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  1. #11
    Join Date
    Dec 2007
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    Tennessee
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    1,381

    Default Re: HVAC options for addition

    Have you considered using vaulted trusses instead of a conventional cathedral roof? You could keep the same 12' ceiling height but you would have a slightly higher roofline. This could be cheaper. It certainly would be more energy efficient and it would give you space for conventional ducts.

  2. #12
    Join Date
    Jun 2012
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    81

    Default Re: HVAC options for addition

    i am still looking into the fake beam and rafters. she isnt sold on it.
    i had a truss company look into scissor cathedral truss but due to the design limitations on the project they are not feasable. there are window limitations on the side of the house where the addition is going that the new roofline needs to come under. the roof on the front half of the addition has a ridge beam run ning north-south and then the roof turns over the back half with this ridge beam tying into the middle of the north-south ridge running east-west leaving 2 small valleys.... hope this made sense. in short the roof turns 90* at the half way point. i dont have the space alloted for an indoor system and i cant put it in the free vally sections in the attic where the roofs tie together because there isnt enough space for the code to allow it.......
    my original design had a stand alone a-c and heat pump deal but i was talked out of that and steered towards split systems. she likes them after spending time in with her sister who had them running thru thier complete small home...... now i am trying to determine the proper ones to get but all sites steer you to a contractor that installs them but only want to do turn key install and not DIY labor-grunt work. so i have been trying to figure out which one to use and the size for my application...

  3. #13
    Join Date
    Dec 2007
    Location
    Tennessee
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    Default Re: HVAC options for addition

    I believe I see your point. You don't want to use the trusses because that would raise your roof line higher than the existing roof. I've seen that done and I have always thought it looked ugly, but I have even seen it in new construction and wondered what are they thinking.

    It is looking like mini splits are fast becoming your best alternative. You might find that a turnkey is the best way to go during construction. It shouldn't be to expensive if you have all the framing done so that all they have to do is install, then you do the finishing.

    Here is one last though, sacrifice the cathedral ceiling in the closet if the closet wall shares a section of wall with each or the other rooms and put the air handler and ducts up there. Who looks at the ceiling in the closet, you could probably lower the closet ceiling to 7' if the closet is along a short wall.

  4. #14
    Join Date
    Jun 2012
    Posts
    81

    Default Re: HVAC options for addition

    keith- you are thinking on the same path as me.
    the truss idea is also problematic with how the roof turns for tie ins....... i am looking and have been looking at the closet cieling for an air handler. problem is that this area is in the lower section of a valley of the 2 roof sections and there isnt enough clearance in the joists to suit the inspectors interpretation of "Clear" adequate path for service. they require a wide walkway and platform and clear space around said unit. i drew it and had others draw it and the cileing would have to be ridiculously low to clear the rafters above and it would still be too close for all side isues....

    the mini splits are looking clear. now i need to determine size of required unit(s) and manufacturer.....

    thanks!

  5. #15
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: HVAC options for addition

    There is one other option I mentioned in another post yesterday if you are still open to the lower closet ceiling, that is an all-in-one, AKA gas pack. This may not get past the committee though as it isn't the prettiest solution. An all-in-one has all the airhandling outside in one unit and the ducts go through the wall. This is very popular down here where I live. I have one. They can be natural gas, propane or heat pump. I don't know if there are oil fired units available.

    Normally these are used with conventional foundations so all the ducts are under the house, but I have seen one used on a slab. They ran the trunks up the side of the house and into the attic. In this case, the trunks were not covered so they looked ugly, to say the least. At least they painted them with the house color.

    You could build a false chimney to hide them, but that only solves half the problem. The other half is the return. This would have to be located in the exterior wall next to the unit and that is where the air filter would be housed, in a grate in the wall. You can paint the grate to match the wall so it blends a little, but there isn't much else you can do to hide it short of a piece of furniture in front of it.

    The reason these are so popular is that they are cheap, about $3k for the unit installed. You will have to add the ducts, but they are bonehead simple to install. You can use insulated flex duct off the trunk in the attic over the closet, they are only about a foot in diameter, 8" ID and 2" insulation.
    Last edited by keith3267; 08-02-2012 at 12:08 PM. Reason: spelling

  6. #16
    Join Date
    Jun 2012
    Posts
    81

    Default Re: HVAC options for addition

    my inspector said he would look at the height issues after i have my framing in so he can verify one way or the other on space issues but he doesnt think anything will work in the limited attic........

    any split ideas or solutions?
    thanks

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