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Bosch Geothermal Heat Pumps

Bosch Thermotechnology Corp.

Data subject to change

Applications Manual

17.6 Differential Pressure Switch

Speci c models of 208/230V Bosch geothermal heat
pumps may be equipped with a factory installed
Differential Pressure Switch (DPS). The DPS prevents
compressor operation if there is inadequate water ow
(gallons per minute) through the geothermal heat pump
water to refrigerant heat exchanger.

The DPS operates by monitoring the water side pressure
drop across the water to refrigerant heat exchanger. When
the pressure drop between the water in and water out
lines reaches a pre-set value, compressor operation is
enabled.

Fig. 141 Differential Pressure Switch (actual design may differ)

17.7 Electric Heat

Internally mounted supplemental electric heat is an
available option for speci c models of 208/230V Bosch
geothermal heat pumps. Electric heating elements can
operate along with reverse cycle heating as auxiliary heat
or in lieu of mechanical heating (refrigeration heating) as
emergency backup heat. Heating elements are available
in nominal kW ranges of 5, 10, 15 and 20 - note that
not all sizes are available on all models. Internal heat is
only available on top blow vertical cabinets, end blow or
straight through blow horizontal cabinet or on down blow
counter ow cabinets. Always refer to the speci c model
installation manual for heater selection.
Internal electric heat cannot be provided with hot gas
reheat. Units with internal electric heat must have 2 eld
power supplies.

Fig. 142 Electric Heat

17.8 Sound Package

Speci c models of 208/230V Bosch geothermal heat
pumps may be equipped with a factory installed sound
reduction package option. This option improves the
already industry leading noise levels of the heat pump
by adding a heavy duty, multi density blanket over the
compressor. The materials in the blanket are engineered
to attenuate the most objectionable frequencies of sound
coming directly off of the compressor shell, further
reducing the operating noise of the heat pump.

F

ig. 143 Sound Package

17.9 Soft Start (SecureStart™)

Speci c models of 208/230V Bosch geothermal heat
pumps are available with the SecureStart™ start assist
device as either a factory installed option or a eld
installed accessory. This device reduces starting current
for compressors by 25 to 60%. This reduction in starting
current can eliminate or greatly reduce "light icker"
during compressor starts and can reduce the required
size of back-up transformers. The adaptive technology of
the device can also extend compressor life by providing
smoother, lower current starts and by protecting the
compressor from transient low voltage. Over time
SecureStart™ self-adjusts to motor starting current
thereby eliminating any manual calibration.

F

ig. 144 Soft Start (SecureStart™)

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Summary of Contents for Geothermal Heat Pumps

Page 1: ...Bosch Geothermal Heat Pumps For Residential Applications Applications Manual ...

Page 2: ...2 Bosch Geothermal Heat Pumps Bosch Thermotechnology Corp Data subject to change Applications Manual ...

Page 3: ... 9 2 Ground Characteristics 49 9 3 Soil Analysis 49 9 4 Closed Loop Design Fundamentals 53 9 5 Soil Groundwater Temperature 54 9 6 Piping 55 9 7 Pipe Fusion Methods 56 9 8 Heat Transfer Fluids Antifreeze 58 9 9 Closed Loop Con guration 60 9 10 Underground Piping Installation Criteria 61 9 11 Closed Loop Header Design 62 10 Vertical Closed Loop Ground Heat Exchangers Vertical Loops 64 10 1 Groundwa...

Page 4: ...nce of Operation 104 16 8 Bosch Geothermal Water to Water Heat Pump Piping System Installation 105 17 Bosch Geothermal Heat Pump System Options 106 17 1 Bosch Cupronickel Coaxial Heat Exchanger 106 17 2 Bosch Heat Recovery Package HRP 106 17 3 Bosch Hot Gas Reheat HGR 108 17 4 Emerson Comfort Alert Diagnostic Module 110 17 6 Differential Pressure Switch 116 17 7 Electric Heat 116 17 8 Sound Packag...

Page 5: ...t information Important information that presents no risk to people or property is indicated with this symbol It is separated by horizontal lines above and below the text WARNING Follow each appliances instructions precisely For assistance or further information contact a trained and certi ed installer service provider or the gas licensed plumber or gas tter Application drawings in this manual are...

Page 6: ...ater heating available today In this applications manual we will provide a complete review of geothermal heat pump technology components and operation as well as guidance on the design and installation of ground heat exchangers and Bosch geothermal heat pump systems for domestic use residential This manual is focused on both contractors and designers It provides detailed guidance focused on the is...

Page 7: ...ground it can result in enhanced savings in fossil fuel consumption and provide a reduction in the emission of greenhouse gases as well as other pollutants Today geothermal heat pump systems are referred to by several different names These include geothermal earth coupled geoexchange groundwater ground coupled closed loop open loop and water source heat pump systems just to mention a few All geoth...

Page 8: ... to obtain water to pass through the geothermal heat pump f Geothermal heat pump sub system Unit or units that exchange heat between the fluid and the air that conditions the structure f Distribution sub system An air delivery system that delivers the conditioned air to the structure The foundation of any Bosch geothermal heat pump system is the Bosch geothermal heat pump unit itself The most comm...

Page 9: ...Multiple air ow con gurations for most any installation are also available Several of the Bosch geothermal heat pump offerings are equipped with an exclusive sound package The compressor is surrounded by a multi density sound blanket and the units come standard with a provisions to separate a vibrating compressor from the exterior cabinet This arrangement helps by reducing sound and vibration to a...

Page 10: ...ous two stage unit features improved cost aesthetics serviceability sound power and energy ef ciency and is available in vertical horizontal counter ow and split system con gurations from 2 to 6 tons Its energy ef ciency makes this unit the best in class in operating cost savings Requiring less energy compared to other manufacturers these two stage units achieve the same output to cool or heat a h...

Page 11: ... Available from 2 up to 6 tons in a vertical con guration these exceptional units provide best in class operational cost savings that help the consumer by reducing monthly utility bills The unit comes equipped with many of the exceptional features of the water to air unit including two coaxial style uid to refrigerant heat exchangers a refrigerant reversing valve a bi directional thermal expansion...

Page 12: ...c connections on top f Electrical connections on top or sides f Reduced footprint for additional space savings and for retrofitting existing systems f Plenum collar on supply outlet The Bosch Air Handling Unit is a single piece air handler providing the exibility for installation in any up ow down ow or horizontal application These versatile models may be used with or without electric or hot water...

Page 13: ...p boils to become a low temperature vapor The reversing valve sends the refrigerant vapor to the compressor The vapor is then compressed which reduces its volume causing it to heat up Fig 13 Water to air heating cycle In the compressor the refrigerant rises in temperature From the compressor the reversing valve sends the now hot gas to the air to refrigerant heat exchanger air coil where the heat ...

Page 14: ...g cooling As it enters the refrigerant to air heat exchanger the temperature of the refrigerant is relatively cool around 50 degrees Here the geothermal heat pump s blower Fig 14 Water to air cooling cycle circulates warm humid air across the cold refrigerant to air heat exchanger The refrigerant in the refrigerant to air heat exchanger absorbs the heat energy from the air and dehumidi es the air ...

Page 15: ...gs obtained for water source heat pumps were tested using two speci c sets of criteria the three standards developed by the Air Conditioning Heating and Refrigeration Institute AHRI AHRI Standards 320 325 and 330 1998 and the single standard developed by the International Organization for Standardization ISO ISO Standard 13256 1 1998 Table 1 Water to Air Geothermal Heat Pump Ratings ARI 320 ISO AH...

Page 16: ...ps are rated based on one of the four standards by the AHRI Table 1 These standards are ARI 320 ARI ISO 13256 1 Water Source Heat Pumps ARI 325 ARI ISO 13256 1 Groundwater Source Heat Pumps ARI 330 ARI ISO 13256 1 Ground Source Heat Pumps and ARI 870 Direct Geoexchange Heat Pumps Notice that the reference to the particular AHRI standard also includes the ISO standard as well For water source heat ...

Page 17: ...igher than for other conventional systems and economies of scale are more limited There are multiple load calculation procedures available in the HVAC R industry There are also computer programs and procedures that accompany most all of them Some of the accepted calculation methods are available from ACCA Air Conditioning Contractors of America HRAI Heating Refrigeration and Air Conditioning Insti...

Page 18: ... db 71 wb 34 99 26 07 0 75 1 21 39 12 28 9 60 33 38 25 08 0 75 1 37 38 04 24 4 70 31 77 24 17 0 76 1 52 36 97 20 9 85 29 36 22 92 0 78 1 76 35 35 16 7 100 26 94 21 77 0 81 1 99 33 73 13 5 Tab 2 EFT Range Standard 50 F to 100 F Following the tenants of ACCA the unit selected must meet 100 of both the calculated structure sensible and latent loads at design conditions for the locale for cooling ACCA...

Page 19: ...p provide the appropriate capacities at design conditions and at part load conditions Proper Bosch geothermal heat pump equipment sizing is still important in this situation but installers are provided with exibility by utilizing the two stage compressor geothermal heat pumps in northern climates Regardless of location local codes and or electric utility program requirements always supersede any r...

Page 20: ...d decreases while its latent load typically remains the same resulting in a decreasing space sensible to total ratio requirement i e 0 75 to 0 65 or lower This means that the latent removal requirement is a higher percentage of the total load Yet as the total load decreases the latent capabilities of most single stage geothermal heat pumps are generally less able to meet the changing sensible to t...

Page 21: ...5 1 67 41 81 21 6 60 34 64 22 76 0 66 1 86 41 00 18 6 70 33 18 22 08 0 67 2 05 40 19 16 2 85 30 99 21 16 0 68 2 34 38 97 13 3 100 28 80 20 36 0 71 2 62 37 75 11 0 50 75 db 63 wb 38 68 28 14 0 73 1 68 44 43 23 0 60 37 12 27 23 0 73 1 87 43 52 19 8 70 35 56 26 41 0 74 2 06 42 61 17 2 85 33 22 25 33 0 76 2 35 41 24 14 1 100 30 87 24 37 0 79 2 64 39 87 11 7 50 80 db 67 wb 42 47 31 08 0 73 1 70 48 26 2...

Page 22: ... ton geothermal heat pump will not be operating at the cooling outdoor design temperature of 88 F except during the warmest summer days the unit will revert to low cooling or part load capacity most of the cooling run time Examining the actual bin hours for Capacity Data Part Load Cooling all performance at 1000 CFM and 9 0 GPM Entering Fluid Temp F Entering Air Temp F Total Capacity MBtuH Sensibl...

Page 23: ...233 462 677 169 513 60 70 77 442 12444 54 30097 41 1 13 206 405 859 574 589 205 76 72 613 3556 53 30250 12 1 11 80 155 835 1 203 920 431 14 67 701 0 52 0 0 1 554 960 556 85 62 704 0 51 0 0 1 561 620 559 23 57 614 2407 50 25188 10 2 69 0 00 100 275 335 1 086 64 389 14 52 552 6420 49 24922 26 2 66 0 00 243 660 510 563 941 201 95 47 478 10432 47 24656 42 2 64 0 00 345 930 051 130 253 46 64 42 487 144...

Page 24: ...open windows open etc these supplemental heaters will energize but will occur only for a short period of time The supplemental heaters will also operate in the emergency heat mode if the compressor fails These heaters must be sized to meet the total structure heat loss at design conditions to adequately provide emergency heating if necessary The size of heater should typically meet 90 of the heat ...

Page 25: ...rmine the capacity of the Bosch three 3 ton geothermal heat pump at these conditions as well Examining the Low Temp Heating part load data for the Bosch three 3 ton geothermal heat pump Table 9 we nd that at 30 F EFT and 70 F Entering air temperature return air temperature the part load heating capacity compressor operating at 67 ability of the Bosch three 3 ton geothermal heat pump will be 20 930...

Page 26: ...ump will revert to low cooling or part load capacity most of the cooling run time This will improve humidity removal and still meet the structure heat gain even though the Bosch four 4 ton geothermal heat pump is theoretically oversized The increased cooling capacity of the unit also allows an increase in heating capacity provided by the compressor during winter months more closely aligning with t...

Page 27: ... 6 70 57 85 43 47 0 75 2 79 67 36 20 8 85 54 20 41 80 0 77 3 13 64 87 17 3 100 50 54 40 35 0 80 3 47 62 38 14 6 Tab 10 EFT Range Standard 50 F to 100 F Capacity Data Part Load Cooling all performance at 1300 CFM and 12 0 GPM Entering Fluid Temp F Entering Air Temp F Total Capacity MBtuH Sensible Capacity MBtuH Sensible to Total Ratio Power Input kW Heat of Reject MBtuH EER 50 70 db 61 wb 37 65 28 ...

Page 28: ... 43516 69 1 54 146 301 677 0 0 00 82 285 21333 54 43662 49 1 52 212 445 674 186 516 66 79 77 442 12444 53 43809 28 1 50 188 393 182 587 266 210 30 72 613 3556 52 43955 8 1 48 73 151 859 1 207 900 432 56 67 701 0 52 0 0 1 554 960 556 85 62 704 0 51 0 0 1 561 620 559 23 57 614 2407 50 33957 7 3 26 0 00 96 295 558 1 066 420 381 89 52 552 6420 49 33571 19 3 25 0 00 233 710 570 513 882 184 03 47 478 10...

Page 29: ...83 2 79 25 31 3 7 30 36 84 2 83 27 17 3 8 40 40 88 2 93 30 89 4 1 25 80 32 49 2 85 22 77 3 3 30 34 37 2 89 24 49 3 5 40 38 13 2 99 27 93 3 7 Tab 14 Antifreeze required EFT Range Standard 25 F to 80 F If the installation location in Minneapolis Minnesota is experiencing milder warmer winter days the Bosch four 4 ton geothermal heat pump unit will be able to operate at part load conditions The insta...

Page 30: ...on of structure heat loss not met by the compressor at that condition The heater will still provide the necessary heating if operating in emergency heat mode compressor failure Capacity Data Full Load Low Temp Heating Entering Fluid Temp F Entering Air Temp F Total Capacity MBtuH Power Input kW Heat of Abs MBtuH COP 25 60 27 79 1 82 21 59 4 5 30 29 35 1 84 23 08 4 7 40 32 47 1 88 26 04 5 1 25 70 2...

Page 31: ...than the maximum allowed by ACCA Manual S Capacity Data Full Load Cooling all performance at 1700 CFM and 12 0 GPM Entering Fluid Temp F Entering Air Temp F Total Capacity MBtuH Sensible Capacity MBtuH Sensible to Total Ratio Power Input kW Heat of Reject MBtuH EER 50 70 db 61 wb 48 95 31 89 0 65 2 28 56 74 21 4 60 47 04 30 90 0 66 2 51 55 59 18 8 70 45 13 30 01 0 67 2 73 54 45 16 5 85 42 27 28 85...

Page 32: ...698 503 150 180 18 72 899 2857 73 40926 7 1 89 118 285 847 1 227 800 439 69 67 827 0 67 0 0 1 392 420 498 64 62 701 0 66 0 0 1 180 270 422 67 57 671 2283 65 38957 6 3 40 0 00 90 296 595 833 168 298 36 52 565 6087 64 38553 16 3 39 0 00 203 667 521 283 771 101 62 47 556 9891 62 38148 26 3 38 0 00 327 936 138 0 0 00 42 529 13696 61 37744 36 3 37 0 00 434 890 678 0 0 00 37 411 17500 60 37340 47 3 35 0...

Page 33: ...ing Fluid Temp F Entering Air Temp F Total Capacity MBtuH Sensible Capacity MBtuH Sensible to Total Ratio Power Input kW Heat of Reject MBtuH EER 50 70 db 61 wb 37 65 28 42 0 75 1 17 41 65 32 1 60 36 39 27 70 0 76 1 37 41 06 26 6 70 35 12 27 08 0 77 1 57 40 47 22 4 85 33 23 26 30 0 79 1 86 39 58 17 9 100 31 34 25 67 0 82 2 15 38 69 14 6 50 75 db 63 wb 40 35 33 98 0 84 1 18 44 37 34 2 60 39 00 33 1...

Page 34: ...ng the Bosch four 4 ton geothermal heat pump see Figure 34 we nd that the heat pump providing compressor heating will operate until the structure balance point of approximately 7 F outdoor temperature without auxiliary heating typically being required It is unlikely that this application even needs supplemental heat but the installer should still install electric heaters for use as emergency heat ...

Page 35: ...e to re inject groundwater into the same aquifer from which it was drawn but discharge is Fig 19 Extreme Frost Penetration In Inches Based on State Averages Courtesy of http www dpwater com also possible to the surface where allowed Ponds and or lakes are often used for this type of system as well Typically closed loop geothermal heat pump systems have two parts dedicated to the uid ow a circuit o...

Page 36: ...d whenever an open loop geothermal heat pump system is being considered This open loop geothermal heat pump system method is used less frequently today than a couple of decades ago but may be employed cost effectively if groundwater is plentiful and water quality is appropriate Open loop geothermal heat pump systems are the simplest to install and have been used successfully in areas where local c...

Page 37: ...t pump system may require a yield of 20 30 GPM to meet the peak ow requirements Groundwater occurs below the surface at depths where all the open spaces in the soil sediment or rock are Well Area of influence Cone of depression Aquifer Groundwater flow Aquifer Evaporation Water table Condensation Precipitation Recharge or infiltration Runoff Groundwater flow Discharge area Water Cycle Fig 21 Water...

Page 38: ...rigerant coaxial heat exchanger in the geothermal heat pump Fig 22 Fig 22 Scaling Courtesy of International Ground Source Heat Pump Association Oklahoma State University Scaling reduces heat transfer and increases pumping costs The minerals that combine to form scale are normally present to some degree in groundwater If the water temperature rises suddenly and or the water pressure drops suddenly ...

Page 39: ...iron bacteria Iron Fouling All 0 5 ppm of Oxygen Above this level deposition will occur Corrosion Prevention pH All 6 8 5 Monitor treat as needed 6 8 5 Minimize steel pipe below 7 and no open tanks with pH 8 Hydrogen Sul de H S All At H S 0 2 ppm avoid use of copper and copper nickel piping or HX s Rotten egg smell appears at 0 5 ppm level Copper alloy bronze or brass cast components are OK to 0 5...

Page 40: ...ured during waterside diagnostics and gallons per minute GPM can be determined from manufacturer s speci cations Due to pressure and temperature extremes PVC SCH40 is not recommended Fig 25 Well water application In Bosch open loop geothermal heat pump system applications water pressure must always be maintained in the water to refrigerant coaxial heat exchanger This can be accomplished with eithe...

Page 41: ...ace and sub surface methods During severe cold outbreaks the pumps may require constant use The largest volumes of water will be produced during the coldest part of winter The disposal method must be compatible with the volume of water that will be discharged and must be able to handle the extreme weather conditions During the spring and fall the volume of water required will be reduced Because of...

Page 42: ...nerals Also the return well should be properly developed to remove nes and stabilize the borehole Mechanical surging and some types of chemical treatment can promote a stable well or successfully treat a clogged well The rate of discharge acceptance for a return well can be estimated based on values determined from a pumping test of the well A pumping test is accomplished by pumping the water well...

Page 43: ... equivalent of the water table in con ned or artesian aquifers and is known as the Static Water Level SWL When the pump is started water level will normally drop to a new lower level referred to as the Pumping Level The pumping level is a function of the rate at which the well is being pumped the greater the rate the lower the pumping level The optimum groundwater ow rate is a function of many var...

Page 44: ...tion well serving the system preferred or from information on nearby wells Also included in the lift is the friction loss in the pump column between the pump and the ground surface which is usually on the order of 1 to 3 ft Surface losses are those associated with the piping from the well to the structure and equipment heat exchanger etc and piping from the structure to the disposal point Unless t...

Page 45: ...hole and returned to the top Removal of small amounts of water from the domestic groundwater well greatly enhances the heat transfer Typically standing column wells are 250 to 500 feet deep but can be deeper Heat transfer occurs via conductive processes meaning the heat energy is moving through the rock molecule by molecule Heat transfer also occurs via advective processes meaning water in moving ...

Page 46: ...arth as a heat source and or heat sink Fig 30 31 32 Piping con gurations are typically reverse return header type Both horizontal and vertical designs are used predominantly and the type installed depends on local practices site conditions and the geothermal heat pump The energy ef ciency of the system is dependent upon suf cient ground loop to produce favorable water temperatures for the geotherm...

Page 47: ... design and size them together The length of ground loop piping required depends on the structure load soil conditions loop con guration local climate and landscaping Sizing of the ground loop is critical The more piping used over sizing the greater the output of the system but since the costs associated with the ground loop typically represent 30 to 50 of the total system costs over sizing is une...

Page 48: ...gns using the smaller pipe the pipe length is normally increased to compensate for the small heat transfer reduction although it still results in around 50 savings in pipe costs over the larger pipe in series Parallel systems normally have lower pressure drop and require smaller pumps due to the multiple ow paths of smaller pipes in parallel Smaller diameter pipe is typically much easier to handle...

Page 49: ...hus the ground is warmer than the ambient air in the winter and cooler than the ambient air in the summer Fig 36 Ground temperature annual variation Courtesy of American Society of Heating Air conditioning and Refrigeration Engineers Inc www ashrae org 9 3 Soil Analysis The thermal conductivity of the soil must be analyzed or estimated from local data for any particular geothermal heat pump system...

Page 50: ...ermal conductivity of soil types Courtesy of American Society of Heating Air conditioning and Refrigeration Engineers Inc www ashrae org Btu hr ft F Reasonable values for use when no site or soil speci c data available Moderately conservative values for minimum heat loss through soil use in soil heat exchanger or earth contact cooling applications Values from Salomone and Marlowe 1989 Moderately c...

Page 51: ...mphibolite 42 8 1 1 2 7 0 8 2 8 1 5 2 2 0 9 4 47 0 12 175 195 160 1 1 4 7 Andesite 42 8 1 1 2 7 0 8 2 8 1 5 2 2 0 9 4 47 0 12 175 195 160 1 1 4 7 Basalt 42 8 1 2 1 4 0 17 0 21 180 0 7 0 9 Gabbro Cen Plains 42 8 0 9 1 6 0 18 185 0 65 1 15 0 85 1 5 Gabbro Rocky Mtns 42 8 1 2 2 1 0 18 185 0 65 1 15 0 85 1 5 Diorites 11 2 1 2 1 9 1 2 4 7 0 22 180 0 7 1 0 Grandiorites 11 2 1 2 2 0 0 21 170 0 8 4 3 Sedi...

Page 52: ...e Cuttings For Back lling Around U Tube U Tube Dia SDR or Schedule Pipe Bore Thermal Resistance h ft F Btu For water ows above 2 0 US gpm 20 Prop Glycol Flow 3 0 US gpm 20 Prop Glycol Flow 5 0 US gpm 20 Prop Glycol Flow 10 0 US gpm in 0 15 ft SDR 11 0 09 0 12 NR NR SDR 9 0 11 0 15 NR NR Sch 40 0 10 0 14 NR NR 1 0 in 0 18 ft SDR 11 0 09 0 14 0 10 NR SDR 9 0 11 0 16 0 12 NR Sch 40 0 10 0 15 0 11 NR ...

Page 53: ... balance between geothermal heat pump uid supply temperature and the capital cost of the ground loop At steady state conditions there is heat transfer from the geothermal heat pump uid to the ground Temperature difference between the ground and the uid in the ground loop provides the impetus for the heat energy to move The challenge in ground heat exchanger design is that the ground temperature ty...

Page 54: ...heat pump systems utilize for heating 52 F 57 F 62 F 67 F 72 F 77 F 72 F 67 F 62 F 57 F 52 F 47 F 47 F 42 F 42 52 F 52 F 42 F 42 F Figure 62 Fig 40 Approx ground water temperatures Courtesy of epa gov accessed September 2012 and cooling Even if soil temperatures rise to 90 F during the summer or even 50 F during the winter these systems can still utilize the 90 F soil temperature to provide adequa...

Page 55: ...n for all Iron Pipe Size IPS dimensions HDPE is manufactured according to dimension ratios to determine wall thickness Dimension ratio DR is the ratio of the outside pipe diameter to the wall thickness DR relates to the pressure rating for the pipe Factors affecting the pressure rating of pipe include the material it is made from wall thickness and temperature Never use pipe where the system worki...

Page 56: ...ve joining devices They provide simple assembly and only require the installer use a chamfer tool Note Earth loop systems require a hydrostatic test of typically 40 50 PSI before back lling to test for leaks Fig 42 Pipe fusion Stab method Courtesy of International Ground Source Heat Pump Association Oklahoma State University Socket fusion joins two ends of pipe by fusing each pipe end to a socket ...

Page 57: ...quipment and tools prior to fusing Then he she must prepare the fusion machine correctly clean and heat the heater to the proper temperature prepare the pipe ends properly for fusion heat the pipe ends and fuse the pipe properly No Gaps or Cavities Proper Alignment of Pipe Ends Uniform Melt Bead Fig 46 Butt fusion Courtesy of International Ground Source Heat Pump Association Oklahoma State Univers...

Page 58: ...ide corrosion protection to system materials and not produce an unacceptable risk to the environment in the event of a system leak Fig 49 Heat transfer uids The antifreeze is normally placed in the system from inside the structure after the entire ground heat exchanger or loop eld is completed pressure tested ushed and purged The concentration of the antifreeze solution should be checked to assure...

Page 59: ...d freeze protection down to approximately 15 F in most situations As with methanol ethanol is also very ammable in concentrations greater than 10 and can cause explosions and asphyxiation The U S Bureau of Alcohol Tobacco and Firearms ATF limits its distribution Ethanol used for geothermal applications must not be denatured with any petroleum based product Denaturing agents that are petroleum base...

Page 60: ...ve application for later installations For most horizontal ground heat exchangers the depth of the piping is typically around 5 to 6 feet below the surface This is often due to trench safety concerns and the volume of earth soil that must be moved For most vertical ground heat exchangers parallel series ground heat exchanger designs prove more economical due to increasing drilling costs This desig...

Page 61: ...hould be installed following standards set by the International Ground Source Heat Pump Association IGSHPA in Closed Loop Geothermal Heat Pump Systems Design and Installation Standards Fig 50 Reverse return piping Special attention should be paid to avoid sharp bends in piping and remove sharp edged rocks or other material in the trench back ll Either can cause damage to the piping potentially cau...

Page 62: ...rge air from the ground loop A typical header for capacities up to 15 tons of cooling is shown Fig 51 Fig 51 Header capacities up to 15 tons of cooling The header shown next Fig 52 is designed for capacities up to a nominal 5 tons of cooling It uses 1 1 4 inch IPS pipe for circuits 4 to 7 and inch IPS for circuits 1 3 allowing minimum pressure drop while maintaining 2 Feet per Second FPS velocity ...

Page 63: ...by the ushing ow rate of each circuit Header layouts are more cost effective with short headers This means the installer must centrally locate the header with relationship to all circuits and then bring the circuits to the header Some installers use a closed header as shown Fig 53 at the end loops to balance ow more evenly Fig 53 Closed header Courtesy of International Ground Source Heat Pump Asso...

Page 64: ... is required the vertical loop con guration is a more appropriate choice The number of boreholes is directly related to the depth of the boreholes that is fewer boreholes for deeper boreholes The depths of the boreholes will generally depend on the needs of the structure as well as the cost Fig 54 Courtesy of International Ground Source Heat Pump Association Oklahoma State University With vertical...

Page 65: ...can also cool the surface soil and improve horizontal loop performance The presence or absence of groundwater also in uences total borehole length requirements Groundwater movement assists in heat diffusion and can help overcome an imbalance in the annual thermal loads cooling dominated loads to prevent long term temperature buildup in the ground around the loops The loop installer designer should...

Page 66: ...ractical limits by exercising good judgment and care Borehole alignment is more critical when utilizing deeper boreholes Misalignment of boreholes is typically related to the type of the material penetrated while boring the trueness of the surface or bridge casing the tension of the cable tool drilling line and the pull down force on the drill pipe when using rotary drilling The borehole should be...

Page 67: ...ps 67 Bosch Thermotechnology Corp Data subject to change Fig 57 Courtesy of International Ground Source Heat Pump Association Oklahoma State University Fig 58 Courtesy of International Ground Source Heat Pump Association Oklahoma State University ...

Page 68: ... is planned near a ground heat exchanger loop eld or if repairs to the loop eld are necessary Fig 60 Tracer wire and magnetic tape responds to electromagnetic locating equipment above ground The tracer or magnetic tape should be laid in horizontal trenches and along the supply and return lines between the header and structure The wire or tape should be laid in a continuous loop and be buried at le...

Page 69: ...feet from a household drinking water well f 75 feet from a public water supply well f 25 feet from an on site wastewater system serving a single family dwelling f 10 feet from a buried water service line or sewer line f 10 feet from a property boundary Water lines and sewer lines that are crossed by piping or header piping should be protected by insulation and not less than 3 feet of separation Lo...

Page 70: ...f bentonite drilling uid until the loop piping is installed Before grouting the drilling uid in the borehole should be thinned until the drilling uid density is lower than the grout density Surface water should not be used as a source of water during the drilling of a vertical closed loop system borehole unless it is obtained from a municipal water supply system Water that is used for drilling pur...

Page 71: ...lly clean water with engineered bentonite additives is circulated from a mud tub through a suction hose by a mud pump and forced down the drill string through portals in the drill bit to ush cuttings out of the borehole while the bit is fed down the hole The uid and cuttings are then run through a series of separation chambers so that the solids can be removed and the uid re circulated Fig 64 Cour...

Page 72: ...05 1 in U tube 0 07 0 03 0 09 0 02 0 02 0 11 NR 0 04 Tab 30 NR Not Recommended Air Gaps add 0 2 to 0 4 h ft F Btu to Bore Resistance Note some adjustments are negative which indicates a thermal enhancement and a lower net thermal resistance compared to natural back lls Various sources in the industry are available indicating the thermal conductivities for enhanced grouts Enhanced grouts can signi ...

Page 73: ...ottom of the borehole before the grouting process begins By pumping from the bottom of the hole up water in the hole is completely displaced with high solids low permeability bentonite grout The grout provides a median of heat transfer between the loop pipe and the earth and protects from surface contaminants Typically grouting is performed with a rig or trailer mounted grout unit Fig 66 This incl...

Page 74: ...ng for a period of not less than 12 hours Additional grout should be added if necessary and the monitoring period should be extended until the settling of grout stops A borehole drilled using horizontal directional drilling techniques should be grouted by pumping grout as the Tremie pipe is retracted through the borehole Grout manufacturers product speci cations should always be followed for mixin...

Page 75: ... chemical compositions of the water and bentonite pH etc For example inappropriate mixing ratios can lead to ineffective seals Also improper emplacement techniques may lead to gaps in the seal For each type of bentonite the manufacturer s instructions must be followed In addition it is critical for the contractor to be experienced and prepared for the grouting operation Different bentonite types a...

Page 76: ...p Association Oklahoma State University To install a horizontal loop installers typically dig trenches 5 8 feet below the ground surface and then install a series of HDPE pipes that comprise the geothermal ground heat exchanger The trenches are then back lled ensuring that no sharp rocks or debris are present to damage the pipes When retro tting a home with a Bosch geothermal heat pump system a ho...

Page 77: ...of a vertical or horizontal loop Fig 74 Pond or lake loop 11 1 Horizontal Loop Layout The deeper a horizontal ground loop the more stable the ground temperatures A typical horizontal loop system consists of buried polyethylene pipe containing water and antifreeze solution which is circulated by means of a small pump Fluid runs through the pipe in a closed system in a certain order Many loop layout...

Page 78: ...nge the number of pipes that can be placed in a trench A single pipe loop is typically not common but may be used if there is plenty of land Fig 77 To complete the circuit each trench must go out and circle back to the starting point If using pipe there is usually one trench per ton of cooling capacity required for the structure A parallel circuit design might look like a ower petal If the ground ...

Page 79: ...o utilize smaller land areas A four pipe ground loop typically has two 2 circuits per trench so if pipe is used one trench can typically handle a two 2 ton geothermal heat pump Typically the four pipes are spaced a minimum of 24 inches apart horizontally and vertically in the trench with the upper two pipes at the average depth determined for the locale As four pipe ground loops have an even numbe...

Page 80: ... affect system performance The Bosch Geo Solutions software program will help determine the appropriate depth for these applications Antifreeze will be necessary in the Northern Zone to prevent freezing of the circulated water and to allow the system to gain capacity and ef ciency by using large amounts of heat released when the water contained in the soil is frozen Installers should always back l...

Page 81: ...in excavations Fig 84 OSHA s Standards contain the speci c information for employee safeguards in excavations Cave in protection as de ned by OSHA will not be present during a ground loop installation Therefore the loop must be installed into any 6 feet deep trench by dropping it into the trench from the ground surface In some cases the loop may not fall to the bottom of the trench or lie at on th...

Page 82: ...sity of the pipe in the trench by coiling it to achieve more pipes per foot of trench When rst introduced the Slinky design included both horizontal Fig 86 and vertical Fig 87 applications Vertical Slinky loops were designed for installation with a trencher This design in less popular today as it has been found to be extremely dif cult to back ll unless ne soil e g sand or owable back ll is used T...

Page 83: ...track loop Fig 89 90 Typically all of the pipes used and installed are at the same elevation in a much larger trench or even a large pit area Fig 91 This method is often more cost effective than installing four and six pipe horizontal designs as the depth of the frost line in moderate and or colder climates is deeper than warmer climates resulting in more dif culty when excavating The distance bet...

Page 84: ...stallation of all types of pipelines HDD is also a good method for many retro t geothermal applications as there is very little excavation Only a small square hole is used for headering the pipes Like a horizontal two pipe loop or a Slinky loop a horizontal bore ground heat exchanger loop has one circuit per trench and typically one trench per ton of cooling capacity Typically HDPE pipe is used wi...

Page 85: ...s to rest in its own isolated temperature layer in the body of water throughout the year This is where the coil of pipe is ideally placed In winter as heat is extracted from the 39ºF water around the loop coils the water cools and ascends by way of its own convective current upward toward the surface This draws in fresh ambient 39ºF water from the thermo cline thin but distinct layer in a body of ...

Page 86: ...86 Bosch Geothermal Heat Pumps Bosch Thermotechnology Corp Data subject to change Applications Manual Fig 94 Slinky matt style Fig 95 ...

Page 87: ...urface of the body of water top of plate at this depth In colder climates the top of the plate should be below the anticipated freeze layer of the body of water must be below any ice that forms on the surface While pond and lake loop and plate applications remain the most ef cient type of loops there are still a noticeable difference in heat transfer rates between silt and water exist If part of a...

Page 88: ...nd heat exchanger into a residential structure Hydraulic cement is recommended With a new construction situation exists installers should attempt to position the pipe in the proper location prior to any wall construction or slab pouring As piping can wear due to expansion and contraction it should be protected with a chase through the slab with PVC elbows and sleeves as shown Fig 99 Fig 99 Courtes...

Page 89: ...niversity With below grade situations always bring the pipe through the wall as indicated Figure 102 If the ground heat exchanger could be subject to freezing always insulate the piping at least 4 feet into the trench This will prohibit ice formation near the wall Fig 102 Below grade wall penetration Courtesy of International Ground Source Heat Pump Association Oklahoma State University ...

Page 90: ...system to avoid any possible vibration and should be limited in length to 10 15 feet per run to reduce pressure drop Typically 2 feet of head pressure drop is normal for all closed loop ground heat exchangers ttings which include 10 to 12 elbows for inside piping to a ow center Closed cell insulation at least 3 8 inch wall thickness should be used on all inside piping to avoid condensation and pos...

Page 91: ...Applications Manual Bosch Geothermal Heat Pumps 91 Bosch Thermotechnology Corp Data subject to change Fig 103 Fig 104 ...

Page 92: ...wever the thermal expansion of ground loop piping may cause the circulating pump or pumps to cavitate without the use of an expansion tank Any entrapped air will not leave the system over time Additionally a ush cart is typically necessary for lling and ushing the ground heat exchanger and ground loop system Check and isolation valves must also be eld installed Generally you will see what s referr...

Page 93: ...then out to the ground heat exchanger and then returns the uid directly back to the ow center Non pressurized ow centers allow any entrapped air within the system to remove itself over time Also the circulating uid level and freeze protection level can easily be monitored and replenished as necessary These ow centers can directly measure system ow and typically come equipped with check valves and ...

Page 94: ...help in determining the ground heat exchanger pressure drop for accurate ow estimation Regardless of the use of either a pressurized or non pressurized ow center it must be located between the Bosch geothermal heat pump and the ground heat exchanger Additionally the ow center should be located as closed to the Bosch geothermal heat pump unit as possible to limit the length of hoses and associated ...

Page 95: ...ith water from a garden hose through the ush cart before using the ush cart pump to insure an even ll Fig 111 Connect the ush cart hoses to the ow center ush ports using proper adapters Connect the water supply to the hose connection on the return line of the ush cart Turn both 3 way valves on the ow center to the ush ports and loop position Turn on the water supply making sure the water is of pro...

Page 96: ...the ground loop turn the 3 way valve to the ush port unit position and repeat the purging process The unit side purge should only take approximately 5 to 10 minutes While the ush cart pump continues to run turn the 3 way valve to the ush port unit and loop position Fig 114 Once ushing and purging is complete the system can be pressurized Fig 114 Flush cart step 4 Always operate the Bosch geotherma...

Page 97: ... motor s to allow any trapped air to be discharged and to insure the motor housing has been ooded not required for Taco circulators Always insure that the ow center provides adequate ow through the Bosch geothermal heat pump by checking the pressure drop across the heat exchanger and comparing it to the pressure drop tables in the Installation and Maintenance Manual for the particular Bosch geothe...

Page 98: ...ing spa or hot tub heating For optimal cooling and dehumidi cation Bosch recommends a separate Bosch water to air geothermal heat pump for cooling Controls are much simpler when a Bosch water to water geothermal heat pump is used for space heating and or domestic water heating and a Bosch water to air geothermal heat pump is used for cooling Since the Bosch water to water geothermal heat pump and ...

Page 99: ...ics must be considered for Bosch water to water applications Bosch geothermal water to water heat pumps sizing is dependent upon the type of hydronic system application load side indoor and the type of ground loop system source side outdoor Since the capacity and ef ciency of the Bosch geothermal water to water heat pump is directly related to the entering source temperature care should be exercis...

Page 100: ...dered the most practical economical and safe heat transfer medium available The most popular application for Bosch water to water geothermal heat pumps is likely radiant oor heating Some examples are shown Figure 119 Bosch water to water geothermal heat pumps are an excellent heat source for framed oor as well as slab type oor heating systems The low water temperature required by such oors usually...

Page 101: ... in a suspended ceiling space typically commercial applications or on a wall Fig 120 Fan coils and air handlers typically have one or two coils and a blower Air is heated by hot water circulated through a hot water coil Chilled water is circulated through the coil if cooling is needed Depending upon the application the unit will include one coil for both heating and cooling hot water chilled water...

Page 102: ...and 80 90 F EFT For cooling buffer tanks should be sized at one U S gallon per 1 000 Btu h of cooling capacity at the minimum EFT and the maximum EFT the point at which the Bosch geothermal water to water heat pump has the highest cooling capacity usually 50 70 EFT and 50 60 F EFT Always select the size of the buffer tank based on the larger of the two calculations heating or cooling The minimum b...

Page 103: ...ter application source side is shown Fig 122 as well as an earth coupled application source side Fig 123 Fig 122 Proper design of the delivery system is crucial to the Bosch geothermal water to water heat pump system performance reliability and life expectancy Bosch recommends only type L straight length copper tubing for connection between the Bosch geothermal water to water heat pump and a buffe...

Page 104: ...or cooling Y the loop pump or solenoid valve if present is energized and the compressor will start Once the thermostat is satis ed the compressor shuts down accordingly Note that a fault condition initiating a lockout will de energize the compressor Heating Mode Heating operates in the same manner as cooling but with the reversing valve de energized The compressor will run until the desired set po...

Page 105: ...ch may be used but care must be taken not to overheat the piping which can cause the material to become brittle When preparing copper joints for soldering tubing should be cut square and all burrs must be removed Do not use dented or pitted copper Clean the inside of the tubing with a brush clean the outside with emery cloth approximately from the end of the tting Debris in the system could cause ...

Page 106: ...heat transfer surface area per unit length This allows full ow of both water and refrigerant around its entire periphery for improved performance Thermal performance is enhanced by the convolutions to both the water and refrigerant ows All cupronickel coils are insulated Fig 126 Fig 126 17 2 Bosch Heat Recovery Package HRP The Bosch Heat Recovery Package HRP is a factory mounted option Fig 127 It ...

Page 107: ...re due to freezing will void the HRP warranty as well as the Bosch geothermal heat pump warranty A typical example of the HRP water piping connections on a unit is shown Fig 128 Electric water heaters are recommended If a fossil fuel water heater is used typically a second pre heat Fig 128 tank is recommended If the electric water heater has only a single heating element the dual tank system is re...

Page 108: ...d be between approximately 5ºF and 15ºF Allow the Bosch geothermal heat pump and the HRP to operate for 20 to 30 minutes to ensure the HRP is functioning properly The HRP pump will de energize automatically when the water temperature entering it reaches 120ºF The Bosch HRP is typically equipped with a low gas limit which closes at approximately 125 F and a hot water temperature limit that opens at...

Page 109: ...ts of the reheat relay coil The O circuit is energized thus energizing the reversing valve The compressor contactor is energized though the R side of the transformer run through normally open contacts on the reheat relay The cooling relay remains de energized thus the reheat solenoid is enabled the reheat mode always operates simultaneously with the cooling mode The best way to control geothermal ...

Page 110: ...urately detect the cause of electrical and system related failures without any sensors A ashing LED indicator communicates the ALERT code and guides the service technician more quickly and accurately to the root cause of a problem Fig 131 This module does not provide safety protection The Comfort Alert module is a monitoring device and cannot shut down the compressor directly When an abnormal syst...

Page 111: ...heck wiring and connectors between supply and compressor Check for low pilot voltage at compressor contactor coil 4 High pressure switch is open and requires manual reset 5 Open circuit in compressor supply wiring or connections 6 Unusually long compressor protector reset time due to extreme ambient temperature 7 Compressor windings are damaged Check compressor motor winding resistance Yellow ALER...

Page 112: ...hat suit the different application for the models offered by Bosch User settings such as the time and schedules can be preprogrammed or also change during the installation of the product The controller should be installed on the right side of the unit mounting holes are available on the DDC panel behind the electrical box as shown Figure 164 The DDC kit includes all the necessary components requir...

Page 113: ...e a drill as it may strip the screw Remove the cork insulation and route the sensor wire leads to the electrical box along with the existing wires through the knock out available on the blower divider panel Fig 133 To install the second sensor on the condenser water coil remove the insulation tape from the top pipe near the corner post of the water coil and place the sensor as shown Fig 135 Fig 13...

Page 114: ...MPRESSOR GRN OR G Y WHT BLK ALR DRY HOT ALR C C GND COND FREEZE R G HPC HPC LPC1 Y Y CC R R DRY HOT LPC2 POWER C UNIT PROTECTION MODULE STATUS FREEZE NO YES TEMP 35F 15F LOCKOUT 4 2 RESET R Y ALARM CONT PULSE TEST YES NO TRANSFORMER PRIMARY LEADS LEADS FROM BLOWER MOTOR ORG OR RED BLK ORG OR RED FROM DDC CONTROL B L K BLU R E D O R G Y E L B R W W H T C C O C G R Y CONNECTION BLOCK THERMOSTAT T1 T...

Page 115: ...VAC Electrical technician T1 T2 L2 L1 TRANSFORMER ECM MOTOR INTERFACE BOARD CONTACTOR COMPRESSOR RED OR ORG ORG OR RED BLK ECM MOTOR POWER HARNESS GRN OR G Y WHT BLK ALR DRY HOT ALR C C GND COND FREEZE R G HPC HPC LPC1 Y Y CC R R DRY HOT LPC2 POWER C UNIT PROTECTION MODULE STATUS FREEZE NO YES TEMP 35F 15F LOCKOUT 4 2 RESET R Y ALARM CONT PULSE TEST YES NO Y R C CADM COMFORT ALERT DIAGNOSTIC MODUL...

Page 116: ...er ow cabinets Always refer to the speci c model installation manual for heater selection Internal electric heat cannot be provided with hot gas reheat Units with internal electric heat must have 2 eld power supplies Fig 142 Electric Heat 17 8 Sound Package Speci c models of 208 230V Bosch geothermal heat pumps may be equipped with a factory installed sound reduction package option This option imp...

Page 117: ...n exposed to both diffused and direct sunlight The absorber contains pipes to transfer heat uid The absorber collects the heat and transports the solar heat to the tank where it can be stored for later use When the heat transfer uid in the collectors is warmer than the bottom of the storage tank the solar controller will turn on the solar loop pump to transport the hot uid from the collectors thro...

Page 118: ...25 000 BTU hr maximum inputs are available These tankless units are all compact offering easy access and 100 serviceable parts and all have a 20 Year estimated life expectancy Indoor and outdoor models are both available with freeze protection Bosch also provides peace of mind to customers with our 15 year limited residential heat exchanger warranty for all tankless water heating models Finally th...

Page 119: ...he heating season Fig 149 18 1 1 Solar Thermal Sequence of Operation When the switch on temperature difference between the collector array and the solar DHW tank is reached the solar circulator is switched and the diverter valve SBU module routes the heat transfer uid through the solar tanks heat exchanger Once the DHW tank reaches its upper limit and solar energy is still available the diverter v...

Page 120: ...ided by the modululating Tankless Water Heater 3 100 domestic energy provided by the high output Bosch Tankless Water Heater Fig 150 18 2 1 Bosch W2A with Optional HRP and Tankless Water Heater Sequence of Operation Waste heat is recovered during the cooling months via the Bosch water to air geothermal heat pump equipped with the optional HRP Waste heat is collected and stored in an appropriately ...

Page 121: ... to the structure This energy is stored in a buffer tank sized according to the size of the Bosch geothermal heat pump The structure demands energy from the buffer tank independently of the operation of the Bosch geothermal heat pump The Bosch condensing gas boiler constantly monitors the current temperature of the buffer tank and compares this temperature against the system supply temperature req...

Page 122: ...eowners reduce their monthly utility bills while protecting the environment The Bosch Net Zero Home is a 1 650 square foot structure and features a complete suite of Bosch technologies such as a geothermal heat pump heating and cooling system equipped with the optional heat recovery package desuperheater for domestic hot water production solar photovoltaic panels and an electric heat pump water he...

Page 123: ...aic System The Bosch PV system includes all necessary components such as modules inverters and mounting and is connected to the power grid converting direct current DC generated from sunlight into alternating current AC The system creates electricity during the daytime to power the home and feeds any excess energy into the grid of GreyStone Power Corporation If the energy generated is less than th...

Page 124: ...nd offers a functioning demonstration of its home and commercial building energy systems supporting technologies tools appliances and lifestyle applications Fig 158 Bosch Experience Center The Experience Center is now a destination for a large cross section of audiences because it provides a clear demonstration of how sustainable technologies for everyday use are readily available much like conven...

Page 125: ...n stored in the water for later use The collectors the pump station and the storage tank are connected with supply and return piping that is insulated to minimize heat loss As the system heats up or cools down an expansion tank accounts for safe expansion and contraction of the heat transfer uid in this maintenance free and fully automated system Fig 162 Bosch Solar Thermal System In addition to t...

Page 126: ...126 Bosch Geothermal Heat Pumps Bosch Thermotechnology Corp Data subject to change Applications Manual ...

Page 127: ...Applications Manual Bosch Geothermal Heat Pumps 127 Bosch Thermotechnology Corp Data subject to change ...

Page 128: ...United States and Canada Bosch Thermotechnology Corp 50 Wentworth Avenue Londonderry NH 03053 Tel 603 552 1100 Fax 603 965 7581 www bosch climate us BTC 436001101 A 01 2013 ...

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