3 ton vs 4 ton, conflicting load calcs: PLEASSE HELP!!!

Discussion in 'Quotes and Proposals' started by hren, Jun 22, 2011.

  1. hren

    hren New Member

    Hi All,

    I have gathered a total of 8 quotes for a geothermal system and all bidders have done manual J load calcs. All are respectable companies and seem to know what they are doing.

    However, the system estimates range from a 3-ton to a 5-ton, from 40,000 to 75,000 BTU of heating load, and from 23,000 to 46,000 on cooling load. All contractors used software programs, so there were no guesstimates. The reason for this broad spectrum of estimates is the energy efficient improvements that we will be doing to the house, so I guess some contractors factored in more and some less. So, I need an expert opinion on what seems to be more reasonable. Here is the info on the house.

    Location: Greensboro, NC 27408
    Year built: 1957
    Split-level, 2000 sq feet upper level (the split one)
    1400 sq feet lower level (has heating and cooling), 1/3 below ground on one side of the house, at the ground level on the other side; lower level has concrete slab floors (to be finished).
    So, total is 3400 sq feet of heated/cooled space.
    the house has about 600 sq feet crawl-space and mechanical room on the lower level (not heated or cooled).

    We moved in the house only 4 months ago, so we don't know how leaky it is in the winter, but it does not really matter since we will be doing a lot to the house in the next few months.

    Improvements that we are doing this summer/fall:
    - Spray 6" open cell foam in the attic and seal the attic;
    - Blow-in cellulose in the walls on the upper level;
    - Insulating the lower level cinder block walls with 1" of polyiso boards on the inside (5.5 R value);
    - Replacing all 20 windows with double-pane argon filled, low-e glass windows (also replacing 3 older doors with new tight doors);
    - Spray 3" closed cell foam in the crawl space and mechanical room to insulate the floor in the main living room above the crawl space and mechanical room.

    As you see, the entire house will be much tighter and well insulated.

    The load calcs that I have so far (heating, cooling):
    1) 55169, 25062, 4-ton
    2) 59000, 46000, 4-ton
    3) 75432, 40777, 4-ton
    4) 49402, 30069, 3-ton
    5) 73068, 42535, 4-ton
    6) 49462, ??, 4-ton
    7) 40000, 23000, 3-ton
    8) 66000, ??, 5-ton

    The questions:
    1) What seems to be a reasonable heating/cooling manual J load calc given all the improvements that will take place?
    2) Should it be 3 or 4-ton system?
    3) How long should the vertical wells be?

    Please, Please help! It seems that however many contractors there are, that many opinions I will have. I don't want to run heat strip all the time in the winter and neither I want to oversize the system that will run in short cycles in the summer.

    Thank you very much for all input in advance.

  2. zach

    zach Member Forum Leader


    Has your envelope improvement contractor done a blower door test? Is the contractor BPI certified?

    I'd suggest having a blower door test done now, pre-building envelope improvement. This will give you a current infiltration/leakage number.

    I'd want a blower door test run before and after the improvements to quantify results of your substantial envelope improvement investment.

    When do you plan to do the envelope improvements relative to the geo install?

  3. hren

    hren New Member

    We thought of blower test and then eventually decided against it. We know that the house needs more insulation in the attic and in the walls (they have no insulation or it deteriorated over time). Spray foam in the attic will completely seal it. The windows are old (and likely leaky), so we will replace them and the full-frame replacement will involve foam spraying around the new frame, so that will prevent any leakage around the windows. The crawl space will be sealed with closed-cell foam, so that will take care of any leaks there. We have two fire places, but we will be putting fireplace inserts there, which will prevent leaks. All minor leaks on the lower level (water lines to outside faucets, cable/telephone, electrical outlets, etc.) I will seal myself with foam and/or chimney mortar. The only potential leak after all is done will be through the walls packed with cellulose insulation, which is minimal.

    Before/after blower test would be good to have, but we want to minimize the equity loan amount and don't really want to spend extra $600 on that.

    The spray foam in the attic and crawl space will take place at the same time as the geo installation (in fact, done by the same company). The wall insulation will be blown in when the windows will be installed (a couple weeks after the geo). Or, if windows will take longer to manufacture/get here, then the blow-in insulation will also happen simultaneously.

    Window installation, with a possible delay, will take place in September/October. Finally, I will install polyiso sheething over the next two years (still, we should account for that in the calculations, although lower level has little cooling load and smaller heating load).

  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    On paper, you would be below 40 KBTU/H after the upgrades, so a 3 ton system would be more than efficient. But I do not want to contradict boots on the ground. Actually, it should be less than 35 KBTU, I calculated generously, not know more details.

    As a professional on the other side of the table, I always see a red flag people get more than 5 estimates. Those kind of jobs are one reason why the price of geo does not come down quicker. There is certainly the need for competition, but in your case 7 out of 8 people put a lot of work into the manual J and the proposal, and are going home empty. Geobids are more complex, you can't just go and put a generous sized furnace in.
  5. hren

    hren New Member

    I absolutely understand that the contractors would not want me to shop around a lot. However, the huge range in the calculations was one of the reasons I needed to get more estimates. The other important reason was that the prices ranged from $28,500 to $37,500 for the same scope of work and similar equipment packages (all including drilling).

    Pardon me, but I'd rather upset a contractor a bit than pay extra 9K. In the end, these quotes let me negotiate with the better company, so I got a better price, they got new business, and this is the exact competition that helps bringing the prices down. Everyone is happy, right?

    About work to compute Manual J loads, it is not that enormous. One guy did it right in my house in 30 minutes. So, I guess this should be a regular part of doing business - making calculations to bring forward a proposal.

    But, regardless of the buyer/seller side arguments, I very much appreciate your help and advice. Thank you.
  6. geome

    geome Member Forum Leader

    We had six quotes. After meeting everyone, and after reviewing all quotes, I was confident that only two installers would do a good job. As it turned out, the installer we went with was the second installer to come out, and the other installer we considered was the last one to come out. I would have preferred to only meet the two installers we ended up considering, and I'm sure the other four installers would have preferred not to waste their time either, but there was no way of telling ahead of time.
    Last edited: Jun 22, 2011
  7. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    Contractors don't care if you shop around a lot. We just don't like being strung along for free advice, ideas, etc... On a job site, not this forum.

    Sending out 8 copies of your house plans to 8 installers to quote on is also different than having each come out to the site, measure your house, suggest options, and quote on it.

    My advice, throw out any numbers ending in "000". Also the larger numbers "may" just be a polite method contractors use to not win the job.
  8. zach

    zach Member Forum Leader

    It is your money to spend as you see fit. My guess is the envelope improvements are not a cheap investment so wouldn't you want to be able to quantify the result? How will you know if your contractor did an adequate job? For what you are spending on shell improvements, I'd demand a blower door test from your contractor.

    I asked if your contractor was BPI certified as the work you are doing requires a blower door test in and test out according to BPI technical standards.
    http://www.bpi.org/Web Download/BPI Standards/Building Analyst Professional_2-28-05nNC-newCO.pdf

    In addition to quantifying results, one must be aware of your building's airflow standard (BAS). ASHRAE standard 62-89 requires a certain number of air changes per hour in your building. If your measured BAS is between 70% of the calculated BAS and the calculated BAS, mechanical ventiliation is recommended. Below 70% of the calculated BAS and mechanical ventilation is required.

    A tight house is good, but beware you need to be aware of your indoor air quality. You can tighten the house enough that without mechanical ventilation the IAQ suffers.


    Last edited: Jun 23, 2011
  9. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    From my perspective, sometimes it is necessary or worthwhile to spend another 9K.
    As someone here said before, I am also never the cheapest, but I am also proud that I never had an unhappy customer.

    You might think that the scope of the work is the same or the equipment is the same, but trust me, it is not. There is a huge difference between installing a geosystem which works, and a system which works ultra efficient and every component is extremely long lasting.

    I give you one tiny example: To seal the entry point into the building we use metraseal, which is a mechanical seal where you tighten screws which tighten the rubber elements. The screws are made of steel, which will rust in the next 25 years. You can also get them in stainless steel, but they are more expensive. The supply shop tells me that we are the only one among all the geo installers who orders them in stainless steel. Silly little example, and you might not care what happens in 25 years, but why bother putting in a loopfield with a life expectancy of 200 years when its weakest point is a component which fails after 25 years?

    Or circulation pumps. You get a 4 ton system and chances are they will use (2) 26-99 pumps as circulators, both using 520 watts when running. A Wilo stratos will use less than 100 watts for the same pumping power needed, affecting the overall geosystem performance by roughly 12 percent. What kind of flowcenters and what kind of pumps are in the proposals?

    Again, just two silly examples of how you can make real differences as an installer. You think that you are getting the same equipment and it is the same scope of work, but I would questions that. All that cost money and effort.

    I admit that it is tough to know as a consumer who is giving you the best value. Eight different estimates will not tell you that.
  10. geome

    geome Member Forum Leader

    Doc, I don't think your examples are silly (they are great.) Are you saying it is up to the installer to convince the homeowner (at least verbally) of the added value so the homeowner knows what he is getting for the money? I would agree with that. How else is the homeowner supposed to know...

    I didn't have one installer tell me of any niceties that they would have included in their job. It could be that they either didn't want to divulge the information (for fear of me taking their ideas to another installer), or it could be that didn't include any niceties that would have made their installation better than the competition. Since I was not told, I really don't know and had to make a decision on what I did know. 2+ years later, I still have no idea why one installer's quote was roughly $9,000 more than the other typically priced quotes for the same equipment.

    P.S. I ordered and installed 304 stainless steel concrete anchors for our generator so I can unbolt the generator in 15-25 years (probably from my wheelchair) when a replacement generator is needed. Everyone thinks I'm silly too, but we know better! :)
  11. hren

    hren New Member

    You are absolutely right - I have little idea about the difference in pumps and screws. However, based on the installers' quotes, there is no difference. Based on what they told me, the only difference is this: "We've done a lot of jobs like that and all others screw them up and leave for us to clean." Really, half of them said this. so, if there is no difference in any information I received and the credentials are similar, I would naturally go for a lower price or use the lower quote to negotiate with the company I trust more (which I did). And, the company whom I negotiated with easily dropped about $4,000 to match the lower quote, and keeping in mind that they have to travel 50 miles, while the competitor was 1/4 mile away from my house.

    My guess is that there is a good profit margin there. If the job costs $28K minus $13K for drilling, minus $6K for equipment, minus $4K for labor, it leaves $5K in profit, which is 50% margin on $10K installer expenses. And, the margin jumps to $14K on $37K quote.

    Sure, if an installer told me why their cost is higher not just because they are the only ones who do a good job, but because of pumps, screws, joints, etc. I would have a better understanding of the cost difference. But they don't explain - why? I am not an idiot and I spent dozens of hours reading about all this stuff, so I can pick new info very easily. Just educate me and I won't mind spending extra couple $K on a better job.

    About the pumps, they use the flowcenters from WaterFurnace:
    FPT Flow Centers and Accessories Pre-assembled with pump(s), 3-way valves with flush ports, internal components injected with foam. Horizontal or vertical mounting capability. FPT and FPTB use brass valves and have 1” FPT connection.

    It sounds like the pumps come with the Waterfurnace equipment. I guess, a more efficient pump is better, but how does it tie into the main system? Would a different pump affect the warranty?

    Again, thanks a Lot for all helpful advice - I think I decided to go ahead with a 3-ton system.

  12. geome

    geome Member Forum Leader

    From one can of worms to the next...

    You're on your own from here! :)
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    There is always a difference. No system is alike.

    Unfortunately, they are right that there are many incompetent installers out there, we are called in as well when others screw up. But avoid talking about it during a meeting with a customer. I don't like to bash the competition. Unfortunately,this is exacerbated by sales guys as a scare tactic.

    There is more than $6K going into material with a 3 ton system, trust me. PM me and I will send you the waterfurnace price list.

    A different pump does not void any heatpump warranty, even if it is off the heatpump has safeties built in to protect itself.

    I guess you did the best you could do, check out the references, follow your instincts and go with the guys you clicked with most, and ask them to be competitive and match other prices. The rest is keeping fingers crossed.

    The pump/flowcenter will be interesting. The 3 ton heatpump only needs 7.5 - 9.0 gpm of flow, and a vertical loopfield will have a small pressure drop, so it likely needs only a 1 pump flowcenter. If they install a 2 pump flowcenter, check the pump models, and ask them for the pressure drop calculations. Call it an internal test.
  14. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    It looks like some of the contractors have not included your improvements in their load calcs.
    This is a case of GIGO. Results based on imaginary (yet to take place) improvements.
    Do your insulation et al and then shop for a heat plant.
    Speaking of imaginary, 6K for a heat pump and all the trimmings is not particularly accurate either. That is however another conversation.
  15. hren

    hren New Member

    The installer said that 3-ton system will need only 1 pump and two 250-foot wells, which I guess is good news. One pump sounds twice as efficient as two pumps for 4-ton system :).

    Thank you for all the info. I did negotiate and agree on a price with the installer I liked the best and they already came and took out all old junky furnace and the drilling will begin in a couple days. So far the crew was very good.

    you are absolutely correct - there are many incompetent installers. I spoke to about 15 companies over the phone. It is very clear if they know what they are talking about of if they have no clue. but then 2 out of 6 installers who came over immediately began with scary stories: how they fix all the mess all the time by everyone else. It's understandable if they do, but it shouldn't be the sales pitch. If they have competence and confidence in their work, they should not begin scaring the customer just to justify jacking the price $5-6K more than others. It reduces their credibility. I like honest and fair negotiations without scare-pressure.

    Thanks again for all the advice - this forum and the people here are awesome. You've been the best resource and help on the Internet, in my experience.

    When the work is done, I'll post how everything went.

  16. hren

    hren New Member

    True, it would have been better to do the improvements and then the calcs, but we wanted to put everything in the same package for Uncle Sam and tax dollars. The company we went ahead with does provide all the services (insulation, foam, etc.), so this will be a single package, which would be good for the potential IRS audit: the system design includes all other improvements and they are an internal part of the entire system, not just additions. Without the improvements the system would have to be much larger and much more expensive (which would result in the same or greater tax credits).

    I realize that estimating the improvements is less precise than measuring what there is on the ground, but we can tolerate a larger margin of error. In the worst case scenario we will reduce the thermostat to 63-65, put a sweater on, and run a wood-burning stove on several coldest days to avoid running aux strip.

  17. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It all sounds good, post the feedback.
  18. zach

    zach Member Forum Leader


    I'm with you. Envelope improvements first, heat plant later.

    I am surprised the contractor is not utilizing a blower door test in and out.

    hren, I'll say again, blower door test in and out is worth every cent.

    Your contractor should be able to estimate for you how many hours a year you'll need aux heat. Aren't you also intetested in how many btu's you'll save via the envelope improvements? A reputable contractor will give you that information.


  19. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I too

    having retired and turned the keys of the geo-gypsy-mobile over to steph, wonder where these numbers come from.

  20. hren

    hren New Member



    We've had the foam insulation sprayed in the attic and crawl space. the attic temperature dropped significantly. On a hot mid-90° day the attic was about 100°. I am going to rent a large vacuum to suck up the old crumbly insulation to make the attic space storage useful.

    The crew installed the geothermal unit - we finally have a/c going, which is very nice. We'll see what the energy bill will look like at the end of July. We'll probably do a blower test after all the improvements are done. the crew did a good job, although there is a flimsy part: a small pump outside the unit that pumps the condensation outside (the unit is below the ground, so the water cannot just run out on its own). This was a bit strange to me - I thought WF would have thought of that and had an option of a small internal pump incorporated in the main unit. Now, that additional pump is exposed - anything can hit it and it will disconnect.

    DSH is also on and (I assume) generates hot water. Is there any way to check how well DSH is performing? The piping that connects DSH to the unit and to the storage tank is a bit flimsy, but I guess we can live with that.

    I'll post another update once everything is complete.

Share This Page