March to October... but we will say June to September... That is 122 days. Say you only need to cool between the hours of 4-6 pm (when kids get home and before it starts to cool a little). That is 244 hours per year.

    Say a SEER 12 on average can do 5 kw for 60,000 btu/hr and SEER 18 on average can do 3.3 kw. That is a difference of 1.6 kw.

    244 hr X 1.6 kw = 390.4 kwh... 390.4 kwh X 0.157 cents/kwh = $61.3 dollars a year.

    Life of a HVAC... say 15 years, that gives us $920 in savings...
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  6. #6
    Join Date
    Jun 2012
    Location
    Florida
    Posts
    41
    You're most bang for your buck with just about any manufacturer is going to be in the 15-16 SEER range. Most 21 SEER systems have expensive diagnostic controls and bells and whistles that add cost that don't affect efficiency. If the unit works right now, I'd go with it but budget for a new system. It's life has lived.

  7. #7
    I'm back!

    I have lived in the home now since Sept 2011, so 3 years with the 2001 York 5 Ton unit still installed, and my electric bill is kinda crazy during the summer.
    I basically pay $300 a month from July through Sept in just A/C costs ($500/mo with everything else). During those months the A/C is running about 200 hrs a month (according to my NEST).

    I've started to look into my system more, and I think they squeezed a 5 Ton unit into my home which has 2.5 Ton Ducting according to the rule of thumb I've read.

    For example, I have only 1 return, which has a 14"x36" grill = 504 Sq-Inch Return. The rule of thumb is you need 200 Sq-In of return per ton cooling, which should be 1000 Sq-in.

    The Supply Plenum has 5 supply flex ducts that it feeds, 1 10", 2 9", 1 8", and 1 6". According to the rule of thumb, that is only enough ducting for 1280 CFM, and a 5 ton unit should be pushing 2000 CFM.

    I imagine they probably didnt do Manual J or Manual D back in 2001, when the A/C was installed.
    Well, now I'm curious if my cooling bill is so high because the 5-ton unit can't push the 2000 CFM it should be pushing.

    I bought a digital manometer and anemometer so I can get a better idea of the static pressure's and CFM the system is doing.

    I'm a DIY'er, so I like learning how all this stuff works, but I'll definitely be hiring a professional to install a new a/c if I end up going that route. However, I'm thinking of possibly increasing the size of some of the ducting on my own for the warmer room's upstairs, and see if I can get more CFM flowing.

    Anyone got any comments on how they'd approach this situation?

    -Aaron

  8. #8
    Also, if I end up getting a new a/c unit, I'm considering a variable, or 2 speed compressor, and variable speed fan, so I can zone off the downstairs with electronic dampers, and cool just upstairs when needed.

    The downstairs cools off fairly quickly to 73 degrees, but the upstairs stays 78-79. Seems to be a waste to be cooling downstairs when it has reached the desired temp.

  9. #9
    Here is the data I got on the unit:
    Static Pressure Air Handler by return (no filter): -0.29 wc
    Static Pressure After Heat Exchanger but before A-Coil (no filter): 0.52 wc
    Static Pressure After A-Coil (no filter): 0.23

    So this would make my TESP: 0.81 wc (w/o filter installed)

    I also computed CFM w/o filter.
    Added up all the individual Supply Registers (area x Air Velocity) = 1,804 CFM
    Measured Return Area (1.638sqft) x Air Velocity (1100 fpm) = 1,803 CFM

    Looking at the York Diamond 80 furnace (model Num: P4HUC20L09201A) chart for TESP to CFM at HIGH speed = 1825 CFM

    What do you guys think?
    The MAX ESP marked on the unit says 0.50" wc, and I'm at 0.81 wc.
    What would you do in this situation?

    A drop of 0.29 wc across the A-Coil seems high, but looking at it from the output side it looks clean.
    I cant find a way to see the a-coil input side since the a-coil sit right on the output of the heat exchanger.
    Maybe it is dirty?

    I got pictures if anyone would like to see.

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,387
    Quote Originally Posted by aaronrryan View Post
    Here is the data I got on the unit:
    Static Pressure Air Handler by return (no filter): -0.29 wc
    Static Pressure After Heat Exchanger but before A-Coil (no filter): 0.52 wc
    Static Pressure After A-Coil (no filter): 0.23

    So this would make my TESP: 0.81 wc (w/o filter installed)

    I also computed CFM w/o filter.
    Added up all the individual Supply Registers (area x Air Velocity) = 1,804 CFM
    Measured Return Area (1.638sqft) x Air Velocity (1100 fpm) = 1,803 CFM

    Looking at the York Diamond 80 furnace (model Num: P4HUC20L09201A) chart for TESP to CFM at HIGH speed = 1825 CFM

    What do you guys think?
    I got pictures if anyone would like to see.
    I DON'T KNOW WHY YOU made measurements without the filter?

    To make it simple,
    What's the air velocity WITH the filter?
    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

  11. #11
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,387
    Quote Originally Posted by aaronrryan View Post
    I'm back!

    I have lived in the home now since Sept 2011, so 3 years with the 2001 York 5 Ton unit still installed, and my electric bill is kinda crazy during the summer.
    I basically pay $300 a month from July through Sept in just A/C costs ($500/mo with everything else). During those months the A/C is running about 200 hrs a month (according to my NEST).

    The Supply Plenum has 5 supply flex ducts that it feeds, 1 10", 2 9", 1 8", and 1 6".
    -Aaron
    What is the KiloWatt usage for EACH month for the last 24 months?
    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

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,591
    .5" is the ESP it was working at to get its efficiency rating. Its not the max allowed.

    Your supplies and return are probably a bit loud.
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    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,441
    Quote Originally Posted by AJ1534 View Post
    You're most bang for your buck with just about any manufacturer is going to be in the 15-16 SEER range. Most 21 SEER systems have expensive diagnostic controls and bells and whistles that add cost that don't affect efficiency. If the unit works right now, I'd go with it but budget for a new system. It's life has lived.
    +1 on the 15-16 SEER, best value IMHO. EER is very close to that of the fancy 17+ SEER systems. Look at the AHRI data on he actual match up you are considering, many get very different numbers than the "UP TO" SEER.

    If you REALLY want to save $$$, figure out how to get the cooling load down and install a SMALLER SYSTEM. Your ductwork struggles to do 1800CFM, but could easily do the 1400-1600CFM required by a 3.5-4 ton system. Noise levels drop dramatically along with electric bills. For the smaller system to work it MUST be installed and commissioned properly. Most systems only deliver about 2/3 of their rated capacity and SEER, the smaller system will need to deliver it's full capacity.
    Want to REALLY save energy? Tighten up the house/ductwork and downsize the HVAC system. Smaller units keep stable temps, dehumidify better, run quieter in addition to using less power.

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