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  1. #1
    Join Date
    Nov 2007
    Posts
    9

    Need Help with new heat pump system

    Dear All,

    I am about to replace my water to air heat pump. I have many questions and options. Any help would be greatly appreciated.

    So here is my story. I have a 2000 sq ft house in central FL. It presently has a 20+ year old 2 ton Marvair water to air heat pump in the attic. We never used it too much over the last 17 years in the house. I want to replace it with a regular air conditioner that is efficient enough to use it.

    I’ve been working on car air conditioners for years. I got EPA certified and bought a recycling machine. I have way too may tools so I could install it myself.

    I just had an estimate for a Bryant 15 SEER puron system to be installed by a very nice company.

    I had bought a used 3 ton 10 SEER system to install myself as a sort of test to see if 3 tons was sufficient. The base part of the house was 1400 sq ft. The 2 ton was probably great for it. A 600 sq ft addition was put on with lots of windows. The 2 ton barely keeps up and runs almost continuously.

    I need to install the line set if I install it myself but what size? The run will be 65 feet. The final system will be between 3 and 4 ton.

    So the first question is what size unit? I was originally thinking 3 or 3.5 ton. The pro thought it better to go to 4 ton. I’m afraid that it may be too big since we rarely cool the house below 80. I do like the idea of being able to cool the house quickly so if visitors show up we turn it on and keep them comfortable.

    Should I just go ahead and pay the $50 to get the one time heat load calc program and figure the size unit needed? Any ball park estimate for a 2000 sq ft house in central FL? It is a frame house with 19 single pane windows but I have awnings to keep out the sun. The program looked complex but it may be worth it since this is a rather large investment.

    If I install the used unit, will the line set need to be replaced when I put in the new, efficient system? With that long run, I was thinking of using 3/8 and 1 ¼. Do the new puron systems use smaller suction lines? I saw a chart that cautioned about too small a line and the 65 feet is rather long.

    I know I should probably let the pro put in the nice 4 ton Bryant but I’ve got all these tools.

    Any insight would be greatly appreciated.

    Thanks,
    Joe

  2. #2
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    384
    Well just from what you've told me, a 3.5 ton unit sounds sufficient. However a heat load calc would be the way to go inorder to get a proper idea of how many BTU's of cooling you require.
    For that, you need the total outside dimensions, how big each window is, how many windows there are, which walls are exposed to the sun, how many doors, and dimensions, how thick your walls and ceiling are, and types of lights, (incandesent, florescent) and there total wattage.
    Sounds like alot lol, but there not that bad to do, but i do them by hand, and i've done alot over the last few weeks.
    If your going to redo the system, you have to replace your existing line set. Each manufacturer has there own pipping recomendations, its best to follow there instructions.
    With the length of the line's you will have to add refrigerant, and the puron system, I do beleive is R-410A, so the operating pressures are 3 times gretter than an R-22 system.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,272

    Smile

    Quote Originally Posted by JoeFL77 View Post

    So here is my story. I have a 2000 sq ft house in central FL. It presently has a 20+ year old 2 ton Marvair water to air heat pump in the attic. We never used it too much over the last 17 years in the house. I want to replace it with a regular air conditioner that is efficient enough to use it.

    I just had an estimate for a Bryant 15 SEER puron system to be installed by a very nice company.

    I had bought a used 3 ton 10 SEER system to install myself as a sort of test to see if 3 tons was sufficient.

    The base part of the house was 1400 sq ft. The 2 ton was probably great for it. A 600 sq ft addition was put on with lots of windows. The 2 ton barely keeps up and runs almost continuously.

    The final system will be between 3 and 4 ton.

    So the first question is what size unit? I was originally thinking 3 or 3.5 ton.

    ... I’m afraid that it may be too big since we rarely cool the house below 80.

    Any ball park estimate for a 2000 sq ft house in central FL?

    It is a frame house with 19 single pane windows but I have awnings to keep out the sun. The program looked complex but it may be worth it since this is a rather large investment.

    With that long run, I was thinking of using 3/8 and 1 ¼.
    Do the new puron systems use smaller suction lines?

    I saw a chart that cautioned about too small a line and the 65 feet is rather long. Thanks, Joe
    BaLlPArK
    I was originally thinking 3 or 3.5 ton.

    Manual J needed:
    ... send me floor plans with R-value of ceiling / walls,
    windows sizes on each side of house
    & house orientation.
    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

  4. #4
    Join Date
    Nov 2007
    Posts
    9
    Dear Crazyforthenucks,
    Thanks for the reply!
    Those linesets... I was hoping to use the same lineset for the used Trane R-22 system as the new super efficient R410a system. I guess it would be best to change out the lineset because of the different oils to insure there isn't any problems.

    The heat load is going to be difficult to figure because of the addition. I'll attach a diagram in my next post.

    Thanks,
    Joe

  5. #5
    Join Date
    Nov 2007
    Posts
    9

    Thanks

    Dear Crazyforthenucks,
    Thanks for the reply!
    Those linesets... I was hoping to use the same lineset for the used Trane R-22 system as the new super efficient R410a system. I guess it would be best to change out the lineset because of the different oils to insure there isn't any problems.

    The heat load is going to be difficult to figure because of the addition. I'll attach a diagram in my next post.

    Thanks,
    Joe

  6. #6
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    384

    Talking

    Joe
    unfortunatly the old linesets wont work, any oil trapped in them from the old system wont mixwell with the new POE oil. Not to mention the POE oil doesnt run along the botom of the pipe like mineral oil, it mix's well with 410A and coats the entire pipe, picking up any carbon left from the original install, not a good idea.
    Ya a diagram would be great.

  7. #7
    Join Date
    Nov 2007
    Posts
    9

    My Crazy house diagram

    Here is a diagram. It is a bit confusing. I don't know the R value but I'll just descibe what I know about it. The orginal part of the house is 50 X 28. It has a hip roof with trusses and fiberglass insulation about to the top of the truss 2 x 4 so it is about 4" thick. So that part of the roof is 1400 sq ft. The odd shaped addition is about 600 sq ft and is a low sloping roof with 2 X 6s and it is fill with fiberglass insulation so it is about 6". There are 21 windows, all single pane. All are shaded from the sun either by aluminum awninigs or the house itself.

    Windows (all have aluminum awning that protect from sun)
    18 36 X 62 (3 south, 4 east, 7 north, 4 west)
    2 52 X 62 (south)
    1 36 X 38 (east)

    Doors
    2 36 X 80 French (west and south both covered from sun)
    1 36 X 80 ½ French (east block from sun by house)
    1 72 X 80 Sliding Glass (south on covered porch)


    The walls are simple wooden frame 2 X 4 with some kind of perhap s1/8 or 1/4 foam board coverd by plywood and vinyl siding. It has fiberglass insulation between the 2X4s.

    Roof 1400 sq ft 4” insulation Truss
    400 sq ft 6" insulation flat roof


    28 X 50 = 1400 Truss roof with 4’ fiberglass
    14 X 14 = 196 Flat roof with 6’ fiberglass
    14 X 30.5=427
    2023 sq ft

    I hope this helps. It is not a very "tight" house. The original part was made well but the addition is marginal. Some day I'll fix those leaking doors, heck maybe I'll go to the dentist instead.

    Thanks,
    Joe
    Attached Files Attached Files

  8. #8
    Join Date
    Nov 2007
    Posts
    9

    Calculations

    Dear Dan SW FL,

    I agree that 3.0 to 3.5 sounds about right. My brother-in-law runs his house at 72. I'm too cheap. It kills me to go below 80. With a real efficient machine it might not hurt as bad but 4.0 still sound too big.

    All of my south facing windows are covered by aluminum awnings. Do double pane windows change the calculations much? They are on the list of things to do. I should get to them in about 10 years.

    Thanks,
    Joe

  9. #9
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    384
    dear Joe
    I took a look at your diagram and crunched some numbers. I would figure a 3.5 ton system should work just fine for you. Now you need to select your equipment.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,898
    The 2 ton kept up, but had to run continuos to do so.
    So now you want to put in a 3.5 ton?

    On the hotest days when you had the stat set to 80, how warm did it get in the house?
    A 3 ton 2 stage may be all you need.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  11. #11
    Join Date
    Nov 2007
    Posts
    9

    3.0 or 3.5?

    First, thanks for all your help!

    On the hotest day, it may have gotten to 83 but definitely 82. To keep it there, I have to ask the boss not to use the oven, close that door, and all the usual. Also, when we have the relatives over, the extra 20 bodies add quite a bit.

    That 3 ton, two stage sounds interesting. Is it a common thing? When I talk to the contractor, is it easy to determine he is talking about a true two stage? How does it work? Is it a "2 ton" that kicks up to a "3 ton" if needed? Do they make them in heat pumps?

    I'm pretty much sold on a heat pump. Do they make it prone to trouble? We don't use the heat much here in central FL. We have a fireplace and a kerosene heater. When we lived in Japan, all we had was the kerosene heater so the smell makes us feel young again.

    So I was thinking of a 3 or 3.5 ton, with R410A. Feel free to recommend a brand or two. What SEER should I look for? The 14-15 seems reasonable. The higher seem rather exotic at this time. As we get older, we may use the air more but now no too much. Of course, now with the old system it adds between $80 to $110 a month. With the more efficient system, we would probably use it more. I was thinking if a simpler system that would last for years and I equate that with the mid SEER systems say a 14 -15. That old Marvair system has been great. All it has asked for all these years was a capacitor for the fan.

    Before I found this web site, I had a bid with a 4 ton Bryant Lagacy with puron, condensor 223ANA048, airhandler FV4BNF005 (variable speed), and a 05 kw heat strip.

    I will get another bid to get another opinion since it is an rather unusual install. Running copper, removing the water to air from the attic, installing the air handler in a closet and ducting it into the attic...

    The original plan was for me to install the used 3 ton I bought. See how it works out. Have a pro install a new system which would be a simpler change out. Now I will probably just have a pro do the new install and skip my part. He would do a much better and efficient job on the duct work and all around install.

    Thanks,
    Joe

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,898
    Many manufacturers make a 2 stage unit.
    Some in their 15 SEER, others in their 16 SEER line.

    Get 2 more estimates.
    If you can't find a contractor to do a load calc. You can click on teh HVAC CAlc link, pay the 50 dollar fee and do your own.

    Some 4 ton 2 stage units will be around 3 tons in first stage. So if you only need 3 tons, you will not get any of the benifits of a 2 stage unit.

    York, Carrier, Trane, to name a few all make 2 stage units.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,272
    Quote Originally Posted by JoeFL77 View Post
    First, thanks for all your help!

    On the hotest day, it may have gotten to 83 but definitely 82. To keep it there, I have to ask the boss not to use the oven, close that door, and all the usual. Also, when we have the relatives over, the extra 20 bodies add quite a bit.

    That 3 ton, two stage sounds interesting. Is it a common thing? When I talk to the contractor, is it easy to determine he is talking about a true two stage? How does it work? Is it a "2 ton" that kicks up to a "3 ton" if needed? Do they make them in heat pumps?

    I'm pretty much sold on a heat pump.

    We don't use the heat much here in central FL.

    ... So I was thinking of a 3 or 3.5 ton, with R410A.

    What SEER should I look for? The 14-15 seems reasonable. The higher seem rather exotic at this time.

    As we get older, we may use the air more but now no too much.
    Of course, now with the old system it adds between $80 to $110 a month.

    Before I found this web site, I had a bid with a 4 ton Bryant Legacy with puron, condensor 223ANA048, airhandler FV4BNF005 (variable speed), and a 5 kw heat strip.

    Running copper, removing the water to air from the attic, installing the air handler in a closet and ducting it into the attic.
    3.5 Ton Is Required based on Manual J 8th Edition ( 93'F / 78'F Dry Bulb/ Wet Bulb outdoor)
    Clear Glass as described previously by H.O. with awnings on the South windows
    R-11 walls
    R-13 Ceiling
    90 CFM infiltration
    78'F / 50% R.H.

    Double pane glass is not generally used in central FL.
    Temperature difference is 15'F ( 93'-78'F).

    With use of tinting on the South and West windows, a 3.0 ton may be sufficient.
    However, if infiltration is > 90 CFM the late afternoon (and definitely party time) indoor temperature may not be suitable.

    14 SEER, single stage
    TRANE
    http://www.trane.com/Residential/Pro...mps/XL14i.aspx

    16 SEER 2 Stage
    TRANE
    http://www.trane.com/residential/pro...mps/xl16i.aspx

    Bryant, single stage
    4-ton 223ANA048 with V.S. FV4BNF005


    BRYANT Alternate

    http://www.bryant.com/products/achea...referred.shtml

    Condenser >> Air Handler Capacity SEER __ EER Heating HSPF Heating __ ARI #
    _______________________Cooling _____________ 47'F ____ 17'F
    263ANA036-A _ FE4ANF005 37500 14.50 11.70 36000 _ 8.2 23400 __ 814003

    Joe,

    Send me an e-mail ( see my profile) for a report on the load analysis.
    Last edited by dan sw fl; 12-01-2007 at 10:32 AM.
    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

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