If you need 150 feet per ton for a vertical well install do you need the same length for horizontal. Now if you say have a 3 ton unit thats 450 feet deep well right? 450 down and 450 back up connected at the bottom? So in realality you have 900 feet of pipe? vertical?
Pipe Length In order: 1. Length of vertical bore does not equal length of horizontal trench. In my area, and likely in most, the vertical "ft-bore/ton" is less than the "ft-trench/ton". This is mainly because ground temperature is more stable the deeper you go. 2. A 450 ft bore will support 3 tons assuming the 150 ft/ton was calculated under the assumption of a 450 ft-bore. In most areas the depth is selected by the economical drilling depth and the the number of bores is determined by finding the ft/ton at that depth and applying it. 3. Assuming one circuit per vertical bore, the feet pipe is twice the depth of the bore. 4. Horizontal is more tricky. You may have only one pipe in the trench if it makes a giant loop. You typically have two to four. Using a slinky or triple-slinky you may have up to 10 times the length of trench in a pipe. The may thing to remember is that the ft/ton is a factor of many things including: soil type/conductivity, ground temperature, spacing between bores/trenches, the loop type (horizontal, vertical, slinky, pond), the grout, and design heat pump water temperatures It is possible for various designs to have similar ft/ton although in my area that is not common. Most contractors have simplified systems that can be applied with good results in residential applications.
