Difference between revisions of "Ken Flaherty's Geothermal Adventure"

Revision as of 19:07, 14 February 2012

This page is designed for the work we are doing to help Ken Flaherty select and install a geothermal system in his home.

Background

• Location: 17166 Beechwood Ave, Beverly Hills, MI 48025
• Ownership: Jen and Ken Flaherty
  • The Flaherty's have owned the home since 1998
• Construction History and Type: Built in 1928. Block foundation, first story brick, second story stucco.
  • Renovations: 1) 1948- first floor room addition on west side 2) 2002 - North two story addition with master bedroom, bath, family room and mud room (additional ~1000 ft2) 3) 2006 - Three car detached garage (~700 ft2)
  • Thermal Improvements:
• Pictures

Satellite image of 17166 Beechwood 48025 can be seen maps.google.com

• • Ken need some pictures of house
    • All four sides
    • Lot

Determine the Heating/Cooling Load

Size

• House: sqft total and by floor
• Land: 3-1/2 lots: 140 wide, 158 deep. 22,129 ft2

Utilities

Electric

Underground 240 volt, 200 amp service upgrade in 2002

• Major Loads
  • 2 HVAC units
  • 240 volt wall heater in addition #1: Heating current draw was measured on 2/10/2012 @7.5 amps on 240 volts. Unit decommissioned on 2/10/2012.
  • 120 volt electric heater in basement: Turned off. Current draw in the off positon is zero.
  • Subzero 650S refrigerator/freezer: power usage is 481 kwh per year
  • Asko D3531, It consumes 194 kWh/year and 3.8 gallons/cycle, based on an annual usage of 215 loads per year, or around 4 per week. "The Top Five Most Energy Efficient Dishwasher Models, Early 2010 Edition". http://ecovillagegreen.com/2601/the-top-five-most-energy-efficient-dishwasher-models-early-2010-edition/
  • Frigidaire upright freezer with auto defrost: Model LFFH17F7HW, 16.7 ft2, Energy Star, power usage is 615 kwh per year.
  • Heat tape for north roof and gutter (120V): Current draw was measured on 2/10/2012 @10.2 amps
  • Sump pump: 120V, 1/2HP
  • GE front-load washer, Model: ??, Energy Star rated.
  • Thermador PRDS304US: 240 volt oven on 20 amp circuit (unknown Kwh/yr)

• Bills last two years

Gas

• Major Loads

Furnace 1 Furnace 2 Hot water heater: 75 gallons, Installed in 2002. Over-insulated therefore model information is not available. Gas clothes dryer: Kenmore 90 series, 15 years old. Thermador PRDS304US gas stove top: For 15,000 BTU/HR burners (4.4 kwh)

• Bills last two years

HVAC + DHW Equipment

Furnace/Boiler

• 2 gas furnaces; Furnace #1 is in the basement, Furnace #2 is a skid mounted unit that sits outside on the west side of the house
• Furnace #1: Comfortmaker by SyderGeneral: GUG141A020IN. Installed in 1991, Input 141,000 btu/hour, output 111,000 btu/hour, ~80% efficiency. Heating current draw was measured on 2/10/2012 @7.0 amps on 120volts. Filter size; 20"*24"*4". Heat exchanger part number: Z10-GUG141A020IN-06CMW
• Furnace #2: Bryant Model: 583B 024. Two ton capacity. 240V one piece heating and cooling unit. Installed in 2002. SEER (Seasonal Energy Efficiency Ratios) of 12.0 and AFUE (Annual Fuel Utilization Efficiency) ratings as high as 81%. Variable speed blower. Heating current draw was measured on 2/10/2012 @2.5 amps on 240 volts. Filter size; 20"*24"*1"
• Controls: Each one has own controlled thermostat. Winter settings: Summer settings:

A/C

• 2 A/C Units
• manufacturer, year, model/size, efficiency ratings
• Controls: Each one has own controlled thermostat
• Integrated w/furnaces??
• Controls: Each one has own controlled thermostat

Controls

• Number of thermostats: Two
• Features: Programable with both running the same time and temperature profiles

Hot water tanks

• manufacturer, year, model/size - photograph plates)
  • • •  ?? total, gas
    • Fans: Hunter open bearing "Original" fans in all bedrooms, master bath and new addition family room. The amp ratings are 0.71/0.46/0.23 for the fast, medium and slow positions.
      •  ?? total
      • Exhaust fans in all 4 bathrooms and main kitchen (5)
      • Ceiling fan in common room (1)
    • Thermostats
      •  ?? total (all at 67 degrees)
  • Insulation
    • Roof: ??R, type
    • Walls: ??R, type
    • Basement Floor: ??R, type
  • Roof
    • Type: Color:
• Building Materials and Measurement (Google Sketchup)
  • Walls
    • Exterior walls: layers ??
    • Interior walls: layers ??
  • Floors
    • Basement:
  • Doors
    • # and type
  • Windows
    • Basement: #, type, pane type, R-value, size and direction
    • 1st floor: #, type, pane type, R-value, size and direction
    • 2nd floor: #, type, pane type, R-value, size and direction
  • Orientation
    • Which way does the home face?
    • Any trees shading?
• Comfort Profile
  • Winter
    • Coldest spots are:
  • Summer
    • Hottest spots are:
• Inspection and Testing
  • Thermal Inspection by Ken Byczynski - Kenco (Date??)
    • Carbon Dioxide test
    • Blower door test + infrared thermal imaging (Ken)

Design Considerations

Characteristics of Geothermal Energy

Because the earth releases and absorbs energy at a slow rate, you want your geothermal system to do the same...since it's connected to the earth. This means that you typically only have a small setback (1F - 3F)at night...if one at all. You want the system to have long slow runs. This means that you want the size not to be too large (i.e. over sized) or you will get "short" cycling.

Comfort

One of the most underestimated benefits of a geothermal system is it's comfort. It is suggested that you have the fan running at all times at a low level to circulate air in the home. Check with the manufacturer of the system to see what options you have to do this (e.g. selection of fan speeds.) Since the heat is more moderate than gas fired heaters...it's not as dry and closer to the current temperatures...so the home temperatures stay in a much tighter range....i.e. less variability up and down.

Sizing of the Geothermal Unit

The geothermal unit is sized to meet the peak hourly demand (load in BTU/hour) for the home. Sizing of the geothermal system has two components 1) the sizing of the heat pump and 2) sizing of the loops. These need to be matched to create the heating/cooling capacity. In Michigan, the summer peak hour cooling load is usually what sets the size of the unit. It is best to do a thermal model of the home to determine the exact sizing requirements.

Location of the Geothermal Unit in the Home (Noise)

Typically the geothermal unit just replaces the existing furnace/ AC unit in the same location to take advantage of the existing duct work. It is worth the time to look at whether this is still the optimal location. When locating the geothermal unit in the home you need to take several things into consideration:

• Existing duct configuration.
• Electrical power source. Where does the main power come into the house.
• Noise; the compressor of the unit will make some noise. Some are loader than others. Consider how this noise will be isolated from the main living areas as not to create a uncomfortable sound in the living space. If you have a HVAC room in the basement you are probably ok. Do check the noise level ratings of the heat pump. They can vary greatly.
• Room for connection to hot water tanks.

Ground Loops

These are typically 300ft in length...although this can vary. For a 4 ton Geothermal heat pump in Michigan you could expect to have four 300ft loops. The length is 300ft, but only requires 150 of property as the loop goes out 150ft and then returns the same 150ft...making it a total of 300ft long. They are typically 8 - 12ft below the surface. There are three general types of ground loops:

• Vertical: borings straight down using a well digging equipment. There is a lot of soil waste that re brought up and significant damage to the property. Also, you need to think about how this equipment is going to get on and off the property and who's doing the repairs of the tracks. These costs need to be considered in the bid. This is the only option on really tight properties.
• Horizontal - Trenching: This requires digging long (e.g. 150ft) trenches 8+ feet deep. They are spaced 10 - 12 feet apart. Obviously you need quite a bit of property and the disruption can be very high. In a rural area this is pretty straight forward... in an urban area this is impossible.
• Horizontal - Directional Boring: This requires a directional boring machine and contractor to put the loops in the ground. They can steer the the loops as they are placed in the ground typically making a large arc under the ground. This has the least disruption to the existing property. Only a small amount of waste soil.

There needs to be a manifold where all the loops come together. This is in the ground outside. Then there is a supply and return that connects the manifold to the geothermal unit in the basement. This requires boring two holes through the basement wall. It goes without saying that holes create a risk of water leakage and these need to be carefully sealed.

Domestic Hot Water Tanks

• Typically configured with a preheat water tank and then either another active HW tank or a tankless hot water heater to bring the water up to the exact temp levels (120F - 130F) needed. The preheat tank is piped to the geothermal system which preheats the water using excess/waste heat for it's operations. The preheat tank is not heated by electrical or gas sources. It is just a thermos for the warm water.
• Consider putting an on/off timer on the hot water tanks. For example, it could go on at 5am and off at 10am. This saves energy during the other 19 hours of the day. Most have a manual override for days you need more hot water.
• Suggest the Rheem marathon electric tanks. Super insulated.

Electrical Considerations

Electrical Meter

You will need to have DTE (electrical company) install a new time of day meter that has a special geothermal rate. This is a longer lead item and can be prepped early on. An added benefit is you get a separate bill for this so you know exactly how much energy is used for heating/cooling and hot water.

Electrical Panel

Typically the installation of a geothermal system will require an additional electrical panel to be installed in the home to meet the power demands of the geothermal system. This also provides separate shut offs.

Duct Work

• Cleaning
• testing for leaks...Changes

An Holistic Approach

Reduce Demand - envelop insulation and Air Infiltration

Air Infiltration (10 - 15%)

• Doors...weatherstripping / thresholds
• Windows caulk exterior
• Venting fans...sealed and on timers
• Outlet / Switch boxes foamed
• Windows - R + low-e Coating

Size Geothermal Unit