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  1. #1
    Join Date
    Jun 2011
    Location
    Virginia
    Posts
    9

    Choosing a new HVAC, cost vs. features

    I've been doing some reading here and decided to sign up since

    I am doing early research into replacing my existing system and I am trying to determine what the best balance would be between cost and features. I am trying to get some information to have some idea of what I should be looking for before having somebody come out and give me estimates. At least while I have time as an option when deciding on what to do.

    Current HVAC:
    17 years old
    80k BTU York Diamond 80 Furnace
    3 Ton York Condenser (SEER 11)

    House:
    2000 sq foot
    2 floors + unfinished basement.
    Location:
    Virginia

    Here is what I am looking for in a replacement
    1. Reliability
    2. Improved temperature balance between 1st and 2nd floors.
    3. Less noise from the Furnace. Most of the noise is from the burners and draft inducer.
    4. Same or less noise for A/C.

    I'd like to improve efficiency on the A/C and air handler (ECM blower motor), but I don't think improving the furnace efficiency is on the table since using anything other than the shared b-vent may be problematic.

    Problem with the current system:
    During cooling season the temp difference between 1st and 2nd floor is 3-4 degrees plus one more degree difference for the master bedroom. Placing a fan at the bottom of the stairway during cooling season reduces the difference to 1.5 degrees between the 1st and second floor. The fan probably does not move much is any cold air upstairs and I think it is mostly preventing convection. I have not taken any measurements during the heating season, but the master bedroom is noticeably colder than the rest of the house. The problem with the master bedroom is that it is larger than the other rooms, has more windows, and has probably same amount of supply air as the other bedrooms.

    Possibly zoning with 2 or 3 zones. Maybe Carrier Infinity since it is integrated, right? I'd rather have a one vendor solution if possible. Or is the Infinity system potentially overkill and overspending. I really have no idea what the cost difference is between the different systems. This year we had a very wet spring and although the temp was lower than the A/C set point some dehumidification was need since the humidity was way to high. I had to turn down the thermostat just to make it comfortable, cooler with but still with high humidity. This might be one of those instances where getting something like the Carrier Infinity is probably worth it.

    I may be doing some other improvements before replacing the furnace to see if that helps the improve the situation in the master bedroom, such as low-e windows. My current system is working fine with the exception of the problems noted. I hate to replace something that isn't broken, but with the potential of a tax break that may not always be there, plus potentially lower utility bills may be enough incentive.

    I know there is more information needed to give a fully informed opinion, but what would be a good choice when trying to balance cost vs. features? Zoning adds significantly to the cost? I'm thinking of going with Carrier or maybe Trane. Are things like 2 stage heating and cooling worth it? Variable speed blowers?

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    The correct installation is #1. The 3 ton is too big for the home. You'll probably find (when someone does a Manual J) that out.

    I'm guessing a 2.5 ton (they don't come in 2-stage). That's okay.

    You're on the right track when considering a ECM (variable-speed) motor.

    A two stage or modulating furnace is nice. I might recommend waiting on the zoning until you see how the right size A/C works.

    Also get the Infinity control (with the Carrier) or a HW IAQ thermostat (for any other brand). Both will make the A/C go into a de-humidification mode.

    Depending on your ductwork, I think the Arzel zone system will be more affordable (if needed at all).

  3. #3
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,962
    Variable speed blower is a definite to help resolve your HVAC issues. Staged heating will also be a help. In most cases, zoning for an existing duct system is expensive and not so easy to do properly.

    I am not familiar enough with the Infinity systems enough to know what is available in an 80% furnace. I currently deal with the JCI Coleman line, so I will give you what I think would be best in that brand;

    For the ultimate in comfort and efficiency, I would go with a dual fuel set up using a heat pump and modulating furnace in the Coleman Echelon series which would include;
    80k modulating furnace with variable speed blower.
    3 ton 18 SEER two stage heat pump
    matching indoor coil
    JCI communicating t-stat

    This particular set up would have your system operating nearly all of the time in both heating and in cooling, only providing as much cooling or heating as is required. What this does is causes a very slow moving, constant air exchange throughout the house, eliminating stratification of the air causing warm and cool areas.

    Because the system would be operating nearly constantly, it will operate at a very low air volume. This allows for the quietest system you can have.

    This system adjusts the temperature leaving the furnace in the heat mode, so there are no cool air movements in the house.

    The heat pump and furnace already have the controls that allow them to operate together without any other controls. My recommendation for the communicating thermostat is mostly for your being able to adjust the air volume for constant air movement even during the reduced time when the air is not being heated or cooled. With the communicating thermostat, you can adjust your blower to operate anywhere from 20% to 100% capacity when the system is not calling for heat or cooling.

    If you do go with a heat pump, make sure the contractor puts the outdoor unit on some sort of risers to get it up off of the pad for proper condensate drainage. There is a pad on the market called a Heat Pump Pad that is a star shaped one piece pad that looks really great under the Eschelon heat pump.
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  4. #4
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,380
    High end equipment plus a zoning system may price out close to 2 13SEER systems (one for each floor). You could do a small furnace + A/C for downstairs and a heat pump for upstairs. Each level would have it's own t-stat, no more temp difference between floors unless you have it set that way. As an added bonus if one system goes down you could live on the other floor until you get it fixed.

  5. #5
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    Please have some one do a Manual J. Three (3) ton is WAY too much for your home.

    I know a two-stage (3 ton) will run on low all the time but why spend the money for a one stage (because low is more than the house needs) when the money could be used towards zoning in the future (if needed).

    As far as two systems, you probably don't have enough return to support one system.

    I bet you could use a 2 ton if you zoned.........but get the Manual J and let us know.

  6. #6
    Join Date
    Aug 2009
    Location
    Long Beach CA
    Posts
    182
    The deal with zoning is the duct work needs to be over sized so it can handle the air flow when only one zone is calling. In an existing house redoing duct work can be a challenge. If there is an accessible attic for the second floor those ducts can be redone.

    You might start by having an energy audit done. Some utilities offer them or rebates for having them done.

  7. #7
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    Quote Originally Posted by egads View Post
    The deal with zoning is the duct work needs to be over sized so it can handle the air flow when only one zone is calling. In an existing house redoing duct work can be a challenge. If there is an accessible attic for the second floor those ducts can be redone.

    You might start by having an energy audit done. Some utilities offer them or rebates for having them done.
    I have zoned many existing homes. Seldom have I needed to use a by-pass. However, if a by-pass is needed, no prob.

    Arzel (and others now) make a modulating by-pass (if needed) so the ECM motors don't ramp up and down.

  8. #8
    Join Date
    Jun 2011
    Location
    Virginia
    Posts
    9
    Thanks for the comments. I had to go out and check the model number on the condenser to make sure that I was remembering things correctly. The first part of the model no. is H2DA036 which means that this should be a 36,000 BTU unit. I did notice that some of the house built after mine have what appears to be a smaller condenser... I have no idea how they determined the size.

    The 2nd floor ducts are in the joists between the 1st and 2nd floor. Accessing them will include paint and drywall work. The 1st floor ducts are fully accessible from the basement. Maybe I should hold off on some of my paint work until we determine what if anything should be done for the second floor ducts.

    I definitely plan to ask for a manual J when the time comes. I was going to wait till slow season to have somebody come out. An energy audit has been in the back of my mind for a while. My state offers a rebate towards an audit, but the program ran out of money 3 weeks after the program opened. I'll have to watch to see if it gets more funding this year.

  9. #9
    Join Date
    Apr 2009
    Location
    Central New Jersey
    Posts
    253
    Carl,

    How many square feet is the first floor, and the second floor? The basement adds very little to the heat and cooling load.

    Does the duct work have a main branch in the basement for the first and second floors? If yes, then this could be how you can zone each floor.

  10. #10
    Join Date
    Aug 2010
    Location
    Denver, PA
    Posts
    32
    Quote Originally Posted by George2 View Post
    I have zoned many existing homes. Seldom have I needed to use a by-pass. However, if a by-pass is needed, no prob.

    Arzel (and others now) make a modulating by-pass (if needed) so the ECM motors don't ramp up and down.
    The Carrier Infinity zoning system does not use a bypass damper because of the modulating dampers and the variable speed motor. Everything communicates to determine what speed the fan needs to run at.

  11. #11
    Join Date
    Mar 2011
    Location
    North Eastern NC
    Posts
    80
    Please have some one do a Manual J. Three (3) ton is WAY too much for your home.

    Just love when someone offers advice without heeding thier own...

  12. #12
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    Quote Originally Posted by JamesCPH View Post
    The Carrier Infinity zoning system does not use a bypass damper because of the modulating dampers and the variable speed motor. Everything communicates to determine what speed the fan needs to run at.
    Yes, I'm aware of that. It's a very nice system that I've sold as well. I mentioned the Arzel because it's more cost effective on a retrofit job such as his.

  13. #13
    Join Date
    Jun 2011
    Location
    Virginia
    Posts
    9
    Quote Originally Posted by mike_home View Post
    How many square feet is the first floor, and the second floor? The basement adds very little to the heat and cooling load.

    Does the duct work have a main branch in the basement for the first and second floors? If yes, then this could be how you can zone each floor.
    Rough estimate of square footage.
    1st floor 900 sq. ft. - open floor plan
    2nd floor 1050 sq. ft.


    Off of the trunk is 3 main branches an 1 supply.
    Here is the layout.
    Supply
    main branch 1 - 8x20 with damper - all branches accessible from basement
    - 3 - 6" round 1st floor
    - 1 - 6" round 2nd floor master bedroom
    - 1 - 6" round 2nd floor bedroom
    - 1 - 5" round 2nd floor master closet

    main branch 2 - 8x12 with damper - all branches accessible from basement
    - 3 - 6" round 1st floor

    main branch 3 - 8x12 - branches somewhere between 1st and second floor
    - 1 - 6" round 2nd floor bedroom
    - 1 - 6" round 2nd floor bedroom
    - 1 - 4" or 5" 2nd floor master bath
    - 1 - 4" round 2nd floor main bath

    supply branch 4 - 4" round - 1st floor powder room

    Return
    1 - 10 x 12 1st floor
    2 - 10 x 12 2nd Floor

    Splitting that 8x20 branch and moving the one 4" off the trunk to 1st floor 8x12 branch would allow for separate control of the 1st and 2nd floors.

    Correct on the basement. The basement requires no cooling and just a little bit of heat. There is one register in two of the main branches that stay closed in the summer and opened very slightly in the winter.

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