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  1. #1
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78

    Basement cooling, zoning

    First I want to thank everyone on here for all the advice you have given me. Last fall I upgraded from my old 80% 100k furnace to a 70k Goodman 95% VS 2 stage unit and it is amazing. *some problems have popped up and I'll discuss.

    However, now is time to upgrade the AC.

    Location: Kansas City, MO.

    House Properties: 1960 build, R48 attic insulation, R13-19 wall insulation, Double pane argon low E windows, Cedar shake siding, Professionally air sealed, split level 1200 sq ft home, 2 car garage 3 bed, 2 bath.

    Current ducting: Main truck is 16x14 to lower level and 16x10 to upper level. lower level ducts run along floor joists in basement (conditioned), upper level run along floor joists of garage. (Garage is uninsulated, both walls and ceiling.[will add R30 insulation in joists this spring) All branches are 6" round ducting, hvac tape sealed to room exterior walls then a mixture of vents, mostly 10x6 ones. Return has two lower wall mounted 24x6 vents into a 22x8 truck feeding a 20x25 filter.

    Current system: Goodman 70k VS 2 stage LP furnace, 2.5ton 1990 Nordyne AC *10ish SEER.
    * House is currently zoned via Honeywell zoning control board and two 2 stage thermostats. Both areas heat and cool 600ish sq ft with the Zone board only allowing 2nd stage if both zones are calling. The lower level allows some bleed off when only upper level is calling.

    Current problems: Upper level vents have high velocity, thus are somewhat noisy (I was told by you and the contractor this would happen). Currently blower is set to lowest cfm limit of 850ish for heat (no AC need yet). This spring when I replace the AC I'm getting 2 new supply branches installed in upper level (master bath doesn't have a vent and 3rd bedroom only has 1 vent) and 6" rounds will be upsized to 7" rounds.

    Goal: I am finishing the basement and want HVAC down there. I would really like to just get ducts ran off the main branch that runs along the joists so I'm wondering what needs to happen. The space is concrete walls with R6 foam board then drywall (originally built so 2x2 framing and drywall). There are 3 windows each 3'x2', the ceiling is uninsulated but I will have R19-21 installed before floor joists then drywall. There is a completely closed off utility room that will not be included in this HVAC area. Thus basement sq ft is 450ish with small bathroom (has fan vent to outside). Ceilings are 8'. I want a low velocity system with 1 duct in the game room area 13'x14' and 1 duct in bar area 7x17, and 1 duct in small bath 5x8ish. Because the game room will be able to get closed off I think I'll need a return in there. Currently there is a 8x8 return in bar area of basement which ties into return trunk.

    Tradeoffs: I DO NOT want a mini split. Although this may be the BEST option, I do not want it. I do not care if the basement has it's own zone, it can share with the lower level.

    Questions: (1) Can I get branches off the main duct to feed this basement area, with minimal negative impact?
    (2) What size branches to get lowest velocity, joists are 16" on center?
    (3) What size AC should I get, contractor said up size to 3 ton 2 stage?
    (4) What size return for game area?
    (5) Will up sizing from 6" rounds to 7" rounds + 2 new 7" rounds resolve my upper level high velocity problem?


    Sorry so long and if you need more information let me know. I'm asking because my contractor has told me A or B and I want to verify before I pay more money, especially if it isn't going to solve my problems or make me happy.

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,609
    I would suggest a heat pump for your area (Kansas). It would be worth the extra money, particularly because of the LP gas. Zone the basement. Yes, the larger pipes should help the noise, if not, a by-pass may be needed or a dump zone. I've done both.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,248
    Add Dehumidifier in the game room.

    Set Minimum Lower Level zoning damper at 30+ degrees open (a.k.a. increase the bleed)

    ----------------------------------------------------------------------------
    http://www.checkpropaneprices.com/?f...many_to_one=KS
    about $2 / gallon, $2.40/ therm at 90% efficiency.

    Heat pump is a good suggestion.
    $0.10 / kw or ~$2.95 per therm, with C.O.P. 3.0 near 30'F equivalent operating cost is $0.97/ therm
    LP =~ 2.5 * heat pump operating cost > 28'F.

    http://www.climate-zone.com/climate/...i/kansas-city/
    -----------------------------------------------------------------------------
    Zoning a Small system in a Split Level would challenge anyone.


    I don't understand the need for insulation in the garage or basement ceiling.

    I can not imagine in a small Well Insulated, Tight house how the heat loss could be > 28,000 BTU/hr at 0'F { 400 BTU/hr per 1'F O.A. is less than t-stat set-point}
    Does the 70K 2-stage furnace cycle with operating time < 12 minutes when it's about 20'F outside {~ 20,000 BTU/hr if my heat loss estimate is close}?

    It seems like your house has quite low energy requirements even in extreme KC conditions.
    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

  4. #4
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78
    George2 - I already have a gas new furnace so I would have to replace it with a dual heat unit to get a heat pump.

    Dan - I'm going to answer backwards. Yes I am very frugal and my energy requirements since the air sealing and added attic insulation are very very low. When it is under 20 degrees outside and only one zone is calling my furnace does only run sub 12 minutes an hour. When it is sub 20 the furnace does run longer, all in 1st stage. I want to add insulation above the garage because (1) I don't heat it, (2) the floors above are chilly, and (3) one room, my office, is always cooler or warmer then the others. As for the basement ceiling mostly the insulation will be for noise reduction but the added r-value will be nice. I will get my contractor to come increase the lower level damper and I will purchase a de-hum for the game room.

    Can I tap off the lower level trunk for the basement supplies and returns?
    Should I get 6" or 7" supplies for the basement...I want whisper quiet down here because all surfaces are hard and smooth?
    What size and should I get a return added in the game room? 8"?

  5. #5
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78
    OK I have an American Standard "NATE" certified contractor coming out tomorrow to discuss AC replacement options. Mind you that I have a goodman furnace. What should I ask him in particular? TXV? Thermostat questions? He said he can do a Manual J but typically doesn't. I really hope I can get him to listen to the upstairs ducts, as they are noisy when the furnace is on in 1st stage with 800+cfm and crazy loud when 2nd stage 1000+cfm.

  6. #6
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,609
    Quote Originally Posted by rebelranger View Post
    OK I have an American Standard "NATE" certified contractor coming out tomorrow to discuss AC replacement options. Mind you that I have a goodman furnace. What should I ask him in particular? TXV? Thermostat questions? He said he can do a Manual J but typically doesn't. I really hope I can get him to listen to the upstairs ducts, as they are noisy when the furnace is on in 1st stage with 800+cfm and crazy loud when 2nd stage 1000+cfm.
    You can put a HP on your new Goodman. The variable speed is ideal for a 2 stage HP and/or zoning.

    Noisy at 800 cfm? It sounds like (sorry for the pun) you're short on return air and the furnace blower (fan) is ramping to higher cfms.

  7. #7
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    If you have a Goodman VS HE furnace, why not install a matching heat pump. It will have an AHRI match and you should be able to get utility rebates and tax credits if available and you qualify.

    As mentioned above, I would defnitely bleed some airflow if you short of supplies for the CFM in low stage. If you house is well shaded and insulated, you should only need a 2 ton heat pump, even with hot Kansas summers. With zonin and comfort, you could go 2 stage, where 1st stage would only be about 600CFM on low stage. You'll get nice long run times with a heat pump.

  8. #8
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78
    I am having the HVAC tech bleed some more airflow off. Any last minute questions I should ask? He'll be here in an hour.

  9. #9
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78
    OK so the tech recommended upsizing from the 2.5ton single stage AC to a 3 ton single stage Lennox 13ACX036 and upgrading to a VisionPro thermostat. Price was about the cost of a high end fridge. He didn't do a Manual J, saying it runs the risk of undersizing. This is a 70 year old company with a good reputation. I asked if there would be any problems with my new Goodman furnace and the AC and he said No and that it would actually make the AC better. This is the third HVAC tech who has come out and didn't do a Manual J in the past 9 months and they all say just do a 3 ton. My house is only 1200 sqft foot and got top of the line windows, air sealing, and increased attic insulation from R15 to R38, why does everyone want to increase my old 2.5 system to a 3ton?

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,248
    Quote Originally Posted by rebelranger View Post
    OK so the tech recommended upsizing from the 2.5ton single stage AC to a 3 ton single stage _ )_ _

    This is the third HVAC tech who has come out and didn't do a Manual J in the past 9 months and they all say just do a 3 ton. My house is only 1200 sqft foot and got top of the line windows, air sealing, and increased attic insulation from R15 to R38, why does everyone want to increase my old 2.5 system to a 3ton?
    Because they are Dumb.

    Or Al Gore has brain_washed them all.
    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
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    If any thing manual j still oversized a little. Especially on larger homes with more thermal mass. The problem lies in the expectations of some customers that want the system to recover from a 10f et back in a hour when it above design. Or the myth that if it rubbing continously it must be too small or my favorite.. That it uses more energy.



    Sent from my SGPT12 using Tapatalk 2

  12. #12
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,609
    Quote Originally Posted by rebelranger View Post
    OK so the tech recommended upsizing from the 2.5ton single stage AC to a 3 ton single stage Lennox 13ACX036 and upgrading to a VisionPro thermostat. Price was about the cost of a high end fridge. He didn't do a Manual J, saying it runs the risk of undersizing. This is a 70 year old company with a good reputation. I asked if there would be any problems with my new Goodman furnace and the AC and he said No and that it would actually make the AC better. This is the third HVAC tech who has come out and didn't do a Manual J in the past 9 months and they all say just do a 3 ton. My house is only 1200 sqft foot and got top of the line windows, air sealing, and increased attic insulation from R15 to R38, why does everyone want to increase my old 2.5 system to a 3ton?
    Use some common sense here.........if the existing 2.5 ton does the trick, why would they want to oversize the A/C? And why has no one mentioned a H/P? It would probably make good sense in K.C.

    P.S. It is really a bad idea to over size the new higher efficiency A/Cs or H/Ps.
    Last edited by George2; 03-25-2013 at 10:30 PM. Reason: Added a P.S.

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    If anything it sounds like you've made a lot of improvements to the building in insulation and windows, so I'd think your want ot downsize to a 2 ton unit. With your humidity, a 2 stage isn't a bad idea. A heat pump as mentioned above for dual fuel is a good idea as well. It adds another level of comfort, especailly with a 2 stage heat pump, as well as some savings. The utilities usually give a rebate for a heat pump that covers nearly 1/2 the increase in price.

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