Ok let me start at the beginning. I have been working on geothermal A/C for 20 + years. We just called them water cooled a/c systems. BIG PUMPS 50 HP pump seawater through the heat exchanger (condenser). Yes I work offshore as a maintenance engineer. So I do have a little bit of background in HVAC. I bought an old house in the small town I grew up in with 2 acres. There is no A/C or heat in the house at all. I am going geo but there is not any installers in the area I live in(deep east Texas). The nearest installer is in Louisiana across state lines so I am not worth their time (permits bonds travel). Now that my background stuff is out of the way I am going to have a local company install the A/C unit and ducts less ground loop system. I just don’t want to do that part on my limited time off. It will interfere with my beer drinking and patting my wife on the butt. On to the question I need answered. 1 Can a ground loop be too big I am planning on installing around a 5 ton unit (depending on what installer comes up with from load calculations)? I will be running a 4 pump QT-EA flow center two pumps running two pumps stand by (maintenance guy). I should flow about 20 GPM with the head the flow center is going to have. The reason I was asking about the length I need to dump a lot of heat (Texas 100 + F summer). The ground temperature is about 70 F 2 foot down hard clay. I was thinking about 1000 foot per ton 5 loops for a total of 5000 foot. I am not worried about heating we have romantic natural gas fire places to snuggle up to during the winter (one in the living room one in the master bedroom) and it is cheaper to boot. Also on the loop there will be temp gauges on all returns for balancing and one on LWT. Discharge out of the flow center will have a flow gauge and check valves (separating the circuits) going to the manifold. Another thing to ponder I have been reading this forum for some time. As efficiency of units will increase 20 years from now I do not want to be short of looped in the future and have to reinstall a new loop system because I was cheep now. Thanks for any help Chris
Too big You can't really be too big. You can end up paying for too much capital that you can't recover and you can end up paying for two much for operating oversized circulating pump costs. But for the system efficiency - I guess you can't be too big. Keeping the two aforementioned concerns in mind. Disposing of heat in clay soils is a nightmare, but I'll let someone in that climate speak specifically about what they see for designs. Don't even worry about sizing your circulating pumps until you have the loop design sorted. Head loss through 3/4" x 1000' pipe is ridiculous for example. At a 1000'/loop you should be in the 1-1/4" pipe world for pump efficiency. If you are worried about having standby pumps, might I suggest a non-pressurized system as it becomes quite easy to replace out the circulating pumps without worrying about loop pressure losses and introducing air in to the system. If done right of course.
Yes I was planning on a horizontal loop the clay layer there is over 500 foot deep so going down will be the same. That is great if you work at one of the potteries or the brick plant not so good for cooling. If not geothermal the only other way to go is a standard a/c system. Air source heat pumps struggle here because of the abetment air temp. That is the reason for the length of pipe I will need to overcome the clay. If I have to go with bigger pumps it should still be cheaper to operate than a standard high efficiency a/c system with a soaker hose wrapped around the condenser. You might laugh but they will do that here. I don’t blame them anything to drop the heat off the unit. Last year 100 + for longer than a month with high humidity. I don’t see this year being any better on the bright side winter temp does not drop below 20.
The soil temp will be lower if you do vertical loops. You will still need a lot of loop. There is a poster here by the name ; a0128958 who has a system in Texas. You might contact him for some info.
AMI contracting “Did you check here and IGSHPA web site for geo well drillers?” More or less I checked for anybody in the state of Texas. There is only 7 listed in the hole state not one closer than 250 miles. If you remove distributors the list gets smaller. So not a lot of help there. Dewayne Dean “The soil temp will be lower if you do vertical loops” Ground water here runs to 200 feet data on that is 66°F surface temp is in the 40°F to 80°F range I don’t think going down is going to be cost effective http://www.seco.cpa.state.tx.us/publications/renewenergy/pdf/c07-geothermalenergy.pdf That is the link for ground water data and surface temp. If you keep going down you get into this yes I live in the beautiful blue area. It is a lot deeper though but will effect ground temp. Texas Renewable Energy Resources - Geothermal I will try to get in touch with a0128958 don’t know if he can help. Depending on where he is it could be completely different. Chris
A quick side note, Loops do not have to be in the water table to work. The ground temp vertically is more stable even if dry. Sometimes vertical is cheaper than expected when you get the quote. Eric
I really wonder if a horizontal system in a deep south climate will operate much more efficiently than premium air source heat pumps. We in the south (I'm in north Florida - similar climate to EastTex) are fond of saying how hot the weather is, but in the grand scheme of things, our summers are long but not nearly as hot as they are further west. Where ASHPs REALLY struggle is in El Paso, Tucson, Phoenix or Las Vegas. If a horizontal system is providing 90+ degree return water from June through October, it won't operate much more efficiently than an ASHP. Only, in place of the $100 fan pulling air through an ASHP, there is a $5k+ system of trenches, pipes fittings and pumps...pain with little or no gain. It would shine during what passes for periodic cold snaps here in the south, but blink your eyes here and the outdoor temp is back above freezing. I'd worry that if a drought hits and the clay around the horizontals dries and shrinks, opening up air pockets, 90*F EWT could become a distant fond memory. Much of our soil is sand, which, if wet, conducts well. If it dries during a drought, look out!
I am not sure, living in Cleveland OH How many people know what a swamp cooler is. It is like adding RH up north in the winter. It is anti-logical.
Loop contractors in East Texas I know several companies, including ours, installing loops in East Texas. We also install horizontal loops successfully for about 60% the cost of drilled loops. Depending on actual load, we have to put about 800' of pipe in the ground at 5' depth per machine ton. More if you want loop temp to stay no higher than 95. In winter, loops hardly reach 50-55.
Horizontal loops in Texas I don't understand why so many people say horizontal loops don't work in Texas. I install them all the time when people have room. Takes more pipe/ton but the ditching costs less than drilling, and works well. Seldom get loops that operate over 95 at worst. My favorite is 4 pipe, 2 @ 5' and 2 at 3'. Does tear up terrain to install.
Greetings from East Texas I have had a geothermal system in east texas (Lufkin) for 6 years and am currently in the process of adding an additional unit. Vertical loops are THE only way to go. I, too have mostly clay soil and have had absolutely no problem with the loop system. Geothermal Drilling in Huntsville WILL come to your residence and drill your wells. They did my first 5 wells and just completed 4 additional wells that are all connected on a common manifold. I'm not sure where you are located, but there are dealers in East Texas. If you have any questions feel free...... Steve Wardlow
I have several horizontal loops running in South Texas with great success. Typically 880 lf of pipe per ton keeps loop temp around 92 at hottest. Costs about 1/2 of drilled loops to install. I dont know why so many say doesn't work. Of course, many say geothermal is not effective in South Texas at all. Both wrong. It does take more linear feet of ground contact than most installations, but both drilling and ditching costs are fairly low here.
I installed 10 systems in Lufkin for the Federal Govt two years ago. 250'/ton vertical bores work well. Temps rise to about 94 on some loops overworked, but efficiency still outweighs installation of more loop.
