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prizm74

Need expert guidance for a new HVAC system

Prizm74
8 years ago

Hi,
I am in a process of figuring out a replacement HVAC system for the existing dual fuel HVAC system which is almost 20 years old now. Here is the system and house info
Existing System:
- Rheem 10 Seer Heat pump
- Rheem single stage 100K BTU gas furnace
- Vision AIQ thermostat
- Aprialair pass-through humidifier, controlled by HW IAQ
Home:
- Located in Atlanta, GA
- 2000 sq ft Ranch house on the slab with Cathedral ceiling
- Open floor plan Kitchen, living room, dining room and foyer - 3 registers and three returns
- Master bedroom with vaulted ceiling - 2 registers and one return ( return is sized to account master bathroom and toilet)
- Master bathroom and separate toilet - each one has a register
- Two small bedrooms, second bathroom one register for each and no individual return ( a large return in the hallway for them)
- Most of the windows are dual pane energy efficient windows with argon gas except 6 of them are still dual pane aluminum frame windows
- Insulation at the attic should be close to R19
We have been heavily using the heat pump throughout the heating season that is set to cut over gas furnace when the outside temperature is below 30 degrees F. The system is still operating fine but due to the age I'd like to get it replaced before it quits working.

The duct work is the flex ducts and installed in unconditioned attic. From previous experience we know that the duct work is not in the greatest shape and needs some work. Actually registers and returns are undersized compared to output of the heat pump. We have one missing register in the living room and as well as missing one or two returns.
The equipment was installed in the attic and at the far left side of the house therefore a large supply and return trunks runs from furnace to across other end of the house. I guess it is 30 ft or so long. Return trunk has many sharp turns and supply trunk has a split at the middle without a joint transition. Supply plenum is fiber glass box and the distribution box at the other end of the supply trunk is another fiber glass distribution box that distributes the air six ways. I know it sounds horrible so that the comfort level is not that good. We have hot/cold spots because of to that but overall level comfort we have had wasn't very bad
so I am in a process of calling in reputable HVAC contractors to get their suggestions about proper size of a new system and required modifications/changes on the duct work
I have gotten quotes from Trane, Carrier/Bryant and Rheem dealers. I thought it is not worth to spend time and effort to get quotes from a Nordyn brand or Goodman/Amana.
Based on experience we had at house in several years, I assumed the existing 3.5 tons heat pump should have provided much better performance and comfort with the correct duct work. And I think the 100K BTU gas furnace is too big for the house.
As far as technical specs that I have been thinking are
- Heat pump with 15-16 SEER and 8.5 or better efficiency
- Demand defrost - I hate the timed defrost which what my current unit has
- Gas Furnace - two stage, 80% efficiency with variable speed blower
- a good quality air cleaner

Based on above here is my short listed options and I am looking at the HVAC experts of the forum in order to avoid overlooking some important points.
Trane Dealer #1:
- XR17 2 stage heat pump - 4TWR7048
- Coil - 4TXCC049BC3HCB
- 2 Stage 80% w/ Variable speed Furnace - TUD2C080A9V4
- Flush and reuse existing line set
- Reuse the flue line
- Reuse existing HW VP IAQ
- New supply and return plenum, manual dampers at the supply plenum
- Add two new returns - one for each guest bedroom
- Add one new register to the living room
- Replace the junction box with manifold with dampers. Supply trunk will be replaced with a larger flex duct due to the additional register
- Sealing duct joints and registers
- Doesn't want to reinstall the existing AprilAir humidifier unless I am insist because of it is in unconditioned attic
Trane Dealer #2:
- XR17 2 stage heat pump - 4TWR7048A1
- Coil - 4TXCD063BC3
- 2 Stage 80% w/ Variable speed Furnace - TUD2C080A9V4
- new line set and new flue line
- Reuse existing HW VP IAQ
- New supply and return plenum, manual dampers at the supply plenum
- Instead of too many direct output from the supply plenum, will use WYE splits in order to reduce from 7 direct output to 4
- Add one new 8" return to the kitchen area - high side at the wall
- Add one new register to the living room
- Replace the junction box with metal pipe and WYE splits
- Sealing duct joints and registers
- Suggest replacing the register vents with correct type and adjustable register vents for the open floor area. Existing register vents distributes the air three way
- Doesn't want to reinstall the existing AprilAir humidifier unless I am insist because of it is in unconditioned attic
Bryant Dealer:
- Evolution 2 Stage Heat pump - 286BNA048
- Coil - CAP4817A
- 2 Stage 80% w/ Variable speed Furnace - 315AAV04890
- Flush and reuse existing line set
- Reuse the flue line
- New Evolution Controls
- New supply and return plenum, manual dampers at the supply plenum
- Add two new returns - one for each guest bedroom
- Enlarge the return trunk line that goes other side of the house
- Add one new register to the living room
- Replace the junction box. Instead use a larger supply trunk split WYE and use reducer to reduce the supply trunk at each split in order to maintain velocity
- Sealing duct joints and registers
- Suggest replacing the register vents with correct type and adjustable register vents for the open floor area. Existing register vents distributes the air three way
- Doesn't want to reinstall the existing AprilAir humidifier instead suggest Honeywell steam humidifier
- Recommends Bryant air purifier for better air quality as well as removing cooking odor
- Also mentioned that he can get higher efficiency with a larger coil and/or furnace but the suggested system would provide a better comfort
- This is the only contractor who did the load calculation. Based on that the required load is 44K BTU or 3.7 tons system based on the condition of my house. I was told that a 3 tons system would be enough if the insulation at the attic got improved to R30 or R38. He did the design calculation based on standard design temperature cooling 75/105(indoor/outdoor), heating 70/27degrees. By the way we keep our thermostat 73 degree for heating and 80 degree for cooling
I got a few quotes from other contractors but these three I liked the most. Sorry for the very long post but I'd like to hear your comments, suggestions or objections.

Thanks in advance

Comments (34)

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Prizm

    I agree that you are grossly oversized on the gas furnace.

    Not sure I agree with a 4 ton XR17 or 4 ton Evolution HPs without supporting documentation from a correctly performed load calculation. Ductwork should be looked at closely both in size and modifications to straighten out what seems to be a genuine mess.

    Not sure I understand the reluctance about the humidifier in the attic. What other choice is there? Any performance issues with existing?

    Trane dealer #2 has quoted correct coil and that system does qualify for Fed Tax Credit. Dealer. Trane dealer #1 quote does not qualify.

    AHRI HP Directory Matching number below

    5768794 Active Systems XR17 TRANE 4TWR7048A1 4TXCD063BC3 1190 950 *UD2C080A9V4 47000 12.50 16.50 44500 8.50 30200 1 HRCU-A-CB 345 912 Yes

    I was unable to research the Bryant quote on the Directory. Something wrong with AHRI file.

    How do you currently filter return air? How many returns do you currently have? I would want a pleated media box cabinet at the minimum.

    IMO

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Duplicate post

    This post was edited by tigerdunes on Tue, Sep 24, 13 at 7:25

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  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Tigerdunes,

    thank you for your prompt response.

    the point of the first two contractors is water leak from cracked water line due to freeze temperatures in winter time. Even though the waterline connected to the hot waterline they say it won't warrant waterline crack during the blackout. So the primary point is to avoid from water damage. They also say that pass-through humidifier doesn't provide enough humidity and just wasting a lot of water which I agree with them because my humidifier (Aprilair Model 500) can slightly increase in house humidity during very dry winter time. I don't know whether or not it is related with wrong installation of the humidifier. Since my supply plenum is fiber the humidifier was installed right on the plenum of the coil.

    You're right about Bryant. AHRI database cannot find out the file. I found Bryant's performance data for the exact configuration and AHRI file number but it cannot be pulled up in AHRI web site either. I'll ask the contractor the AHRI file number for the offered the system.

    Current air filtering is standard 1" pleated filter. We have experiencing some excess dust in house too. All of the systems listed above comes with 4 or 5" pleated filter. the quote one includes 5" MERV11, the quote includes 5" MERV 13 and the last one 4 or 5" MERV 10 pleated filter.

    I am also considering GPS 2400 plasma air purifier as an alternative to the Bryant or Trane air purifiers. Do you have any knowledge about it? They claim it is ozone and maintenance free air purifier that eliminate viruses and odor in the air.

    in terms of number of returns I have total 5 returns that are
    2 x 10"
    3 x 8"

    based on my understanding it is way low then the current system capacity. specially the return trunk that runs longer than 25" and it makes 5-6 turns from return vent to return plenum

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Prizm

    Back to the humidifier. Have you had trouble with existing. After all, you live in a location with relatively mild winter climate.of course that's your call whether to reuse or replace.

    I would say returns need to be enlarged to handle minimum 1600 CFMs in cooling. Also any hot/cold spots in home should be addressed with ductwork modifications.

    It's difficult for me to believe the cooling load. Do you plan to upgrade attic insulation. Should be minimum R30 or better. Any idea what code is for new construction?

    I am not familiar with the air purifier. The box filters you refer to would be fine. I personally like Trane's Perfect Fit because it is made to fit the their furnace like a hand fits a glove. I am not a fan of electronic air filters. Be careful here.

    IMO

  • cecash1
    8 years ago
    last modified: 6 years ago

    The GPS-2400 is not an electric air filter. It is a bi-polar ionization unit that works in conjunction with the air filter. The positively and negatively charged ions attach to and break up odors and kill viruses and mold spores. The only key is proper installation as it needs to be installed after the filter and before the coil.

    And on a side note, they are a local company in Savannah. They have some exceptional products that we have installed in hospitals, and they have not cleaned their coils in years. In fact, they still look like the day they were installed. Much improved technology over the UV light.

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    For cash

    What's the cost?

    IMO

  • cecash1
    8 years ago
    last modified: 6 years ago

    I can buy the unit for about $400.(contractor price) The install is simple (15 min or less) and it can be run on either 24v 115v or 208v power. Zero maintainable parts. Ultra low power consumption. Global Plasma Solutions is the company name. If you check it out, the I-Bar technology is the product I am most familiar with. The GPS-2400 is packaged as their "residential" alternative.

  • energy_rater_la
    8 years ago
    last modified: 6 years ago

    while I'm not the hvac expert that tigerdunes is,
    there are a couple of things that stand out to me.
    btw...td is giving you excellent info.

    why in atlanta do you need a humidifier?
    I would think a dehumidifier would be the
    option.

    you write:
    "- This is the only contractor who did the load calculation. Based on that the required load is 44K BTU or 3.7 tons system based on the condition of my house. I was told that a 3 tons system would be enough if the insulation at the attic got improved to R30 or R38. He did the design calculation based on standard design temperature cooling 75/105(indoor/outdoor), heating 70/27degrees. By the way we keep our thermostat 73 degree for heating and 80 degree for cooling."

    105 as an outdoor temp is not really ideal design temp.
    it rarely gets that hot for an extended time. we should design for what temps are 90% of the time & not 10%
    of the time.

    adding an additional R-11 to your attic lowers tonnage
    by one ton...doesn't make sense to me. cheaper option
    would be to add more insulation...but from an energy rater's
    perspective..air sealing prior to insulation, then downsizing
    system & mastic sealing ducts is a better use of $$.

    the added benefit of these suggestions is less dust intrusion
    which comes from openings between
    attic & living space. and insulation type. for example...cellulose insulation produces
    a fine particulate matter of borate treated newspaper that
    is mistaken for dust.
    air sealing @ the ceiling of the rooms will help to reduce dust & reduce the heat/cold gain from attic into living space.
    this sealing can be done from both attic side of ceiling
    (attic floor) and from inside the house around areas like oversized cuts of supply boxes for hvac, bath fans, stove vents, recessed lights, attic accesses.
    btw..do you have recessed lights?

    the benefit of mastic sealing ducts is to reduce the amount
    of duct loss into the attic. most hvac companies focus on install, and duct sealing & duct install isn't the main priority.
    paint on mastics..applied 'nickel thick' & mastic tapes are the right materials that will provide a long lasting seal.
    duct & foil tapes fail in extreme attic temps quickly.

    once ducts and returns are sealed air tight a media filter
    will suffice. adding uv lights & such are not necessary when
    duct system isn't allowing foreign matter into system.

    my personal preference is to eliminate wyes..tri boxes
    or whatever the companies are calling them. straight tight
    runs of duct properly supported with duct strapping or duct saddles provide better distribution of air. so my testing & verification shows me.

    best of luck.

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Let's just say on the box filter along with air purifier is around $1 K installed. Unless one has specific issues that the air purifier would help, I think this setup would be overkill for 99%+ homeowners.

    Now the add on insulation is an entirely different issue. Once installed, it pays for itself year after year. The best bang for the buck! Especially if you can reach a 3 ton condenser for cooling.

    I really would like to see both electric and nat gas rates to see if HP even makes economic sense based on current market conditions.

    IMO

    This post was edited by tigerdunes on Tue, Sep 24, 13 at 11:31

  • cecash1
    8 years ago
    last modified: 6 years ago

    They could easily reach a three ton condenser with 75/92 design criteria and added insulation. The Average temp in Atlanta is 91. The 105 rating has added some wasted tonnage. very rarely do I see anyone specify 105 design temps even in the hottest parts of Texas.

    The humidifier in the south baffles me.........

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Tigerdunes,

    I haven't had issues with the humidifier other than it is being slightly effective. I think I'll think through about it to decide whether or not get it put back in

    as you stated return needs to be enlarged. I think the contractor 3's modification on return gets it to 1600cfm. He is also fix the long running and turning return trunk line. I would say the contractor 1's suggestion for addition to returns appropriate since his first quote actually accounting a 3.5 tons single stage system so that stand point he's modification seems appropriate too. Will double check the duct work mods on the revised quote that includes the 4 tons dual stage heat pump.

    I'm considering improvement in attic insulation but not this year.

    interestingly enough the Trane quotes doesn't have the Rane perfect fit. they quoted a 3rd party like Aprialaire and another one

    I am agree on the elctronic cleaner too. That's why I a very confused about what I should do. They tend to create ozone and I don't know how much maintenance they would require. I have found some consumer reports test data that states the Trane and Carrier air purifier provides good IAQ with very minimal ozone and another reports also shows that Carriers air purifier works better as the time goes by. I guess as much as it gets used/dirty it gets more efficient but Trane's seems work opposite. the first month or two it works at the peak and plummeted down after the second month and going down to road. However; while the test results helpful to understand their performance, level of bias doesn't warrant the real life performance.

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    wow, thank you guys all. tons of invaluable information.

    I tried to answer all of the questions in one post. I realized I miss stated the outdoor design temp for summer. It should be 95 degrees

    a few years back natural gas was very expensive and we had paid high gas bills then figured out how to get the heat pump running. I thought to convert all electric but cost of modification on the electric line was very close to having a dual fuel system. since I cannot completely get rid of from gas service, I thought that having gas furnace give me flexibility to swing one source to another when it makes sense

    I see your point in terms of humidifier but the air inside of the house gets very dry and drops desert level of dryness like 25%. That may be because of two reasons. the night time mostly gas furnace runs due to below 30 degrees temperature and single stage 100K BTU furnace just dries out entire air. Since outdoor air is also more tended to be less humid in winter time and leaky duct system may work against the humidifier too. My notion from the contractor one was I shouldn't/wouldn't need a humidifier with the new system. I guess that's why he was adamant not to put it back

    Energy rater - I agree on your points. duct sealing and overall sealing is the paramount for a better comfort and saving money. actually all of the contractors I listed will reseal the ducts and registers with mastic. Contractor 2 and 3 also gave me very good tips about the sealing. which are easy fixes and very effective.

    the required attic insulation may be more than addition of R11. My interpretation about the current is it is close to R19 but may be more off. I guess we suggested R38 in order to downsize the system to 3 tons. I guess it makes to see cost difference between 3 tons vs 4 tons and spending that money on better attic insulation. By the way we don't have any recessed lights

    in terms of air purification. I do agree with all. a good 5' pleated filter is just what we need. I am inclined towards to electronic cleaner or plasma thing because of it seems eliminating the odor. Having open floor plan with cathedral ceiling gets the some cooking smell in the house for awhile

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Hey Tigerdunes,

    here is the AHRI number for the Bryant system - 6129135

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    6129135 Active Systems BRYANT HEATING AND COOLING SYSTEMS PERFORMANCE 13 PURON HP BRYANT HEATING AND COOLING SYSTEMS 286BNA048****B CNPV*4821AL*+UI 1300 1040 315(A,J)AV048090 45500 11.50 15.50 46000 8.20 29600 1 HRCU-A-CB 355 1140

    The Trane is a nicer system. Plus according to this matching number, the Bryant system does not qualify for Fed Tax Credit.

    If you provide me your electric and nat gas rates, I will run a fuel comparison.

    IMO

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Tigerdunes,

    here is my electric and gas rates. The gas rates fluctuates and my gas provider which the city doesn't want to post per therm price for gas so it is based on an average of the winter time of last year

    Electric:
    Winter - Summer
    7.9 - 8.32 cents First 650kWh
    7.25 - 7.79 cents Next 350 kWh
    5.99 - 9.36 cents Over 1000kWh

    Gas:
    Average of November through March
    0.88 dollar per 100 cubic feet.
    I do have fixed gas rate per month which somewhere around $9-$10 that covers first 10 Ccf. Basically my gas kicks in from November through march or april. the rest of the year I do use 2-3 Ccf due to Gas dryer.

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Prizm

    Tiered rates can be difficult to calculate.

    I will use $.08/KWH for electric and $1.00 therm for nat gas.

    I will give you two comparisons, one at 80% eff and one at 95% for nat gas, 2.60 COP for HP.

    Keep in mind this is to be used as a guide only.

    80% nat gas eff

    Cost per 100,000 btu of useable heat
    Electric baseboard: $2.11
    Heat pump: $0.90
    Natural gas: $1.21

    95% eff nat gas

    Cost per 100,000 btu of useable heat
    Electric baseboard: $2.11
    Heat pump: $0.90
    Natural gas: $1.02

    There is a good economic advantage to a dual fuel system with 80% eff nat gas furnace backup.

    IMO

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Tigerdunes,

    thank you so much. Much appreciated.

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Guys,

    I am evaluating the quotes further based on your feedback and suggestions. I have been also searching and reading more about duct work design, sealing and I am comparing the current state of my system against to what it ideally should have been.

    Here is my findings I would very appreciate your comments and suggestions

    the total supplies in current duct work
    3 x 4"
    5 x 6"
    3 x 8"

    Total returns:
    3 x 8" (only one is direct connected to the return plenum)
    2 x 10"

    based on my understanding in ideal conditions like correct installation, straight runs, minimum friction etc; the total supply is just 3 tons (1220 CFM) and return is 2.7 tons (1080 CFM). By the way the trunk lines run long with many turns, sag, crappy distribution box, leaks etc I would assume the current duct work may be 15-25% less than what the calculation suggest.

    - First of all am I getting this right?

    so that the 3.5 tons of heat pump and 4 tons of Gas Furnace actually cannot operate their peak performance because of undersized supply and return duct work.

    Based on above would you agree a dual stage 3 tons system would perform way better, more efficient and much more comfortable with an appropriate duct work compared the current setup? on top that if I got he insulation improved, it would save more money in the long run as well .

    I guess the heat load/loss calculation that one of the contractors did should be way off otherwise I wouldn't keep using the current system for years.

    the other question I got is that I plan to add in a bonus room in attic in a couple years. If my math work correct it should ~200s q ft addition that will be sitting on top of master bedroom. My concern is if I go with a 3 tons system, would I end up having a separate system for the bonus room or not.

    any thought?

  • energy_rater_la
    8 years ago
    last modified: 6 years ago

    "the other question I got is that I plan to add in a bonus room in attic in a couple years. If my math work correct it should ~200s q ft addition that will be sitting on top of master bedroom. My concern is if I go with a 3 tons system, would I end up having a separate system for the bonus room or not."

    bonus rooms in attics are surrounded on all sides by extreme attic temps. when walls are insulated with just insulation in the stud bays...these rooms are difficult to condition. better idea is to either insulate & use foam sheathing boards nailed to faces of wall studs to attic side..or to foam insulate the roofline.

    one is labor intensive, the other expensive.
    however if in the framing stages if the walls are correctly insulated & sealed...it is easier.

    below is a link to an article that explains the sealing of these walls (called kneewalls) very well.

    if you want to be able to enjoy & afford to use this future room...incoperate a better wall assembly. personally I like R-6.5 foil faced foam sheathing.

    link:
    http://www.greenbuildingadvisor.com/blogs/dept/building-science/solving-comfort-problems-caused-attic-kneewalls

    best of luck.

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    energy_rater,

    it is good point. Thank you for the article, it is very educative. I think the spray foam insulation for the bonus room would be the best way. I am also looking at foam sheathing boards to replace fiberglass insulation used in the knee walls.

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Tigerdunes,

    do you know capacity ratio between 1st stage and 2nd stage of Trnae XR17? I asked the question contractor but they haven't gotten back to me with the answer yet and finding technical data about Trane system on the web is really difficult. I have found the Bryant's performance data the ratio between stages varies between 22-25% based on outdoor temperature. Basically it gets the 4 ton system running as 3 to 3.1 ton system at the 1st stage.

    Thanks

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    As a general rule using these two stage step compressors, low stage about 66-70% of high output. Not sure why this is important.

    For Atlanta location/summer climate, I don't see how you can go down in HP size without straightening out an obvious ductwork mess plus bring attic insulation up to R-30 standard.

    Returns need to be connected to ductwork system and resized correctly to the AC output of new equipment whether HP or straight AC condenser.

    IMO

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    I have been trying figure out why all of the contractors want to put a 4 tons system as opposed to 3 tons. Their point is a 2 stage 4 ton system will provide better dehumidification since the unit will be working on low side most of the time that provides 3 tons or little more is pretty much equal or higher to the capacity of the existing system

    once my duct work gets fixed, the supply and return will provide the correct CFM which would/should be substantially more than current state even for the 1st stage of a 4 ton unit. My interpretation to that is the unit will keep doing short cycles so that dehumidification wouldn't be that much improved.

    the other thing that I realized is the cooling and heating operational cost for the 4 ton systems published at the AHRI web site is considerably higher compared to a 3 ton system. I don't know exactly how that cost figures are calculated and how much accurate they are in real-life scenario but given the guidance there the delta of annual heating and cooling operating cost is $478 for Bryant and $284 for Trane

    based on that instead of paying extra $ to a 4 ton system; spending that money on attic insulation makes much more sense. And downsizing the system to 3 tons along the correct duct work and good attic insulation seems provide better comfort and saves more in long run

  • energy_rater_la
    8 years ago
    last modified: 6 years ago

    "I have been trying figure out why all of the contractors want to put a 4 tons system as opposed to 3 tons. Their point is a 2 stage 4 ton system will provide better dehumidification since the unit will be working on low side most of the time that provides 3 tons or little more is pretty much equal or higher to the capacity of the existing system."

    this is a fudge factor. while you will get better than 4 ton dehumidification when they adjust fan speed to 3 ton size
    than you would with 4 tons all the time.
    it also allows for higher loads...the 10 times a year when you have a lot of people in and out of the house, the week of 99 degree weather. the 4 ton will ramp up and handle any issues at that time.
    so hvac company doesn't have to add you to their list of calls during the heat wave.

    it is one way to address the issue. pay more upfront for
    above. or size right & get the dehumidification always.

    I'm still suprised at humidifier in atlanta.
    just can't imagine adding moisture when humidity outside
    is so high.
    do you have any idea of RH inside?

    best of luck.

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    The need for humidifier would only be with heating. Really I think for location, it is not necessary.

    I do not want to be borderline sized for Atlanta. You might consider a 3 1/2 ton condenser and set up for dehumidify on demand in cooling since you plan on reusing HW VP IAQ thermostat.

    First though I would want to see a new load calc taking into consideration R30 or better attic insulation.

    IMO

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Duplicate post

    This post was edited by tigerdunes on Thu, Sep 26, 13 at 10:13

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    That's correct. The humidifier runs during the heating season only. the RH inside of house drops below 30%. I guess it was going down to 20-25%. The weather outside also gets dry but I don't know RH humidity for outside at winter. I guess excess dryness might be caused due to over sized furnace and leaky duct work.

    I'll ask the details of load calculation with R-38 insulation. I was told R38 insulation get the system down 3 tons but didn't ask him details at that time.

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Guys,

    I have gotten stuck in between two systems for my final decision. Please help me out to pick the right one. I am trying to decide in between these two
    ; #1 - Bryant
    6129135 Active Systems BRYANT HEATING AND COOLING SYSTEMS PERFORMANCE 13 PURON HP BRYANT HEATING AND COOLING SYSTEMS 286BNA048****B CNPV*4821AL*+UI 1300 1040 315(A,J)AV048090 45500 11.50 15.50 46000 8.20 29600 1 HRCU-A-CB 355 1140

    also includes - Evolution touchscreen thermostat and comes with free Bryant Air purifier
    - one year test drive - I don't know how it works but they say they will provide 100% refund if I am not satisfied with the system within a year from the installation date

    #2 - Trane
    5768796 Active Systems XR17 TRANE 4TWR7048A1 4TXCD063BC3 1370 1090 *UD2C080B9V4 48000 12.50 17.00 45500 9.00 30400 1 HRCU-A-CB 342 1077 Yes

    Not include thermostat. will use exiting HW VP IAQ
    includes GPS-2400 plasma air cleaner

    price wise the Trane is roughly $200 more expensive than the Bryant after the tax credit is deducted

    Both contractor will add two returns and one supply and will fix the distribution issues in my current duct work. Based on the notion I got; both contractors are very capable and have very good reputation

    I am more inclined to Bryant due to evolution controls. I do know Trane is very reliable and efficiency wise it is a little more efficient compared to the Bryant system.

    to me $200 difference in price is very negligible. I just want to make right decision.

    I got stuck! PLEASE HELP...

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    The systems are quite similar. The pricing difference is really inconsequential and I am certain that it could be smoothed out from one to the other. You say you like and have confidence in both dealers. I personally prefer Trane HPs because they have electronic demand defrost which eliminates/reduces unnecessary defrost calls which are a nuisance, hard on the condenser, and expensive. Since this will be your primary heating method, I would take that alone into consideration.

    Of course your ductwork must be straightened out and Trane dealer should include a filter media cabinet, preferably their matching Perfect Fit model which I would recommend.

    IMO

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Thank you Tigerdunes. I was told that Evolution controls has intelligent defrost control that eliminates unnecessary defrost cycles. I guess it is not as good as Trane's demand defrost. It is very surprising to me though. The evolution controls has all the rings and whistles but not a proper demand defrost...

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    Certainly not the same and inferior to Trane's electronic demand defrost.

    TD

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Thanks Tigerdunes,

    I am glad asked for a second thought. Otherwise I got decided going with Bryant. I would love to have the evolution controls it is very slick but demand defrost is more important to me. I hate when my heat pump goes to defrost for no reason.

  • tigerdunes
    8 years ago
    last modified: 6 years ago

    More on these defrost systems on HPs.

    Carrier has always used the cheap and expensive to operate time/temp defrost method. This until recently was across their HP offerings. Basically you get a defrost call whether needed or not. You get a setting of frequency of 30,60, 90 minutes. Now on their upper end HP models, they have this intelligent defrost method. This method is really an upgrade to the time/temp method using software and history to determine when a defrost call occurs. Make no mistake you will still get defrost calls using this method whether needed or not.

    Trane still uses their tried and true electronic demand defrost which depending on location and winter climate should prevent thousands of bogus defrost calls over the life of their pumps.

    IMO

  • Prizm74
    Original Author
    8 years ago
    last modified: 6 years ago

    Yes you're right. I have found the way how the Intelligent defrost works and I didn't get why they think it is inteligent. As you stated it will go defrost cycle every 90 minutes or less based the duration the latest defrost cycle once the coil temperature is 32 degrees or less. which means minimum 8-10 defrost cycle everyday during the winter time. I guess I wouldn't recognize it in many cases due to variable speed blower but it is wasting money and wearing out the system.

    Thank you for your insight. much appreciate it