Discussion in 'Vertical and Horizontal Loops' started by TowPro, Feb 20, 2013.
Would you get started on that please ?? We could use some Lake Erie water out here.
I would love to help out, but all the Great Lakes States and Canada have this agreement about shipping away our water. Hey with Greenland melting maybe we could get you some fresh water from there.
But first step is to pull my pump and measure how deep my well really is. Original driller don't have records (drilled 19 years ago). I am going on memory on the 265'. I still have a good memory, but we need to know for sure.
We are working up a couple proposals. I need to know the total price for everything.
If my well is not as deep as I seem to remember, we will be making it deeper.
There is a min price to bring the drill truck on site. (he's not going to charge X dollar a foot to come in and drill just 35').
So if we need to add say 35', but the min price will drill 100', I will go for the max depth the min price allows.
Does everybody agree if I need to spend X money to make the well deep enough for min required loop length, but that same X money will give me more then the min required loop, It is OK to oversize the loop?
that is a yes in my book
The guy I thought was going to do my well is so hard to get a hold of, I called someone else for a price.
Before he gives me a price, he wants me to answer some questions, and he wants to do an onsite visit.
1: He said after he puts the loop in the hole, he likes to put rice chips (small rock the size of rice grains) into the well, then grout the top 20' or so.
Since my well is full of water, how does water saturated rock chips compare to true grout for BTU transfer? (this is what he did to his own Geo system).
2: He is asking me of I want the 1.25" pipe rated to 160psi, or the new stuff rated at 200 psi?
3: He said he prefers to put some steel casing in to stop the top soil from falling into the well during the construction, which stays in after he is done.
Is this normal?
I am finding most drillers are not very interested in putting there equipment down my existing well (and all have story's of stuck and or broken bits)
so if I add another well, then do 2 loops (both the same size), I have thoughts of maybe putting the manifold inside.
Is it just me over engineering things, or is there any positive outcome from running the extra 150' of pipe to put the manifold inside?
I think it would be easier to flush the loops if I could turn 1 off at a time, but this might not even be a problem if both loops are truly the same size with manifold outside.
If I did run the manifold inside, I think I need to size the total loop, and not just the loop in the well.
Example (numbers just made up for this example):
1 well is 75' away and the other is 100' foot away
The well that is 75' away would have a 200' loop, for a total loop length of 275' (550' of pipe).
The wall that is 100' away would have a 175' loop, for a total loop length of 275' (550' of pipe).
Since all 4 pipes are in a thin trench 4' down, I don't think I can add the trench length to the loop field for BTU transfer calculations, so I would use 375' for my loop size calculations?
Edit: I forgot to mention, in my area, the water level in the well is always within 10-15' of the top of the well. There are no drinking water wells within a mile or 2 since everybody was hooked up to city water 10 years ago.
The drillers concerns are valid in regard to deepening your exisiting well. Have you talked to any of the geo guys about double looping the bore you have now and grouting it shut? IGSHPA prefers that you grout the entire bore, most software for loop design does as well. Not all local codes are up to speed with the enviroment or IGSHPA standards for closed loop installations.
I was just reading my local code.
501.14.3.2.3.1. Casings are not required for Closed-Loop Geothermal Boreholes that are grouted
from bottom to top with bentonite grouting material. Casings are required for any installation that
does not include bentonite grout from bottom to top of the borehole. There are specific conditions
required for each method of construction.
My current well is already cased (steel) but it will need to be shortened since it now sticks out of the ground.
Then after they shorten it and grout the top 20', it would stop surface water from getting into the ground water.
I can see in some areas of the US where the bore hole can be dry, and it will only work by grouting the whole bore hole.
A full bentonite mix grout job guarantees repeatable results and it not dependent on water content in bore hole.
In my area, while the water level might change, most wells are always full of water. (that is why he likes to fill everything but top 20' with rice chip).
How well does rice chip stone conduct BTU when its dry? Will I ever have a dry well?
To really peel this onion will require a little more. I am not a big fan of backfilling based on future water content as it may change and have a adverse effect on your loops performance. What if only 1/2 your loop is wet and the other 1/2 is in dry rice chips? Grouting the entire bore ensures that no matter what happens there is a consistant thermal link between the ground and your loop. Also I have seen my fair share of surface caseings that were rusted off. Sooo in theory the contamination that percolated the overburden could then enter the aquifer. I understand you are allready contaminated near by, but I would be remiss in not bringing this up for others and regulators to ponder over at beer thirty.
How come nobody will loop the existing well for you, then grout it shut? I am not loving the idea of using rice chip(honestly not sure exactly what they are either). I would rather see a complete grouted bore for the best possible thermal connection to the ground, while protecting the ground water at the same time.
I don't get all the back and forth here either. Stick the 1.25" pipe down that 265" hole and grout it from the bottom up. Done.
The first driller I was working with has a geo salesman who is very hard to reach,and he never returns calls.
My problem is the Software says 245', but the "boots on the ground" say 300. Everyone here says to go with the local "boots on the ground"
because they know my area (But I think the "boots on the ground" are using a "rule of thumb" 150' per ton. The last guy said 175' per ton for assurance.
So I wanted a price on the following
a: Drill my well deeper (I understand the risk to your equipment, and understand if they don't want to do this).
b: Add another well and use 2 loops. I also wanted to find out the min fee to bring drill truck on property. If that min fee drills X feet, that is what my 2 loops would be).
the first driller (who I will probably use if he calls back) is telling me "$X per feet" which includes the pipe, trench and grout. But what about the pipe and grout for the current well? I don't want any GotCha's like "well we need another $2000.00 to pipe and grout the 2nd well"
c: My current well can be put back into use (for washing cars, watering the yard) if I put a new expansion tank on the inside.
I just want a price on paper so I have a good idea of the price (and that I can afford it before we pull the pump to measure the depth. Once the pump is pulled there is no turning back .
Calladrilling, in my area they take granite and grind it up into real small pieces about the size of a grain of rice. Its used for fill (easy to tamp) as well as spread on the streets with salt in the winter time. The local turn is "rice chip". Its also a popular term with anthracite coal used in auger feed stoves.
You will never get software generated numbers to match a " boots on the ground " number or vice versa. The choice we usually make is one or the other. The choice you should make IMHO is niether, and loop the bore you allready have. I live in an area where central water is becoming more common. In my CBA, unless you are useing large volumes of water to maintain automatic turf irrigation, the cost of maintaing and operating a well to play with a hose or two once a month does not even come close to the benefit you would see from getting lops installed for geo with no drilling required. I think we have all beat the options you have to death, the only thing left to do is your final word to start.
Agree this sounds like a lot of over-analyzing. Go with what you've got. If boots on the ground says it is just a wee bit short, dig your transit pipe trench a bit deeper that the 4 feet you were planning and be comfortable that you have some extra loop in the ground. Even at 4 foot deep you do not need to completely discount it from the equation.
Thanks. Owner of company called today. He is sending me the price.
Loop it , grout it completely from bottom with TC grout, and see how it performs. If its undersized then add more loop later. It's been said numberous times over and over again. I would not be to excited about "rice chipping" and sealing the top 20'. It may pass your local code/regulations but more than likely not produce the best heat transfer you need..
Sorry for the delay, I finally had a chance to pull the pump and see how deep my 265' well really is.
Well you know that old fish story, and how the fish gets longer every time you hear the story .
Well measures 198'.
Now I have to decide how to go.
Well driller gave me an estimate on backing up to my current well, guessed it was 250' deep and was going to add 50' to it. It came to the same price per foot he first gave me that would drill a new 300' well.
So logic tells me I can pick 1 of the following.
NOTE: I will be doing the trenching.
1: Pay the price and have him add to my current well.
2: Get a price on adding another 150' well, and loop each.
3: (not sure if this will fly with you guys) Add a 100' well, loop current at 200', new one at 100' and run them in series.
If I pick choice 2, is it worth the extra expense of pipe to run both loops back to the house (making sure the total loop length (including trench length) is the same for both loops?
I really only have enough room for a 2' wide trench from house to well locations, so I will have 4 pipes in a 2' wide trench.
If I pick choice 2, and put a manifold out in the ground near the well sites, is it worth any advantage (or savings) to run 1.25" out to the manifold, then run 1" loop in each well?
Thanks for the help.
#1 seems unattractive
#2 is unattractive design as well, given that you have a 200' deep well
#3 should not be a problem, but be aware that you need 1.25" pipe for that, otherwise the presure drop will be far too high.
If you are running 2 loops in parallel, why don't you dig a 200 ft long trench (50ft with slinkies), 8 ft down, and put 400' of pipe in it. The other circuit of 400' you stick into your well.
If you run it in parallel, it should be 0.75 or 1.00" pipe, if you run it in series it should be 1.25" pipe. You only have 7-8 gpm of flow requirement with a 2 ton unit, that is why you can afford to run them in series.
You said you have a heating load of 2500. That does not really tell me much. What is your design heating load? What kind of soil do you have?
Thanks for the reply Doc.
I don't want to do trenches. I currently have the room, but looking at the future I need to preserve that piece of land in case my septic ever fails. The board of health reminded me that I can't put a drain field on top of Geo Thermal Loops .
As for the Pipe size, I was planning on running 1.25" outside, but inside the unit has 1" pipes so I have to do the transition from 1" to 1.25" somewhere in the house.
That's another good question. Unit is 1", I will run 1" flex hose to a wall, then there is at most 20' of pipe to get to where the 1.25" comes through the wall. Should I transition to 1.25" at the end of the rubber hose that attaches to the unit, or can I run 1" along that 20' run and transition to 1.25" where I connect to where the loop pipes come through the wall.
The folks that build these heat pumps do not know flow. If they did they would install more than a 1" NPT fitting at the machine.
They are also clueless on air flow dynamics. I may need a trip to the test lab.
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