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  1. #1

    Heating duct size

    I'm very much uneducated with HVAC systems etc...my husband and I just bought a house (2 stories, 4 bedrooms, 3 bathrooms, one big open area for kitchen/living room) that's about 1800 sq. The sellers of the house, who bought the property, expanded and rebuilt it, had installed a new 70,000 BTU furnace, however, the heat is really only reaching 2 of the upstairs rooms (those located directly above the furnace).

    The duct pipes are only 6"...i had 2 plumbing/heating experts in to look at the situation, both of whom said for a house of this size, 12" pipes at a minimum were required, and that 6" pipes were for 1-bedroom apartments...they also said the guy who installed the pipes was a total idiot for using them.

    I'm located in San Francisco...it seems to install proper sized ducts will be verrrrrry expensive. Does anyone know if there is a city code specifying minimum sized ducts? Trying to see if they didn't build to code (there were zero permits filed with the city) so that we can go back and try to get them to pay for redoing.

    Any thoughts/advice would be much appreciated!

  2. #2
    Join Date
    Feb 2011
    Location
    chicago il
    Posts
    48
    how many supply on sec floor? Are each feed with a 6'' duct from the furnace? do you have return on sec floor.

  3. #3
    Join Date
    Feb 2011
    Location
    chicago il
    Posts
    48
    where is furnace located ?

  4. #4
    Hey kfritz...yes, the return is on the second floor...not sure what you mean by feed or supply? there are vents in each of the upstairs bedrooms (that get almost all of the heat) and ONE for the very big room. I'm not exactly sure where the two pipes coming our of the furnace (there are 2 6' pipes) go to, but judging from the total lack of heat in the downstairs bedrooms i would suspect not there

  5. #5
    Join Date
    Feb 2011
    Location
    chicago il
    Posts
    48
    WHEN I SIZE A DUCT SYSTEM I will run 6'' or 7'' supply duct to each vent. some rooms depening on size might get more than one supply. this is base on a heat load calculation. I will install return in each room. sizing the furnace for right btu and cfm is vary inportant. I don't know how you would go about getting it fix for free. I would start by talk to the seller of the house. good luck.

  6. #6
    I don't know how or if we can get it for free either, but we plan on talking to sellers. One heating expert told us there no way the city should have even approved it so who knows

  7. #7
    Join Date
    Feb 2010
    Location
    Cal
    Posts
    1,596
    California Building Code, section 1204.1, requires that heating systems be able to maintain 68f in habitable spaces. Interpret that how you want. Distribution systems, designs or methods are not regulated by adopted state codes, only system capacity and it's calculation.

    Mechanical budgets are often robbed to subsidize kitchen and bath bling. Home inspectors don't have the time or background to size up system capabilities. Pre-sale due diligence on mechanical confirms equipment existance and thats about it.

  8. #8
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,660
    Quote Originally Posted by jberm2000 View Post
    I'm very much uneducated with HVAC systems etc...my husband and I just bought a house (2 stories, 4 bedrooms, 3 bathrooms, one big open area for kitchen/living room) that's about 1800 sq. The sellers of the house, who bought the property, expanded and rebuilt it, had installed a new 70,000 BTU furnace, however, the heat is really only reaching 2 of the upstairs rooms (those located directly above the furnace).

    The duct pipes are only 6"...i had 2 plumbing/heating experts in to look at the situation, both of whom said for a house of this size, 12" pipes at a minimum were required, and that 6" pipes were for 1-bedroom apartments...they also said the guy who installed the pipes was a total idiot for using them.

    I'm located in San Francisco...it seems to install proper sized ducts will be verrrrrry expensive. Does anyone know if there is a city code specifying minimum sized ducts? Trying to see if they didn't build to code (there were zero permits filed with the city) so that we can go back and try to get them to pay for redoing.

    Any thoughts/advice would be much appreciated!
    I'm totally confused. How many rooms are there on the 2nd floor? How many registers in each of those rooms? Are you saying that (to your knowledge) there are only 2 - 6" supply pipes for the entire 2nd floor?
    Are the 2nd floor registers in the floor or ceiling?

  9. #9
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    Quote Originally Posted by jberm2000 View Post
    I'm very much uneducated with HVAC systems etc...my husband and I just bought a house (2 stories, 4 bedrooms, 3 bathrooms, one big open area for kitchen/living room) that's about 1800 sq. The sellers of the house, who bought the property, expanded and rebuilt it, had installed a new 70,000 BTU furnace, however, the heat is really only reaching 2 of the upstairs rooms (those located directly above the furnace).

    The duct pipes are only 6"...i had 2 plumbing/heating experts in to look at the situation, both of whom said for a house of this size, 12" pipes at a minimum were required, and that 6" pipes were for 1-bedroom apartments...they also said the guy who installed the pipes was a total idiot for using them.

    I'm located in San Francisco...it seems to install proper sized ducts will be verrrrrry expensive. Does anyone know if there is a city code specifying minimum sized ducts? Trying to see if they didn't build to code (there were zero permits filed with the city) so that we can go back and try to get them to pay for redoing.

    Any thoughts/advice would be much appreciated!
    12" Supply runs for probably a 4X12 boot, who are the idiots here?! The so called "experts" you hired to look at the ductwork aren't really experts. I would suggest finding a reputable company to come out and look the system over. 6" and 7" supply runs are very common, much more common than 12". It's possible there should have been more than one supply in the room depending on it's size, but I highly doubt a 12" run is going to solve the problem, let alone fit.

  10. #10
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,660
    Quote Originally Posted by big sky hvac View Post
    12" Supply runs for probably a 4X12 boot, who are the idiots here?! The so called "experts" you hired to look at the ductwork aren't really experts. I would suggest finding a reputable company to come out and look the system over. 6" and 7" supply runs are very common, much more common than 12". It's possible there should have been more than one supply in the room depending on it's size, but I highly doubt a 12" run is going to solve the problem, let alone fit.
    Big (Sky) Country,

    I'm reading this as a 12" riser to feed the 6" (2nd fl.) supplies, but who knows.

    People need to re-read what they write. I can't make heads or tails of this.

  11. #11
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    Quote Originally Posted by George2 View Post
    Big (Sky) Country,

    I'm reading this as a 12" riser to feed the 6" (2nd fl.) supplies, but who knows.

    People need to re-read what they write. I can't make heads or tails of this.
    I read it as "pipes" so I assumed it was the runs themselves, but who knows.

  12. #12
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,660
    Quote Originally Posted by big sky hvac View Post
    I read it as "pipes" so I assumed it was the runs themselves, but who knows.
    It did sound like seperate pipes to me at first, but then they talked about a 12" supply? What register boot is that going to fit? We'll see.

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