Geo install in SE PA, what a difference in quotes

Discussion in 'Quotes and Proposals' started by gbig2, Jun 8, 2012.

  1. gbig2

    gbig2 New Member

    I have some quotes to share. First, I had the house modeled by an energy auditor (resnet/bpi certified) and he has it at 30,000 btu heat loss. HERS rating of 72. Tight house. I have quotes at $32,000, $28,000, $24,000, and $18,000. Some guys want to put in 4 ton , some want to do 3 ton. So yea, $18,000 and that includes desuperheater with buffer tank. That puts me around $13,000 after tax credits. And that 18k quote is from the biggest, most experienced company in the area. They've installed 4000 since 1980. They had A+ BBB rating with no complaints and all 5 star reviews on the Bosch dealer rating page. The quote is for a Bosch 4 ton, TA 049 unit. Vertical loops, 600 foot
    bore, 1200 foot pipe. They do their own drilling, nothing is contracted out. I've since challenged him on it being 4 ton instead of 3. Here's what he said,

    "I just checked my heat loss is 43,000 btuh with an outside design of 0 degrees. Reason I design for 0 degrees is history. We have installed over 4500 geo's over 31 years and I can tell you that with the new 2 stage units you do not want to undersize them. It would take me a long time to give you the reasons but most of the problems that we see in the market place is undersized loops/ ductwork design / improper
    manifolding/ pump sizing / etc. If you want to drop back a ton ok but I would note this on the proposal or if you want to install a 3 ton unit with 3.5 ton of loop ( 535 feet of bore ) let me know."

    I'm not sure why he's using 0 degrees Winter design temp (I'm near Allentown, PA). Other guys were using 11 degrees which seems more reasonable. So I told him I like the idea of going with 3 ton unit and 3.5 ton of loop ( 535 feet of bore as he said above). I asked him what this would do to my costs.

    What design temp would you use for this area, for those who are familiar with this climate? Clearly a 3 ton unit is what I need and 4 ton is oversized, agreed?

    So obviously I'm trilled at the $18,000 and it's a no brainer that I'm going to do geothermal. I am disappointed that he's @ 4 tons, 43,000 btu, but that may be correct using 0 degrees Winter design. Like many of you say, I'd rather size for %90 to %95 of heat loss and spend less upfront on equipment and use a little more aux heat. But at least he's willing to do three ton and isn't fighting me on it. Should be interesting to see what he comes back with as far as costs to do 3 ton, with 3.5 ton loop.

    Would anyone go with 4 ton, especially if the price isn't that different? Plus then it run in stage 1 more.
     
  2. jrh

    jrh Member

    I wouldn't have a problem with 4 tons if the load was 43k. However if it is 30k it might be a bit much. Then again he has installed one geothermal system every 2.5 days for thirty one years. ;)
     
  3. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    It is not uncommon for the best guy to be the most reasonable quote. Practice makes perfect. I also would not argue with him about design. If he is designing for 0 degrees and others are not, he is all but eliminateing stage 3 operation.

    I am an advocate of 100% load being covered by geo if it works with the cost, in this case it seems to be a perfect fit for you.

    Eric
     
  4. ChrisJ

    ChrisJ Active Member Forum Leader

    What about being oversized for cooling? Will first stage run long enough for dehumidification? Any cooling load info?

    ChrisJ
     
  5. gbig2

    gbig2 New Member

    Here's what the energy auditor came up with:

    Heating
    Calculated Peak Loads 30.2
    Sizing Factors 100

    Heating Equipment Capacity (kBtu/Hr)
    Required 30.2
    Specified 110

    Cooling Equipment Capacity (Kbtu/hr) 17.2
    Sensible 14.1
    Latent 3
    Sizing Factor (%) 100

    Cooling Equipment Capcity (kBtu/hr)
    Required Total 17.2
    SpecifiedTotal 24

    Required Sensible 14.15
    Specified Sensible 16.8

    I'll ask the geo company about whether the ac is oversized.
     
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    My Elitesoft Man J s/w suggests 9*F winter design for Allentown. An ACCA Man J design condition PDF I have suggests 10*F for Allentown. I lived nearby from 1984-1995 and my recollection agrees with those temperatures.

    So, based on heat load information here, 3T looks like the better solution. That the required sensible load is just 14k Btuh suggests that a 3T, even in low stage, would be moderately oversized for cooling. A 4T would be grossly oversized for cooling, even in low stage. Since Allentown summers feature high humidity, a system grossly oversized for cooling risks comfort owing to incomplete dehumidification. Tonnage cools a house; runtime dries a house.

    If memory serves, Allentown is served by reasonably-priced PP&L power, so a few hours of aux strip use for a few hours on cold nights would cost a pittance. Right sized equipment is more efficient the other 8700 hours of the year.

    Don't expect significant savings from reducing the system tonnage, perhaps $500 or so.
     
  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Incremental cost/ton around here is about $2,000 for closed loop.

    We have a company around here that has sold more units than anyone else and designs at 10* lower than everyone else.
    Frankly I think it is to keep their salespeople out of trouble. On a recent project they bid a 5 ton to my 3 and everyone elses 4 ton. Propane consumption suggested 40K loss and peak load about 50. Somehow they came up with a load of 80K.
    Many of their customers are pleasantly suprised that it costs less to heat the home than they expected. What they don't know (because they have nothing to compare to) is that a smaller and less expensive to install system may well cost them less to operate.

    The infrastructure and time it takes to be the biggest dealer around and to install 4,500 units appears to have cut into these guys continuing ed hours:rolleyes:

    Open loop Carter administration guys loaded heavy, but to them manual J was a door stop. Why bother doing calculations at all if the first thing you do is break the calculator.
    I always wanna ask these guys if they get the biggest engine they can in their service trucks in case their technician decides to tow a travel trailer. Imagine the conversation...."oh these conditions will never occur?"......."so then you might waste more fuel preparing for something that doesn't happen vs 'right-sizing' the engine to the load?".........."hmmm I wonder if this applies elsewhere".......:rolleyes: "but hey, it will never be underpowered, so you certainly won't have any complaints there."

    Again all people can compare to is their old propane bills so of course they are happy. If they knew they could be paying even less and they could have paid less to install the system, what do you think they would tell the BBB then?

    Forget about the extra 1/2 ton of loop. Mr. big shot is further showing his @$& by suggesting this. A little extra loop never pays for itself. For operating cost impact in my AO you generally need about 1/2 again as much to save 30 or $40/yr (on a 3 ton that's about $2,400 in additional loop).

    I don't suggest you ask anyone to change their design, I suggest you hire someone else.
     
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    My guesstimate of $500 for the ton in question addresses only the system equipment side, not the loop, which I thought was set in stone.
     
  9. gbig2

    gbig2 New Member

    He came back at $1160 less for a 3 ton system with 3.5 ton loop (525 foot bore, 1050 ft pipe) vs the 4 ton system with 4 ton loop (600 foot bore, 1100 ft pipe). Total is $15,700.

    Other companies that gave quotes are using from 8 degrees Winter design temp to 11 degrees. The other big company in the area who came in at $23,463 used 8 degrees and came up with 30,000 btu heat loss, exactly what the energy auditor came up with when he modeled the home.

    The required sensible cooling load at 14,000 makes it a no brainer to do 3 ton system. Yes, 4 tons would be incredibly oversized. I'm going to have to ask this 4 ton guy about the cooling. If I don't get an answer I like, I may go with the guy that's more expensive.

    Engineer, electricity is about 13 cents/kwh around here.

    Is anyone else concerned about cooling being oversized @ 4 tons?

    Bottom line, having all the info that I've provided, 30,000 btu heat loss, 14,000 btu cooling, what size system would you be recommending for your customers in this case? As AMI said, would you automatically eliminate a company as an option because they got the sizing wrong even if it means spending $6500 more? Some of you seemed ok with 4 tons, are you still ok with it knowing my cooling needs?

    It's odd that he's saying he used 0 degrees based on history. I can't remember the last 0 degree day and I'd say we've had no more than a handful of days like that in the last 5 years. At 0 degrees he's probably right about 43,000 btu heat, but I'm going to spend $1100 more and risk being oversized for cooling for a couple days a decade that it's 0 degrees?



    Thanks for the help, I appreciate it.
    Greg
     
  10. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    What size would I use for a 30MBH load?......a 2 ton....a 4 ton is absolutely ridiculous.
     
    Last edited: Jun 17, 2012
  11. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Joe makes a good point - the number of hours a 2T would need strip heat to make up the difference is likely in the low 100s, perhaps assing $100 or less to the annual energy bill.

    2T would be more suitable for the cooling load, yielding both comfort and savings through higher efficiency, offsetting some of the winter strip heat cost.

    Spend the capital saved on weatherization / extra insulation and the strip heat use / cost would fall even more
     
  12. gbig2

    gbig2 New Member

    Seriously, 2 ton? I get your points, but the Bosch ta25 at 32 degrees ground loop shows only 16,600 btu in part load and 20,400 in full load. That's going to be a lot of aux heat. I'll be in aux heat every time it's below 12 degrees. Also, won't the desuperheater knock some btus off the total capacity for heat, in the Winter?
     
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Seriously, indeed!

    Temperature Bin Analysis

    Let's be conservative and suppose that with a 2T you need aux heat whnever it is less than 15*F outside. Elitesoft's weather database shows that the temperature is below 15*F 175 hours per year in A-town. For a first approximation, let's suppose you need an average of 2kW extra strip heat (~7,000 Btuh) during all of those 175 hours.

    That works out to 350 kwh / $45.50 in strip heat per year. Is the purchase of an extra ton of system and loop capacity worth saving <$50 per year? The 2T will be quieter and more efficient during the other 8600 hours of the year, likely offsetting most if not all the $45.50 via rest-of-year efficiency gains, not to mention improved summer comfort.

    We could refine my 2kwh X 175 hour assumption by calculating the design load and expected number of hours at 10*F, 5*F, and 0*F bin points, but that idea wears coveralls and otherwise resembles (unpaid) work, so I'll leave it there.

    The question of desuperheater diversion is valid and worth discussion. The coldest hours are from midnight to dawn. During cold nights the system will already have been operating for several hours before midnight, so the desuperheater buffer tank should already be quite warm (mine hits 130 on cold nights). When the desuper inlet water is that hot, it diverts very little heat from the refrigerant coming out of the compressor, leaving full capacity available for space heating.

    Worst case, assuming a storage electric resistance water heater downstream of the buffer, is a 1:1 trade in resistance electricity use - any excess strip use owing to desuperheater diversion is offset by avoided water heating element energy use. No net increase in cost.

    Fear not the aux strip heat bogeyman!
     
    Last edited: Jun 17, 2012
  14. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    If we use Climatemaster op cost model, and 13 cents kwh I show a $21 yr difference for all heating cooling and hot water between the 2 ton and the 3 ton. The 4 ton is $8 yr cheaper than the 2 ton to run (your expert wants you to buy a unit that costs more to run than the other guys advice).
    You said you'd be cool with covering 95% of the load with geo, well the 2 ton covers about 99% of the load (as it's still running when aux contributes a little).
    Regarding the DSH. The 2 ton due to lengthier run times would actually contribute more to the hot water production than the 3 or the 4 which closes the operating cost gap considerably.
    You must understand that everything is based on a 20 year weather average, so some years are colder and hotter than others. Your installers are trying to make sure you never see a rise in your bill even if it gets down to temps that are extremely rare. To do that they are charging you thousands extra and saving you $10 or $20 dollars a year in op cost.
    Even worse, one dumby wants you to buy a 1/2 ton of extra loop. Same calculator suggests that will save you $5/yr in operating cost.
    I don't know things like the make-up of your soil et al so I have had to make my best guess on some things, but if your design temp there is double digits, 3 and 4 ton units are unneccesary. If any of the guys ran op cost calcs, ask them to plug in a 2 ton and compare results (but they must use real load calc and design temp, not imaginary ones).

    You asked for opinions, I suggest a 2 ton.
     
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Joe has earned a remote design fee!

    I'll echo that you asked for opinions; we provided them
     
  16. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I feel obliged to footnote - if prices are reasonable (which i believe they were), the 3geo ton isn't a horrible pick it is simply a different design practice. Further if it is your forever hiuse and you may want 75* in the winter (when you are on blood thinners) it may be the best choice.
    (I'd still kick the 4 ton to the curb)
    there are old school geo guys just like old school furnace guys who think bigger is better. Curiously with gaas furnaces this is kind of true (if not grossly oversized) as the next size up may only cost $50-$100 more and save $20/yr op cost. In geo (particularly closed loop) the next size up might cost $2,000 more and still only save $20/yr.
     
  17. gbig2

    gbig2 New Member

    Thanks for the advice. When you guys are coming up with like $21 or $45 a year in extra electric costs for 2 ton vs 3 ton, is that just heat strip costs, or are you also factoring in the increased stage 2 use? Certainly will use much more stage 2 at 2 tons vs 3 tons.

    Thanks again, I'm considering 2 tons. I also have a call into a local certified geoexchange designer (only 2 in the state apparently) to see what he has to say, as someone who is not trying to sell me anything.
     
  18. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Of course we factored in second stage and even additional blower usage for longer cycles. Remember a 2 ton in second stage draws about the same amount of juice as a 3 ton in first.

    I'm not picking on you, but if you don't find facts and supporting figures compelling, you can get all the opinions you want and still be in a quandry. No the CGD may not be selling you anything (of course neither am I), but he also may not be expert in operating cost modeling.

    As I said before a 3 ton wouldn't be horrible, just less bang for the buck.........
     
  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Seriously! Even if you use aux heat everytime you are below 12F, it only gives you spikes of heat when each bank of strip heat kicks in, usually only 5 kw at the time. The geo system will still provide 90% of the heat during that hour. In addition, take into account solar gain and internal gains, which should be around 6000-10000 btu for your kind of house. The capacity is rated at entering water temps of 32 F , which you usually reach during the end of the heating season, average EWT is usually much higher, increasing also the capacity.
     
  20. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Stage 2 will not be more expensive or less efficient to run than stage 1. The difference in efficiency (COP) comes pretty much only from the warmer entering water temperature (41 F at stage 1 versus 32 F at stage 2) used for the rating. However, in real life the loop temp does not drop when the unit goes from stage 1 to stage 2. Only the leaving source temp drops, EWT stays pretty much the same.
     
    Last edited: Jun 26, 2012

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