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  1. #27
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
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    629
    Quote Originally Posted by jramunni View Post
    I cool my 3 zone, 2000sq ft home with a 2 ton a/c.

    Serving Zone 1 (1st fl Main) 3 %
    Serving Zone 2 (1st fl kitch) 38 %
    Serving Zone 3 (2nd fl Bd Rms) 62 %

    Serving Single Zone 70 %
    Serving Two Zones 29 %
    Serving All Three Zones 1 %

    The zoning allows for a focused effort of supplying cooling capacity to the parts of the house that have higher loads. The lower load zones (1st fl Main) tend to remain at set-point not stealing capacity that can be used for the hard to cool/heat areas.
    That's what I was thinking if you have a house that has dedicated parts (floors) for different times of the day. You can use a slightly larger than Manual J'd system for the floor with the largest heat gain, zone it to the other area and set back the floors (areas) not in use and the system will do great unless you need the whole house at the design point at one time at the OD design temp. which would be never in my case. The recovery time would be less due to the other zone not calling. You could have a 10* spread between zones and still maintain humidity control over the entire house.

    Am I missing something?

  2. #28
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
    Posts
    316
    Quote Originally Posted by Daltex View Post
    That's what I was thinking if you have a house that has dedicated parts (floors) for different times of the day. You can use a slightly larger than Manual J'd system for the floor with the largest heat gain, zone it to the other area and set back the floors (areas) not in use and the system will do great unless you need the whole house at the design point at one time at the OD design temp. which would be never in my case. The recovery time would be less due to the other zone not calling. You could have a 10* spread between zones and still maintain humidity control over the entire house.

    Am I missing something?
    Not sure about your sizing method, although my house, according to a manual J load calculation, requires a 3.6 ton a/c and I do fine with a 2 ton. I will have to look at the print out and see what the individual zone loads are.

    I am also not sure if you could actually maintain a 10 deg spread between zones. I am sure my 2nd floor zone would drift to a 10 deg spread, and I believe I could, at will, drop it 10 deg in less than 60 min if it was the only zone calling. I don't believe my 1st fl zones would ever drift 10 deg warmer than my 2nd fl (in cooling).

    Zoning has tremendous savings potential if it is designed properly and allowed to operate to save energy with programmable set-back stats.

    Much of the design criteria and savings potential are influenced by the type of structure and the usage patterns of the HO.
    jr
    "When you perceive zoning not as a bandage but as an enhancement, you truly understand the dynamics and limitations of forced air heating and cooling"

  3. #29
    Join Date
    Jan 2008
    Posts
    78
    JR--interesting info...and it backs up what I suspect....if entire house needs a 4 ton system, is there any reason why I couldn't get my 1 zone to drop more than 20 degrees if the system is working properly?

  4. #30
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
    Posts
    316
    Quote Originally Posted by njhusky View Post
    JR--interesting info...and it backs up what I suspect....if entire house needs a 4 ton system, is there any reason why I couldn't get my 1 zone to drop more than 20 degrees if the system is working properly?
    20 deg is a lot of cooling...it will depend on the application, duct capacity, register types and their location, relative size of "1 zone" etc. You should be delivering 50% to 100% more cooling capacity when serving a single zone that is less than 50% of the total duct volume. If that cooling capacity is distributed effectively (plenty of upward velocity from a floor register) you could potentially drop a degree every 5 to 10 min so a 20 deg make up would take 1.5 to 3hrs
    "When you perceive zoning not as a bandage but as an enhancement, you truly understand the dynamics and limitations of forced air heating and cooling"

  5. #31
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    If your zone panel is set up not to use second stage when only one zone is calling.
    It may take a long time to get 20° or more temp difference.
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  6. #32
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
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    316
    Quote Originally Posted by beenthere View Post
    If your zone panel is set up not to use second stage when only one zone is calling.
    It may take a long time to get 20° or more temp difference.
    Yes it is...

    Zone 1 (1st fl Liv area) 30%
    Zone 2 (1st fl kitch area) 30%
    Zone 3 (2nd fl bd rms) 40%
    second stg output to Blwr @ 70%

    This allows low wattage blower operation until I need the volume
    If I had a two stg a/c it would stg up based on supply air temp
    "When you perceive zoning not as a bandage but as an enhancement, you truly understand the dynamics and limitations of forced air heating and cooling"

  7. #33
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    Jan 2004
    Location
    Lancaster PA
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    Quote Originally Posted by jramunni View Post
    Yes it is...

    Zone 1 (1st fl Liv area) 30%
    Zone 2 (1st fl kitch area) 30%
    Zone 3 (2nd fl bd rms) 40%
    second stg output to Blwr @ 70%

    This allows low wattage blower operation until I need the volume
    If I had a two stg a/c it would stg up based on supply air temp
    LOL.
    Sorry, I was ansering njhusky.
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  8. #34
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    Feb 2008
    Location
    Dallas & Longview, TX
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    Quote Originally Posted by jramunni View Post
    Not sure about your sizing method, although my house, according to a manual J load calculation, requires a 3.6 ton a/c and I do fine with a 2 ton.

    I am also not sure if you could actually maintain a 10 deg spread between zones. I am sure my 2nd floor zone would drift to a 10 deg spread, and I believe I could, at will, drop it 10 deg in less than 60 min if it was the only zone calling. I don't believe my 1st fl zones would ever drift 10 deg warmer than my 2nd fl (in cooling).
    The sizing method I was referring to is to size the unit to the zone with the highest heat gain (ductwork designed to handle full load on each zone) and use the zoning for example to drop the upstair bedroom from 80* to 70* at night while the downstairs climbs from 74* to 80*. The time for the downstairs to rise to the new set point would allow the full load to be delivered upstairs dropping the temp much faster than an individual unit sized exactly for just the upstairs. This is assuming the load for each zone is close to each other.

    Never thought of that approach before but it does sound interesting.

  9. #35
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
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    316
    Quote Originally Posted by Daltex View Post
    The sizing method I was referring to is to size the unit to the zone with the highest heat gain (ductwork designed to handle full load on each zone) and use the zoning for example to drop the upstair bedroom from 80* to 70* at night while the downstairs climbs from 74* to 80*. The time for the downstairs to rise to the new set point would allow the full load to be delivered upstairs dropping the temp much faster than an individual unit sized exactly for just the upstairs. This is assuming the load for each zone is close to each other.

    Never thought of that approach before but it does sound interesting.
    You would just need to be sure the occupied programs were staggered and your good to go. My guess is a 10 deg set-back would get you at least a 3 hr window to focus on your "1 Zone".
    "When you perceive zoning not as a bandage but as an enhancement, you truly understand the dynamics and limitations of forced air heating and cooling"

  10. #36
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    24
    Hello again. An update from the originator of this conversation. I have been following the thread with interest even though it got a bit too technical for me. In my original question I talked about my neighbor who had his 2 systems (one for each floor like mine) replaced with one big 5 ton, and zoned 4 ways with Carriers Infinity zoning. Even though my question regarding adding zones was more "should I”, rather than how it's done, it's interesting to eavesdrop on you guys talking tech.

    Unlike my neighbor, I have decided to keep 2 systems, for redundancy. I got differing opinions on this here too, but right now my downstairs air conditioner is broken, and if I didn’t have 2 systems I’d be typing this on my laptop from a motel room. I don't know yet if I'll be adding zones but I do have one area of my home that would benefit from being a separate zone; my den has a cathedral ceiling with a loft above. There are returns in this area for each floor/system, but it never seems to know which should run because the thermostats are in the middle of the main part of the house. It’s hard to describe without a picture but the house is a center hall colonial, but between the garage and the main house there is a 2 story section containing the den, laundry, and powder room. This area is more of an issue with cooling because it has 2 large sky lights, which tend to over heat it. Ideally, this should be a 3rd zone, but since I'm doing 2 complete systems, I may not be able to afford it. I have a guy coming out in a few days to look things over.

    The units he can install are Carrier and I want the Infinity S (for scroll?) and if anyone has been following this thread they know I questioned the 2 compressor technologies as well. The installer works for a very reputable company, and has 10 years experience, but he is pricing this as a side job. He has done work for friends and family and they were happy with both pricing and his work. The only concern I have with this is whether Carrier will honor their warranty when it's installed this way. So that's where I'm at. No new questions really but I promised an update, and as always, I welcome advice.

  11. #37
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    If you have the area with the high ceiling zoned. And its a small zone. The 2 stage recip would be better because of its lower capacity in first stage.

    If this side job johhny, buys the equipment and installs it, Carrier will honor the part warranty.
    But who you gonna get to honor the 1 year installer warranty?

    Any company can get teh warranty parts for a system another contractor installed. They can also charge you handling fee's since they didn't install teh system.

    I advise most people that think a side job johnny is their best solution, to go with a standard single stage system. Side jobbers don't seem to have the time to come back out and work on them in the middle of the day when tech support is available.
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  12. #38
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    I agree with Beentherre. If side job Jonny is going to do the job I would just get a low end system. The higher end stuff requires more knowledge to size and set up and most installers don't have that kind of experience.

    Also as said how do you know how long he may be around and doing side work. If he goes away then there goes your labor warranty if one is supplied anyway. The parts warranty comes from the manufacturer but the labor comes from the installing contractor. Buyer beware.

    Remember that side jobs are done cheaper because there is usually no insurance involved, company parts are often used with company tools and most times its a tailight warranty. Also is this guy licenced with your city or state? Are permits needed?
    Its a good Life!

  13. #39
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    24
    Cubic feetwise, it's a lot of space. It would be nice to zone separatly, but for simplicity and cost I may skip it. Is there no point in going with a 2 stage system if I'm not zoning? Keeping the 2 systems is easier for a side job because it doesn't involve ducts, assuming I don't opt for a 3rd zone. He recommended a Carrier 2 stage sytem even before I told him I wanted it. He says he installs 2 stage systems all the time, and in fact installed one for a freind of my inlaws which is how I learned of him. I have confidence in his ability. I was worried about the parts warranty if it wasn't installed by an authorized installer. I realize there is an element of risk doing it this way. If I use this "side job Johnny", I'll make sure he stands behind the labor for one year. He knows I have concerns about the warranty. He is a friend of the inlaws side of the family so I trust him ethically and technically.

    I'm leaning towards a Copeland scroll only because it's been around longer and has fewer moving parts. I'm sure both have pros and cons. Does one cost more than the other?

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