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  1. #1
    Join Date
    Sep 2005
    Location
    Chicago
    Posts
    2

    Hmm

    A friend and myself are doing a full gut-rehab on an 1890 greystone in the city of Chicago. This is a 5500 square-foot home. We are putting two forced air heating systems into the house. We do not want any extremely large returns in the house. We would prefer a bunch (perhaps equal to the # of supplies) of returns vs. a few very large returns. Our HVAC contractor basically told us that a few centrally located large returns = a better system than the system that we are propossing. This is basically new construction, everything is currently ripped out.

    Any thoughts on this would be much appreciated. E.g does it basically come done to cost (a bunch of returns = more $ than a few centrally loacted returns)? Also, which system would be better (for the most part) a bunch of smaller returns all over the house OR a few (large) centrally located returns?

    Thanks,
    Mike

  2. #2
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,968
    Not quite clear Mike, from your post exactly who is doing what.

    Don't know if it was your idea or the contractor's to do the two forced air furnaces in the home. If his, then I would defer to him (your contractor) to make the correct recommendations for the most efficient air distribution.

    Not having the luxury of seeing the job, it is difficult if not impossible to say what you should have, and what can realistically be put into the home.

    You talk about the system 'you are proposing.' Is this contractor just following your recommendations and doing what you want done, or is he offering any input of his own?

    When all is said and done, he is going to be responsible for the system (right?) so I would allow him to do what he has determined is best for the system and the house.

    How much do you trust this contractor? Do you trust his judgement?

    I realize more questions than answers, but hopefully you can appreciate the fact, the he is there, and we are here, and 'all things considered' we can't make the call.

    We can make generalizations regarding air distribution, but if they don't apply to your system and your home, we could inadvertently give you incorrect advice. That would certainly not do you any good.

    Sounds like a big project. Hopefully you are using a licensed and insured contractor that provided you with a ton of references, and is pulling the necessary permtis for inspection of his work upon completion.
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

  3. #3
    Join Date
    Apr 2004
    Location
    Bartlett, IL
    Posts
    6,619
    Bunch of returns = more materials = more $$$

    A few large returns = less materials = less $$$

    As long as the returns a properly sized it does not matter.


  4. #4
    Join Date
    Sep 2005
    Location
    Chicago
    Posts
    2

    More Info

    Thanks for the reply, I suppose my initial entry does create a situation for more questions than answers and unfortunately I am not sure if this additional response of information will improve the situation for anybody.

    But here goes. I guess I am mostly wondering why the houses that I (and my friends) grew up in didn't seem to have these large (sometimes 24" x 36") returns that I seem to see so often in new construction today (especially in condos, but I have even seen them in $1,500,000 new construction single family homes [certain areas of Chicago have very high priced homes]). I find them to be unattractive and often noises. I would like a situation where most bedrooms and main living area rooms have an equal number of supplies and returns (and be about the same size for the most part).

    Unfortunately this HVAC contractor bid off of our architectural plans (everything is permitted correctly). However, our architect told us that he would create a system that would get approved but that in the field the HVAC contractor would undoubtedly make numerous necessary alterations. His quoted price was based on those plans (we received 4 written quotes and went with this particular one [he was the second least expensive, but installed Carrier which is what we wanted). Apparently our architect put in a few centrally located returns (?). However, I can assure anyone reading this that our architect (a college buddy) knows very little about HVAC systems (vs. what an HVAC contractor would know). I hope that makes sense. I think our HVAC contractor bid a system with a few central returns and now that he has met with us and found out that we want numerous small returns he is not too happy about the change. If it just means x% more $ that will be fine.

    I guess I just think that today’s systems tend to use these large centrally located returns not because they have too, but because they are less expensive to install; and with all of the increased residential construction that has been going on the past 5-10 years more systems installed = more revenue for the HVAC firms, but they are not necessarily "better" systems than the ones that include systems with more (small) returns. I guess that I can really babble.

    Given a system with a few centrally located large returns, what happens when you close a door to a room that just has a supply (and no return), that doesn't sound like a very balanced system?

    Also to answer some of your questions specifically:

    1) It was our idea to do the two forced air furnaces. This was based off of many consultations with other (knowledgeable) people. We have been doing this project for 2+ years. Based on our realtor the home will be listed for about $2,300,000.

    2) The system that we are propossing is simply to put in NO large returns and just numerous small returns. This is based off of our walking through many open houses of similar projects and seeing what we didn't like and what we'd like to do differently.

    3) I do trust the contractor, I trust his judgement; but I don't want him to think only with regard to $ (if that is the major reason he is wanting to install systems with a few large returns). I have no problem with him rebidding the quote; I am just wondering if this is even necessary.

  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Every room ,except baths and kitchen,needs a return or a return "path" for the supply air to get back to the furnace,when the doors are closed.

    The return "path" can be under the door,if the door is cut a inch or so above the flooring,this often is not enough,can't tell from here.So a pass-thru return,openig from the room to the area of the central return is located.


    Without a return or a return "path",the supply air pressurizes the room,causing exfiltration of conditioned air.At teh same time the areas with central reurns become depressurized,causing infiltration of unconditioned air.


    More returns,more cost,more restrictve duct system so ducts sizes become larger ,if designed properly.

    It's generally accepted the ducted returns are the best way to go.There is nothing wrong with central returns,IF there's a return "path",from each room.

  6. #6
    Join Date
    Nov 2003
    Location
    northern mass
    Posts
    411
    You need to sit him down and go over this with him.

    It might be an issue of $$. Or, it might be an issue of accesability to routing ducting for the returns. Who knows without seeing. Maybe it's just a matter of less work for him to do.

    Central returns are ok in the right situations. I myself try hard to stay away from them.

    I try to put as many returns in as I can. I always try to put high returns in cathederal rooms and the like. And I make sure that Masters have returns as well. After that I see what I have left for return needs and divide it up amongst what's left. I hope for each bedroom, a hallway, and whatever space needs one. Sometimes it's hard or imposible, but then you have to make sure the air can be pulled from a neighboring room.

    I find central returns to be usefull in single large room systems, or garage systems, or something of that nature.

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429

    Exclamation Multiple Returns

    Originally posted by dash
    Every room ,except baths and kitchen,needs a return or a return "path" for the supply air to get back to the furnace,when the doors are closed.
    Dash KNOWS! ....

    Actually, several returns is essentially FL State Law
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836

    Re: Multiple Returns

    Originally posted by dan sw fl
    Originally posted by dash
    Every room ,except baths and kitchen,needs a return or a return "path" for the supply air to get back to the furnace,when the doors are closed.
    Dash KNOWS! ....

    Actually, several returns is essentially FL State Law

    Today it is ,but you know how many bad jobs are out there, as well as I do.

  9. #9
    Join Date
    Jan 2002
    Location
    East Grand Forks, MN
    Posts
    1,375
    We would prefer a bunch (perhaps equal to the # of supplies) of returns vs. a few very large returns. Our HVAC contractor basically told us that a few centrally located large returns = a better system than the system that we are propossing.

    So many contractors are of the same ilk, low ballers..low quality work.

    Bunch of returns = more materials = more $$$

    A few large returns = less materials = less $$$


    See. What about quality work from top-notch company.

    It was our idea to do the two forced air furnaces. This was based off of many consultations with other (knowledgeable) people. We have been doing this project for 2+ years. Based on our realtor the home will be listed for about $2,300,000.

    For a house like this, i would give the best value, matter of fact, i always do; no matter what the value a house is.

    Every room ,except baths and kitchen,needs a return or a return "path" for the supply air to get back to the furnace,when the doors are closed.

    A real professional, a company that does detail work, would do this. Many of my competitors just don't seem to care.

    I suggest, Watch out for unconcern HVAC contractors that ignore customers for money.


  10. #10
    Join Date
    Nov 2003
    Location
    northern mass
    Posts
    411
    Which is where we run into problems as contractors. We try hard to do the best job we can, but that in turn lends to higher material costs. So, home owners, only seeing #'s from quotes, just assume we are high priced.
    When in fact it is simply a matter of higher costs due to higher quality materials ans labor.

    The "low-ball" guy has worked it out over the years so that he has the cheapest of everything, from equipment to tape. He most likely has the bottom of the line help as well.

    In the end, I wonder if they (low-ball) might even make more money ?


  11. #11
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304

    Return paths?

    Being an old Chicago house, I wonder if this one has transoms which could allow air to exit from a closed room, if there is not a return built in that room. Also I wonder if there are space constraints which inhibit (probably not prevent) having the larger number of returns you wish.

    What I hear about best new-construction practices is ideally any room with a closable door and a supply duct, should have a return. Excepting the kitchen and bathrooms. Generally that translates to a return in each bedroom plus a central one or two. Of *course* that costs more than one big central one, and it's seldom implemented.

    You might benefit from reading this article on pressure balance in houses:
    http://www.tamtech.com/PDF/R.A.P.%20...L.%2008.02.pdf

    Has anyone on your HVAC team done a Manual D analysis? If not them maybe you should get one done, even if it means changing HVAC contractors. I am operating on the idea that if they shun doing this calculation, then you will get less of a professional job in the end.

    BTW I am a homeowner in S.Texas so what I learn by osmosis is likely not to apply in Chicago. But the laws of physics are the same here and there, and should be respected.

    Best of luck -- P.Student

  12. #12
    Join Date
    Feb 2005
    Posts
    249
    Originally posted by mike8743
    This is basically new construction, everything is currently ripped out.


    Thanks,
    Mike
    I would thing they could do whatever they want ,based on the above info..

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