Total Home Automation

Geothermal Project: Drilling Holes

Installing Geothermal can be a mess.  In my case, they are drilling 18 - 250 ft deep holes in my drive way area.  The holes are about 6 inches in diameter.  So, imagine how much material comes up when you have a 250 ft x 6 in hole.  For those that have never seen this done, they use a big portable rig on a truck that looks like.....

   

To get a sense of the mess from materials pulled out of the ground, our yard and driveway now have mud all over them.  This is the Driveway....

 

This is the yard just below the driveway....

 

Once they drill a hole, the put down pipe.  The pipe looks like this.....

 

If you look carefully just to the left of the picture, you can see a plastic return for the water loop.  These use to be installed in the field, but now come out of the factory fully tested so that there is less chance of a leek occurring through field installation.

The pipes are fed into a drilled hole and basically look like this once done...

 

They then scoop as much mud as they can down the hole, and in some cases inject a gunite like material, so it looks like this....

 

Once they put all the pipes in, they will clean up the residual mud, then sometime this week they will backhoe a channel through the drive way (5 ft deep) to run all the wells back to a header section that will then feed back into the house. 

Geothermal Project: Heating, Cooling and Energy Usage

So, I have decided to replace my HVAC system with a geothermal system.  They just started drilling the other day.  I will get some pictures up soon.  I have decided to use the Water Furnace product line.  They are drilling 18 - 250 ft vertical bores in my driveway area.  These will be tied into 5, 5 ton units.  2 of those units will be split systems (that means just the compressor for the refrigerant and tie into existing air handlers), the other 3 will be complete integral units to replace my three air handlers in the basement.

Estimates are that my heating and cooling costs will drop about 60%, more if electricity costs go up in the Midwest with the introduction of Cap/Trade.  So, the payback looks like it will be about 6.5 years.  I also get a 2K tax credit for going to geothermal, but given the size of this system that does not pay the bills......

In the end I am a bit of a geek, so I am buying my units with BacNet controllers.  These controllers will let me gather more data and store it for trending purposes.  The controllers are Johnson Controls (JCI) FX10 units, which are oddly not shown on their website.  These are part of the Facility Explorer product line. The FX10 is a standard feature for the Waterfurnance commercial units.  I am guessing I will feed them all into an FX20/40/60, which is the JCI version of the Niagra/Tridium framework for aggregation.  I really wish I could just buy these parts on line rather than pay a controls company to come in and do what I already know how to do.

I will probably use a standard thermostat to operate the units. My Crestron system has all of the programming for manipulating their thermostats, but crestron and BacNet don't play well together, so I will use a conventional crestron thermostat using R/G/Y/B type connections to the units. 

Geothermal units don't have a lot of "Recovery" compared to a boiler.  So they can't pour out BTU's to heat a house quickly, so it does not make sense to do dramatic setback schedules.  For extra and quick heat, these units have electric elements.  For efficiency reasons, we don't want those electric elements to go on often, so setbacks are a bad idea especially on the heat side.  I do want to investigate the notion of some form of anticipator - essentially building a real heat transfer model for the house that over time can determine that on a 25 degree winter day with no moon, the compressor units need to come on 2 hours ahead of time to achieve a certain temp without use of the electric elements.

I am also installing a Shark Meter at my primary utility box.  I have an 800 amp service.  The shark has a lot of data storage and is easy to get to (modbus or Ethernet).  That will let me more precisely understand overall load.  Correlated to the bacnet data I will be able to get a very precise breakdown of HVAC vs. other loads on a minute by minute basis.  I will probably install a Veris meter system for each circuit breaker load.  They have a great unit that has 40 or so C/Ts in a row that easily fit in a conventional circuit breaker box.