Geothermal System - November 2014

We did a lot of research on heating/cooling systems and decided to go with a geothermal  heat pump system.  Geothermal heat pumps are recognized as the highest efficiency heating, cooling and domestic hot water system available.  Since our house will be extremely energy efficient, we wanted our heating system to be equally as efficient.  Geothermal systems can be up to 70% more efficient as compared to traditional systems.  Plus, we can say that we HEAT AND COOL WITH DIRT, NOT OIL!  The other deciding factor was that there are government incentives and rebates for installing this type of system, making it cost-effective and a smart decision.  

Basically, a geothermal system uses the ground to heat and cool the house.  It works by using the difference in temperature between the outside air and the ground.  The ground absorbs the heat of the sun keeping the ground temperature at a constant 55 degree temperature during both the summer and winter months.

The system has two components:  a heat pump, which is the inside unit, and the ground loop, which are underground pipes which connect to the heat pump.  There are two main ways to accomplish the ground loops: geothermal wells, where several wells are drilled hundreds of feet down into the ground, or horizontal ground loops, where the pipes are laid in trenches about 5-6 feet deep.  Either system works well.  We decided to use horizontal ground loops because we have the space, and we were able to do the digging ourselves, versus paying to have several wells drilled, which would have cost around 10K, just for the wells.

How does this work?  The heat pump circulates a water mixture throughout the entire underground loop.  In the winter, the water absorbs the heat from the earth and returns it to the indoor heat pump.  The heat pump extracts the heat from the water and then distributes it throughout the home as warm air.  In the summer, the indoor heat pump takes the heat and humidity from the house and places it back into the earth.

So here is how we accomplished this…. We dug, dug more, and kept digging until we dug 1000 feet of trench.  It sounds like a lot, but it feels like even more when you are digging through rocks and hardpan.  We actually excavated MORE dirt than the actual house.  This was a TON of work and took a TON of time.  We started this project towards the end of October.

Steve digging a geothermal trench.

Our system required 1000 feet of underground pipes, and this was done by digging four 250' trenches.  Since our lot is wooded, the bulk of the trenches were in the woods.  We laid out the trenches in the woods with as minimal disruption of the trees as possible, except when we had no choice.  This made the project take longer, so hopefully it will be worth it when the woods fill back in to their natural state.

Three of the trenches partially completed.

 The photo below is standing at the end of one of the trenches looking towards the house.

Once the trenches reached the tree line, they were merged and opened into one HUGE hole!  Each geothermal water pipe needs 18" of soil around it before another pipe can be laid, so there would be 8 pipes coming through this section.

The photo below is the view from the roof of the house.  You can see the four trenches and where they join into one large trench.  The trenches were 5-6 feet deep.

Once the trenches were all dug, we needed to prepare the trenches for the pipe.  This included moving all the large rocks out of the trenches…. and there were SO MANY rocks!

Once this was completed, King Energy came in to lay the pipes and start installing the actual geothermal system.

Does this look like 1000' of pipe?  

I unfortunately don't have a photo of the pipes being installed in our trenches, but basically, it looked similar to the photos below.

All of the pipes go directly through the house concrete walls and into the utility room in the basement.  From here, they will be connected to the geothermal heat pump.

And then the clean up begins.  Backfilling the trenches was quite a process, but we got it done… and only a week or so before the first forecast of SNOW!  Phew!!!

Backfilling the geothermal trenches.

After we backfilled the trenches, the weather turned really rainy, and the ground was VERY soft, which meant, we were not able to do a good job of grading until the ground firmed up again… which may be next year!  We finished the backfilling of the trenches around November 15, 2014.

Rough backfilling of the geothermal trenches.

Very rough grade over the large geothermal trench.  

The next step for the geothermal system will be the duct work and installation of the geothermal heat pump inside the house.