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  1. #14
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    Quote Originally Posted by addamsmasher View Post
    This is how I've always been taught: On an 80% furnace for every dollar you spend on heat you get .80 usuable heat and .20 goes up the flue. With a 90% its the same. However, with a heat pump (not counting electric or auxilliary heat) for every dollar you spend on heating you get $3 worth of heat. Something for you to think about. If you have concerns about ductwork, check it out for yourself. The duct MUST be insulated. If possible the joints in the ductwork should be sealed with tape or what I prefer, mastic.
    Your logic is somewhat flawed or at least your line of reasoning. The statement that for every $1 you spend on heating you get $3 worth of heat is only truly comparable (to any extent) to electric heat. Basically, assuming a HP uses approximately 1/3 the energy that electric heat uses then your argument stands. However, you cannot then compare the cost and efficiency to oil, natural gas, or propane without considering how many BTUs each of those generate and the quantity of usable heat from each.

    For example:
    Oil at $3.50/gallon... 138,000 BTUs per gallon... at 80% efficiency 110,000 BTUs per gallon or 31,000 BTUs per $1... at 90% efficiency 124,000 BTUs or 35,000 BTUs per $1.
    Propane at $2.50/gallon... 95,500 BTUs per gallon... at 80% efficiency 76,000 BTUs per gallon or 30,000 BTUs per $1... at 90% efficiency 85,000 BTUs or 34,000 BTUs per $1.
    Natural Gas at $1.25 per therm... 100,000 BTUs per therm... at 80% efficiency 80,000 BTUs or 64,000 BTUs per $1... at 90% efficiency 90,000 BTUs or 72,000 BTUs per $1.
    Electric Heat at $0.14 per kWhr... 3,412 BTUs per kWhr or 24,000 BTUs per $1... assuming HP uses 1/3 Electric Heat then 72,000 BTUs per $1 for HP.

    Yes, the HP is the most efficient provided no calculations need to be made for aux heat... and even then will almost certainly be cheaper than utilizing any other furnace as your primary heat. However, the only valid comparison to say $1 for $3 worth of heat is with the electricity. The others are currently somewhat similar although NG is quite cost-effective as well. The real problem is not knowing what future energy prices are going to be and how they will be in relation to on another.

  2. #15
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,108
    Its not knowing how much either will go up in the futrure, that makes duel fuel the best choice for many area.
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  3. #16
    Join Date
    Mar 2008
    Location
    Salinas, CA
    Posts
    3
    I am going with American Standard because that is what my contractor recommended. You guys are experts in what you do and have a lot of training, and yet you still discuss the merits of one brand over another. It would take me hours and hours and hours of research to be able to do that, and still I am not sure I would make the right one. (To be able to make every decision (best value on doors, best value on windows, flooring, light fixtures, tubs, sink cabinets, toilets, etc, etc, etc,) I would practically have to quit my job.)

    Anyway, I now understand what a heat pump is, like a refrigerator, makes the cold place colder and the warm place warmer, and that it uses a refrigerant? And it lives outside? Does it also use a fan and ductwork? But how does it compare in initial cost? For example, in your area, what would, say, a good 90% efficient furnace run and what would a good heat pump run? (just a range for both, for comparison purposes)

    I'm going to ask my contractor about the attic placement again. Would the duct run through the wall itself? Or through a closet so that it could go through the ceiling and floor?

  4. #17
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,108
    A split system heat pump has an outdoor an indoor unit.


    Sorry.
    Even ballpark pricing is not allowed on this forum.
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  5. #18
    Join Date
    Feb 2007
    Posts
    999
    [QUOTE=Buck_Taylor;1800271]

    Yes, this duct run is probably leaking and improperly insulated and/or it can be too restrictive. You should remove the insulation from all your ducts, when exposed make sure all the joints are tight, then seal the joints with mastic or UL 181 approved tape (not "duct tape" from hardware store), then re-apply R-6 insulation.

    There is currently no insulation (except in exterior walls). I have inspected all accessable ductwork and sealed all leaks.

    If the ducts have a lot of sharp bends, or loose flex duct you caould also have an air balancing problem, so some duct runs can be starved of proper airflow. The restricted ducts wont get the heat carried by the air and will be cooler than the others.
    All ductwork is sheet metal. By sharp bends, are you referring to close-radius 90's (elbows or boots)? Have lots of them, but don't see any alternatives. Air flow is about equal in all registers, except the longest one. Had to dampen a few runs that are close to the furnace. This run originates from the butt end of the trunk. There are 5 90* turns and it is over 30' in length. I'd be shocked to see what the equivalent length is.

    Would having the takeoff removed from the butt end and relocated to the bottom of the trunk offset any loss of static due to the present location of the run? It could be connected with an additional elbow and short length of flexible metal duct. Depending on the flexibility of the duct, it might eliminate 1 or 2 90's.

    My gut tells me no. My reasoning is that being at the end of the trunk, any increase in static would benefit runs that are upstream of this (they are doing o.k.) leaving less air for the 'end run'.

    AM
    Last edited by ampulman; 03-21-2008 at 03:50 PM. Reason: add information

  6. #19
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    Quote Originally Posted by BantyMom View Post
    Anyway, I now understand what a heat pump is, like a refrigerator, makes the cold place colder and the warm place warmer, and that it uses a refrigerant? And it lives outside? Does it also use a fan and ductwork? But how does it compare in initial cost? For example, in your area, what would, say, a good 90% efficient furnace run and what would a good heat pump run? (just a range for both, for comparison purposes)

    I'm going to ask my contractor about the attic placement again. Would the duct run through the wall itself? Or through a closet so that it could go through the ceiling and floor?
    I'll try to simplify how a heat pump works compared to an AC unit using your refrigerator analogy. As you know the refrigerator makes its inside cold by removing heat... the heat ends up in your kitchen. An AC unit works by removing heat from your home and dumping it outside. A heat pump has two functions... in the summer it works like a typical AC unit and removes heat from inside your home and dumps it outside your home... in the winter it reverses and removes heat from outside (even 40 degree air still has heat in it) and dumps the heat inside your home. The heat pump would use your existing ductwork... or at least could provided the ductwork is properly sized. While we cannot comment on initial costs of each system, your contractor should be willing to discuss the costs of each with you.

    If you decide to place the unit in the attic, the contractor could (theoretically) run the ductwork to the existing ductwork by using the space where your existing furnace is located or they could use another closet in your home. That really depends on your home.

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