I'm planning a geothermal install and wanted to run my loop design past you guys to make sure it makes sense. The heat load part seems to make sense given the heat load of the house as we have saturated sand at 15'. However, I'm not too sure of my flow and circuit part. I lost the original software that I did calculations with 5 years ago so I'm new to using the climatemaster spreadsheet. I'm planning to have 2 ~400' holes (1600 feet of pipe total) using 1.25" HDPE ubends. I plan on running the loops in parallel. With two units (2 and 3 ton) receiving a split portion of the water at all times, it seems I'll get about 12-14 gpm thru the units with 1 26-99 pump, and 18 gpm with two 26-99 pumps. Does this make sense? I'm not sure I'm putting the right numbers into the software/spread sheets as I've never used these before. It looks like my Reynolds numbers are good, with 4 gpm in a 1.25 pipe being good. I'd really like to use a non-pressurized controller but have not worked with any that have more then one circuit. Ideas? To complicate the matter, I may want to add a 3rd unit to make domestic hot water. Then I could add in some radiant floor heat in the colder areas of the house, and even a hot tub heating circuit via a heat exchanger. But how do I set this up? Use a separate pump for each heat pump? Also, the sizing software I'm using doesn't seem to take this into account. Ideas? Do 2 parallel 1.25 loops make sense here? Thanks for all comments.

In respect to your loop design, have you talked to any local drillers? The amount of pipe required and diameter to carry a given load varries wildly from the software generated design. If you are in a non consolidated formation i.e. sand the cost of drilling a six inch bore 400 feet may exceed the cost of more holes that are a smaller diameter. The local talent will guide you on efficent installation.
Eric

In respect to your loop design, have you talked to any local drillers? The amount of pipe required and diameter to carry a given load varries wildly from the software generated design. If you are in a non consolidated formation i.e. sand the cost of drilling a six inch bore 400 feet may exceed the cost of more holes that are a smaller diameter. The local talent will guide you on efficent installation.
Eric

http://welserver.com/WEL0424/

Similar system, but open loop with 6 heatpumps. For more than 2 HPs and closed loop, here is the distributor for custom made B&D flowcenter (non-pressurized)

http://www.phoenixflowcenters.com/GvLinks.html

A single Wilo variable speed pump feeds multiple highCV zone valves, who open up when the heatpumps come online.

Multispeed pump? Nice! Thanks for the info!

Posted By daveumbc on 30 Sep 2011 03:25 PM
Multispeed pump? Nice! Thanks for the info!

Variable speed circulation pump for the loopfield that is. We use it for multiple (3 or more) heatpump application.