Manual J - Number of bores and \"Expected\" EWT

Discussion in 'General Discussions' started by JRBGEO, Feb 17, 2009.


    JRBGEO Member Forum Leader

    Manual J - Number of bores and "Expected" EWT

    I have a question for the techies on the forum and hope I can narrow down an option soon to correct my loop problems. I have a 4 TON WF Envision system.

    I have two options on the table as follows:

    Option 1

    Add another parallel bore at 225 feet that will bring the total bore depth to 675. This option would require flushing the Environol out of the system and replacing it with Methanol diluted at 20% to ensure we have proper Turbulence (Re #) in the loops. Total number of cicuits 3.

    Option 2 (Optimal solution)

    Connect two existing bores at 225 in series and add a new bore at a depth of 450 in parallel. Total number of circuits 2. Based on the analysis we have done we feel the existing pump module should be able to handle the additional load (Geolink Flow Center with two Grundfos Type UP26-99 pumps). This option gets me past the industry standard of 200 feet of bore depth per ton of equipment. This option we believe will also yield the highest EWT.

    I also did my Manual J Calcs using HVAC Homeowner 4.0 and I found out that at 4 Tons the system was sized properly. This is what we have:

    Design conditions 0 F (outside) : The total heat loss is 52,988 BTUH
    Design conditions 10 F (outside) : The total heat loss is 45,421 BTUH
    Design conditions 20 F (outside) : The total heat loss is 36,270 BTUH
    Design conditions 30 F (outside) : The total heat loss is [SIZE=2][B][FONT=Arial][SIZE=2]29,023 [/size][/FONT][/b][/SIZE]BTUH

    I am also looking at the WF manual p. 39 & 40 for ND049 ECM Low speed (Stage 1) and ECM High speed (Stage 2) and trying to tie all this with the Manual J I did and determine what the best course of action would be Option 1 or Option there a way to anticipate with some certainty what the EWT would be with these options? Obviously Option 2 would allow me to run on Stage 1 most of the time and would yield the higher electricity savings. I am guessing Option 1 would yield an EWT in the mid 30's to low 40's but this is just a guess....Option 1 potential cost: around 5K....option 2 potential cost...around 10K....I am hoping some of the techies can help me sort this out...I am trying to find the right balance between "acceptable EWT" temps, higher % of Stage 1 run time and cost to get to a final decision on this....

    I would be happier with Option 2 (for the high EWT's) but I guess I need some good reasons as to why Option 1 may be ok too....this is tough for sure!!!
  2. Bergy

    Bergy Member Industry Professional Forum Leader

    Loop field

    What is the current loop configuration? How many bores? How deep? How far apart? Current EWT and LWT?


    JRBGEO Member Forum Leader

    Bores are 225 feet each 17 feet apart. From the first bore to the foundation there are about 20 feet. I don't have current data on EWT / LWT but last reading in the coldest part of January was EWT of 24 LWT of is probably better now as temps in CT this month have been quite mild....see current and proposed layout below....

    I got this reply from a WF rep regarding loop temperatures. Does this makes sense?:

  4. Bergy

    Bergy Member Industry Professional Forum Leader


    You only have two bores on a 4 ton system? I have never seen 24* EWT with a Properly Designed GSHP and vertical loop. You need to seek another "local" opinion about the amount of pipe you have in the ground. You only have 900' of pipe!!

    Standard practice in Eastern Iowa is... "One loop per ton" With good soil conditions a vertical loop is 150' deep. A 4 ton system would have 1,200' of pipe in the ground. Our design temp is -5* and I would not expect to see EWT lower than 30*.


    JRBGEO Member Forum Leader

    I think I have covered that part already. Yes I know the loops are screwed up - 450 feet of bore is not enough for a 4 Ton system. Unfotunately my WF installer did not do his job properly....that's why the EWT was so low back in January....thanks for your input...
  6. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Who ever told you this needs to go be a greeter at Wal Mart. He or she knows nothing about loop design or performance. :eek::eek::eek:
  7. geo fan

    geo fan Member Forum Leader

    One thing a designer needs to remember is we want the loop temp to be colder than the earth in a progressive rate. What that means is that as the winter comes to end of Jan or Feb. we want the loop colder because we actually get a quicker heat transfer due to the larger delta "t".

    Well thats a positive spin
  8. Bergy

    Bergy Member Industry Professional Forum Leader

    I would not recommend

    Adding one more deep bore. I would suggest adding two more 225' loops.Keep your loops the same length, pipe them reverse return and they will perform as expected. What is the required depth per bore for YOUR soil conditions at YOUR design temperature??

  9. Looby

    Looby Member Forum Leader

    It's best to fall behind early, because that gives you more time to catch up.

    ...I'm going home early today -- to make up for coming in late,

  10. JRBGEO

    JRBGEO Member Forum Leader

    Believe it or not....this statement:

    Came from another WaterFurnace installer. If WaterFurnace knew the clowns they have working for them in CT they would be sorely dissapointed. Maybe he went to the WaterFurnace School for Loop wonder all the loops done this winter by WF are freezing!!!!! This fellow also told me that WF does not follow industry standards of 200 feet of bore per TON of equipment, that's why they go by their GEOLINK Design studio software....more BS for sure....translation: we prefer to short loop all our jobs so the customer gets a WAL-MART grade install and get's stuck with higher utility bills!!!!
  11. John Preston

    John Preston New Member

    I see a lot of guessing going on here about loop sizing. There is no average loop length for any job, each job is different and if a good loop installer is going to do it correctly they should be running some type of program to come up with the best sizing.

    What hasn't been mentioned unless I overlooked it was the actual pipe size. I understand that people in the Midwest go by the 150-200 feet per ton with .75" pipe but out east the drillers mainly use 1.25" pipe and try to go as deep as possible so they don't need to move the rig. It is not uncommon to have one loop with a capacity of 1-2.5 tons capacity.

    The comment of all WF loops are freezing out east in slanderous at best and I suggest this person gets their facts straight. WF does not train people to undersize loops by any means and if people use their GeoLink program correctly (which has been around longer than most contractors on this site) they rarely if ever have any issues with loops. The remark out the Delta T on loop temps is relative IF the person really understands loop design and the benefits economically for the homeowner.

    Lastly, the person that started this thread sounds like they have no idea what they are doing and like most internet posts is just looking for someone to agree with them.
  12. thaas53

    thaas53 New Member

    I suggest you talk to Steve at Nutmeg Mechanical in Manchester. They are not a WF dealer however, they did my install of a Bryant 6 ton unit and they were very good.

    Maybe they could give you an independent review of your situtation.

    Here is my system, I'm located outside Hartford, CT:
    Web Energy Logger:
  13. arkieoscar

    arkieoscar Member

    Lastly, the person that started this thread sounds like they have no idea what they are doing and like most internet posts is just looking for someone to agree with them. [​IMG]
    This person is the victim of some of the "professionals" out there and is trying to learn their business to solve his problem. I know that happy people don't tend to post here but it's a shame that so many have spent mega-bucks to get systems that don't work and have no recourse but to come here to get some answers. As far as formulas and programs to size ducting, loop systems and equipment size- they're only as good as the numbers that are inserted. Garbage in=Garbage out. As far as loop sizing goes- I think most are undersized to get the job, not to give the customer the best system. While I'm ranting (Not about Preston)- you lose your pants because they are too loose.
  14. JRBGEO

    JRBGEO Member Forum Leader

    I started this thread because this forum has been the "only source" to get answers to the issues I had with my install. If I were happy with the results I am getting from my system I would not be here "double" checking and "triple" checking things. The "techies" on this forum have been more than helpful with their insight and their "honest" answers. I wish from the onset I was given the proper amount of bore depth for my system but when 3 folks at WF can't agree on giving me the same answer that tells you a lot about high tech loop sizing software etc etc. Even my well driller admitted they would have given me more loop but they can only drill to the specs from the installer. I trusted my installer to do the right job and give me the right amount of loop and a system that would not lock due to low temps and a system that will save me $$$$. That did not happen. Fortunately I am heading on the right direction now as I think a have a solution that will get me where I want to be.
  15. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    John, I suspect that you might work for WF. Glad to have you join our discussion.

    Are you saying that this is an accurate statement?

    I realize that in an economical loop design the EWT will drop as the season progresses.

    The part that I have trouble with is the statement about "quicker heat transfer".

    What exactly does this mean and how does it effect EWT?
  16. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I too welcome an official WF member, HOWEVER...

    I'm disappointed that WF's apparent spokesperson's very first post here includes a disparaging barrage at a 7+ month member who is also a WF customer...that was simply uncalled for and counter to the tone and spirit of this site.

    Facts on the ground are that senior members here and at Green Building Talk have devoted countless hours helping homeowners diagnose and work around short-looped geo systems. That a seemingly disproportionate number of these systems may have been installed by WF dealers gives rise to suspicions of incompetent dealers countenanced by WF. This apparent sacrifice of quality at the altar of unit sales is NOT what the nascent geo industry needs at a time of potentially rapid growth.

    Unhappy WF customers multiplied as winter deepened. Alarmed by the trend, on 6 January 2009 I emailed a carefully considered alert and plea for action to WF at their company site. Troublingly, I have received no response.

    I have a 3 ton WF Envision and can't sing its praises enough. I've been considering becoming a WF dealer since a lengthy conversation with their Marty Cromartie in summer 2006. My conclusion that WF's efficiency, selection of subcomponents, build quality and zoning controls met my needs best has been borne out.

    HOWEVER, the best system in the world won't succeed if installed by ignorant dealers especially if the corporate response is months of silence followed by the public bullying a customer by a Johnny-come-lately marketer or PR manager.

    I tried a measured approach, but Mr Preston's outburst in response to a homeowner / customer's reasonable complaints could not go unanswered on my watch.
  17. Waukman

    Waukman Member

    I agree that the statements by Mr. Preston were uncalled for, but it is not clear to me that this individual is a WF employee. It would be nice if the major geo vendors would all have official reps as clearly identified members of this site. As an end user I would find that big help.
  18. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    It would be great ......but don't hold your breath.
  19. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I'm fairly certain he is - shows up in Google associated with WF
  20. sunnyflies

    sunnyflies Member Forum Leader

    Is great depth necessary? I know people here on Long Island, NY with holes no deeper than 60 feet and their systems work. I have a proposal now for an open system, two holes, a 50' supply well and a 60" diffusion well.

    I plan to try to contact the field reps for several HP companies in the morning to ask that question.

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