The header system for ground heat exchangers should be designed to allow easy removal of air. Headers are usually fabricated at the shop and trucked to the job site. Header connection procedures for both above ground and bell hole fabrication have proven successful.
When making the final header connections above ground, pigtails are used to allow the loop connections to be made. After connections are complete, the headers and loops are placed in the trench. The advantage is that minimal trench excavation is required.
In the bell hole procedure, a pit is dug large enough for a person to make the loop connections below grade. This method is generally used for multiple parallel loops where the number of loops exceeds four or five.
A reverse bend can be used when the spacing between the loops and the header is small. This procedure requires the pipe to be looped before connection to the header pipe. This added loop allows the pipe to be freely moved in the horizontal direction, making the connections easier to finish. Take care not to force this loop into a smaller bend radius than recommended by the pipe manufacturer.
To bring the header piping into the building, the point of entry must be identified, protected, and sealed. This entry point will be slab-on-grade, below grade, or crawl space, and new or retrofit construction.
For new slab-on-grade construction, position the pipe in the proper location prior to slab pouring and protect with a layer of insulation. If a slab is to be poured, create a chase for the pipes with 4-inch PVC street elbows and sleeves.
For retrofit slab-on-grade construction, trench close to the footing and bring the loop pipe up the outside wall until it is higher than the slab. Enter the building close to the slab. Protect and insulate the pipe to protect it from damage and the elements. The antifreeze solution in the loop will not protect against extreme outdoor, attic or crawlspace winter temperatures. The pipes must be insulated and protected.
For all below grade construction, bring the pipe through the wall and seal it well. For applications where freezing temperatures may occur, insulate pipe at least 4 feet into the trench to keep ice from forming near the wall.
With all crawl space construction, bury the pipe beneath the footing and between piers to the point directly below the entry point. Stub the pipe up into the building and shield and insulate the piping to protect it from damage.