SO Ineed help with advice for finishing my install.  I have a 3800sq ft home.  The heat load calculation has been done and shown that I need 9 tons of heating/cooling.  Because of the layout of the house I am going with a 5 ton unitl in the basement, a 3 ton unit in the attic and a 1 ton console unit in the bonus room over the garage.  I have 4 vertical bore holes 345 feet deep with 1.25" pipe installed into the holes.  I have a sheet metal contractor ready to install the duct work but wants the heat pumps installed first.  I have all the rough plumbing and the rough electric in.  I have wiring to run each of the heat pumps and the heat strips.  I also have wire run over to the part of the basement where the well penetration will be.  So I have a few questions. 

1) I am assuming the wires run over the area of the well penetrations is for a flow center.  How do I calculate the size of the flow center?  How do I connect the three heat pumps to the flow center?  Should I use check valves to prevent backflow, if so any recommendations?

2) I need to fuse the pipes coming out of the bore holes and put them into the basement.  I have looked around a fusion tools.  Can any one recommend a fusion tool and what fitting I need?

3) How do I calculate the amount of water and antifreeze I need to put in the loop? Also when I go to do it, I was going to use a 1.25hp jet pump to flush the loop and get the air out.  Any tips and techniques on doing this?

ANy other hits would be helpful and please ask for any information I have left out.

Thanks

Manual J, S, and D calculations all done and support the load and units you have selected?

I'm surprised the design work that led to the bores you describe didn't also include flow center calculation / specification.

You'll need enough water to completely fill the loop piping. required antifreeze will depend on volume of loop plumbing, type of antifreeze, andrequired freeze protection temperature.

I'm astonished that a 3800 SF new construction home needs 9 tons. Is it located in Death valley or the North Slope?

I agree that 9 tons is out of whack. What is the actual BTU loss/gain?
Joe

The home is not new construction, it was built 20 years ago. It is in the Northeast.  The design of the house is not really sutable for the northeast.  It has tall ceilings through the house, the lowest on is 8'6".  There is lots of glass including two 4 pane sliders and two 3 pane french door.  all of the windows are a minimum of 48" tall.  So as you can imagine the house looses a lot of heat.  I don'thave the heat load calculation, but I had three different contrators look and bid on the job and all of them determined 9 tons as the size.  Two did the calculations from the plans for the house and one measured the house and did the calculation with those measurements.

So I can calculate the number of gallons required by calculating the area of the cylinder described by the pipe in the wells.  Once I know how much water is in the well how do I figure out the size of the pumps n the flow center based on the number of gallons in the loop?

I recommend that you find a certified designer and have him spec all of the questions you have and do the parts that you don't have the tools for.

Pump size comes not from total loop volume but rather from flows required throughout the system. Minimums exist for effective heat transfer within the heat pumps' heat exchangers as well as maintaining turbulent flow in the individual bores, again, for good heat transfer

I guess I'm hard pressed to offer design advice without data.
sry

landis......everything I've read here in the past suggested at least 600' per ton. You only have a little over 300'/ton?? I'm no expect in any since but you might want to ck this out. I did noticed you were using 1 1/4" pipe instead of 3/4-1". Don't know if this made the diff. but I've also read that larger dia. pipes have thicker walls and doesn't dissipate the heat as well.

I have had multiple people look at the design.  One suggested a 1000' well for an open loop, one suggested a 660' well for an open loop system.  Both of these people suggested 9 tons of total capacity  Two other people looked at it and one suggested 4 bore holes of 345' for a closed loop system.  The other person suggested 3 bore holes at 345'.  Both also recommend 9 tons of capacity.  So I am fairly certain I need 9 ton of capacity.  The units I am looking at require 30gpm at full load.  I don't know what the heat load number of my house so I can't provide it.  Sorry. 

If you really want to stick with your plan, I would:

1) read the installation manuals for heat pumps from several manufacturers
2) look at a few existing installations, especially ones in your area
3) search for and read many of the postings in this forum
4) download some geothermal design software

I'm not surprised at variations in well and boreholes recommendations. Predicting what is down there isn't an exact science.