That is how it works. It is not a two way transaction. See above for the reason it can snow 6 feet in a day in Buffalo. If it was a two way transaction, that is bi-lateral. It would be snowing orange helmets in Cleveland, scared with blue and red. Go Bills. I want anyone who has been in a farm pond for what ever reason to tell me they came out of the pond without very wet silt on their feet. Mark
Mark, you keep stating this for years now. Be aware of the 1st law of thermodynamics,which is a version of the law of conservation of energy, adapted for thermodynamic systems. The law of conservation of energy states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but cannot be created or destroyed. As much as heat goes to cold, the same amount of cold goes to heat. Indeed it is a 2 way transaction, since by definition the total energy within the system remains the same. If you look at our heat pumps, as much heat we transfer from the source side into the refrigerant, the same amount of cold goes from the refrigerant to the source water, which leaves the heatpump significantly colder. Sure there is silt in farmers pond, which inhibits the heat exchange compared to free flowing water around the pipes, which takes advantage of the pond stratification. So the cold has to travel through the silt to get to the stratified warm water, and the heat has to travel through the silt to get to the pipes. So the silt is an insulator compared to free flowing water around the pipes. One reason why pond loops should be sized to account for the chance that they will be buried in silt soon or later, with lesser heat exchange performance.
Hey I am not a trained engineer. I was wrong, it is the second law. http://theory.uwinnipeg.ca/mod_tech/node79.html I do make the first and second law work every time. I have spent enough time in ponds to know silt does not matter. To feet or loop fields. All geothermal loops should be designed to account for their ability to make the heat transfer for the space that they are conditioning. Water does not care if it is plain 100% water or it is mixed with silt. The stratification of the pond stays the same. Now you are going to tell me I need to have "Pond Doctor", out to control the algae so it does not impead heat transfer. Mark
Mark, the second law states that heat goes spontaneously from hot to cold until an equilibrium is reached, but in view of the 1st law, it also means that the same amount of coldness needs to go from cold to hot. Importantly, the second law also states that heat cannot go from cold to hot. This is where heat pumps come in to overcome this. It is great that you make the 1st and second law work all the time. Wonderful. I am not sure about your feet, but for heat exchange, compared to free flowing water (which was the point of discussion), silt does matter. I am glad you size your loops that they work fine under all the circumstances. Sure, water does not care if plain 100% or mixed with silt. But heat exchange cares, when silt is covering the around geo pipes and inhibits the free flow of water around the pipes. Again, I am glad that you make the loop big enough that loops buried by silt still work fine for a given load. The pond continue to stratify, the water around the pipes do not anymore with silt, that is the whole point. Sure, algae impair the flow around the pipes and thus the heat transfer as well, but since you make the loops large enough, no need for the "Pond Doctor"!
Doc: You and I have been agreeing to disagree for years. Let us ignore my lack of store bought knowledge. Our discussion is based on conductivity of water vs silt. Is that correct? Mark
Possible analogy for the silt covered pond loop; If a indirect fired waterheater was full of lime (silt) up to the top of the coil, Would it be as efficient? Would it still work?
No, the conductivity of water saturated silt and water itself is probably pretty close. It is the free flow of water around the pipe what the silt limits, thus it limits the convection. Again, when heat is transferred from the water into the pipe (and coldness from the pipe into the water), the colder water becomes lighter and starts to raise, and is replaced by warmer, heavier 39F degree water, which ensures that the pipes are continuously surrounded by fresh "warm" (39F) water, what makes pond loops so efficient. If pipes are covered with silt you switch over to conduction, which in this case is less efficient to transfer heat to the pipes (and coldness away from it).
Doc: It is all convection when you put HDPE SRD 11 between the two batches of water. One batch has the evil "silt" or lime stone / per Andy's post, and the other has antifreeze. The heat has to transfer from one batch of water to the other. There is no radiant heat transfer, just convection. Water does not transfer heat from flow either, just from being wet. Mark
No Sir. That is the entire point. "Convective heat transfer, often referred to simply as convection, is the transfer of heat from one place to another by the movement of fluids. Convection is usually the dominant form of heat transfer in liquids and gases. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow)." OK, this is wikipedia, but still a pretty good description. So convection is heat coming to the pipe through flow, and then getting transferred into the pipe via conduction. "Heat conduction (or thermal conduction) is the transfer of internal energy by microscopic diffusion and collisions of particles or quasi-particles within a body due to a temperature gradient. The microscopically diffusing and colliding objects include molecules, electrons, atoms, and phonons. They transfer disorganized microscopic kinetic and potential energy, which are jointly known as internal energy. Conduction can only take place within an object or material, or between two objects that are in direct or indirect contact with each other. Conduction takes place in all forms of ponderable matter, such as solids, liquids, gases and plasmas." The silt inhibits the flow around the pipes, thus it inhibits the advection part of the convection, compared to free flowing water. The more silt you have the more of an insulator you have around the pipe. And water does not transfer heat from flow? Sure, but without the flow the and the replenishment of water through flow, the heat source would be very much diminished quickly. How much heat transfer do you think is going on inside a coax without the flow? Try it out and shut off your circulation pump!
Doc: I am on a road trip. I am looking for the pond you describe above. Ponds do not flow. They are big water puddles. Lake Erie is not a pond. It flows. It flows right by your home and makes a big splash going to Lake Ontario. That I will give you is turbulent flow. Ponds do not do that. They just sit there being a big puddle waiting for Mother Nature to turn them into grass land or what ever the climax canopy is locally. I may have misled you, conduction is what geo loops are all about. I will take your definition to shorten this thread. I hate quoting others writings as I find most folks able to read and remember. I did not think all this pond stuff up. I did think up putting radiant floors in ponds. The pex-al-pex tubing you see floating beside me in the photo to the left, is still giving me 41* ewt with the pond frozen over after 7 years of silting and algae growth. I short looped the guy, 5 loops of 5/8" X 300' of CTS pipe to a radiant floor manifold buried at shore line. Piped to the building it serves with 1 1/4" CTS pumper with a Wilo pump. I will get you the M/N if needed. If I am not putting loops in the Niagara Gorge, I plan for no flow on the out side layer of the loops. I do not care how and where the loops go. No flow. Ponds: NO FLOW Wells: NO FLOW Ditches: NO FLOW NO FLOW< NONE< ON THE OUTSIDE OF THE LOOP. If flow happens that is a good thing. It is not a design issue. I have seen the come and goes of pond experts here over the years. I am one of the few left typing. It occurs to me to spend money on keeping pond loops elevated in a (farm) pond that is not as turbulent as the Niagara Gorge, is maybe wasting the customer's money. Plan for silting. Design for silting. Add a few feet of HDPE SRD 11 at 3/4" go home and sleep at night. I always treat my customer's wallet like it contained my money. Mark
Don't know where to start here: Ponds do have flow. Especially those with geo pipe in there. It is called stratification. Puddles do not have stratification. Especially ponds where you extract heat at the bottom create flow by raising colder water being replaced by sinking warmer water. No one was talking about turbulent flow. You made that up. http://ohioline.osu.edu/a-fact/0007.html By definition, your water at the bottom of the pond is always 39F in the winter when an ice cover is on it. You take heat out of that water with your geo pipes, it will become colder, thus lighter. Water is, as far as I know, the only element which has its highest density not at freeze point when it undergoes phase change from liquid to solid, but 7 F above freeze point. How can your EWT be 41 F when the warmest water surrounding the pipe can only be 39F by definition. Remember, heat goes to cold! So you indeed are making this up. If water is above 39F it would be lighter, and raising up. If water is colder it would be lighter and raising up. The water at the bottom of a frozen pond is always 39F, thus your EWT cannot be 41F when the water surrounding the pipe is only 39F. Sure, you can make the loops bigger so they always perform well, even when covered in silt. Again, I am glad you are doing this. No one accused you of wasting your customers money, nor do people who keep loops resting on blocks so they don't cover up by silt so easy and perform so well thanks to it.. Bringing in Niagara Falls turbulent flow in the discussion appears more cynical than useful. No, you did not misled me, it appears you did not know better about the first and second law of thermodynamics, and that heat convection going on at the bottom of the pond thanks to pond stratification. Again, convective heat transfer, which we have in the pond, involves the combined processes of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow) coming from stratification, especially when you suck out heat from the surrounding free flowing water which starts the stratification and advection. For someone who claims to have seen come and goes of pond experts here over the years, and who is claims to be one of the few left typing, you won't be the one who is the one to overcome the law of physics. You have to read up on the physics and get better informed before making your statements here.
I may not be a well known professional. I may not be a trained engineer. I did come hardwired for thermal dynamics and electrical properties. Stratification in a pond is not flow. Mark
The fact that the ponds is stratified results on the warmest water on the bottom -> loops take the heat out -> colder water raises and flows away from the pipes -> warmer water flows to the pipes -> creates very efficient heat transfer by convection compared to loops covered up by silt -Again, convective heat transfer, which we have in the pond, involves the combined processes of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow) coming from the attempt of the pond to stratify. 1) pipes will take heat out of the water (remember, heat flow from warm to cold!) 2) water colder than 39F water is lighter, it will rise! 3) creating natural convection No saying that Waterfurnace is always right, but they describe it pretty nicely: Excerpt from the Waterfurnce pond loop installation manual (attached): "Under an ice cover in the winter, ponds can maintain approximately 39° F throughout. This is due to the density characteristics of water. Water has maximum density at 39° F. As water becomes colder the density increases, thus the colder water falls to the bottom. Then, when the water approaches the freezing point (<39° F) its density increases significantly, thus the coldest water will then rise (ice floats remember!). This creates a natural convention current of constantly rising colder water (<39°) and falling water (see Figure 2). The heat transfer of pond loops is better when this natural convection can flow around and between the pipe coils. Therefore, it is best to allow the coils to float 9-18 inches from the bottom to prevent sediment from blocking this flow and reducing the heat transfer. (See Figure 3) The coils are in affect utilizing the bottom surface area of the pond as the loop, allowing the water to flow through to enhance the heat transfer." Mark, you have been a valuable contributor here so far. Please read up on the physics before you claim to be one of the few experts and continue to make completely incorrect statements. Especially when you go as far of suggesting that one is wasting the customers money when following the manufacturers instructions and suggestions, and not you incorrect statements.
Since IGSHPA refers to manufacturers instructions for pond loop design, which is kind of silly (why would the people who know how to build heat pumps know how to design pond loops), but for understanding the concept, here is another installation manual: "X. CLOSED LOOP SYSTEMS SUSPENDED IN PONDS AND LAKES The pond or lake should be a minimum of 1/2 acre in size with a volume of water equal to twice the size of the house being heated minimum depth of 7 feet for plastic lake exchanger. A larger pond will be required in colder climates. The zone where the exchanger is placed should remain above 38 degrees in winter. CAUTION: The performance of this type of system sometimes is hard to predict due to water stratification and other factors. Be very cautious about using this type of system. Again, make sure the ground water heat pump is designed to operate at lower water temperatures. LAKE EXCHANGER CONSTRUCTION—PLASTIC Use 3/4 inch or larger polyethylene or polybutylene piping approved for earth loop installation. 350 feet of tubing length will be required for each ton of heat pump capacity. The piping may be laid out for series flow (or parallel) as shown. See FIGURE 35. With an increasing number of pond loops being installed, it has been reported that there are several pond loops going in with 500 - 600 feet coils. It is recommended that pond loops (either Polybutylene or Polyethylene) use 300 - 350 feet coils due to the heat transfer in a pond application. The larger coils simply do not have as much surface area exposed (i.e. the extra 200 - 300 feet of pipe in the center of the coil), thus heat transfer by natural convection is impaired. For instance, FIGURE 35 shows a typical 3 ton pond loop—3 coils of 350 feet. CALCULATING HEAD LOSS To determine head losses for sizing pipe, circulation pump, and antifreeze quantities, follow procedures under section entitled, “The Circulation System Design”. PLACEMENT The plastic lake exchanger will float. The lake exchanger will need to be weighted so it will sink to the bottom of the lake or pond. The loop is not designed to settle into the soil in the bottom of the pond." http://www.bardhvac.com/digcat/volume_3_cd/install_pdf_file/2100-099(n).pdf page 63, see also figure 35 on page 64
If you do not agree with me we have an exchange of ideas, opinions, a discussion, and a providing of facts and evidence. This is what this place is all about. The bashing you get is for what I consider ignorance, and further more paired with arrogance and cynicism, throwing phrases on people who who dare to challenge your non-founded point of views. Ignorance is citing the first and second law of thermodynamics without knowing what they are. Nor not knowing the difference between convection and conduction. The following statements you might consider a disagreement with my point of view, but I consider it ignoring the science ponds as a source of heat for heat pump technology are based on. "The stratification of the pond stays the same." "Ponds do not flow." "Ponds: NO FLOW" "NO FLOW< NONE< ON THE OUTSIDE OF THE LOOP." "I do not care how and where the loops go. No flow." "Ponds do not flow. They are big water puddles." "Water does not care if it is plain 100% water or it is mixed with silt." "Water dose not transfer heat from flow either, just from being wet." Here is where for me the arrogance and cynicism comes in: "It occurs to me to spend money on keeping pond loops elevated in a (farm) pond that is not as turbulent as the Niagara Gorge, is maybe wasting the customer's money." "Now you are going to tell me I need to have "Pond Doctor", out to control the algae so it does not impead heat transfer." "I did come hardwired for thermal dynamics" "I do make the first and second law work every time." "I have spent enough time in ponds to know silt does not matter. To feet or loop fields." "Let us ignore my lack of store bought knowledge." "I have seen the come and goes of pond experts here over the years. I am one of the few left typing." Look at the amount of phrases you threw out in a single page thread. I'd be embarrassed to have made one of them in front of my fellow colleagues here.
I just wanted to say that I mostly lurk on this forum, and look up to you both as fountains of wisdom and fascinating, brain-stimulating conversation. Thanks!
birkie: Hello and welcome. Thanks for lurking. I did not get dumber arguing with the "well Known expert",geo police. I think in many different languages. My language of choice is English when I think and when I write. I think in light, electricity heat transfer, music and all forms of human communication. I am not a trained engineer so I do not have to follow their rules. I do look at what they write, but I do not limit my thinking by what is wrote. I started this thread as bait for the DOC. I meant to upset him because he bashed a customer of mine because he can be mean. He was mean to a student. Slap the students in the face so they shall never lean again, I thought. My Grandpa drove U-Boats for the Kaiser in WW I, I get german engineering. I also get attitude. DOC: I am sorry that I pointed out your "atta-boy" church job. I will never type to you again: You do not listen. You do not communicate. You are the "well know expert" so you are always right. What I type is from what I learned doing this stuff for a living. Real loops in real ponds, beting my farm on the job, not what the clueless experts write. It is an amusement to me that you quote all the stuff you thinks refutes my thinking, but never engage in a conversation. Talk with me and we might understand each other. TY Birkie, I welcome the help. Mark
