Ken Flaherty's Geothermal Adventure

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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
    • Longitude: -83.2, Latitude: 42.5
    • Elevation: 712 feet above sea level
  • 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. Original interior walls and ceiling are plaster. Addition walls and ceilings are all standard sheetrock.
    • Renovations:
      • 1) 1960's- First floor room addition on west side (~200 ft2)
      • 2) 2002 - North two story addition with master bedroom, bath, family room and mud room (additional ~1000 ft2)
      • 3) 2006 - Three car detached garage (~704 ft2)
    • Thermal Improvements:
      • Original windows replaced with Marvin wood/clad windows
      • New addition windows are all Marvin wood/clad windows
      • 1960's addition windows are original and are in poor condition
      • Front door - facing south: reclaimed solid oak door with three single glass panels with glass screen door
      • Back door - facing north: new solid wood door with double pane insulated glass
      • French doors to patio - facing west: New Marvin
      • Side door to driveway - facing east: New composite door with insulated glass
      • Insulated and conditioned crawl spaces
      • Upper perimeter of basement walls sealed with closed cell foam
      • Return air ducts sealed
      • Attic insulation: high density cellulose (Assume 12" thick and R-4 per inch for energy modeling purposes)
      • Attic ventilation: added multiple ventilation roof cans and multiple gable vents
      • Second floor lighting cans insulated; they are not visible with infrared imaging
      • Hot water tank insulated with thermal blanket

Determine the Heating/Cooling Load

Size

  • House: 2950 sqft total: First floor: 1560 ft2, Second floor 1390 ft2
  • Land: 3-1/2 lots: 140 wide, 135 deep. 18,900 ft2

Utilities

Electric

Underground 240 volt, 200 amp service upgrade in 2002

  • Major Loads
    • 2 HVAC units; not zoned
      • Unit #1: Heating current draw was measured on 2/10/2012 @7.0 amps on 120volts.
      • Unit #2: Heating current draw was measured on 2/10/2012 @2.5 amps on 240 volts.
    • 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
    • Zoller sump pump: 120V, 1/2HP; Kill-a-watt, 2.1 Kwh 357 hours. 10 amp draw when on.
    • GE front-load washer, Model: WCVH6800J, Energy Star rated. 144 Kwh/year, gallons of water per year 5713 (Based on an annual usage of 392 loads per year, or around 8 loads per week)
    • Thermador PRDS304US: 240 volt oven on 20 amp circuit (unknown Kwh/yr)
  • Bills last two years
Gas
  • Major Loads
    • HVAC #1
    • HVAC #2
    • Hot water heater: 75 gallons, Installed in 2002. Over-insulated, therefore, model information is not visible.
    • Clothes dryer: Kenmore 90 series, 15 years old.
    • Thermador PRDS304US stove top: Four 15,000 BTU/HR burners (4.4 kwh)
  • Bills last two years

HVAC + DHW Equipment

Furnace/Boiler
Unit #1
  • 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
    • Unit #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
    • Unit #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: 9:30pm - 6:45am (60F), 6:45am - 8am (63F), 8am - 4:30pm (65F), 4:30pm - 9:30pm (66F) M-F Summer settings:
    • Unit #2 Manual File:Bryant583-024.pdf
A/C
  • 2 A/C Units
    • Unit #1: Comfortmaker by SyderGeneral: GUG141A020IN. Installed in 1991. Tonnage?
    • Unit #2: Bryant: 583B 024. Two ton capacity, Installed in 2002
    • Controls: Each one has own controlled thermostat
    • Both AC units are Integrated with its respective furnace above.
Controls
  • Number of thermostats: Two
  • Features: Programable with both running the same time and temperature profiles
Hot water tanks
  • Hot water heater: 75 gallons, Installed in 2002. Over-insulated, therefore, model information is not visible.
    •  ?? total, gas
Fans
  • Ceiling Fans (6): Hunter open bearing "Original" fans in all four bedrooms, master bath and new addition family room. The fan amp ratings are 0.71/0.46/0.23 for the high, medium and low positions.
    •  ?? total
  • Bath Exhaust fans (3): externally vented in all 3 full bathrooms. Two upstairs baths have the NuTone Ultraquiet exhaust fans; model: Model LS100: 110 CFM at 0.1" S.P., 80 CFM at 0.25" S.P, .30 amps, 120 volts. The fan in the master bath is on a timer. No exhaust fan in first level 1/2 bathroom. No details on basement exhaust fan yet it is externally vented.
  • Kitchen exhaust fan: Thermador externally mounted exhaust fan. Model ??, ~1000 cfm on high
Insulation
  • Insulation
    • Roof: ??R, type
    • Walls: ??R, type
    • Basement Floor: ??R, type
  • Roof for main structure
    • 3,400 ft2. Type: 30 year dimensional shingles with EPDM in all north valley's. Color: Black, installed 2009
    • Roof for 1960 addition
    • 250 ft2, EPDM, installed 2009
  • Building Materials and Measurement (Google Sketchup)
    • Ceiling heights
      • First floor: 98"
      • Second floor (original structure): 91"
      • Second floor (addition): varied geometry averaging 104"
      • Basement: half is 98" (unfinished) and half is 89" (finished)
    • Walls:
      • Exterior walls: First floor - brick, second floor - stucco and stucco board.
      • Interior walls: Original walls are plaster. Addition walls are standard sheetrock.
    • Floors
      • Basement: Poured concrete
      • First floor: all oak; exceptions (mud room and 1/2 bath are tile. 1960's- First floor room addition on west side is carpeted)
      • Second floor: oak; exceptions (both full baths are tile)
    • Doors (4)
      • Front door 36*80*1.75" - facing south: reclaimed solid oak door with three thick single glass panels with glass screen door:
      • Back door 36*80*1.75" - facing north: new solid wood door with double pane insulated glass on upper level
      • French glass doors to patio (2) (23*79*1.75") - facing west: New Marvin
      • Side door to driveway 32*78*1.75" - facing east: New composite door with insulated glass on upper level
    • Windows
      • Basement: 4 (2 facing east, 2 facing west), glass block with vinyl screened ventilation opening, pane type, R-value, size and direction
        • 13"H*34"W; each with a 7"H*16"W vinyl opening
      • 1st floor: #, Marvin clad ultimate double hung; aluminum/clad wood, 11/16 IG LowE II argon.
        • U Value = 0.32 (Btu/hr−sq ft−*F). The lower the U−Value, the greater the resistance to heat flow and better its insulating value.
        • R Value = 3.125 (1/U−Value). The higher the R−Value, the greater the resistance to heat flow and better its insulating value.
        • Solar Heat Gain Coefficient (SHGC) = 0.27. The lower a window’s SHGC, the less solar heat it transmits, and the greater its shading ability.
        • Visual Transmittance = 0.45. Percentage of visible light transmitted through the unit.
        • Condensation Resistance = 57. Condensation resistance measures the ability of a product to resist the formation of condensation on the interior surface of a product. The higher the CR rating, the better that product is at resisting condensation formation.
          • pane type, R-value, size and direction
      • 2nd floor: #, type, pane type, R-value, size and direction
    • Orientation
      • The front fo the house faces directly south.
      • Limited shading from the south and west. In late 2011, two very and old large silver oak tress (on the south sidewalk/street easement) were removed by the city due to safety concerns.
      • It may be worth investigating the use of a window film to reduce solar heat gain on the large West window in the sunroom. --Ken saw it done in Kentucky to good effect.
  • Comfort Profile
    • Winter
      • Coldest spots are:
    • Summer
      • Hottest spots are:
  • Inspection and Testing
    • Thermal Inspection by Ken Byczynski - Kenco (Date??)
      • Carbon Dioxide test
      • Infrared Imaging
      • Blower door test; by Kenco, 8/09/2011
        • Test @50Pa
        • 3000*8 (room height) = 24,000 (1st and 2nd floor)
        • 975*8 = 7,800 basement
        • 31,800*0.35 / 60 min = 185.5 cfm combustion air
        • For two story: 185.5 * 14.58 (two story constant) = house needs 2704.6 CFM @50Pa
        • Test actual: 3,325 CFM (can go up 30% w/o make-up air?)
        • Old master closet: 6.5 Pa
        • OM bed: 3.3 Pa
        • Kid's bath: 2.4 Pa
        • Drew's bed: 1.1 Pa
        • Jake's bed: 1.5 Pa
        • Master bath: 3.5 Pa
        • Master bed: 5.4 Pa
        • Master closet: 0.1 Pa
        • Sump closet: 0.4 Pa
        • Basement bath: 0.1 Pa
        • 1st floor bath: 0.5 Pa
        • Basement unfinished: 2.8 Pa
        • Basement finished: 0.2 Pa
        • Celler door: big leak

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.

Sound / Vibration

The vibration and sound from the heat pump compressor can be an issue. Design considerations include:

  • Locate the heat pump unit in an area of the basement where the sound will not affect people in the basement or living above the area of the basement.
  • Consider have vibration suppression installed in:
    • ducts coming from the unit need flexible separators (usually quite standard) in each of the duct lines.
    • the water lines coming to and from the unit.
      • suggest using Anaconda Bronze Vibration Eliminator (1212FY) which can be purchased at HVACTool.com
    • a pad under the unit. To absorb vibration....would consider having this upgraded.
  • Some manufacturers units are quieter than others. Ask for the dB ratings of the units. Small differences in dB mean a lot in sound. Water Furnace are on the louder end of the scale.

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

  • Testing for leaks...having ducts sealed
  • Evaluated whether zoning would be helpful. A great way to reduce the energy demand.
  • Cleaning of the ducts while they are disconnected.


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

Recommendations

  • Get two bids
    • Find similarities and differences
    • Warranties
    • What's included same / differences?
  • Size the unit: looks like 5 - 5.5 tons based on modeling

SpacePeakLoadsSummary.jpg

Space Peak Loads Summary report from eQuest model confirms contractors' equipment sizing estimates


  • When selecting the unit compare:
    • Efficiency COP and SEER
    • Noise level Db
    • Warranty
  • Loop Field
    • Suggest using directional boring
    • Drill from front east near entrance walkway to back west corner.
  • Sound dampening
    • Insulation pad below (get the best)
    • Add vibration dampeners to the water pipes
    • Watch where you locate the unit...avoid under areas where the noise will be an issue
    • Sound insulate the ceiling above the unit
  • Hot Water heating
    • Use two marathon tanks in series
    • use first tank as pre-heat tank
    • consider having the second tank on a timer
  • Ducts
    • Zone the ducts to eliminate the the need for a second unit
      • Use inflatable dampers to eliminate noise
    • Clean ducts if you haven't since a construction project
  • Existing HVAC Equipment
    • Donate newer furnace, AC units and hot water tanks to Habitat Restore
    • Recycle old duct work