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  1. #1
    Join Date
    Sep 2009
    Posts
    12

    Heat Pump Replacement Questions

    First, I want to say this is a great forum. Thank you! I wish I had found it a few weeks ago but better late than never!

    I am in the process of obtaining bids for a heat pump replacement and I have some questions. My existing system has been referred to by some as a "triple split" system where the heat pump is outdoors, the compressor is in my garage and the air handler/furnace is obviously inside. I will be replacing it with a more common split system where the compressor is contained in the heat pump housing.

    I have had 5 companies come to my home (approx. 2700 SF) and provide quotes. Two have been very throough and measured square footage of the house, looked at my windows, counted registers/returns and worked up load calculations to determine the appropriate size of my replacement unit. They recommend a 4 to 4.5 ton unit. Others have simply asked how well my old 3.5 ton heat pump has worked over the years and took a quick look at my existing ducting and said as long as the old unit worked then they recommend using the same size because the duct work would not likely handle a larger unit (I understand oversizing the unit can lead to problems if the ductwork can not handle the increased output). Can you tell me which of these two approaches is better?

    Another difference of opinion has to do with reusing the old the refrigerant line. All agree it isn't ideal but because of how the system was built, it will be difficult to replace the line without tearing up some of the inside of the house. I prefer not to do this unless it is absolutely necessary. I am told the size is the same as what they would replace it with. One said he would flush it with mineral spirits. Another mentioned flushing with something else that was specially designed for it. Do you see a problem with reusing the existing refrigerant line?

    Last question (for now) - how can I tell for sure if the system I am considering qualifies for a tax credit? I have seen this site (http://www.ahridirectory.org/ahridir...ultSearch.aspx) and can't figure out how to use it!

    I appreciate all the help with my pending project I can get. Thanks!

    Ron

  2. #2
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,903
    If the old 3.5 unit did a good job, there's no need to get a larger unit; if you upsize, have the duct system inspected to make sure that it can handle the additional airflow.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  3. #3
    Join Date
    Apr 2008
    Location
    Rochelle Il / Chicago
    Posts
    169
    4 - 4.5 ton? something odd about that :/

    using old line sett? lots to consider, [ size, length and state of current refrigerant] if size is ok, many other things can be done to prep for use of 410a.

    if you're not having problems with current size I wouldn't worry to much about changing it. Common question asked is how your current system has worked. this is to drum up anything we may need to be alarmed of.

    And the " tax thin "
    Bottom line, the size and model of the unit you're going to put in needs to be 15 seer mn. Now it gets confusing because a Lennox xc15 is a 15 seer depending on the tonnage and if was installed with a variable speed blower. My co. certifies our sales for the "tax thing". Whom ever you are buying from should do the same.

  4. #4
    Join Date
    Sep 2009
    Posts
    12
    Thanks for the replies!

    The "4 to 4.5 ton" means the load calcs were in between the two units and he said if it were a new house he could go either way.

  5. #5
    Join Date
    Jun 2009
    Location
    Kamloops B.C.
    Posts
    31
    As far as the line set (refrigerant lines) our company only re uses them if they are very hard to replace. You say the home is finished. Will you tear it apart in areas for them to run a new one ? if not there are cleaners to clean the line set out but If at all possible... Replace it. Always replace the coil.

    AHRI gov grants the company that sells you the equipment will provide a AHRI certificate to prove eligibility ask in advance for the copy.

    Size of the unit is difficult to tell they are the pro's that are there ask them there thoughts onwhy they sized it the way they did and there experience in the field. A 3.5 should work well in a 2700 sq ft home but what is the design 2 floors 4 floors ? duct size is a factor as well as how many supply vents and return vents you have

  6. #6
    Join Date
    Sep 2009
    Posts
    12
    I have a multi-level home with approximately 15 registers and two large returns - one upstairs near the thermostat and one downstairs. There is also a small return in the master closet, which is in between the master bedroom and master bath.

    Heat pump, air handler/fan coil will all be new. As far running a new line set I would likely have to tear into the downstairs ceiling and I prefer not to. But if I will have issues down the road with premature failure of my new system because I did not replace the existing set then I will re-think it. That's is a decision I am trying to balance now - what makes sense in the long run.

    Thank you.

  7. #7
    Join Date
    Apr 2008
    Location
    Rochelle Il / Chicago
    Posts
    169
    ok........first. Don't ever size system over the phone, internet or mail. Equipment is sized by your local service team based on your location in this great nation. 2700 up in the mountains might get away with 3.5 ton, but in Chicago? that's 4 - 5 ton all day long in average construction.

    Bottom line is, have a load calc done to prevent any further confusion.
    You have some great tips and most of them are saying the same thing, Have a load calc done / let the pros figure out what you need / ask for tax cert up front.

    Most important.............you get what you pay for.

  8. #8
    Join Date
    Sep 2009
    Posts
    12
    Sorry, should have mentioned that. I am in the Seattle, Washington area. Fairly mild climate here. The old Carrier 3.5 ton heated adequately.

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