industry average

Discussion in 'General Discussions' started by waterpirate, Jan 20, 2009.

  1. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi all,

    Let me start by saying I am not trying to open up the same dead can of worms, just looking for data.
    Now that the recent cold snap is diminishing I would like to re-address the design day issue. I realize that no 2 designs are the same, nor are the projects.

    My question is:

    Is there a industry average for the percentage of time or days that supplemental heat is a part of the design in regard to tonnage?

    Most recently we have fielded a rash of calls about systems running with aux. heat on. The units all check out, ewt and lwt are all fine, the units just needed a push.

    Is there an average?

    thanx in advance
    Eric:)
     
  2. geo fan

    geo fan Member Forum Leader

    I beleive at least 2 options should be given 0% only record setting days require ,1% ,2.5% I beleive this is standard.
    The other big question is AC sizing , having a little aux might be cheaper then a 3 ton oversized ac . Could go on but wont
     
  3. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Design

    These are heat pumps. Design for cooling and buy the rest.
     
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Could not the statement be made in heating dominant areas " size for heat and idle the ac?
    Eric:)
     
  5. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    NO

    You could hang meat in the parlor and still not feel cool. Dehumidification is the key here.

    A water to water system using radiant floors and high velosity cooling might work.

    Solar and geo with low temp heat emitters are your best buy. They will not do 100% OF DESIGN TEMPURATURE WORK. One needs to have backup heat from some place.
     
  6. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    I think that 3 - 10 % of total heat load on Aux heating would be a good target for years with average demands. In years with high demands ( like this year)
    customers need to understand that aux will have to make up the difference.


    I have attached three design reports. One for a 3 ton system that covers 87% of the load, one for a 4 ton system that covers 95% of the load and one for a 5 ton system that covers 99 % of the load.

    The projected annual operating cost is:

    3 ton $1408
    4 ton $1230
    5 ton $1168

    So the 3 ton is going to cost $240 more per year to operate than the 5 ton.

    If the 5 ton costs $5000 more to install, then you have a 20 year simple pay back.

    If you lay this out for the customer and let them choose, then they know what to expect.
     
  7. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I am a chicken

    I never quote savings. Your results may very well be differant than MPG numbers listed on the sticker.
     
  8. geo fan

    geo fan Member Forum Leader

    Would that statment even be close to true in main , or further north.
    3500 sq home 2 ton system , 40kw backup
    sounds good to me

    Just bustin chops
     
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I do this

    for a living. I allow my customers to make trade offs. I do not make them for them. I even bail out DIYers.
     
  10. geo fan

    geo fan Member Forum Leader

    Thanks

    Do I need to post my Licence #'s
    DIY , I spend my 60 hours a week bailing out hack companys
    that live by the rule of thumb

    THERE IS NO SUCH THING
     
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Ruffled feathers

    Whats up with this.

    Am I stealing business from You?

    I think NOT.

    BTW, yes what are you licensed to do? Bash folks?
     
  12. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Blanket statements like this are not well recieved on a geo dedicated web site that also focuses on cost efficiency. It fly's in the face of inteligent design.

    Bump

    So we are agreed that 10% is okay, with more being anticipated during cold snaps and off years like this one for average temps?
    Eric:)
     
  13. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I do not think

    they have changed the laws of thermal dynamics for geo/heat pumps.
     

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