existing 80% plus heatpump vs new 95% plus a/c
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  1. #1

    existing 80% plus heatpump vs new 95% plus a/c

    Had planned on replacing old a/c unit with a heat pump and having a dual fuel with existing 80%. (about 10 years old)

    Was also given a quote for a new 95% two-stage furnace plus a 2 stage A/C unit. Because of rebates and price points this option is only about $1600 more. But this is with an a/c unit and not a heat pump. (he quoted me the heat pump option as well on this but it was quite a bit more.)

    Obviously, I want the most bang for my buck. I like the dual fuel option, but do the advantages of a 2 stage blower, higher efficiency, and using outside air for combustion outweigh the benefits of a hybrid system?

    Thanks,

    Dan

  2. #2
    Join Date
    Feb 2009
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    Portland OR
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    It all depends on your home and your fuel rates. How much do you pay per therm of natural gas vs KWh for electricity? How long do you plan on living at the house for? Both systems have their advantages, personally I have a heat pump with a two stage variable speed furnace, have you looked at a two stage variable speed 80% and heat pump? Often they are about the same as a two stage variable 95% and AC and since you would have a heat pump the extra 15% in efficiency would not matter much.
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  3. #3
    Guess I'm having trouble wrapping my head around this. Seems like there are too many variables to truly calculate which system would save me more. (heat pump days + 80% furnace on cold days plus cooling with single stage heat pump versus 95% two stage heating, and cooling with dual stage a/c. different seer ratings, different electrical usage on more efficient blowers, outside combustion air, better humidity control on 2 stage a/c which might mean less cooling required.)
    I see the path to making some of these calculations, but with variable (and always rising) fuel costs, and crazy weather patterns, it will feel like a wild guess.

    I started looking at it differently. I plan on being in this house for 10 years. So, going with the 2 stage furnace and a/c would only have to save me an additional $13/month to pay for itself over a 10 year time frame. (upgrading even further to a 2 stage furnace and 2 stage heat pump would require a savings of about $20/month to pay for itself in that timeframe)

    Does this logic seem sound, and do these savings seem attainable with these systems.
    Fwiw, I'm just looking for a 'gut feel' answer. I live in central illinois. My combined gas/electric is generally about $240/month.

    Thanks again,

    Dan

  4. #4
    Join Date
    Feb 2011
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    Cloverdale,Ca
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    305
    I would put in a new heat pump and a new high efficient furnace, and not look back. You are looking at a 15 year investment, compare it to what you spent on your car. Comfort is as important to me as efficiency. If you are comfortable in your home you have a higher quality of life every day. I would not beat myself up to save a dollar...
    Living the dream !!

  5. #5
    Join Date
    Feb 2009
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    Portland OR
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    You still have not mentioned your KWh rate or your gas therm rate, without this we can't do the calculations for you. Also if we know your load calculation numbers we can better find your savings. There are a lot of variables and if the contractor is not showing you your savings and load calculation and giving you his recomendation its time to look for a new contractor.

    In my area the most cost effective yet comfortable solution with the best Return On Investment is an 80% variable speed two stage furnace with a 15 SEER plus heat pump with 9+ HSPF rating.

    I know there are a lot of variables so don't rush your decision, read some of the posts around here and let a few of us respond and you will be happy you waited.
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  6. #6
    Thanks for the replies!

    Sky, natural gas is running $1.23/therm (that's actual cost after taxes and other fees added on) and electric is 7cent/Kw.

    I don't know my load calculations. Although, Carrier dealer assures me he will do manual J at some point.

    Thanks again.

    Dan

  7. #7
    Join Date
    Feb 2009
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    Portland OR
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    Quote Originally Posted by reef tank guy View Post
    Thanks for the replies!

    Sky, natural gas is running $1.23/therm (that's actual cost after taxes and other fees added on) and electric is 7cent/Kw.

    I don't know my load calculations. Although, Carrier dealer assures me he will do manual J at some point.

    Thanks again.

    Dan
    In my area we are at 1.12 a therm for gas and 11.4 cents/KW for electricity and the heat pump makes good sense, at your rates you really need to look at the heat pump option for both short(5 year) and long(10) year terms. I think the benefit of a two stage heat pump with an 80% furnace would be much much higher than a two stage AC and gas furnace, you will have better comfort with the heat pump(2 stages of heat pump plus two stages of heat on the furnace) is 4 stages with heat pump vs 2 with a furnace. My most popular option is the Trane XL20i, I know its more than what you have been looking for but there is a reason its so popular, watch some of my Youtube videos in the customer testimonials section to hear it straight from them why they bought such a nice system. Other brands like Carrier and Rheem/Ruud make great equipment as well, select the contractor first and brand second, because if it is not installed properly then its not working at rated efficiency.

    Also be leary of anybody that "says" they will do a manual J after you sign the contract, what if you need a larger unit, does it cost more? What if you need a smaller unit, do they make more money and only give you a slight discount or are they honest and give you the full discount? What if their "manual J" is not a true manual J, I have had many customers tell me my competitor did a full load calculation... he counted the regsiters, or measured a window or two or looked at my old equipment size, those are all horse and pony shows, they mean nothing as far as equipment selection and sizing.
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  8. #8
    As a fact check: One of the reasons the two stage appeals to me is because of the more efficient blower. Did I understand my dealer correctly in that potential electrical savings are included in the seer rating of the heat pump, but not in the furnace? He made it sound like there could be a substantial electrical savings just from the blower.

    We use our blower a lot. My wife will often turn on fan/only just for air circulation or even white noise. On a two stage system, does turning on the fan by itself use the lower fan speed? My understanding is yes, but thought I'd double check. don't want any surprises.

    thanks again,
    Dan

  9. #9
    Join Date
    Feb 2009
    Location
    Portland OR
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    The variable speed blower is a must for comfort, noise level(assuming your ductwork is sized properly) and will help the efficiency of your heat pump or AC.
    Check out my YouTube channel - http://www.youtube.com/user/skyheating1 We have customer testimonials, product reviews and more!
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  10. #10
    Join Date
    Jul 2004
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    Massachusetts
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    With your electric rate, I'd highly recommend you look at the new variable speed heat pumps from Bryant/Carrier. They run as high as 13 HSPF and can often beat even a high efficiency furnace for cost of operation. It's an entirely new wrinkle in the industry and not everyone is tuned into the tremendous efficiency of these new units. Because they'll ramp down to such a small output at minimum operation, it's even possible to put in a vs HP that's a full 1-ton larger in size that what is arrived at as ideal from a load analysis and yet summer cooling/humidity control does not suffer. I don't know where you've located but at $.07/kwh for electricity, it's hard to beat the HP. As to your question about the vs motor in a furnace, that is additional savings, so far as I know. The thermal efficiency of the combustion process is the AFUE rating and that does not include electrical savings.
    If YOU want change, YOU have to first change.

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  11. #11
    Join Date
    May 2008
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    Missouri
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    Bear in mind that VS blowers/motors are great BUT once they are outside the warranty period, then these are VERY expensive to replace. I don't know what kind of warranty the "invertor" technology units have on them but hope it's at least a ten year warranty. Get the longest warranty provided!

  12. #12
    Thanks for all the replies. FWIW, I have used this site a few times over the years both to post questions, and to browse for info. I very much appreciate the time and info you guys share.

    And I was even folllowing the oft repeated adice to pick the dealer over the equipment.

    However, now he is telling me that he doesn't usually do manual J's, that he did a 'Block Load' when he was here and that's all he needs. He also said that since I was going with a 2 stage system that sizing was less critical. True?

    This guy has been in business for decades and seems trustworthy and knowlegeable, and has a good rep. Who am I to argue with him. OTOH, I've read a lot of threads here and the only thing you guys all seem to agree on is the manual J. (okay, maybe not the only thing...)

    Do I shop around more, or trust that the guy knows what he's doing.

    thanks,

    Dan

  13. #13
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    Feb 2009
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    A two stage piece of equipment is sized the SAME way as anything else. What does he mean he did a "block load" sounds to me like he guessed on sizing. There are two types of Manual J's a block load(doing the hole house as a single system) and a room by room. If he did a "block load" it is by no approved method beyond his own guestimation of system sizing and no matter how long you have been in the business there are no absolutes to sizing except the Manual J.
    In his "block load" did he measure all windows, doors, get insulation values, floor area and ceiling area and input all this into software? I hate when HVAC guys use block load in the manner that it doesn't represent. So far what you are saying says get another estimate and ensure before hand that they do a full Manual J and actually measure things, this should take at least 10 minutes and up to 30 minutes depending on the person.
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