Tonnage Dilemma

Discussion in 'Quotes and Proposals' started by Matt4geo, Jun 14, 2011.

  1. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Boots on the ground allways trump the software. Familiarity with the local geology and anticipated problems trump a design from engineer that may even be in a different region of the country.

    The reason good drillers change designs in the field is that they care. The construction of the heat exchanger must be cost effective as well function to design parameters. I.e. the drilling of two 500' bores with bedrock or hard rock presenting in the hole at 250' it is allways cheaper to drill 4 250's in soft rock or better yet in the overburden using mud rotary than push 500' into hard rock.

    For vertical drilling it is allways about the cost per foot to the consumer to drill, including the grout that makes the wheel turn.

  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Hitting gas at 250' when you had planned to drill for 400' would be one example to change plans on the fly.

    I am not a big fan of duct board, it is susceptible to dust collection, moisture accumulation and resulting mold problems on the collecting dust particles. I am sure that other people think different about it, but I have seen those things happen.
  3. Matt4geo

    Matt4geo New Member

    Beverly Hillbillies

    Ok, now I'm curious. What happens when you do hit gas? Would I suddenly be transformed into Jed Clampett? Sink a pipe and run from my own natural gas well for free the rest of my life? Because in my heating dominated area, that would be a big relief to the wallet. :p

    I have to say I'm not thrilled about the possibility of a duct board product. I've seen them sag after years of use. However, the contractor was recommending a 2" thick brand that has a pretty decent cut sheet singing its praises.

    I would prefer a fully sealed system, since all the duct will be installed in my attic. So I'd also prefer a fully insulated one. But I keep getting the feeling from my bidders that they think putting in a flex duct octopus in my attic would be ok. I couldn't be more against that idea. Qualifications for installing my ductwork should not consist of: Scissors and tape capability.
  4. ACES-Energy

    ACES-Energy Member Industry Professional Forum Leader

    Tore out an existing geo unit yesterday another geothermal company installed incorrectly and with duct board. Most people say ductboard is not susceptible to dust collection or anything else, well now I have a show-n-tell to tell the true story, it was NASTY! Ill be sure to share pics when the trailer returns with the remains!!!

    We have done normal Tin and than insulated the outside of it, takes time but if dont correctly, works great!
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I have used ductboard where homeowner budget calls for it (IOWs has me bid against people using it).
    I look at duct board and flex duct as temporary where steel is permanent.
  6. Matt4geo

    Matt4geo New Member

    I have to agree that the steel would be best for a more permanent install. I guess I'll have to see what the adder is for the difference when I get the quote. The other kicker will be the installer's comfort level with it. If he's done nothing but duct board for awhile, and he doesn't have guys used to installing steel, I could end up with a worse system anyway. I wouldn't want to pay for all this and still have to go back and seal / insulate the system correctly. I've spent enough time in my attic already.

    What are IOWs?

    I seemed to have picked the worst time of the year to start this adventure. I'm having a hard time getting calls back from reputable contractors in my area. I can't think they know what a jerk I am already. :D
  7. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    What is

    duck or duct board?

    In the land of CLE steel wins.

    I love duct tape in a can. Sealing is everything, in and out. Why build it otherwise?
  8. Matt4geo

    Matt4geo New Member


    The Duct board stuff he was talking about is ToughGard duct board by CertainTeed. I would insist on the 2" thick to get the R-8ish. But it still reminds me of the stuff I've seen sagging and falling apart in an old warehouse I worked in. :(

    Going to have to look up the can stuff you mentioned. And perhaps see what the premium is for steel.
  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    IOWs actually should be IOW.....
    in other words.
    just trying to make my teenagers proud.....ROFLMAO.

    A friend taught me a new one recently- PWI.....kind of like a DUI for posters on a blog site.

  10. Matt4geo

    Matt4geo New Member


    IOWs..... gotcha..... allow me to respond with my own teenage reply: {facepalm}

    I should have figured that out, but me engleesh be not so gud sumtymes.


    Had a blower door test on the house today. Won't get the results for a week. But here in PA if you get a certified energy audit, you qualify for better percentages on home energy loans. Could benefit me to go from a 5% loan to a 1%, which is practically free.
  11. Matt4geo

    Matt4geo New Member


    Turns out that I could get a lower percentage rate, but only if I combine the geothermal loan with other home improvement loans. Well, I know how much I can bite off and chew, so that's not going to work for me.

    Hey, how would you guys prefer to broach the subject of oversizing with your client? One of my bidders has proposed a three ton unit, even though his manual J shows 24kbtu for cooling and 48kbtu for heating? I told him heforehand that I'm looking for a glorified airconditioner that would save me a little oil in the shoulder months. So to me a 2 ton unit would be better.

    By the way, I have a Manual J from two years ago when the boiler guy did it that says cooling at 19kbtu, and I recently used the HVAC-calc program Joe recommended and came in at 17kbtu cooling.

    Is there a way to tell him that he's not bidding what I asked without blatantly saying he's oversizing the unit for no good reason? Or ticking him off for second guessing his calcs?
  12. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Simple enough:

    Direct everybody to bid / propose 2 tons. Obviously you are on the hook for the result, so you;d need to freely acknowledge that, probably in writing.

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