I have two areas I am trying to work on within a large metal building (12k sf).  Approx 1/3 of the building will be devoted to living space, the other is a shop area.  I will be designing a radiant tubing system for the entire floor.  As well, I have a 5T Climate Master I will use for the additional heating/cooling of the living space only.  I intend to let the radiant tubing in the floor be the primary heat source.  I also intend to maintain the correct humidity and dew point to run geo loop fluids directly through the radiant system in the summer to help maintain a standard temp.  I verified this summer that in a non-climate controlled and insulated building, concrete was around 90*F.  That is a HUGE heat load for cooling. 


I own an excavator, dozer, and building a drilling rig right now for my personal water wells.  What I am trying to find is some reasonable data in my area (KS) to determine at what depth  a horizontal loop would be best.  I know many here install at 4ft depth but I just cannot agree with that.  My gut is saying 8ft for a nice stable soil temp BUT we are starting to get to a depth where vertical starts to make sense as well as the HUGE amount of excavation for this.  I have not finalized any numbers yet but I expect about 10,000ft of pipe to be in the ground just for the radiant system plus around 2500ft for the 5T Climate Master. 

I have to have help drilling wells but I can sit in the excavator almost solo and do a horizontal system.  I DO have the room but that is still a massive amount of dirt to move around costing me $30/hr just in fuel on the hoe. 

I have sourced a pipe supplier yet but I know those costs will have to factor in. 



Thoughts?


EDIT:  I did have the thought to run a horizontal loop but orient the looped piping verically.  So I might dig 10ft down with my narrow 2ft bucket and build the coils to 3-4ft in diam.  4ft would bring the tops to 6ft obviously but my numbers show I should get about 625ft per 100ft trench this way with half the soil moved. 

Design and loop size starts with load calculations. Loops are not superior to one another (vertical vs horizontal- well vs trench) some simply fit the job challenges better (i.e. verticals fit on small lots while horizontals are generally cheaper).
Your questions and conclusions so far indicate that you have a lot more home work to do.

I realize my post probably seems like I have not done my homework but I have. I have looked at my soil thermal conductivity, flowrates, pressures, heat gain/loss in the building, etc.

The main issue here is there are several ways to skin this deal. I do NOT mean to imply to ask whether horizontal or vertical is better, what I am trying to get at is given no consideration to cost or area, which might be "preferred" and why?

Yes, I am using some averages on pipe lengths for this discussion but don't plan on me putting "about 500ft/ton" on the hole just because some guy on the forum said so.

I will know a little more once I test the soil conditions at depth but is a fair bet I will have moist clay at 6-8ft. I would assume the KS geo services would have some temperature data somewhere but for now, I can only rely on regurgitated chat online. The only other way would be to dig to different depths and test the temp.

I realize after examining the conductivity of soils that the temp in the soil local to the piping likely will not stay real stable as it will take time to dissipate any heat gain. I am sure it would be the hope that incoming water would match the soil temp but not sure that will be a reality or a prudent design parameter.

test the soil conditions at depth

An empiricist might get that hoe runnin' and dig a hole as deep as that thing can, stick a pipe in it, back fill and send down some temp probs and record your readings; record the soil strata, too.

$30/hr just in fuel on the hoe

What are you running? That is a nice big hoe; maybe 8 gal/hr? That is like 7.5 mpg...


btw, how big of a cheapskate are u:} It sounded like you did not want to pay even a laborer to help you with your project.

I would like to know more about the drilling rig.

. I am sure it would be the hope that incoming water would match the soil temp

It will if you use open loop. Which sounds like a possibility since you are drilling wells.

"I have not finalized any numbers yet but I expect about 10,000ft of pipe to be in the ground just for the radiant system"

Do I understand correctly, you are going to circulate water from the 10,000' of pipe to the radiant floor in winter to make your floor 48*-55*F.

" I intend to let the radiant tubing in the floor be the primary heat source"

For the living area wouldn't you want something to raise the temp of the floor, I am assuming the 5T CM is water to air.

Chris

The reason for building the drill rig is that we have an area that could have low performance wells. I stand to lose thousands trying to find water.  There is not many wells in the area though. The next door neighbor 1/8mi away seems to be good for 20gpm but we did not get to test it long enough to confirm that.

After having to fix a disaster for someone that lost their water well on a water source system, I just did not want to hang my hat on water as well as put additional strain on the water supply.

I guess if I end up hitting some good wells though, I might go that way and construct an ejection well. I could have nothing from 5gpm wells though.

Hoe I have is a turned up CAT225LC with 3208. I am not opposed to help but I won't hire someone due to liability reasons. I hurt someone while drilling and it is game over. I have family to help but doubt I can get them to help through 20x holes.

Chris, the geop loop for the floor was primarily going to be used in the summer basically just to reject the slap heating from the high soil temps which approach 90*F. I will use a wood fired boiler or other solar ideas for heating the floor. However, if the numbers work, I might be able to use the geo loop to collect some heat, then heat it a bit. I don't want to get into a situation of sending heat back out to the geo loop though!

Yes, CM is water to air.

"I realize my post probably seems like I have not done my homework but I have. I have looked at my soil thermal conductivity, flowrates, pressures, heat gain/loss in the building, etc."

That's a start

"The main issue here is there are several ways to skin this deal. I do NOT mean to imply to ask whether horizontal or vertical is better, what I am trying to get at is given no consideration to cost or area, which might be "preferred" and why?"

Do you have a grout pump? You'll need one for vertical. Do you wanna install these without help? Not gonna be vertical. So I guess horizontal makes sense if we follow previous advice....
"Loops are not superior to one another (vertical vs horizontal- well vs trench) some simply fit the job challenges better (i.e. verticals fit on small lots while horizontals are generally cheaper). "

"Yes, I am using some averages on pipe lengths for this discussion but don't plan on me putting "about 500ft/ton" on the hole just because some guy on the forum said so. "
"Chris, the geop loop for the floor was primarily going to be used in the summer basically just to reject the slap heating from the high soil temps which approach 90*F"

So you wanna cool an 8K slab without the benefit of a refrigeration system (or all 12K)? In texas? You're right 500ft/ton won't do it. You might wanna be closer to a gazillion feet/ton. (My first instinct was to say "Bat Crazy" but I softened it.)
This is where I suggested your research might be a little lite.

"I realize after examining the conductivity of soils that the temp in the soil local to the piping likely will not stay real stable as it will take time to dissipate any heat gain."

Now your on to something.

" I am sure it would be the hope that incoming water would match the soil temp but not sure that will be a reality or a prudent design parameter."

Right again not a prudent design

It is not my design goal to cool the building with the geo loop, but rather reject the additional "heat gain" in the slab that is gaining heat from the soil. However, I have not been able to test a slab with proper insulation and it could well be that just insulating the slab per proper radiant slab design will null most issues with heat gain/loss.

Ground source radiant cooling without refrigeration is feasible with open loop in climates like KS.

Do you happen to know of any installations in KS, preferably South Central? I do not intend for this to be the sole means of cooling because in KS, there will be certain dew point problems but if I can reduce demand on a refrigeration system that can mostly focus on dehumidification, that would sure help.

I know they did this very thing for a Walmart somewhere. I would have to look up the details. I just don't want to get to a situation of the slab sweating.

somewhere

This isn't KS, but one install (at least) was in Sacramento, according to this article:
http://www.newportventures.net/PDF/RadiantCooling-ASHRAE.pdf

Luckily the amount of dehumidification you need is primarily determined by how well you air seal. So it can be quite low, even in humid weather.

I agree and we intend to install only 2 roll up doors and the main one with a double door air lock. I think the building, just being this big, will exchange enough air. I am working pretty hard to design in good R value and air seals. Pretty much the opposite of what we work in now... I think just dropping some humidity and a little temp will make all the difference. I intend to keep the building locked down most of the time unless conditions are perfect for the doors to be open. I hate a dirty shop!

OOps my bad KS.

So you wanna cool an 8K slab in KS without refrigeration but with closed loop or do you wanna go with open loop now as jonr suggested (that would at least work but wasn't what you were preposing).........

you don't wanna cool, but you wanna reject heat? you say potato.......

you do have a couple guys who might help you with this design, 1 is a very well researched engineer with no geo installs to his credit (at least none he's shared) and the other a DIY who actually has a system installation under his belt.

Heating and cooling are math problems. If you want to displace XBTUs then you will need a system that can move them. It is not rocket science, but your proposal to "reject heat" vs cool a slab with a closed loop system (and even suggesting reject heat means something different than cooling) goes back to "you have a lot more research to do."

I'm really not trying to bust your chops, Pros here will even help you, but you first have to get past less practical ideas before we can help you with good ones.

I do again understand the difference in heat rejection and I meant what I said. The primary goal really is heat rejection BUT you will never achieve a perfect R factor without a vacuum and my only goal here is to primarily mitigate the heat GAIN associated with the hot summer soils surrounding a huge thermal mass (concrete). Insulation will play a big part here but there is still thermal conduction so without cooling or removal of that heat, the slab is guaranteed to continue to try and equalize with the surrounding soil temp.

It is actually pretty straight forward math here and it will not take a "bazillion" feet of pipe because I am not proposing to make a space 68* with 60* ground temps. The BTUs available is a function of the delta T between mediums. There has to be a designed practical limit in this. As well, as I said, without any consideration for moisture in the air, I am going to create a big problem anyway.

What I am trying to arrive at is a discussion of the practical limits and an idea pool. No, I don't really need exact figures just yet. Actually due to the size of the building, Just a little messing with the degree days really affects the requirements and I have so many variables such as adding insulation, more boiler heat, more tubing in the ground, deeper tubing, etc.

I am still playing with how air currents might work to actually cool the building a bit but unlike the natural convection currents associated with heating, the cooling side might need forced which due to the hotter/wetter air, might condense if I get the concrete too cool.

I don't care to get into entitlements here but I am a mechanical engineer and I can grasp the concepts. I will admit I have not done a geo system yet but that does not mean I can't get it right. I designed and built an HVAC system I am currently in. Operates spot on to design parameters. Math still works!!! LOL I also learned that I had to learn expansion valves and super heat/subcool charging because 90% of the HVAC guys out there don't even know how to do it right.

Posted By fastline on 08 Oct 2013 01:20 PM
BUT you will never achieve a perfect R factor without a vacuum

Vacuum won't do it. Didya notice that big shiny thing in the sky?

LOL. I KNEW someone would pick the fly shit out of the pepper!!! In a vacuum, under a rock, surrounded by darkness and blackness, not near any anti matter, where Neutrinos do not exist.... Or about 3" of EPS.....:-)


I have had entirely too much coffee today....  I hope I am not ruffling feathers...

"I do again understand the difference in heat rejection"

Okay so since you are an ME perhaps you can explain to me the difference between cooling and rejecting heat (cause that's generally how we cool in unsophisticated HVAC land).