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  1. #1
    Join Date
    Feb 2008
    Location
    NY
    Posts
    99

    Is a heat pump even possible?

    I plan to replace my 3.5 ton 8 SEER compressor with a 3 ton 16 or 18 SEER compressors very soon. I own an Armstrong Air Ultra 80 oil furnace, Model LUF80C112/125D 20. The furnace is 4 years old and works well.

    I had a past post regarding a coil match with an Amana 18 SEER compressor to go with the current 5 ton direct drive blower in the Air Strong furnace…got some great links/info, thanks.

    Needless to say, with the high price of distillates not going down any time soon, should I purchase a compressor with heat pump? Could I heat my home in NY with a heat pump on days where the temperature is 40 or higher and only use the oil furnace on days when it is very cold?

    Do I have any shot of lowering my bills this way? If I were going to buy a new compressor, coil & TXV either way, would tossing in a heat pump be much more?

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,389
    In most cases I would expect a considerable savings using oil and heat pump. You won't get much above 13 SEER with a conventional blower though so buying an Amana 18 is a waste of money. You also won't get the benefits of a 2 stage compressor with the standard motor.

    Best bet is look for a good installer and look at his offerings. Look at the ratings, high heat output and good HSPF.

  3. #3
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    A heat pump shouldn't cost a lot more to install over the same efficiency air conditioner, and you'll save a lot on energy costs. New low voltage wiring needs to be run from the thermostat to the heater, and from the heater to the outside unit. Try to get someone who's done it before, you don't want to be someone's guinea pig.

  4. #4
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,852
    Quote Originally Posted by BaldLoonie View Post
    In most cases I would expect a considerable savings using oil and heat pump. You won't get much above 13 SEER with a conventional blower though so buying an Amana 18 is a waste of money. You also won't get the benefits of a 2 stage compressor with the standard motor.

    Best bet is look for a good installer and look at his offerings. Look at the ratings, high heat output and good HSPF.
    The SEER rating would not drop below 17 for the 18 SEER system or below 15 for the 16 SEER system, but they would not have an official ARI rating or the advantage of two stage cooling or dehumidification.

    I have had contractors install these Amana systems (matching heat pump and indoor coil) on standard blower oil furnaces with decent results though.
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  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,758
    You won't get the blower to slow down enough to get any benefit from 2 stage.
    If you insist on 2 stage, you may want to check into getting a fan handler installed.

    Especially using a 5 ton drive with a 3 ton system.
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  6. #6
    Join Date
    Feb 2008
    Location
    NY
    Posts
    99
    I am scraping the 2 stage system concept. I am likely going to head toward a Single stage 14 or 15 SEER unit with heat pump. 14 or 15 SEER should get me some saving the hot months of July and August while the heat pump can keep me from using almost no oil when the temp is above 40. Under 40 I will still have the Arm Strong 80 oil furnace to kick in. I think I have a fair shot of saving 400 to 500 gallons of oil annually that way. Now can I find a person to put all of this in to play. Any one know a good HVAC man (person) on Long Island NY?

  7. #7
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    If the oil furnace has a multispeed motor in it, it would be very easy to set the system up to use a lower blower speed in 1st stage than in 2nd stage. Just add a SPDT blower relay, like used to be done with Lennox 2 speed systems.

    If the control board in the existing furnace uses different blower speeds for continuous fan and cooling, a relay doesn't even have to be added.

    Lennox was making 2 speed systems for a couple of decades before variable speed blowers were available, duno why people think it is a "must have" item to make a 2 stage cooling system now.
    If more government is the answer, then it's a really stupid question.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,758
    And they had high SHR in first stage.

    Did you install any of those Lennox units. If so, were any of them 3 ton units, on 5 ton drives.
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  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,987

    Smile Lower the heat pump operating point to the

    Quote Originally Posted by jrongo View Post
    14 or 15 SEER should get me some saving the hot months of July and August while the heat pump can keep me from using almost no oil when the temp is above 40 { 30'F }.

    Under 40 ( 30 ?) I will still have the Arm Strong 80 oil furnace to kick in. I think I have a fair shot of saving 400to 500 gallons of oil annually that way.

    Now can I find a person to put all of this in to play.
    Any one know a good HVAC man (person) on Long Island NY?
    Heat Transfer balance point which is generally ~ 30'F.

    LI has a relatively mild climate for the Northern U.S.

    Your economic balance point and annual heating/cooling costs can be determined based on the building envelope, selected heat pump, oil and electric rates.

    For example,
    Oil at $2.80 per gallon and 80% efficiency
    = $2.54 per therm ( 100,000 BTU)

    H.S.P.F. of ~ 8.6 might be in the ball-park for a 14 SEER heat pump. Effective electric cost would be $0.19 (?)/ 2.6 (C.O.P.) or $0.073 / kWH operating near 30'F equating to $2.14 per therm

    Savings of 20% to 30% IF electric rate is as high as $0.19 (larger savings with lower electric rate).

    In other words, the heat pump should be set-up to
    operate down to the Heat Transfer balance point of 25' - 30'F.

    I am not aware of your specific LI/NY costs, buiilding envelope
    or the equipment to be selected.
    Last edited by dan sw fl; 03-02-2008 at 09:15 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

  10. #10
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    Quote Originally Posted by BaldLoonie View Post
    Best bet is look for a good installer and look at his offerings. Look at the ratings, high heat output and good HSPF.
    yes, that is some good advise for the o.p.

    sounds like he is heading for a "match up disaster"

    why down size from 3.5 ton to 3 ton, especially since the blower is a 5 ton

    i wonder if he is you having humidity problems!

    also, he should save some money going to a heat pump as primary fuel source!

    i got to hand it to him atleast he is trying to be innovative



    .

  11. #11
    Join Date
    Feb 2008
    Location
    NY
    Posts
    99
    I want to go from 3.5 ton to 3 ton so the AC will cycle on and off less. The prior home owners were rather large people and used the AC a lot. 76 is the lowest I will set my stat to in summer. I thought running more often will reduce humidity...
    Needless to say, when the AC is running in the summer the house is not too humid, it is fine.
    I am trying to do the proper research so I am not blind-sided.

    dan sw fl - the only part is truly understood in you post is that the 40 F number is put in my post was not the right number. Clearly, I pulled the 40 number out of my bass...It was just a general number for the post.
    I know heat pumps still work well below 40, I am hoping the fine person who I will pay to set this up will know the temp when the cut over should happen. The other numbers on your post are well above my "skim the surface" general knowlage level.

    I am surprised a PHD is not a mandatory to be a HVAC installer.

    Generally speaking what % is hard math and what % is art and what % is luck?

  12. #12
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,987
    [QUOTE=jrongo;1780409] I am trying to do the proper research so I am not blind-sided.

    I am surprised a PHD is not a mandatory to be a HVAC installer.

    Generally speaking
    1 what % is hard math and
    2 what % is art and
    3 what % is luck? [/QUOTE]

    1. House size ... ___10%
    2. Proposal Writing _ 20%
    3. Collecting ______ 80%
    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

  13. #13
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    You need a Pro to do the load calc and determine the size system you'll need.

    Multispeed motor can be made to work with the two speed,again you'l need a
    Pro,to set it up.Variable speed furnace,would be easier,and offer better dehumidification controls,but pricey .

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