Sunday, March 17, 2013

Choosing Geothermal

Guest Post from Kyle:

How much does it cost to run your house on geothermal? That’s a great question, a difficult question at that. Most companies tell you that you will save average 30-70% on your current heating and cooling bills.
While we were saving up for our house we spent a few years living in a 2 bedroom 1 bath apartment of about 950 square feet. It was a 2nd story south-west facing unit, making for some hot summers and breezy winters.
We were fortunate enough to get some of the heat from the unit below us in the winter. Using a programmable thermostat, we would let the unit get down to 58 degrees before the heat would kick in. We kept the unit on a 4 degree setback. During the evenings when we were home, the unit was set to 62 degrees and 58 degrees during the day while we were away. Blankets and sweatpants were quite common in those days. During the summer using a 7 degree setback we would leave the unit at 85 degrees during the day and 78 at night.
Water use was normal for a 2 person household.  Daily showering and 1 or 2 dishwasher loads each week. We lived near family and would do laundry often at a relative’s rather than pay the $3 per load.

For the two years that we lived there our average cost for heating/cooling, water, and electric was around $83 per month or about $1,000 annually. Which, wasn’t terrible but we had to spent about $20-25 each year plus a few hours to seal up all of the openings around the unit to help cut down on heat loss during the winter.
For our house we had kicked around the idea of doing a propane furnace (natural gas not available) with an a/c unit. Then we remembered our frugal heating/cooling methods from the apartment living and thought that we likely be too cost focused that we wouldn’t keep the house at a comfortable temperature. We quickly threw that idea out the window and moved on to geothermal.

Our house is much better insulated than that old apartment unit but is also larger. Total conditioned space at our house is about 2,100 square feet. We opted for forced air rather than radiant heat. We have the house set to stay between 70- 73 degrees year round. In the winter the house stays at 70 degrees (no setbacks) and 72-73 in the summer (1 degree setback), making for a comfortable temperature year round. We also have a heat recovery ventilator that constantly brings fresh air in the house.
Below are a few pictures of our loop field.


 
Loop trench with pipes laid. About 5-6 feet deep.


 
Trench making the shape of a "J" in the yard. Goes out from the house about 350 feet.


 
This is the view from the road during the digging of the loop field. The loop goes out from our house and heads towards the road and then curves back slightly.


 
Piping showing 2 going out and 2 on the return.

 
 
We utilize a two 50 gallon water heater setup. One is wired and heated at about 120 degrees with the other one being a preheat tank. During the summer and winter months when the geo unit runs more frequently heating the preheat tank to a max of 150 degrees. This makes for plenty of “free”hot water being available during these months.

With having a baby, our house is occupied 24 hours a day as little Nolan is watched at home. We also have the pleasure of doing about 5 loads of laundry a week as we elected to do cloth diapering.
For us, geo was the best choice and we haven’t had to spend much time worrying about how much our utilities would cost from month to month. One year cost of operating our house on 100% electricity was about $130 per month or about $1,600 annually. Monthly kWh usage ranged from a high of 1,736 in the middle of winter to a low of 596 during this past summer.

Additional pros of geo are that electric rates are fairly consistent compared to propane or other fuel choices. During the summer months there is a higher tiered rate for electric use over 600 kWh (only 1 month during the summer exceeded 600 kWh).
This definitely ended up being the right choice for us. We haven’t had any second thoughts about going with geo. If you’re thinking about geothermal for your house it’s good to ask around of other people who have had geo installed and learn their results. If there’s anything we can help with please feel free to ask.

-Kyle

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