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  1. #1
    Join Date
    Mar 2008
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    Near Charlotte NC
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    51

    16 year old system replacement.. wow :)

    A little background seeing this is my totally newbie post. Am almost thankful when I was having this house built that I didn't know what I know now as I would probably have driven my builer nuts. Home was NOT a custom built home so the heating choices were basically not mine. Not that I would have known much of anything about hVAC during that time and really without this forum and the internet I'd still be totally stupid.

    My background is as as cientist who works in the nuclear industry, dealing with radiation protection, degreed in same field and with some civil engineering background though I am NOT an engineer!

    My home is approx 2700 heated square feet. The foyer is 2 story and I ahve a 19 x 19 bonus room over the garage. I also have 2 HVAC systems, one fo reach floor. We are not considering replacing the downstairs unit as it is mostly the upstairs one which is having the problem.

    The upstairs is approx 1580 sq feet of living space. The system is composed of a Trane furnace along with a 2.5 ton Trane AC unit. Oddly, the coils used are a cheap 3rd party ( All Style I think? ) and not well matched unit. I am alos less than impressed with the ductwork ( there are 2 separate square/rectangular ( not sure of name ) boxes coming off the coils box along wiht the supply hose for my bonus room. One of these has a very hsort run folowed by a 90 degree bend and has I believe 3 flex lines attached, the third coming off the end of the line.

    The systme has never been stellar since adding the bonus room ( room wass emi finished when home was built and finished out after the fact ). The bonus room also faces south. Bonus rom has a single 10 inch line feeding a pressure box to which 3 6 inch lines are attached feeding the vents to the room. In a nutsheel, in the summer I cannot keep the upstairs cool, and the bonus room often varies by more than 10 degrees. Last summer the upstairs would cool to 78 degrees at best and would be past midnight before it would get back below this mark. Currently I have closed a few dampers in order to keep our bedroom cool and bonus room about right. Thi swill not work in the summer.

    Thus, I began getting quotes for a new system and have been amazed at the difference sin what people want to do! None thus far have even suggested leak testing my current system or fully load evaluating the home. The first company that came in did do a basic heat load calculation for the home and recommended 2 systems. They were a Lennox house.

    System 1 was using a 13 seer Lennox AC unit and a dual speed 80% Furnace ( 2.5 ton unit + 3 ton blower ). They also wanted to run new ductwork from top to bottom. Basically a newer version of what i have but better installed. Price was semi expensive. Now, quote 2 was interesting. They wanted to keep my existing ductwork but wanted to use a Lennox Signature furnace for the variable speed blower and a 16 Seer dual stage AC system. Price about 60% more than the first system. I really disagreed with the decision to not replace the ductwork because the variable speed blower would make up the difference.

    To me, the ductwork needs to be evaluated all by itself. Either it needs to be replaced, modified, repaired or nothing at all but it needs to be evaluated without regard to price of the system. Am I wrong in this assumption?

    Most of the other quotes ranged from " winging it" to again keeping existing ductwork without testing it and using higher end equipment ( one was a 16 Seer Trane Heat Pump along with 80% furnace w/ variable speed fan and doing a hybrid system ).

    The last quote is actually more interesting. It composed of replacing my ductwork, using a Carrier Infinity dual stage variable speed blower 80% furnace, Carrier coils, Carrier 16 seer 2 stage AC, and using a zoned system to provide a separate thermostat for my bonus room from rest of upstairs. Price with 10 year bumper to bumper Carrier warranty was in keeping with other systems. My trust level for the installer in this one is medium to high which is about what I have for the best of the rest.

    I have one more installer coming out who is going to leak test my ventilation now, and will perform more elaborate load calcs. He does NOT do higher end equipment installations unless he has to as he prefers to design the ductwork well ( according to him ) and use single stage AC's and furnaces where possible to keep things simple.

    I live in NC so we have plenty of hot days and usually mild short winters though we do occasionally get down in the teens.

    Based on this, my questions are mostly am I headed in right direction pushing for having my existing duct tested ( even though I doubt it will be useable but again my gut instinct isn’t based on knowledge, just how crappy the current air flow is and how hard it has been to keep the entire upstairs both cooled and evenly cooled ). I do have 2 separate air returns, one in the bonus room the other a few feet away in the hallway.

    Next, is there a lot to be said for a simple 13-14 seer system and just properly designed ductwork versus new ductwork plus more complex solutions such as the zoned system plus variable speed blower and double stage AC unit? I have to admit I really do not want to have to climb in the attic very often to rebalance dampers to account for cooling season and heating season, and the thought of a well designed zones system to help keep the bonus room and rest of upstairs balanced is attractive. Assuming, of course, that it will work in that manner.

    I am learning how difficult it is to find installers you feel very comfortable with as each seems to have their own twist. For example, the one who said I needed new ductwork to run a basic system but my existing ductwork would work with the more elaborate system. Just seemed inconsistent to me and would also seem if my existing ductwork were to have excessive leaking that a variable speed fan would not be a good thing!

    I'm not very brand orientated and do want to ensure the replacement system is properly designed and evaluated. The last quote will come after I have had my existing ductwork properly tested which may well be the deciding factor in what system/installer I go with. assuming I do replace my ductwork ( which is what I am assuming will happen, or at the very least have what I have resealed and slightly modified as needed ), it will then come down to going with either a very basic system, no frills, 13-14 Seer level equipment and only manual dampers, or considering the more complex Carrier Infinity system with 2 zones to assist with temp control between the bonus room and rest of upstairs.

    Of course, if the ductwork is properly sized and designed, would I even need the zoning? I'm fearful the heat load characteristics of the bonus room will make it very difficult at best to maintain constant temps between that room and rest of upstairs using a single stat in the hallway.

    Sorry for long post and any comments are appreciated. I've already benefitted from the many posts I have read and probably learned enough to partially confuse myself )

  2. #2
    Join Date
    Jul 2006
    Location
    NJ
    Posts
    356
    was the system stella before adding the bonus room? was it balanced?
    regardless no system should just be replaced without a manual j load calculation, as for the duct, you must have that recalculated and possibly new trunk designed to handle the bonus room. (manual D). I can not believe no body is worried about the duct. that would be my first and number one priority after the load calc. From there you can pick and chose equipment.

    Use one system, and zone the bonus room with seperate thermostat. DO NOT ZONE WITHOUT USING A MODULATING BY-PASS DAMPER. Its not a hard thing to do, don't spend a dime with anyone who does not perform and present you with a load calculation, get one even if you have to pay for it, and save yourself some money and zone the thing. Just my 2 cents from experience.

  3. #3
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
    Posts
    51
    Quote Originally Posted by bonafide View Post
    was the system stella before adding the bonus room? was it balanced?
    regardless no system should just be replaced without a manual j load calculation, as for the duct, you must have that recalculated and possibly new trunk designed to handle the bonus room. (manual D). I can not believe no body is worried about the duct. that would be my first and number one priority after the load calc. From there you can pick and chose equipment.

    Use one system, and zone the bonus room with seperate thermostat. DO NOT ZONE WITHOUT USING A MODULATING BY-PASS DAMPER. Its not a hard thing to do, don't spend a dime with anyone who does not perform and present you with a load calculation, get one even if you have to pay for it, and save yourself some money and zone the thing. Just my 2 cents from experience.

    Bona,

    Thanks for the reply. To answer your question about bonus room, I can't really say. I moved in the house in December 1992, and completed the bonus room a few months later so I never had any real comparisons. Without question, it has gotten worse as it has aged ( I do have it serviced and in recent years have had to have freon added annually suggesting the obvious ). That said, it doesn't heat evenly , either, so it isn’t just the AC ( my guess is it is a combination of many things.. bad ductwork design, crappy coils, poorly balanced system, etc etc ).

    After reading these forums I have also been surprised at the lack of desire on the HVAC folks to sit down and run heat load and or vent/duct calcs. The first contractor ( the one who suggested new ducts for the more inexpensive system but using existing ducts for more expensive system ) did run some heat load calcs though they were rather simplistic. No design calcs were done for the suggested new ducts at that point though perhaps he was waiting to get the contract before doing that ( but again it was never mentioned ).

    This was why my gut feel has not been feeling warm and fuzzy as it would seem that one would need to identify and quantify the problem first before proceeding to designing a solution and lastly selecting the proper equipment to fit into the solution.

    Only the last company suggested zoning the bonus room which did seem to make sense. It is a long run from the HVAC system ( approx 40 feet of duct to the pressure box and then each line off of that averages about 8-12 feet ). The bonus room has never had good air flow ( it does now because I have partly closed the dampers to the bedroom to keep it cool and bonus room semi warm .. NOT a desired or permanent solution ).

    Your suggestion to pay for a proper evaluation ( heat load, ventilation duct design, etc. ) may be in order. At least then when contracting the work I will have design specs performed by an independent company, and can choose the equipment easily enough.

    I wasn't even considering Carrier , by the way, but after reading here do understand they seem to have a good zoning system. Based upon your reply, it does sound like zoning the bonus room is the way to go to ensure more even temp control versus manually adjusting dampers ( though am assuming if the ductwork is properly done I could adjust dampers as little as 2X per year for heat/cooling and achieve reasonable results, even if less convenient ).

    Thx again for the reply and advice. I have someone scheduled for the 17th to measure my ductwork leakage rate, house in leakage rate, etc., and can ask if they also perform the load and duct design calcs.

    Dumb question.. how much are the duct design calcs dependent upon the system being installed?

  4. #4
    Join Date
    Jan 2008
    Location
    Dothan, Alabama
    Posts
    25

    Go with your gut feeling

    If you think the problem is in the duct work have it tested . Could be you have the right system in place and just need the duct work replaced. This could save you afew bucks especially if theres nothing wrong with the old unit. Most definitly get a (manual J) load calculation on the house .Any decent cotractor will do this. 13,14 SEER units are fine!!! the higher Seer units are fancier .They also have more components to tear up. And can be quit expensive to repair.

  5. #5
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
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    51
    Quote Originally Posted by Jbatchelor View Post
    If you think the problem is in the duct work have it tested . Could be you have the right system in place and just need the duct work replaced. This could save you afew bucks especially if theres nothing wrong with the old unit. Most definitly get a (manual J) load calculation on the house .Any decent cotractor will do this. 13,14 SEER units are fine!!! the higher Seer units are fancier .They also have more components to tear up. And can be quit expensive to repair.
    Thanks Jbatch.

    I may have just located another contractor who at least advertizes using software to calculate heat loads and duct sizing. Just seems most around here are bypassing this.. perhaps is due to the extreme growth in the area and people going for faster installs versus timly ones. Who knows.

    I do have a test scheduled on my existing system which should be interesting. That said, I dont think all my problem is in the ductwork as the old system in place has a poorly matched up coil. If I weren't planning on staying here for another 10-12 years, I might well consider just replacing the ducts and keeping most/all of the existing system.

    Course I might end up being surprised by the test results. hard to say if my gut instinct is correct til it is done. I also keep waffling about the fancier systems versus simple ones. Usually, I prefer simple as it has less to break. But, the 10 year bumper to bumper warranties have all beeen very cheap.

    I have a spousal unit who is VERY hot natured. First woman i've ever met who can freeze me out with temperature ( not talking about freezing out in the more traditional ways lol ). I cannot afford to have a hot house again if I want her to remain happy!

    I also need to see the guarantee of satisfaction *in writing* being offered in the event the system does not perform as we expect. Not sur ehow much this is worth but if they are willing to put it in writing at least I'll feel better.

    Time to find someone who can design the system before they attempt to sell the components. Is just proving more difficult than I figured it would. Thx again

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,712
    Your wanting the ductwork to be exaluated is a good thing.

    The bonus room doesn't lose or gain heat at the same rate as the rest of the second floor.
    Often times the insulation under the floor isn't what it should be.
    So the zoning idea is the best.
    The Carrier Infinity with Infinity zoning is what I would recommend out of the systems you described. No bypass damper required or allowed.
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  7. #7
    Join Date
    Jul 2004
    Location
    Massachusetts
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    6,829
    Totally agree with beenthere. Your challenge is to find a company that does a room-by-room Manual 'J' load calculation. Absent that calc, no one has any idea how much air (Cubic Feet Per Minute or CFM) are needed in each room. Just changing the orientation of a room with windows 90-degrees (relative to true north) can change the cooling load by 1/2 ton or more, depending on the glass area. So a Manual 'J' load is the ONLY way to start. Once that value has been determined for each room, THEN a duct design can begin. Now you know how big the main and branch trunks need to be to service that bonus room.

    Beenthere already stated the bonus room is a separte thermal area and will change temperature at a different rate than the rest of the home. It's over an unconditined garage so the floor is subject to a totally different load than the rest of the house where the floors are over a conditoned space. So zoning is the best way to get you theh comfort you're seeking. Either the Carrier Infinity or the Bryant Evolution (same systems, different monikers) systems can be zoned and as he said, a by-pass damper is neither needed nor allowed in those systems. All the dampers are modulating and the relief strategy is speard over the entire system, based on a math algorithm and room sensors. I'd recomment that you consider moving up to the heat pump. I'm a Bryant guy and that would be the 288ANA... 2-stage, 18-SEER Heat Pump. I believe the comparable Carrier model is the 25HNA9 (19-SEER, they had to make the Bryant 1-SEER less because of patents). These are the top-of-the-line models giveing the quietest operation, smoothest change from 1st stage to 2nd stage using a single scroll compressor. Using the heat pump you'll be turning your expenditure for AC into an investment, gaining back those monies not spent running a gas furnace on milder (above 35F) days. You'll also be reducing your greehouse gasses for the same reason. Using the appropriate Infinity or Evolution zone controls, a new, proper sized, sealed and installed duct system, you'll have comfort to the extreme. Skip any of the requirements and problems will follow.

    Finally, people who don't install high end equipment do not do so because they don't have the training and/or experience to work on the equipment. Someone who puts more emphais on the duct system than the equipment is doing things for his/her own comfort, not the comfort of the client. Sounds to me like you're going to have a visit from a pro who's a tinknocker first and not really much of a technician. Simple systems are not where the comfort is today.

    There are many zoning systems out there. The Infinity/Evolution is the most sophisticated system when coupled to the associated equipment. I have some in my own house and it works beautifully. All other zone systems, to the best of my knowledge, require some sort of relief strategy to be built into the system, such as a by-pass damper or dump zone. Finding a dealer who'll do all the steps necessary to achieve the final goal is the most difficult task you'll face, it seems. The economy is slow. We're in the shoulder season (not a lot of heat or cool needed). Set some minimum standards for the bidder(s) to meet. Let them know that if they can't meet anyone of the standards, they are eliminated from the competition. Then shop till you drop and when you get the company that does it all, understand it's going to be several thousand dollars more than the other wannabes, but you're investing a lot of money in a system you shouldn't have to do more than regular MAINTENANCE on for many, many years. And a properly designed duct system should be good for 100-years!! A knowledgable client is a joy to work with. They've always been the best clients for us. They know what they need to have done, we step up to the plate and do it, they know they're buying a Mercedes and expect to pay the higher rate to be in that game, the job gets done to specification (all documented) and there is no pain. If you're one of those clients, you're on the high ground.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  8. #8
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    Mar 2006
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    The South
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    jdavis

    I agree with skip and beenthere about the zoned system for upstairs. However for NC area/climate, you could go Infinity heat pump system and drop the furnace. This will be better in operating costs.

    IMO

  9. #9
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
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    Thanks beenthere and SkippedOver!

    I'm starting to get the bigger picture that I'm getting bits and pieces from each company thus far but perhaps not getting any one company who is doing all that should be done. I was already working on getting over the sticker shock and now am having to convince myself to get over the battle fatigue of going through installers! I finally have started calling these "interviews" rather than system quotes because in a nutshell that's what I'm doing first and foremost.. interviewing the installer/company! Luckily, there is a lot of good advice here and on the internet suggesting just that and even more luckily I actually decided to listen to it sooner rather than later. So, anyone who in the future is reading this thread and finding themselves in a similar place as I am, please do yourself a favor and listen to what these guys are telling you... make sure whatever company you choose is at least evaluating the ductwork and heat load before they start plugging in components.

    The last company I spoke with was initially not that high on my list. However, he was the only one to suggest zoning the bonus room using the Carrier system. What i do not know *yet* is how he plans to design the actual ductwork and thus is my next question for him. If he does the proper calculations and is not simply winging it ( i.e., I can imagine many would not do all the cals until they know they are going to get the contract ) then I'll probably go that route.

    I did find, last night, a local company who advertises using Wrightsoft software to calculate heat loads, duct sizes, etc. and I'll give them a call as well. Skippedover, I did find your comments regarding simple systems versus more complex ones interesting as I've only spoken with 2 companies that insisted on that approach ( do the ductwork properly and stay with a single stage AC unit plus single stage furnace and no zones ). One was the most expensive of all quotes I've gotten by far ( their service techs also are paid commission so I'm not really interested in that company ) and the other seemed very knowledgeable about testing a vent system and doing that part right but did not like to install anything over the basics. No doubt such a system would be far better than what I have now but I just doubt it would come close to what we'd prefer ( i.e., I'd probably have to work hard adjusting dampers from season to season to get things close to where they should be.

    It would also seem that Carrier/Bryant do a really good job with zoning. Hopefully, the Carrier Infinity quote I have will turn out legit on the heat load/duct calcs and my interviews will be done. What an educational journey this is becoming. Interesting but tiring.

    Oh, as far as using a heat pump versus AC unit, I had asked the Carrier installer that question since another quote from a Trane dealer ( no zoning ) would allow a heat pump hybrid system at very LITTLE additional cost. The Carrier installer, however, wanted a LOT extra for the heat pump and while I'd love to go that route, we do have a budget to maintain and trust me when I say we have already blown that to Hades but need to control it as much as we can. I don't feel comfortable going with JUST a heat pump even though our winters here are reasonably mild. I just prefer gas heat when it gets cold and we do have many nights in the 20s and some in the teens. I'd love to have the hybrid system but there comes a point where trade offs have to be made and a dual stage furnace with variable blower will probably be good enough ( if I compare to what I have now I know it will ).

    We'll see what happens next Always seems to get close to an answer but not quite thus far!

  10. #10
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
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    Quote Originally Posted by tigerdunes View Post
    jdavis

    I agree with skip and beenthere about the zoned system for upstairs. However for NC area/climate, you could go Infinity heat pump system and drop the furnace. This will be better in operating costs.

    IMO
    Tiger,

    No doubt you are right on this one. If I could ever get past the heat pump I had years ago, logic would probably prevail. Right now, my "emotional scars" of the previous heat pump are still with me lol. But with gas prices currently being high and the fact I hate greenhouse gas production, the heat pump probably should be considered more than it has. I was ok with it as a hybrid system, knowing anytime it really got cold outside that I'd have gas to the rescue. The one Trane installer wanted VERY little for going from an AC unit + gas to a heat pump + gas system ( but wasn't wanting to re do the duct work nor did he offer a zoned system in his quote ). The Carrier installer offered a new duct system ( without yet specifying HOW he would design it ), zoned but wanted a large amount of money to go hybrid.

    The good news is we keep our house quite cool overall ( though once zoned I may well heat the bonus room up a bit for myself as my spousal unit actually prefers a temp of 62-64 degrees in the winter which is a tad cool for my tastes ). I'd probably do fine with a heat pump.. will need to think it through a little more. Thx!

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Not to push a hybird, or heat pump only system.

    But. HP's today provide more heat then the older ones did.
    Also, the Infinity HP, with Infinity control will slow the blower so you don't get the cold air out the registers like older HP's did.

    If the main area of the second floor is going to be kept cooler,(62 to 64) the aux heat won't be needed much.
    As a zoned system, when only one zone is calling, even when its 20 outside, the HP may not need the aux except when in defrost.

    Compare your gas an electric rates to find which will provide the most heat for you buck.
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  12. #12
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    Feb 2006
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    Tn.
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    jdavis dont buy into putting a variable speed unit or a more effecient unit is going to fix the problem with your bonus room being hot.I see it all the time .
    This room needs its own system and thermostat.

  13. #13
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    Feb 2006
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    or your contractor could use a zone system.

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