Page 1 of 2 12 LastLast
Results 1 to 13 of 23
  1. #1
    Join Date
    Sep 2012
    Posts
    7

    Confused 2-stage packaged unit efficiency vs split system

    We need to replace our 13 years old packaged unit. We live in North California.
    I know that packaged units are limited to 80% efficiency, and for that reason I was planning to get a split system with ~95% efficiency.
    But my contractor tells me that with a good 2-stage, variable-speed packaged unit, the difference in operating cost due to the 80 vs 95% efficiency difference becomes minimal. He says that since the system will run at reduced speed most of the time, the split system would not really save me an additional 15% in operating cost.
    On the other hand, he says that since we already have a packaged unit, simply replacing the packaged unit would result in ~ in installation cost, compared to installing the split system.

    What do you think? Is his efficiency vs operating cost argument correct?

    I still prefer the look on a split system, but if this means more and if we don't have a substantial operating cost reduction, then we may stick with a packaged unit.

    Thanks in advance for your help!
    Last edited by jpsmith1cm; 10-01-2012 at 06:01 AM. Reason: Removed pricing

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    To get a 95% furnace it will likely be 2 stage, so you will have the 15% increase. A package unit cannot be over ~80% afue because anything above it starts condensing, making water, which could freeze in the winter. I don't know why manufacturers don't make a 90% package unit because it would be easy to do, but that's a whole other discussion. It would cost more to go to a split due to duct revisions and labor time vs a package change out.

  3. #3
    Join Date
    Sep 2012
    Posts
    7

    Both 2-stages

    Quote Originally Posted by jtrammel View Post
    To get a 95% furnace it will likely be 2 stage, so you will have the 15% increase. A package unit cannot be over ~80% afue because anything above it starts condensing, making water, which could freeze in the winter. I don't know why manufacturers don't make a 90% package unit because it would be easy to do, but that's a whole other discussion. It would cost more to go to a split due to duct revisions and labor time vs a package change out.
    Yes, both the packaged and split systems are all same configuration (both 2-stages, both variable speed). Only the efficiency is different. Still , he was saying that at low speed, that 15% difference becomes much less. I tried to get an actual number from him, but all he said is that it would end up being a few dollars difference per year. I can see that it is difficult to put a number on that since we don't really know at what speed and burner level it will be running at, but I was surprised to hear that 15% would become insignificant.

    Thanks,
    Benoit

  4. #4
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,721
    Depending on your gas rate and electric rate a dual fuel package unit might be a good option carrier and trane both have them readily available
    We really need change now

  5. #5
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    Quote Originally Posted by Benoit View Post
    Yes, both the packaged and split systems are all same configuration (both 2-stages, both variable speed). Only the efficiency is different. Still , he was saying that at low speed, that 15% difference becomes much less. I tried to get an actual number from him, but all he said is that it would end up being a few dollars difference per year. I can see that it is difficult to put a number on that since we don't really know at what speed and burner level it will be running at, but I was surprised to hear that 15% would become insignificant.

    Thanks,
    Benoit
    I don't know how he comes up why that, maybe someone else can shed some light on the topic. As for dual fuel package units most manufacturers if not all of them have that equipment readily available

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,302
    I don't buy that 15% is insignificant. BUT since you aren't in a real cold climate. I was thinking along the dual fuel line myself then I saw it brought up already. The cost to go split system 95% over staying packaged probably will negate any savings, something to keep in mind.

    Why no 95% pack? From what I've been told these are the 2 most common reasons: packs are usually used in the south so little need for the super efficiency. Also, packs are used light commercially and utility bills are paid by tenants so there would be little call for anything but the cheapest units.

  7. #7
    Join Date
    Sep 2012
    Posts
    7
    Thanks for your inputs!

    I read somewhere that to get higher than 80% efficiency, the required process generates condensation. If left outside at cold temperature, this condensation can freeze and cause numerous problems. Since a split system is inside, the condensation is simply collected and sent down the drain.

    By dual fuel you mean electric + fossil (in my case, propane), correct? I was told that electric, in addition to being more costly to operate, is also not as comfortable because of the slow turn-on. But maybe this does no apply to dual fuel systems since electric is only used when quick/strong heat is not needed? Another reason why dual fuel may be interesting is that in the future we will install solar panel and hopefully we will generate enough power to reduce the heating costs with an electric furnace.

    From my calculations it seems that IF the 15% savings are still there for the split system, then the increased installation cost is compensated by the operating cost over the next 6 years. After that, I start really benefiting from the reduced operating cost for many years.

    So many variables can throw off these projections, but is that realistic?

    Thanks,
    Benoit

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,302
    Propane? You are definitely a candidate for dual fuel. In our climate, the gas backup will hardly come on meaning cheap heat from the heat pump. We've been doing it for several years with nary a complaint. Get a control that handles the dual fuel and have it switch to gas at 30. you will be comfy.

  9. #9
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    Quote Originally Posted by BaldLoonie View Post
    Propane? You are definitely a candidate for dual fuel. In our climate, the gas backup will hardly come on meaning cheap heat from the heat pump. We've been doing it for several years with nary a complaint. Get a control that handles the dual fuel and have it switch to gas at 30. you will be comfy.
    X2 propane is expensive, heat pump would be a better choice or dual fuel

  10. #10
    Join Date
    Sep 2012
    Posts
    7
    We live in a rural area with no connection to the city utility. Except for electricity, we're on our own (septic, well, propane tank...).
    So the dual fuel can be electricity+propane?

    Thanks.

  11. #11
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    Quote Originally Posted by Benoit View Post
    We live in a rural area with no connection to the city utility. Except for electricity, we're on our own (septic, well, propane tank...).
    So the dual fuel can be electricity+propane?

    Thanks.
    Yes electric heat pump with propane for back up heating

  12. #12
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,372
    Before selecting propane as backup fuel, compare to the cost of electricity. In our area electric heat strips are actually CHEAPER than propane.

  13. #13
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,721
    If you are on dominion power heat strips are cheaper to operate than propane at least in my area .
    We really need change now

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event