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  1. #1

    Excessive air from floor registers-new furnace

    I am new to the forum and looking for some advice. I usually find good information on forums of this kind and have received much help on other unrelated stuff. I had my house remodeled a few months ago. The furnace was replaced as the old one was 25+ years old. My home is 2000 sq. ft. single level (Ranch style) built in 1959. I have installed double pane windows through out and the house is insulated. I live in California on Monterey Bay. The climate here is very temperate; the temperature gets down to the low 30's a handful of days a year.
    The contractor installed a RUUD Achiever Series Super Quiet 80 AFUE downflow furnace (UGLN-12NARJR-125). This is a 125btu unit with a 3/4 Hp motor. The flow of air from the floor registers is very loud and excessive. It blows the drapes around, have to turn up the TV volume each time it comes on, etc. I had a tech come in and reset the heating blower speed to low but it hasn't helped. The tech explained that the 125kBTU 5Ton unit was oversized and recommended a 100K 80% 4 ton replacement. The contractor has agreed to reinstall a smaller unit. I am looking at the spec sheet and thinking about replacing it with a RGLN 10NAMER 1/2 Hp motor unit. I want to educate myself and make sure the job gets done right this time. Am I on the right track?

    Thanks,
    Mark

  2. #2
    Join Date
    Oct 2001
    Location
    Vancouver Island BC Canada
    Posts
    152
    Did your contractor provide you with a heat loss calculation for your home based on the design temperature for the area in which you live? If he did not, I would start there otherwise you are going in blind. Proper duct design and or improvement to existing duct work should have also be a consideration to meet the temperature rise specification set out in the manufacturers installation instructions. Good luck

  3. #3
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    Quote Originally Posted by 65hdtp View Post
    I am new to the forum and looking for some advice. I usually find good information on forums of this kind and have received much help on other unrelated stuff. I had my house remodeled a few months ago. The furnace was replaced as the old one was 25+ years old. My home is 2000 sq. ft. single level (Ranch style) built in 1959. I have installed double pane windows through out and the house is insulated. I live in California on Monterey Bay. The climate here is very temperate; the temperature gets down to the low 30's a handful of days a year.
    The contractor installed a RUUD Achiever Series Super Quiet 80 AFUE downflow furnace (UGLN-12NARJR-125). This is a 125btu unit with a 3/4 Hp motor. The flow of air from the floor registers is very loud and excessive. It blows the drapes around, have to turn up the TV volume each time it comes on, etc. I had a tech come in and reset the heating blower speed to low but it hasn't helped. The tech explained that the 125kBTU 5Ton unit was oversized and recommended a 100K 80% 4 ton replacement. The contractor has agreed to reinstall a smaller unit. I am looking at the spec sheet and thinking about replacing it with a RGLN 10NAMER 1/2 Hp motor unit. I want to educate myself and make sure the job gets done right this time. Am I on the right track?

    Thanks,
    Mark
    The size of the furnace just blows me away. I have a 2500sq. ft. home in Montana, and I'm replacing my 17 year old, 100K Whisper Heat to a 90K, SLP98V. Did they perform a load calc. to verify what size furnace you need? Do you have A/C? What size A/C do you have? What kind of condition is your ductwork in? Do you know how many cfm's your ductwork can handle? I think you need to get several of these questions answered BEFORE you replace the furnace with a still oversized unit.

  4. #4
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    The noise is most likely a combination of two things - The furnace is oversized, and the ductwork is undersized. Modern furnaces achieve their high efficiency partly by higher airflow rates. Hence, a duct system designed for an older furnace with a higher temperature rise and lower airflow will likely not work well with a modern replacement high efficiency furnace. Get the furnace sized properly and then see if your ductwork is suitable.

  5. #5
    Join Date
    Jan 2010
    Location
    Athens GA
    Posts
    1,234
    The question is are you on the right track?
    The answer is NO.
    What you are doing is putting less thought into buying a furnace than youn have put into buying a pair of shoes.
    When buying a pair of shoes you have your foot measured.You take into consideration the type of sock you are wearing or going to wear.You do this without ever imagining that whatever you pick out you will be wearing for twenty years.
    What you NEED is a complete heat load and a/c calculation.Then you need to look at the type sock errr duct system you have.
    These are done using a manuel J and a manuel D load calculation.Then you can talk about what furnace will provide the best COMFORT for you.
    This is the ONLY way you can be sure of what you need.
    By looking at what uinfo yopu have provided I would guess you need an 80,000 furnace but I'm 1000 miles away .
    Do yourself a big favor and do it right.

  6. #6
    Join Date
    Jan 2008
    Posts
    2,030
    You could heat 3 homes your size with that furnace in your climate.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  7. #7
    Thanks for all the replies. The furnace that was installed by the remodeling contractor who I trusted to choose the appropriate unit is actually a 125K/80% BTU unit. I don't have A/C as it isn't generally needed in our area. The duct work looks to be 6" in diameter. I did have a technician from a well known business here look at the system and he recommended an 80K BTU unit. I am not sure of his calculations but he spent some time with it. I am meeting with the contractor in an hour with another HVAC tech to talk over the options. I will post what comes of it later today.

  8. #8
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    Quote Originally Posted by 65hdtp View Post
    Thanks for all the replies. The furnace that was installed by the remodeling contractor who I trusted to choose the appropriate unit is actually a 125K/80% BTU unit. I don't have A/C as it isn't generally needed in our area. The duct work looks to be 6" in diameter. I did have a technician from a well known business here look at the system and he recommended an 80K BTU unit. I am not sure of his calculations but he spent some time with it. I am meeting with the contractor in an hour with another HVAC tech to talk over the options. I will post what comes of it later today.
    There's a big difference between 125K BTU and 80K BTU. Hopefully somebody will take the time to do a load calc. to determine what your home actually needs. I'm not familiar with what the winter temps. are where you live, but I don't believe they're colder than where I live and 125K BTU would have been oversized here for the size of home you have. Good luck.

  9. #9
    Join Date
    Jan 2011
    Posts
    64
    I agree with everyone else. You are WAY oversized. There are plenty of simple load calcs that can be used online. Do a search on google. 100k is still way to big, in my opinion.

    Here is an example. I have a 2000 square foot home. No insulation in the walls, 16" in the attic, and new windows. It's 10 degrees F here today. I sized my furnace on the first floor to run almost all the time on low stage heat on a day like today (makes the temp swing much more even and comfort level is much higher). Low stage is 30K btu and high is 45k BTU. Your furnace is almost 3 times the size of mine

    Also, electrical efficiency and somewhat the same for gas efficiency drops greatly by severely oversizing a unit.

  10. #10
    The contractor and the HVAC tech just left. They went over the system calculating the size of the house, window space, measuring the duct work above the ceiling and the floor ducting, etc. The temps here, a quarter mile from the ocean, are very moderate, usually between 50 to 75 degrees night/day temps. They agreed that the unit is way over sized which is trying to move too much air through the system. The plan is to install a 100k unit with a 80K BTU effective heat output with a 4 ton blower or a two-stage unit of the same size to make the best fit for the duct work that is in place. No cost to me. The existing duct work is in good shape. I will post the final outcome once the work is done. Thanks for the good advice, I felt much better going into this prepared with the facts and info from the replies.

  11. #11
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,485
    Quote Originally Posted by 65hdtp View Post
    The contractor and the HVAC tech just left. They went over the system calculating the size of the house, window space, measuring the duct work above the ceiling and the floor ducting, etc. The temps here, a quarter mile from the ocean, are very moderate, usually between 50 to 75 degrees night/day temps. They agreed that the unit is way over sized which is trying to move too much air through the system. The plan is to install a 100k unit with a 80K BTU effective heat output with a 4 ton blower or a two-stage unit of the same size to make the best fit for the duct work that is in place. No cost to me. The existing duct work is in good shape. I will post the final outcome once the work is done. Thanks for the good advice, I felt much better going into this prepared with the facts and info from the replies.
    It's probably still way oversized. You do realized that this is only a 20% decrease from 125 to 100, right?

    Some people never learn.

  12. #12
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    Quote Originally Posted by 65hdtp View Post
    The contractor and the HVAC tech just left. They went over the system calculating the size of the house, window space, measuring the duct work above the ceiling and the floor ducting, etc. The temps here, a quarter mile from the ocean, are very moderate, usually between 50 to 75 degrees night/day temps. They agreed that the unit is way over sized which is trying to move too much air through the system. The plan is to install a 100k unit with a 80K BTU effective heat output with a 4 ton blower or a two-stage unit of the same size to make the best fit for the duct work that is in place. No cost to me. The existing duct work is in good shape. I will post the final outcome once the work is done. Thanks for the good advice, I felt much better going into this prepared with the facts and info from the replies.
    You've got to be kidding me! A 100K furnace with a 4 Ton Blower, for a 2000sq. ft. home in California with temps in the 70's during the day and 50's at night, really?!?! That's like wiping before you poop, it just doesn't make sense!!! I think you need to get another company out there, get some more opinions BEFORE you commit to anything. Why do you need a 4 Ton blower if you don't even have A/C? With those mild temps, I'd be more inclined to install a heat pump than an oversized furnace. You say you don't really need A/C, but I bet there are times you wish you did. I'm guessing that all you really need is a 70K-90K furnace(depending on brand), with a 3 Ton blower and maybe a 2.5-3 Ton heat pump. I'm just guessing because I haven't seen your home or all the other variables that go into a load calc., but I think you're still going to have noise problems and that furnace is way too big, IMO.

  13. #13
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190
    So you are going to change out the whole unit because the contractor can't install a volume damper to reduce the airflow or can't figure out what to do to reduce the noise coming from the unit? Is that about right?
    If this guy cant figure out the fix for the old unit, what makes you think the new 4 T box is going to be any better?
    Just asking is all!
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

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