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

    Flow rate, duct velocity, duct leakage verification post installation

    I'm curious to know how many installers actually perform any of these tests after they have installed new ductwork, of if I am beginning to be too anal about this part.

    Obviously, if a duct system is properly designed, installed, etc., it should work as needed. That said, there does seem to be benefit to actually measuring for leakage, flow rates, etc to verify that the actual numbers match the calculated values. I'm not finding very many installers who are equipped to take such measurements, and also not finding companies in my area which can be hired to take them. Only one installer thus far that I've spoken with takes these measurements and guarantees the leakage rate and flow rates as well as system pressures.

    This equates to the fact Im down to 3 quotes, and the price range is fairly wide ( I've eliminated 5 other installers already and hope to reach my decision by end of this weekend ). One installer of the 3 is in a distant third place already. But, the other 2 are both seemingly good installers and seem to do things much in line with most recommendations I've read about here. The main difference is one takes many measurements for leakage rates, pressures, flow rates but in doing so has offered a very basic system ( single stage AC and double stage 80% furnace.. upstairs attic install ) for about the same price as the other is offering a dual stage 16 SEER AC and dual stage variable speed blower 80% furnace. The latter will add a 2 stat zoning system for about 10% extra, but they do not test for leaks etc after the installation.

    Both installers have great BBB ratings, good references, and good Angies Lists reviews. Both systems involve completely new ductwork systems, but the one simply tests many aspects after the install and verifies the heat load calcs. The other does not.

    I'm not finding any other local installers who take flow measurements after installation and/or measuring duct leakage. I can perform cost savings between the 2 stage 16 SEER AC and the single stage 13 SEER and the payback in truth takes much longer than I first thought ( several years given our sub 9 cents per kw/hr rates ).

    I'd appreciate any opinions on how common it is to take such measurements after an installation of new duct, and how one can hold an installer accountable for the integrity of the installation. If I could find local people who could take the measurements I would probably go with the better equipment and have the contract written with performance standards that would have to be met via the subsequent test. Yet, I have not yet found anyone who can do this test except for the competing installer. Thx

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,097
    They are far and few between.
    Why not ask the one that does messurements, for a quote on a 2 stage A/C also.
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  3. #3
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
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    51
    Quote Originally Posted by beenthere View Post
    They are far and few between.
    Why not ask the one that does messurements, for a quote on a 2 stage A/C also.
    Thx Beenthere... am hoping to meet with him/them tomorrow morning to discuss. I think we can get to a point where they can install a 2 stage AC ( higher end 16 SEER + 2 stage variable speed 80% furnace ) for *about* the same price as the other installer who is offering similar equipment + zoning.

    The installer who tests the leak rates, etc is not a big believer in zoning as he feels for most part between his heat load calcs and verifications, as well as guranteeing a 2% leakage or less rate, he can keep most rooms in a given area to within a degree or so of one another ( exceptions being when closing doors ). Once the system is set up and measurements taken, he will return a few days later to see how well it is working and make any adjustments as needed. When the folowing season ( winter/summer) approaches, he does same thing ).

    He has already provided a price for a really high end system that was about 15-18% higher than the zoned price installer.. and we aren't talking small dollar amounts where these %'s would be insignificant.This particular system is over our budget.

    Both installers do perform heat load cals though I will say the one who does the leakage measurements is simply more in depth with it. In the end I probably will go with him because of that and know I'm getting a bit hung up on the details of the equipment when payback calculations in many ways do not justify the higher end equipment. Zoning would afford me the ability to keep one room at a diff temp than the rest of the upstairs ( and given how cold my wife likes to keep the master suite when sleeping and I'm still up working, it would be a nice feature ), but it isn't a required feature.

    I was very impressed with the guy's belief in getting the vent duct done with the precision he is after, as well as his insight on eliminating some in leakage of uncontrolled air into the home. My current vent system has about a 20-25% leak rate overall, and is undersized to boot. No wonder the room over garage stays so hot/cold.

    In the end it *may* come down to a choice between different brands but equivalent SEER rated systems, variable speed furnaces at the same price or similar price, one offering a zoned setup and 2 stats and the other offering no zones but extensive duct testing including leakage measurements and guarantees of < or about 2% max leakage. This of course assuming he will upgrade the equipment for tha tlevel of increase Course, I can also stay with same leakage guarantees and a single stage SEER 13/14 AC plus 2 speed 80% furnace option at a 10% discount. If he cannot upgrade the equipment fo rthat amount, the decision will be even harder!

    I must be anal retentive because the duct measurements just seem important. Course, if the calcs are correct and the installation done correctly, the measurements will only verify that it is good. Good news is by Monday afternoon at the latest the decision should be done

  4. #4
    Join Date
    Jan 2004
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    Lancaster PA
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    Keep in mind, that 2 stage equipment is for comfort, not energy savings. The small increase doesn't really pay back. But the increase in comfort is usually well worth it. And some quite often with the lower humidity you caan set the stat a degree or 2 higher.

    When a new unit keeps the humidity down, a lot of people find they can be just as comfortable at 74*, as they were at 72*.
    In situations were this happens because its 2 stage equipment, the equipment does provide a pay back.

    With your leakage rate, a lot of the humidity in your house is from that leakage.
    So weather single or 2 stage, you should notice a big improvement in comfort with the leakage corrected.
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  5. #5
    Join Date
    Mar 2008
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    Near Charlotte NC
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    51
    Quote Originally Posted by beenthere View Post
    Keep in mind, that 2 stage equipment is for comfort, not energy savings. The small increase doesn't really pay back. But the increase in comfort is usually well worth it. And some quite often with the lower humidity you caan set the stat a degree or 2 higher.

    When a new unit keeps the humidity down, a lot of people find they can be just as comfortable at 74*, as they were at 72*.
    In situations were this happens because its 2 stage equipment, the equipment does provide a pay back.

    With your leakage rate, a lot of the humidity in your house is from that leakage.
    So weather single or 2 stage, you should notice a big improvement in comfort with the leakage corrected.
    Thanks. After discovering how much leakage I have, I'd guess a high speed fan and no AC would be an improvement ( kidding ). I've already spoken with the home CEO ( spousal unit ) about the comfort aspect versus $ payback, and her reply was she just wanted to be nice and cool in the summer. I think either proposal will accomplish that so the good news is I'm not talking about success versus disaster.

    We'll see what the leak measuring contractor can do regarding the 2 stage system as pricewise it should be somewhere between the 2 systems he quoted me. If so, it would work out to being about the same price as the other installer's zoned price. I do like the idea of the room over garage having it's own t-stat and ability to maintain a slightly different temp than rest of upstairs but I would sacrifice that versus sacrificing the detailed duct setup that th eother guy provides.

    However, if he cannot quote a 2 stage AC + var speed 2 stage furnace price at or near the other guy's zoned system price ( also 2 stage AC + var speed furnace ), then I'll probably take the zoned system since both installers are highly rated via customer feedback.

    It's tough simply because I don't have the experience base to know which of these 2 itmes is truly important in the big scheme of things. Paying about 10-12% more to include the vent duct testing is a sizeable comittment. But, it does seem to add value to ensuring the ductwork is done properly and eliminating things such as leakage, improper sizing, proper flow rates, proper velocity, etc that in many ways would ensure a more comfortable house.

    Thx again )

  6. #6
    Join Date
    Jan 2004
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    Lancaster PA
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    A 16 SEER unit, with 20&#37; duct leakage, is no more efficient then a 13 SEER with 2% duct leakage.
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  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    True laekage testing,is time consuming,so expect to pay more to have that done.On a new system,it really shouldn't be needed,if the do it right.

    We test the duct static of every install,that takes a few minutes.

  8. #8
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    Testing to verify performance is key to knowing you are getting what you paid for. Air flow through the air conditioner is critical to its performance. Refrigerant charge cannot be adjusted correctly without proper air flow. The ability to dehumidify and cool is affected by air flow. Most don't test because they size by rules of thumb and testing would show the system wasn't design properly. I would add that pay back is focused on to much. The added comfort, system reliability and durability, plus the energy savings all should be considered. You could have your duct work installed for a zone system with only the dampers installed to manually adjust the system and add zone control later. A duct blaster test can be done in less than 2 hours, static pressure or flow plate are quick tests. Room CFM is quick also once the hood is set up. "If they do it right" has always been the problem, most don't do it right and the consumer is none the wiser (but they saved money not using the over priced guy that actually designs his systems). And while you are on the subject of leakage has your house been tested for air leaks? Up to 30% of your energy for heating and cooling can be from infiltration through the house.

    If you don't test it's just a guess!

  9. #9
    Join Date
    Mar 2008
    Location
    Near Charlotte NC
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    51
    Quote Originally Posted by mbarson View Post
    Testing to verify performance is key to knowing you are getting what you paid for. Air flow through the air conditioner is critical to its performance. Refrigerant charge cannot be adjusted correctly without proper air flow. The ability to dehumidify and cool is affected by air flow. Most don't test because they size by rules of thumb and testing would show the system wasn't design properly. I would add that pay back is focused on to much. The added comfort, system reliability and durability, plus the energy savings all should be considered. You could have your duct work installed for a zone system with only the dampers installed to manually adjust the system and add zone control later. A duct blaster test can be done in less than 2 hours, static pressure or flow plate are quick tests. Room CFM is quick also once the hood is set up. "If they do it right" has always been the problem, most don't do it right and the consumer is none the wiser (but they saved money not using the over priced guy that actually designs his systems). And while you are on the subject of leakage has your house been tested for air leaks? Up to 30% of your energy for heating and cooling can be from infiltration through the house.

    If you don't test it's just a guess!
    I just returned from meeting the installer and I have signed the contract. I'm glad I had the old duct system tested to show the leakage rate as it, in the end, proved what I suspect in that I needed new duct work. I say needed because leaks perhaps could have been repaired through proper sealing. Load calculations demonstrated that I was grossly undersized in many of my flex duct lines from the old system.

    New system will be completely new from top to bottom. The system will not be zoned. I ended up going with a 2 stage 16-17 SEER AC and 2 stage variable speed furnace as the pricing worled out well enough that I decided to bite the bullet and go for it, even though we are now severely over budget. I could have gotten a different system ( different installer 0 using a zoned system for about the same price but in the end it came down to the comfort level I felt with this installer as well as the belief that when we get done I will have a properly designed , installed and tested duct system. The other installer may very well have done the same ( without the testing part ), but my comfort level there wasn't as high. So, I traded zoning for gut feeling trust with regard to the ducts being done correctly and verified to a standard ) 2% or less of duct leakage ).

    He also will perform more measurements on both in leakage and out leakage from the house. He has already found some areas for out leakage that I need to fix. I realize there is no free lunch and these leakage tests are part of the cost. Zoning the bonus room would have bene nice from a perspective of having diff temps in that room from rest of upstairs but I couldn't afford both the zoning and all the other testing. I'll be fine with it.. already know the new system will simply work so much better than what I have now.

    I owe many of you here my gratitude and appreciation for you helped in many ways. At times I felt I had become too educated, but am glad that happened. In a few eeeks we'll have anew system and no doubt this summer won't be sweating our rear ends off. In the end that's what counts Course I may need a second job to pay for things and just hope they have good AC there, too! Now I need to call the other installers back to let them know they aren't getting the contract!

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Post before and after pics.
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  11. #11
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
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    415
    It sounds like you will be well served. Take some pictures so we can rip on them! Just kidding but do update us. If the price is expensive see if they have financing, it can help, remember this is a long term investment. Make sure you put in a good filter (4 inch merv 8+). Not to add confusion but what is the EER, that is more telling of efficiency between units.

  12. #12
    Join Date
    Dec 2007
    Posts
    132

    Thumbs down

    WOW ,
    sounds to me like your worries of leakage might have taking all your focus and energy and shortsticked your system,Why would you install an 80% afue furnace that is going to far out weigh a little duct leakage witch could have been easily settled with requesting all duct to be sealed with mastic sealer.Now instead of a nice variable speed 95% afue furnace ,and further more like stated above it does not matter how tightly the duct is sealed if your house is a leaking mess , have a blower door test 9 times out of 10 an energystar rep will perform these and will all tell you if the air is leaking out of the duct witch is inside the home , how fast is the air leaking out of the home is the problem, Bottom line is I see this all the time the home owner gets so focused on one little aspect of something they loose the big picture and the first SALESMAN to satisfiey that little worry sells a whole less system and charges more but the customer thinks they are getting a great deal because they a taking care of the concern they have in this case a 10 duct pressure test and make it sound like a huge deal and charge you out the ass for it, good luck enjoy the gas bill

  13. #13
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    Dog I completely disagree with you. The duct system is the most neglected part of installs that directly affects performance. I wish every consumer knew how important proper duct design is, especially on AC and HP performance. Being a HERS rater myself and helping home owners and builders build Energy Star homes I am well aware of the envelope leakage issues and duct leakage causing pressure problems in the house. Testing ducts and air flow problems make you more aware of bad design. I often tell people here to have an energy audit before changing equipment to provide them information to make smart equipment upgrades. I don't believe the extra money for a 95% furnace is warranted in North Carolina with 3200 HDD, a heat pump would be a good choice. The "box changers" are the ones who neglect the ducts because they don't understand it or don't care... low bid. It is good business to address the customers concerns.

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