It looks as though the geothermal system will start dumping heat into the floors in less than a week. The wells are now complete. The hookup is nearly done. All the plumbing – sans the air handler – has been installed, filled, and pressure tested.

If you look closely at the picture, the two metal boxes on the right represent the two water-to-water heat exchangers. They look nearly identical but the truth is the top one is a 5 ton unit and the bottom as a 3 ton unit. The top one feeds the shop floor as well as the domestic hot water tank. The bottom feeds the 4 zones in the residence. Not in the photo, is the 3 ton water-to-air exchanger that will produce forced hot air for the second floor of the residence. It will also provide all the air conditioning for the residence.

I got a bit of a primmer on the evolution of geothermal technology from the contractor. The latest change in wisdom relates to how the multiple wells are connected. My wells are only about 175 feet deep. This means I have about 1 well per ton of energy. Since there are 11 tons (5 + 3 + 3) that makes 11 wells. In the past, each system would have taken it’s set of wells and run them in parallel, merging all of their capacity as close to the exchanger as possible. The problem they noted was that the circulating liquid (a combination of water and antifreeze) would take the path of least resistance and in this case that meant the shortest well. If one well was deeper than the rest, it would be under utilized.

New systems circulate from the exchanger to the wells in one big loop by connecting all of the wells in series. It puts a bit more load on the circulator and can only be done up to 5 wells. However, it yields better heat exchange with the ground and allows for somewhat slower circulation requirements.

You can see the well lines under the stacked heat exchangers. Originally, all the wells were coming into the equipment room. Now, only the first three pipe pairs are in use. The others are capped.The well circulators are the grey blocks – one bolted to the lower front of the exchanger rack and the other on the side. The 3 ton unit only has one circulator pump but the 5 ton unit has a dual pump. Remember, that pump is responsible for over 2000’ of 1-1/4” pipe (125’ to the first well, 175’ down and 175’ up 5 times 5 , about 15’ between wells, and then 125’ back to the pump) and it takes over 140 gallons just to fill the line. The 3 ton units run just over 1300’ and 90 gallons each.

If you want to have some fun with math and pipe runs, take a look at the manifolds for the radiant floor heat. Each run is a bit more than 200 feet with the manifolds working in pairs with one for the outbound and one for the inbound for each zone. If you count up all the small manifold tubes (the ones going down into the floor) and divide by 2 and then multiple by 200’ you get a close approximation of how much tubing is in the concrete floor.