Geothermal Applications APPLYING GEOTHERMAL COMFORT TO RESIDENTIAL CONSTRUCTION
Geothermal Applications Table of Contents 12 System Components ........................................................................13 Flow Controller Selection ..............................................................25 The Geothermal Heat Pump ......................................................13 Loop Piping Installation ...................................................................25 Packaged Water-to-Air Heat Pumps .......................................
Carrier Geothermal Heat Pump Systems System Components System Components Geothermal heat pumps have a number of names such as watersource heat pump, Geoexchange, ground loop heat pump, earthcoupled heat pump, ground source heat pump, etc. Technically, “Geothermal” is defined as, “energy from the internal heat of the earth.” This type of geothermal energy is called “high temperature geothermal.” Temperatures can exceed 300°F [150°C] in geothermal wells.
Geothermal Applications The Geothermal Heat Pump Packaged Water-to-Air Heat Pumps Carrier Geothermal has a number of choices for packaged geothermal heat pumps with airflow configurations for most any installation. Three families of two-stage products are available. Those are the GT-PC (50YG), GT-PX (50YD), and GT-PB (50YF). The GT-PC (50YG) and GT-PB (50YF) series include the Two-Way Unit Communicating System and the Integrated Variable Speed Water Flow Control.
Carrier Geothermal Heat Pump Systems Two-Way Unit Communicating System Two-Way Communication System and a Gateway Into the GT-PC (50YG) and GT-PB (50YF) Digital Systems GT-PC (50YG) and GT-PB (50YF) Digital are equipped with a Two-Way Communication System that allow users to interact with their geothermal system in plain English AND delivers improved reliability and efficiency by precisely controlling smart variable speed components.
Geothermal Applications Integrated Variable-Speed Water Flow Control Integrated Variable-Speed Water Flow Control Employing the Two-Way Communicating System, the GTPC (50YG), GT-PB (50YF) and GT-PCS (50YGS/50YGP) Digital series utilize an Integrated Variable-Speed Water Flow Control. This technology is built inside the unit with intelligent variable speed components, controlled directly by the DXM2 control based on information from the pump (or motorized water valve) and sensors across the system.
Carrier Geothermal Heat Pump Systems The Geothermal Heat Pump Water-to-Water Heat Pumps Water-to-water heat pumps give the customer “the best of both worlds,” geothermal heating and cooling, plus the ability to enjoy the benefi ts of warm radiant floors. The Carrier Geothermal GTPW (50YER) series water-to-water heat pumps provide hot and/ or chilled water.
Geothermal Applications Heat Source/Heat Sink Heat Source/Heat Sink The heat source/heat sink for geothermal systems is determined based upon the specific application. Where water quality is good and a sufficient quantity of water is available, an open loop (well water) source/sink is a very cost effective solution. Otherwise, one of the three types of closed loop applications may be a better choice.
Carrier Geothermal Heat Pump Systems Water Quality Standards Table 1: Water Quality Standards Water Quality Parameter HX Material Closed Recirculating Open Loop and Recirculating Well Scaling Potential - Primary Measurement Above the given limits, scaling is likely to occur. Scaling indexes should be calculated using the limits below pH/Calcium Hardness Method - All pH < 7.
Geothermal Applications Heat Source/Heat Sink Open Loop System (continued) A closed, bladder-type expansion tank should be used to minimize mineral formation due to air exposure. The expansion tank should be sized to provide at least one minute continuous run time of the pump using its drawdown capacity rating to prevent pump short cycling. Discharge water from the unit is not contaminated in any manner and can be disposed of in various ways, depending on local building codes (e.g.
Carrier Geothermal Heat Pump Systems Heat Source/Heat Sink Horizontal (Trenched or Bored) Loop ®2 Pond/Lake Loop ®2 00 00 9C 9C lim lim ate ate Ma Ma ster ster Horizontal loops may be installed with a trencher, backhoe or horizontal boring machine. Excavation costs for horizontal loops are usually less than the costs for vertical loops, but significantly more land space is required. For rural installations, horizontal loops can be very cost effective.
Geothermal Applications Closed Loop Design/Installation Guidelines Closed Loop Design/Installation Guidelines Closed Loop Basics Closed Loop Earth Coupled Heat Pump systems are commonly installed in one of three configurations: horizontal, vertical and pond loop. Each configuration provides the benefit of using the moderate temperatures of the earth as a heat source/heat sink. Piping configurations can be either series or parallel.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines In smaller loops of two tons [7 kW] or less, the reasons for using parallel loops as listed above may be less obvious. In these cases, series loops can have some additional advantages: • No header - fittings tend to be more expensive and require extra labor and skill to install. • Simple design - no confusing piping arrangement for easier installation by less experienced installers.
Geothermal Applications Closed Loop Design/Installation Guidelines Headers that utilize large diameter pipe feeding the last circuits should not be used. PE 1-1/4” IPS pipe requires 9.5 gpm [36 l/m] to attain 2 fps [0.6 m/s] and since increasing the flow through the last circuit would also require increasing the flow through the other circuits at an equal rate as well, we can estimate the flush flow requirements by multiplying the number of circuits by 9.5 gpm [36 l/m] for 1-1/4” IPS.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines Inside Piping Polyethylene pipe provides an excellent no leak piping material inside the building. Inside piping fittings and elbows should be limited to prevent excessive pressure drop. Hose kits employing 1” rubber hose should be limited in length to 10-15 feet [3 to 4.5 meters] per run to reduce pressure drop problems.
Geothermal Applications Closed Loop Design/Installation Guidelines Chart 1: Flow Controller Performance Chart External Flow Controller Pump Curves 120 [360] 1-Grundfos 26-99 2-Grundfos 26-99 2-Grundfos 26-116 3-Grundfos 26-99 Head, ft [kPa] 100 [290] 80 [240] 60 [180] 40 [120] 20 [60] 0 GPM 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 0.06 0.13 0.19 0.25 0.32 0.38 0.44 0.50 0.57 0.63 0.69 0.76 0.82 0.88 0.95 1.01 1.07 1.14 1.20 1.26 1.32 1.38 1.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines Table 3a: Polyethylene Pressure Drop per 100ft of Pipe Antifreeze (30°F [-1°C] EWT): 17% Methanol by volume solution - freeze protected to 15°F [-9.4°F] 3/4” IPS SDR11 1” IPS SDR11 1-1/4” IPS SCH40 1-1/2” IPS SCH40 PD (ft) Vel (ft/s) Re (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD Vel (ft/s) Re PD Vel (ft/s) Re 1 0.35 0.55 1221 0.14 0.35 975 0.06 0.22 773 0.03 0.17 676 0.01 0.11 541 2 0.89 1.
Geothermal Applications Closed Loop Design/Installation Guidelines Table 3b: Polyethylene Pressure Drop per 100ft of Pipe Antifreeze (30°F [-1°C] EWT): 24% Propylene Glycol by volume solution - freeze protected to 15°F [-9.4°F] 28 3/4” IPS SDR11 Flow Rate PD (ft) Vel (ft/s) 1 0.59 2 1.18 3 1” IPS SDR11 Re (ft) Vel (ft/s) 0.55 716 0.24 1.10 1431 0.48 1.80 1.66 2147 4 4.45 2.21 5 6.96 2.76 6 9.48 7 12.31 8 15.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines Table 3c: Polyethylene Pressure Drop per 100ft of Pipe Antifreeze (30°F [-1°C] EWT): 20% Ethanol by volume solution - freeze protected to 15°F [-9.4°F] 3/4” IPS SDR11 1” IPS SDR11 1-1/4” IPS SCH40 1-1/2” IPS SCH40 PD (ft) Vel (ft/s) Re (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD Vel (ft/s) Re PD Vel (ft/s) Re 1 0.56 0.55 757 0.23 0.35 604 0.09 0.22 479 0.05 0.17 419 0.02 0.11 335 2 1.12 1.
Geothermal Applications Closed Loop Design/Installation Guidelines Table 3d: Polyethylene Pressure Drop per 100ft of Pipe Antifreeze (30°F [-1°C] EWT): 25% Ethylene by volume solution - freeze protected to 15°F [-9.4°F] 30 3/4” IPS SDR11 1” IPS SDR11 1-1/4” IPS SCH40 1-1/2” IPS SCH40 PD (ft) Vel (ft/s) Re (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD Vel (ft/s) Re PD Vel (ft/s) Re 1 0.40 0.55 1048 0.16 0.35 837 0.06 0.22 664 0.04 0.17 580 0.02 0.11 464 2 0.81 1.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines Table 3e: Polyethylene Pressure Drop per 100ft of Pipe No Antifreeze (50°F [10°C] EWT): Water 3/4" IPS SDR11 1" IPS SDR11 1 1/4" IPS SCH40 1 1/2" IPS SCH40 2" IPS SCH40 Flow Rate PD (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re PD (ft) Vel (ft/s) Re 1 0.23 0.55 2,806 0.08 0.35 2,241 0.02 0.21 1,724 0.01 0.16 1,508 0.00 0.10 1,160 2 0.78 1.10 5,612 0.
Geothermal Applications Closed Loop Design/Installation Guidelines Table 3f: 1” Rubber Hose Pressure Drop per 100ft of Hose Methanol* Propylene Glycol* Ethanol* PD (ft) Vel (ft/s) 1 0.12 0.35 895 0.14 0.35 507 0.13 0.35 807 0.12 0.35 923 2 0.42 0.70 1789 0.48 0.70 1013 0.43 0.70 1614 0.42 0.70 1847 3 0.85 1.06 2709 0.98 1.06 1534 0.88 1.06 2444 0.85 1.06 2796 4 1.41 1.41 3604 1.63 1.41 2041 1.45 1.41 3251 1.40 1.41 3720 5 2.09 1.76 4499 2.41 1.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines CAUTION! CAUTION! This manual is not intended for commercial loop design. Horizontal Applications For horizontal earth loops, dig trenches using either a chain-type trenching machine or a backhoe. Dig trenches approximately 8-10 feet [2.5 to 3 meters] apart (edge to edge of next trench). Trenches must be at least 10 feet [3 meters] from existing utility lines, foundations and property lines and at least 50 feet [15.
Geothermal Applications Closed Loop Design/Installation Guidelines Pond/Lake Applications Pond loops are one of the most cost effective applications of geothermal systems. Typically 1 coil of 300 ft of PE pipe per ton [26 meters per kW -- one 92 meter coil per 3.5 kW of capacity] is sunk in a pond and headered back to the structure. Minimum pond sizing is 1/2 acre [0.2 hectares] and minimum 8 to 10 feet [2.4 to 3 meters] deep for an average residential home.
Carrier Geothermal Heat Pump Systems Closed Loop Design/Installation Guidelines Figure 10: Slab on Grade Entry Detail Figure 12: Pier and Beam (Crawl Space) Detail Finished Grade 4-6' [1.2 - 1.8m] Insulation Inside Protective Shield Loop Pipe Figure 13: Below Grade Entry Detail Figure 11: Retrofit Construction Detail Enter Building As Soon As Possible Insulation Inside Protective Shield Finished Grade 4-6' [1.2 - 1.
Geothermal Applications The Heating/Cooling Distribution System Ducted Forced Air System The most common type of heating and cooling distribution system is the ducted forced air system, which delivers warm or cool air to the living space. Water-to-air packaged units or split system heat pumps are typically connected to a central duct layout, which distributes conditioned air to the various zones. As in all forced air systems, properly designed and sealed ductwork is crucial to occupant comfort.
Carrier Geothermal Heat Pump Systems The Heating/Cooling Distribution System and Equipment Sizing Figure 16: Typical Radiant Floor Header System The size of the buffer tank should be determined based upon the predominant use of the equipment (heating or cooling). For heating, buffer tanks should be sized at one U.S.
Geothermal Applications Equipment Sizing Equipment Sizing dehumidification mode. Proper equipment sizing is still important, but some flexibility may be gained by including some of the latest technology. Regardless of location, local codes and/or electric utility program requirements always supersede any recommendations in this manual.
Carrier Geothermal Heat Pump Systems Equipment Sizing Figure 19: Geo A Bin Report From GeoDesigner Software • Once the equipment is selected for sensible cooling and the proper size for heating has been determined, the latent cooling requirements should be considered. In the product catalog data, TC (Total Cooling capacity) and SC (Sensible Cooling capacity) are shown. Latent capacity equals TC minus SC.
Geothermal Applications Loop Sizing required in order to use the GeoDesigner software, since equipment and loop are determined based upon heat loss/heat gain. Carrier heat pumps are designed for EWTs of 20°F [-7°C] to 120°F [49°C]. However, economical minimum and maximum loop temperatures should not be outside the range of 25°F [-4°C] and 105°F [41°C]. A good starting point for minimum EWT is 30 to 40°F [17 to 22°C] above the winter outdoor design temperature.
Carrier Geothermal Heat Pump Systems Options - Whole House Dehumidification Options Carrier Geothermal residential geothermal heat pumps have a number of options to customize the installation to the customer’s individual needs. ECM Fan The ECM (Electrically-Commutated Motor) or variable speed fan motor is standard on GT-PX, GT-PB and GT-PC series units. For GT-PG Series water-to-air units, a PSC (Permanent Split Capacitor) fan motor is standard, and the ECM motor is available as an option.
Geothermal Applications Whole House Dehumidification Rarely does HGR provide 100% reheat, like the Whole House Dehumidification option. It is simple to troubleshoot the Whole House dehumidification circuit. No switching valves or hard to diagnose leaky check valves are utilized. No unusual refrigerant pressures occur during the reheat mode.
Carrier Geothermal Heat Pump Systems Whole House Dehumidification Figure 22: Example Size 030 Performance 3HUIRUPDQFH 'DWD 0RGHO /& 7& 6& 0%WXK %WXK OEV KU NJ KU &)0 1RPLQDO $LUIORZ 3HUIRUPDQFH FDSDFLWLHV VKRZQ LQ WKRXVDQGV RI %WXK
Geothermal Applications Whole House Dehumidification Table 6: Whole House Dehumidification Operating Modes Input Mode Output Backup Reheat Elec Heat O G Y1 Y23 W H O G Y1 Y23 No Demand ON/OFF5 OFF OFF OFF OFF OFF ON/OFF5 OFF OFF OFF OFF OFF Fan Only ON/OFF5 ON OFF OFF OFF OFF ON/OFF5 ON OFF OFF OFF OFF Cooling 1st Stage ON ON ON OFF OFF OFF ON ON ON OFF OFF OFF Cooling 2nd Stage ON ON ON ON OFF OFF ON ON ON ON OFF OFF Cooling & Dehumidistat1 O
Carrier Geothermal Heat Pump Systems Whole House Dehumidification Whole House Dehumidification Application Considerations The reheat coil adds a small amount of resistance to the air stream. Consult the correction tables in this manual for details. Unlike most hot gas reheat options, the Whole House Dehumidification option will operate over a wide range of EWTs. Special flow regulation (water regulating valve) is not required for low EWT conditions.
Geothermal Applications Whole House Dehumidification Figure 23: Whole House Dehumidification Schematic :DWHU 2XW 7R :DWHU /RRS 5HIULJHUDQW ,Q &RROLQJ :DWHU ,Q )URP :DWHU /RRS ,QWHUQDO 3XPS &2$; 'LYHUWLQJ 9DOYH 0RGXODWLQJ 5HIULJHUDQW 2XW &RROLQJ /HDYLQJ $LU (QWHULQJ $LU 1RWH $OO FRPSRQHQWV VKRZQ DUH LQWHUQDO WR WKH KHDW SXPS XQLW 5HKHDW &RLO (YDSRUDWRU &RLO Table 7: GT-PX Blower Performance Data Residential Units Only Airflow in CFM with wet coil and clean air filter Model 026 038 049 064
Carrier Geothermal Heat Pump Systems Whole House Dehumidification Table 8: GT-PG ECM Blower Performance Data Airflow in CFM with wet coil and clean air filter Residential Units Only Model 018 024 030 036 042 048 060 070 Max ESP (in. wg) 0.50 0.50 0.50 0.50 0.50 0.75 0.75 0.
Geothermal Applications Whole House Dehumidification Table 9: GT-PG (50YE) Series PSC Blower Performance Data (Without Whole House Dehumidification) Model Fan Speed Rated Airflow Min CFM HI 018 MED 600 450 LO HI 024 030 MED 950 655 0.20 0.30 0.40 0.50 0.60 0.70 711 693 690 675 640 598 515 602 599 581 585 573 547 492 531 527 517 506 495 462 1111 1105 1066 1006 934 854 765 662 890 879 854 818 770 708 686 623 0.
Carrier Geothermal Heat Pump Systems Whole House Dehumidification Table 10: Blower Performance Data - 50YE Units With Whole House Dehumidification (PSC Motor) Coil Face Velocity FPM 50YEH/V/D with Reheat ESP Loss 50YEH/V/D 018 In. of Water 50YEH/V/D 024, 030 In. of Water 50YEH/V/D 036 In. of Water 50YEH/V/D 042, 048 In. of Water 50YEH/V/D 060, 070 In. of Water 200 0.037 0.033 0.031 0.028 0.026 250 0.052 0.046 0.042 0.038 0.034 300 0.077 0.066 0.059 0.051 0.044 350 0.113 0.096 0.
Geothermal Applications Section Revision Log 50 Date Page # Description 8 April, 14 48 Table Updated for Rev. C Units 27 Aug., 13 All Added GT-PCS Split Unit Information and Removed GT-PX/GT-PE Split Unit Information 1 Feb. 13 All Added 50YG/50YF info.
