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  1. #27
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,824
    Your getting close.

    We're now talking about two different systems at the same time, so its getting confusing, atleast for me.

    1190 cfm is too low for 4 tons, it'll freeze pertty quick.

    I'll have to lok at the chart you did, to get my bearings.

    But trust me, the coleman 4 ton packeage is moving alot more air.


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  2. #28
    Join Date
    Jun 2005
    Posts
    178
    oh ok its 1400 at 0.1 static pressure.

  3. #29
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Presuming your looking at M1MC models.

    4 ton is the max it can handle, and you would have to evaluate the duct work first before you installed a 4 ton unit on it.

    Keeping in mind that it has no return duct, it can have a higher static on the supply side.

    As you just saw, there are multiple cfm ratings on it, the same as any funace.




    Its getting too late for this.
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  4. #30
    Join Date
    Jun 2003
    Posts
    16
    hey thanx for all the replies just to clear things up this is a 4 ton package unit with a 14" return and a 12" supply and rated at .45 external static the existing return is 12" with a 12x20 return floor box and i am going to put in a 14" return and then i want to move the supplies to the middle of the trunk (someone called it a gull wing) i think it will be able to move more air if i do that right now i am getting less than 800 cfm out of the unit

  5. #31
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Rated at .45 ,do you have the fan chart,or is that just printed on the unit?



    How do you know you are only getting 800cfm,by what method ?


    The Gull Wing is a diverter you can install in the trunks to help the air turn.Sheet metal ,like a "V" but with some "curve" to it.You can actually make it out of the 'Round " piece you cut out of the duct to tap the flex in.

  6. #32
    Join Date
    Jun 2003
    Posts
    16
    the book on the unit stated the static pressure .45 as for the 800 cfm I used my alnor annamometer to measure the air flow at the ducts and the return and the number (velocity and duct size = cfm)I got using a ductulator do you think I can deliver more air If I connect the supply in the middle of the duct instead of the end.

  7. #33
    Join Date
    Oct 2003
    Location
    southern mo.
    Posts
    323
    you might wanna go to a 14x20 return yours is a tad small,does your home have a gas furnace also?if so make sure theres a damper under it,if you feel cold air comeing out of the furnace youve got problems.the mobilehome fellas sell install fittings for your supply lines that have dampers in them to keep your furnace from blowing thru your a/c,they dont cost much if you need them,its amazeing how well these systems can work when installed right .

  8. #34
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Connecting in the middle will increase you air flow.

    But, at 4 tons, I think your moving more then 800cfm, unless you got 80% humidity in the house.
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  9. #35
    Join Date
    Jun 2005
    Posts
    178

    Hmm

    wow your right i have neve seen one of those units and i hope i dont because it sounds really confusing.that system has a seperate furnace from the ac unit.i thought it was all one unit with an a coil in it

  10. #36
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Aound here they're very common.

    They're easy to work on.
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  11. #37
    Join Date
    Jun 2003
    Posts
    16

    Smile

    well we have success I just want to thank everyone for the help on this subject this is what I did

    I changed the 12" return to 14" and then I moved the supplies to the middle of the 10x5 trunk lines and this is my results

    the return 12x20 ductbox I have an avrage of 900 fps.

    In the return duct 14" I have 1500 fps.

    at the registers 10@ 4x8 I have an average of 700 fps.

    I think I am moving about 1200 to 1500 cfm of air.

    I have called a a/c company to come out to check the charge now cause I think the charge is alittle low now that I am moving twice as much air

  12. #38
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Congrats.

    It might be alittle over charged, now that your moving more air. If you ever had it serviced, they might have added gas to try and get the suction pressure up.
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  13. #39
    Join Date
    Jun 2003
    Posts
    16

    Confused

    well I had a a/c company come out and check my charge this is
    what he told me:=28
    ambiant temp 84 deg.

    suction pressure 52 psi.
    liquid pressure 215 psi.

    I asked him what the superheat was and he wrote this down

    72(line temp)- 28deg (52psi line pressure) = 44 superheat

    he told me that that was a little low but the outside temp is almost winter here and if he adjusted it to what it should be he said that when it heats up to 95 the charge will be over and I will be calling him back.

    that call cost me 85.00

    I had a friend from work that does a/c come out this morning and he charged the system to:

    ambiant temp 85 deg.

    suction pressure 65 psi.
    liquid pressure 265 psi.

    I asked him what the superheat was and he wrote this down

    52(line temp) - 38deg (65 psi line pres.) = 14 superheat

    do you think the first guy was right when it get's hot will this all change and it will be overcharged..


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