Flow Center and Loop Application/Installation Guide

Transcription

1 2506 South Elm Street Greenville, IL Flow Center and Loop Application/Installation Guide Rev.: P/N: Table of Contents: Section 1: Model Nomenclature Nomenclature description... 2 Section 2: Installation - Pressurized Flow Centers General Installation... 2 Optional Adapter Sets... 3 Mounting Flow Center... 3 Interior Piping... 4 Electrical Requirements... 4 Multiple Units... 5 Section 3: Flushing & Charging Overview... 5 Flush Cart Design... 6 Step by Step Flushing & Charging Section 4: Installation - Non-Pressurized Flow Centers General Installation... 9 Interior Piping/Flushing Section 5: Closed Loop Design Basics Parallel vs. Series Header Design Closed Loop Heat Exchanger Design Rules Soil Moisture Properties Section 6: Antifreeze Selection Overview Antifreeze Charging Section 7: HDPE Pipe Pipe Specifications Fusion Methods Section 8: Flow Center Selection Pressure Drop Calculations Pump Curves Pressure Drop Tables Guide Revision Table: 06 Jan 2014 GT All Formatting and updated flushiong process 02 Jun, 2010 AV All Formatting updates, Addition of Loop design rules, Soil moisture properties 23 Mar, 2010 AV 2 3 Adjusted Nomenclature Revised Pressurized Flow Center Installation Revised Table 1 24 July, 2009 DS All Minor formatting updates 26 Aug, 2008 JH 9 Updated pg 9 illustration 20 Aug, 2008 JH Aug, 2008 JH 4 16 Updated ProCool in table 3 Updated ProCool in table 5 Updated ProCool in table 9 Updated pipe insulation wall thickness Added single UP to pump curve 30 July, 2008 JH All First published

2 Section 1: Model Nomenclature MODEL NUMBER NOMENCLATURE: Model Number Digit: Model Number: A G FC 1 A Part Type A = Unit Accessory Operation G = Pressurized B = Non-Pressurized Accessory Type FC = Flow Center FM = Flow Module Number of Pumps Flow Center Type Pressurized Flow Centers: A = Composite/Brass valve, double O-Ring fittings, UP Pumps D = Composite/Brass valve, double O-Ring fittings, UP26-99 Pumps B = Brass valve, 1 FPT, UP26-99 Pumps C = Brass valve, 1 FPT, UP Pumps E = Brass valve, 1 FPT, UP26-99 Pumps F = Double O-ring XL fittings, UPS Pumps Non-Pressurized Flow Centers: A = UP26-99 Pumps, 1 FPT swivel B = UP Pumps, 1 FPT swivel [Consult the price book for more detailed Nomenclature Flow Center Hose Kit Adapter combinations.] Section 2: Flow Center Installation -Pressurized Safety Considerations WARNING: Before performing service or maintenance operations on the flow center pumps, turn off all power sources. Electrical shock could cause personal injury or death. Before applying power, make sure that all covers and screws are in place. Failure to do so could cause risk of electrical shock. Flow Center Initial Inspection Please read the complete instructions before starting installation. Carefully follow instructions to ensure optimum and safe operation. Leave the instructions with the owner after installation. The flow center and Grundfos UP series circulating pumps should be installed according to all applicable codes. Unpack the flow center and any other component kits required and inspect them for shipping damage before installation. Shipping damage claims must be filed promptly by the purchaser with the freight company. Note: The flow centers are injected with foam for condensation prevention during low temperature operation and for noise attenuation. Pump heads can be field replaced. Typical Pressurized Flow Center Installation The flow centers are insulated and contain all flushing and circulation connections for residential and light commercial earth loops that require a flow rate of no more than 20 gpm. 1-1/4 fusion x 1 double o-ring fittings (AGA6PES) are furnished with the double o-ring flow centers for HDPE loop constructions. Various fittings are available for the double o-ring flow centers for different connections. See table 1 for connection options. A typical installation will require the use of a hose kit. Matching hose kits come with double o-ring adapters to transition to 1 hose connection. Note: Threaded flow centers all have 1 FPT connections. Matching hose kits come with the AGBA55 adapter needed to transition from 1 FPT to 1 hose. 2

3 Section 2: Flow Center Installation -Pressurized Figure 1: Typical Flow Center Installation Figure 2a: Pump Mounting Access Ports GSHP Flow Center Figure 2b: Control box location Source Water IN Source Water OUT Hose Kit P/T Ports To/From Loop Field Flow Center Mounting The flow center must be located between the heat pump and the earth loop and should be located as close to the unit as possible to limit the length of rubber hose and associated pressure drop (hose kits come with 10 of rubber hose - limit one unit per hose kit connection). Other factors for flow center location is the ease of future service. The flow center must be mounted with the pump shaft(s) in the horizontal position. The only adjustment is that the circulator pump electrical boxes be on the horizontal side of the power head in the mounted position to help prevent moisture from being held inside the junction box (See figures 2a and 2b). Table 1: Adapter Sets The flow center can be mounted to the wall or the side of the unit opposite the air coil. If you are mounting the flow center to the stud wall make sure you have isolated the flow center from the studs and/or lag bolts to prevent noise and/or vibration. If you are mounting the flow center to the side of the heat pump, be careful not to puncture any internal parts of the unit when inserting the screws into the cabinet. Keep in mind that heat pump access will be limited in this mounting position. Be sure when mounting the flow center that there is adequate access to both the flush ports and 3-way valves for any service required. Part No. Description Connection Use FC Type AGA5INS Double O-ring x 1 Brass Barb (Pair) Unit Side O-Ring AGA6INS Double O-ring x 1.25 Brass Barb (Pair) Loop or Unit Side O-Ring AGA5MPT Double O-ring x 1 Brass MPT (Pair) Loop or Unit Side O-Ring AGA6PES Double O-ring x 1.25 PE Socket (Pair) Loop or Unit Side O-Ring AGAFP Double O-ring x Cam Lever elbow (male)(pair) Flush Port O-Ring AGBA55 1 Brass MPT x 1 Brass Barb (ea) Unit Side FPT AGBA56 1 Brass MPT x 1.25 Brass Barb (ea) Loop or Unit Side FPT GFMA65 1 Brass MPT x 1.25 PE Socket (ea) Loop or Unit Side FPT AGA5FPT Double O-ring x 1 Brass FPT (pair) Loop or Unit Side O-Ring AGS5INS Double O-ring x 1 Brass Barb w/pt tap (pair) Unit Side O-Ring AGS5MPT Double O-ring x 1 Brass MPT w/pt tap (pair) Units Side O-Ring Note: Hose clamps included with hose kits. 3

4 Section 2: Flow Center Installation -Pressurized Interior Piping All interior piping must be sized for proper flow rates and pressure loss. Insulation should be used on all inside piping when minimum loop temperatures are expected to be less than 50 F. Use the table below for insulation sizes with different pipe sizes. All pipe insulation should be a closed cell and have a minimum wall thickness of 3/8. All piping insulation should be glued and sealed to prevent condensation and dripping. Interior piping may consist of the following materials: HDPE, copper, brass, or rubber hose (hose kit only). PVC is not allowed on pressurized systems. Figure 3: External Pump Wiring T-Stat Connections C, R, Y1, Y2, O, G, W, L Accessory Connections ODD, HW, A, YT,YU, HUM, R Pump Circuit Breaker (added late 2008) ECM Board (Optional -- ECM only) Blower Relay (Optional -- PSC only) NO NC COM NO NC COM Lockout Board (all units) Hot Water Pump Relay (Optional -- Combo only) or Fan Interlock (Optional -- PSC only) Combo Board (Optional -- Combo units only) Table 2: Pipe Insulation Piping Material Insul Description 1" IPS Hose 1-3/8" ID - 3/8" Wall 1" IPS PE 1-1/4" ID - 3/8" Wall 1-1/4" IPS PE 1-5/8" ID - 3/8" Wall 2" IPS PD 2-1/8" ID - 3/8" Wall Electric Heater Connections C, W1, W2, W3 Contactor Pump Connection Wire external loop pump(s) to the pump terminal block in the control box. Transformer Flow Center Electrical Wiring Grounding block Power wiring to the flow center must conform to all applicable codes. Figure 3 illustrates the wiring required at the unit control box. Flow centers are only available in 230V single phase voltage. Pumps are fused through a pair of circuit breakers in the unit control box. Figure 4: Pump Sharing Module 240VAC Power Source 240V IN 240V OUT 240VAC to Pump(s) Multiple Units on One Flow Center When two units are connected to one loop pumping system, pump control is achieved by using APSMA loop pump sharing module. Using this module allows either unit to energize the flow center. Connect the units and flow center as shown in Figures 4 and 5. The APSMA module must be located in a NEMA enclosure or inside the unit control box. Figure 6 shows unit connections to a common loop with one flow center per unit. 24VAC connection to unit #1 (Y1 & C From Thermostat) Relay 24VAC 24VAC Relay 24VAC connection to unit #2 (Y1 & C From Thermostat) 4

5 Section 2: Flow Center Installation -Pressurized Figure 5: Two Units Connected to One Flow Center To Ground Loop Heat Pump Heat Pump Heat Pump Flow Center Controller Flow Heat Pump Field-supplied full-port ball valve for balancing EWT EWT LWT LWT EWT EWT LWT LWT Each heat pump must include P/T ports to verify flow rates Figure 6: Common Loop with One Flow Center per Unit To Ground Loop Flow Center Heat Pump Flow Center Heat Pump Flow Center Heat Pump EWT LWT EWT EWT LWT EWT LWT LWT Each heat pump must include P/T ports to verify flow rates Field-supplied check valve to prevent short-cycling Field-supplied full-port ball valve for balancing Section 3: Flushing & Charging Overview Once piping is completed between the unit, flow center, and the earth loop, final purging and charging of the system is needed. A flush cart (at least a minimum of 1.5 hp pump motor or larger) is needed to achieve adequate flow velocity (2 fps in all piping) in the loop to purge air and debris from the loop piping (unless the header manifold is located inside and has isolation valves). All air and debris must be removed from the system before operation or pump failure could result. The flush ports located on the flow center are access to the piping system for the flush cart. See figure 7 for connection details. The 3-way valves on the flow center include direction indicators on the valves which determine the flow path (see figure 8). A 3/8 socket drive is required to operate the 3-way valves. The valves will turn in either direction, 360 degrees. Make sure during this process that the valves are in the same position so that air does not become trapped in the system. 5

6 Section 3: Flushing & Charging Figure 7: Flush Cart Connections Figure 8: Flow Center 3-Way Valves Loop Loop Flush Port Flush Port Flush Port Flush Port Unit Loop Unit Loop Unit Unit Flush Cart Design The Enertech Global, LLC flush cart has been designed to effectively and efficiently flush the earth loop and to facilitate injecting and mixing of the antifreeze. The single most important element in flow center reliability is the ability to remove all the air and debris from the loop and to provide the proper working pressure. Features of the flush cart: Cylinder: HDPE, SDR15.5, 10 dia. (10 Gallons) Pump: Myers High Head QP15, 1.5hp, 115V Hose connections: Cam Lock quick connects - 1-1/2 hoses Hand Truck: 600lb rating with pneumatic tires Wiring: Liquid Tight metal on/off switch Tubing: SDR11 HDPE Connections: 2-3/4 connections for antifreeze and discharge Drain: one on the pump and the tank Figure 10: Flush Cart Pump Curve Total Head in Feet Meyers QP /2 HP Self-Priming Centrifugal Pump SUCTION LIFT CAPACITY - U.S. GPM 6

7 Section 3: Flushing & Charging Removing Debris During Flushing Most flow center or pump failures are a result of poor water quality or debris. Debris entering the loop during fusion and installation can cause noise and premature pump failure. Enertech recommends a double flush filtering method during purging. When purging, use a 100 micron bag filter until air bubbles are removed. Remove the 100 micron bag, replace it with a 1 micron bag and restart the flushing. provide a surge in pressure to the system piping, helping to get the air bubbles moving. Do not reverse flow during flushing. Water Quality: Even on a closed loop system water quality is an issue. The system needs to be filled with clean water. If the water on site has high iron content, high hardness, or the PH is out of balance, premature pump failure may result. Depending upon water quality, it may need to be brought in from off site. Step 1: Flushing the Earth Loop 1. Connect flush cart hoses to flow center flush ports using proper adapters #AGAFP. 2. Connect water supply to hose connection on return line of flush cart. 3. Turn both 3-way valves on flow center to flush ports and loop position. 4. Turn on water supply (make sure water is of proper quality). 5. As the reservoir fills up, turn the pump on and off, sucking the water level down. Do not allow the water level to drop below intake fitting to the pump. 6. Once the water level remains above the water outlet in the reservoir leave the pump running continuously. 7. Once the water level stays above the T in the reservoir, turn off the water supply (this also allows observation of air bubbles). 8. Run the pump for a minimum of 2 hours for proper flushing and purging (depending on system size it may take longer). 9. Dead head the pump every so often and watch the water level in the reservoir. Once all the air is removed there should not be more than a 1 to 2 drop in water level in the reservoir. If there is more than a 2 drop, air is still trapped in the system. This is the only way to tell if air is still trapped in the system. 10. To dead head the pump, shut off the return side ball valve on the flush cart. This will 7 Step 2: Flushing the Unit 1. Turn off the pump on the flush cart. 2. Turn both 3-way valves to the unit and flush port position. 3. Turn the pump back on. It may be necessary to turn the water supply back on to keep the water level in the reservoir above the return tee. 4. This should only take 5 to 10 minutes to purge the unit. 5. Once this is done, the entire system is now full of water, and the flush cart pump may be turned off. Step 3: Adding Antifreeze by Displacement 1. If the antifreeze was not added when the loop was being filled, it will be necessary to follow the next few steps. 2. Turn both 3-way Ts back to the original position for flushing the loop only. 3. Close the return side ball valve on the flush cart. 4. Connect hose to the return side discharge line and run it to a drain. Open the ball valve on discharge line on flush cart. 5. Turn pump on until water level is sucked down just above the water outlet in the reservoir, and turn pump off. Be sure not to suck air back into the system. 6. Fill the reservoir back up with

8 Section 3: Flushing & Charging the antifreeze. 7. Repeat steps 5 and 6 until all the antifreeze is in the system and reservoir. 8. Turn the discharge line ball valve off at the flush cart. Turn the return line ball valve back to the on position. 9. It may be necessary to add some water into the reservoir to keep the water level above the return tee so that the solution does not foam. 10. The system must be run for 3 to 4 hours to mix the antifreeze and water in the reservoir. The fluid will not mix inside the loop. 11. Check the antifreeze level every so often to insure that the proper amount was added to the system (see antifreeze charging section). Step 4: Final Pressurization of System 1. Once all of the air and debris has been removed, and the antifreeze has been added and mixed, the system is ready for final pressurization. 2. Turn one of the 3-way valves so that it is open to all 3 ports, the unit, loop, and flush port. Turn the other valve so it is only open to the loop and flush port (pressure is also applied to the hose kit in this arrangement). 3. Turn the flush cart pump on and allow the system to start circulating. 4. With the pump running, turn the return line ball valve to the off position on the flush cart, dead heading the pump. 5. There should be a maximum of 1 to 2 inches of drop in the water level in the reservoir. This only takes about 3-5 seconds. 6. Next, turn the supply line ball valve to the off position on the flush cart (isolates the flow center from the flush cart). 7. Now that the system is isolated from the reservoir the pump can be turned off. Do not open the main flush cart ball valves yet. 8. Connect the water supply back to the discharge line hose connection, and open the ball valve. Turn on the water supply and leave it on for 20 to 30 minutes. This will stretch the pipe properly to insure that the system will not have a flat loop during cooling operation. 9. Once the loop is pressured (recommended pressure on initial start up is 50 to 70 psi), turn the water supply off. Turn off the discharge line ball valve, and disconnect the water supply. Maximum pressure should never exceed 100 psi under any circumstance! 10. Turn the 3-way valves on the flow center back to the normal operation mode, which closes the flush port connections. 11. Open the ball valves on the flush cart to relieve pressure on the hoses. Disconnect the hoses from the flow center. Note: Pressurized flow centers and Grundfos UP series pumps need a minimum of 3psi on the suction side of the pump to operate. Maximum operating pressure is 100 psi. Loop static pressure will fluctuate with the seasons. Pressures will be higher in the winter months than during the summer months. In the cooling mode the heat pump is rejecting heat, which relaxes the pipe. This fluctuation is normal and needs to be considered when charging and pressuring the system initially. Typical operating pressures of an earth loop are 15 to 50 psi. Note - Burping pump(s): On flow center initial start up, the pumps must be bled of air. Start the system and remove the bleed screw from the back side of the pump(s). This allows any trapped air to bleed out. It also floods the pump shaft, and keeps the pump(s) cool. Failure to do this could result in premature pump failure. 8

9 Section 4: Flow Center Installation - Non-Pressurized General installation guidelines Standing column flow centers are designed to operate with no static pressure on the earth loop. The design is such that the column of water in the flow center is enough pressure to prime the pumps for proper system operation and pump reliability. The flow center does have a cap/seal, so it is still a closed system, where the fluid will not evaporate. If the earth loop header is external, the loop system will still need to be flushed with a purge cart as described above (Step 1 and 3). The nonpressurized flow center needs to be isolated from the flush cart during flushing because the flow center is not designed to handle pressure. Since this is a non-pressurized system, the interior piping can incorporate all the above-mentioned pipe material options (see interior piping), including PVC. The flow center can be mounted to the wall with the included bracket or mounted on the floor as long as it is properly supported. Flushing the Interior Piping (Non-Pressurized) Do not use the flush cart to purge the interior piping and flow center in a nonpressurized system. Once the loop has been flushed the ball valves may be opened above the flush ports. Take a garden hose from the flush port connected to the water out to the loop pipe, and run the other end of the hose into the top of the canister (see figure 12). Fill the canister with water and turn the pumps on. Continue to fill the canister until the water level stays above the dip tube. Once filling is complete, remove the hose and close the flush port. Turn the system on. Any air that may still be in the system will burp itself out of the top of the canister. Leave the top open for the first 1/2 hour of run time to ensure that all of the air is bled out. Tighten the cap on the flow center to complete the flushing and filling procedure (hand tighten only -- do not use a wrench). See figures 12 and 13 for interior and exterior flushing. 9

10 Section 4: Flow Center Installation - Non-Pressurized Figure 11: Typical Non-Pressurized Installation Figure 13: Flushing Outside Piping Figure 12: Flushing Inside Piping Connect to Heat Pump Connect to Heat Pump To/From Loop Field To/From Loop Field Flush Cart and Pump 10

11 Section 5: Geothermal Closed Loop Design Closed Loop Basics Closed loop earth coupled systems are commonly installed in one of three different configurations: horizontal, vertical, and pond/lake loop. Each configuration provides the benefit of using the earth s moderate temperatures as a heat source/ sink. All closed loop systems must be designed to maintain entering water temperatures above 25 F in heating, and below 110 F in cooling. Temperatures outside this range will cause the heat pump to function improperly and lockout. Select the installation configuration which provides the most cost effective method of installation after considering all application constraints. Determining the style of loop primarily depends on lot size and soil conditions. Loop design takes into account two basic factors. The first is accurately engineering a system to function properly with low pumping requirements and adequate heat transfer to handle the load of the structure/system. The second is to design a loop with the lowest installed cost while still maintaining a high level of quality. In the end, the consumer will have paid approximately the same amount of money for heating, cooling, and hot water no matter which loop configuration was installed. This leaves the installed cost of the loop as the main factor for determining the system payback. Therefore, proper design includes the most economical system possible given the installation requirements. Parallel vs. Series Configurations Initially, loops were designed using series style flow paths due to the lack of fusion fittings and procedures to insure there there were no leaks. This resulted in large pipe diameters being used (1-1/4 to 2 ) to reduce pumping requirements due to the increase of pressure drop because of the pipe lengths. Since the fusion process has become available, parallel flow using smaller pipe diameters for loops 2 tons and larger have become standard for a number of reasons: Cost of the pipe: The larger diameter the pipe, the higher the cost. The benefit of larger pipe only increases performance by 10-20%. Pumping power: Parallel systems generally have much lower pressure drop, which results in smaller pumping stations for reduced pump energy. Installation ease: Larger diameter pipes are harder to work with, especially during cold weather conditions. Antifreeze: Because parallel systems utilize smaller size pipe, the volume of the systems are smaller, requiring less antifreeze Unlimited capacity: Series systems are limited due to pressure drop reasons, whereas parallel systems are unlimited in capacity. Parallel System Requirements Design: Special care in the design is required to ensure that all of the air and debris can be removed from the system. Reducing reverse-return header: Required for all parallel systems. Pressure drop: Loop lengths must remain within +/- 5% of one another for equal pressure drop and balanced flow. Fusion: Special training and equipment is required to provide fusion fittings. Purging: Large pump flush cart is needed to get all of the air and debris out of the system. 11

12 Section 5: Geothermal Closed Loop Design Loop Circuiting Loops should be designed with a compromise between pressure drop and good turbulence in the heat exchange pipe for heat transfer. Therefore the following rules should be observed when designing a loop: 1. Use 3 gpm per 3/4 loop flow rate to reach turbulent flow. 2. Use 3 gpm per ton of nominal equipment installed. 3. Maintain one loop/circuit per ton of nominal capacity with 3/4 pipe and onehalf loop/circuit per ton with 1-1/4 pipe. This rule can be deviated by one circuit or so for different loop configurations. 4. Maximum loop length for 3/4 PE is 800 ft. due to pressure drop. Header Design Headers for parallel loops should be designed with two factors in mind. The first is pressure drop, and the second is the ability to flush the loop. Figure 15 shows the typical layout for a close header (no more than 5 between tees) for up to 12 tons and 2 header main line. Notice the reduction in pipe size as circuits drop off. This design is used to keep the pressure drop down, yet maintain 2 fps for flushing. The other critical design in the header is the reverse return connections. This ensures that there is equal pressure drop through each 3/4 circuit, which eliminates the need for balancing valves. This system will be autobalancing (if all circuits are within +/- 5% in length from one another). Figure 16 shows the reverse return layout of the supply/ return header manifold. Figure 15: Typical Reducing Header up to 12 Tons 2 x 2 x 3/4 T 2 x 1-1/4 x 3/4 T 1-1/4 x 3/4 x 3/4 T 3/4 x 3/4 x 3/4 T 3/4 x 3/4 x 3/4 T Circuit 1 Circuits 9-12 Circuit 8 Circuit 4 Circuit 3 Circuit 2 Return Line Circuits 5-7 (1-1/4 x 1-1/4 x 3/4 T s) Figure 16: Reverse-Return Header Supply Line 2 foot wide trench 1-1/4 x 3/4 x 3/4 T 3/4 x 3/4 x 3/4 T 3/4 elbow 3/4 elbow 3/4 x 3/4 x 3/4 T 1-1/4 x 3/4 x 3/4 T 1-1/4 elbow 1-1/4 elbow Circuit 3 Circuit 2 Circuit 1 Circuit 3 Circuit 2 Circuit 1 12

13 Section 5: Geothermal Closed Loop Design Closed Loop Heat Exchanger Design Rules Loop design is based upon various conditions specific to each job site. Design software based on IGSHPA standards such as GeoAnalyst is the best way to size loops. Factors include building load heat gain/loss calculations, equipment capacity, equipment efficiency, soil conditions, required loop temperature operating design, pipe size, antifreeze selection, weather conditions and lifestyle. Know your soil type. Check the site before you decide. Many sources can be found locally for information regarding the site location conditions. Example: builders, water well drillers, soil conservation district offices, geological maps on the internet. One flow path (circuit) per ton (12,000 BTU S) of equipment (round up or down 1 circuit for ½ ton sized units e.g. 3.5 ton unit uses either 3 or 4 circuits). GPM flow rates should be 2.25 GPM minimum to 3 GPM per circuit for good turbulence and heat exchange to the earth. Parallel vs. series configurations? Jobs 2 ton or larger should use parallel water flow circuits to keep GPM flow rates high and pumping HP requirements low. Series loops are limited to small tonnage unit sizes (2 total tons or less). Divide total trench or bore length as shown in GeoAnalyst software by total tons of equipment being applied to the loop. Example: 4 ton packaged unit trench length = 616 feet or 4 trenches, 154 feet long each. Trench/bore hole area should be located 15 feet minimum from the building. If the trench is longer than 300 feet, be sure to calculate the total piping pressure drop for proper pump/ pipe sizing. Trench/bore spacing should be kept to a 10 foot minimum distance between each trench/bore hole area. Horizontal trenches need not be deeper than 4-5 feet for most locations, but should be approximately 1-2 feet deeper than the lowest expected frost line conditions. This will place the pipe in a stable temperature zone. Horizontal loop circuits installed in trenches should have enough space at the end of the trench to safely turn around and return towards the beginning of the trench without kinks in the tubing or using elbows to reduce the number of fusion joints in the circuit. Good designers try to purchase coil pipe that can go down and back without the use of fittings in the trench, except for the final connections to the manifold header. Horizontal trenches/vertical bore holes should be tapered together at one end of loop field or the center of a bore field to utilize a small header pit for parallel circuits. Supply/return manifolds should utilize reverse return design for equal water flow rates on each flow path or circuit. Try to achieve 10 foot trench spacing as soon as practical as you leave the header pit area and begin the circuit trenches or bore holes. Good manifold header design should keep header tee spacing close together, less than 2 feet between each tee outlet, for easy air removal from piping system. Typical header pit excavated area is approximately 4.5 feet long x 4 feet wide x feet deep. 13

14 Section 5: Geothermal Closed Loop Design Never place supply and return piping next to the building foundation; always maintain 15 feet minimum spacing away from any foundation to prevent frost damage to the building. Supply/return line trenching from header pit to building should taper uphill toward building, but maintain approximately 4 feet below finish grade at wall penetration. Typical trench width is wide. Lay supply and return piping in each corner at bottom of trench. This will reduce the chance of ground water following piping into the building. All piping should be fluid pressure tested hydrostatically with approximately 100 psi for 10 minutes to assure leak free fusion joints and connections before back-filling the trench. All vertical bore holes should be pressure grouted with an approved bentonite grout material utilizing 20% solids minimum for proper sealing and heat transfer. This must be done from the bottom up, not just a cap at the top. Do not use sand or gravel to backfill loop pipe trenches/bores, as it will dry out and impede good heat transfer between the fluid in the pipe and the earth. Normally the same soil should be placed back into the trench. Common sense should be used regarding large rocks or sharp stones that could crush or cut the piping. Do not place rocks near the piping. Cover the loop piping with 2-3 feet of good soil first. It s a good idea to include a foil tracer tape or copper wire in supply/return trenching, placing tracer approximately 2 feet above piping between header pit and building wall penetration area for easy locating of the supply/return and manifold area. Supply/return piping will typically be 1.25 diameter PE from the header manifold (outdoors) to the flow center (loop pump) located in the building near the unit. All piping penetrating the building foundation should be protected in conduit. All piping inside the building should be properly insulated with pipe insulation to prevent condensation damage to the building. Loop fluid should be antifreeze protected to 15 F with an approved fluid type, typically Methanol, Ethanol or Propylene Glycol. Test with the proper hydrometer. All piping and connections should be composed of an approved geothermal polyethylene PE3408 type pipe, utilizing socket fusion or butt fusion and installed by a qualified fusion technician. Notes: Safety First! We strongly suggest that contractors attend either a factory training school or IGSHPA training school for Loop Design and Installation before attempting loop design and installations. Always check BEFORE YOU DIG! Contact your local underground utility locator service and verify any utility that might be located nearby. Stay away from electrical power, septic systems and well water lines. Check with your local building/health department regarding permits, codes and laws that may apply to your location or state/province regarding geothermal loop systems. 14

15 Section 5: Geothermal Closed Loop Design Contact your distributor for additional information on training locations and dates. Good loop design and proper installation are necessary for any system to operate properly. We offer and support several design schools and tools to take the guesswork out of residential loop system design. Ask your local distributor about our GeoAnalyst software tool that will provide you with the science behind the design and the confidence you need to actively design, install and service geothermal equipment and loop systems. Like anything else It s not that hard when you have the proper training and the tools. Soil Moisture Properties An important factor affecting heat transfer between the earth and the loop is moisture migration. When heat is extracted from the earth, soil moisture migrates toward the earth loop, improving heat transfer between the loop and the surrounding soil. In the cooling mode, heat rejection to the soil can drive away moisture, degrading heat transfer. In heating dominated climates, this later negative effect has not been observed in practice. However, in cooling dominated climates, this special condition must be considered in regard to loop lengths due to longer run times in the cooling mode. Another important factor affecting heat transfer between the earth and the loop is soil moisture freezing. Freezing allows the extraction of energy from the soil without the normal drop in soil temperature in the vicinity of the pipe. The net effect is that 15

16 Section 5: Geothermal Closed Loop Design the antifreeze solution returning to the heat pump from the earth loop returns at a higher temperature than if freezing had not occurred. CLAY Cross View (DRY) Microscopic View Earth loops are sized after the house design heating and cooling loads have been calculated, and the heat pump size has been selected. All heat pumps are designed with high and low limits on the energy source liquid which are acceptable. Cross View (WET) H 2 O H 2 O H 2 O H 2 O H 2 O Consistency: Hershey Bar SAND Visible to Eye Microscopic View SILT Microscopic View Moisture Content for All Soils: DRY = No Water MOIST = Damp Feel WET = Visible Water Definition of Sizes: SAND = Visible to Eye - 1/4 GRAVEL = 1/4-3 COBBLE = 3-12 BOULDER = 12 and up 16

17 Section 6: Antifreeze Selection & Charging Antifreeze Overview In areas where minimum entering loop temperatures drop below 40 F, or where piping will be routed through areas subject to freezing, antifreeze is required. Alcohols and glycols are commonly used as antifreeze. However, local and state/ provincial codes supercede any instructions in this document. The system needs antifreeze to protect the coaxial heat exchanger from freezing and rupturing. Freeze protection should be maintained to 15 F below the lowest expected entering loop temperature. For example, if 30 F is the minimum expected entering loop temperature, the leaving loop temperature could be 22 to 25 F. Freeze protection should be set at 15 F (30-15 = 15 F). To determine antifreeze requirements, calculate how much volume the system holds. Then, calculate how much antifreeze will be needed by determining the percentage of antifreeze required for proper freeze protection. See tables 3 and 4 for volumes and percentages. The freeze protection should be checked during installation using the proper hydrometer to measure the specific gravity and freeze protection level of the solution. Antifreeze Characteristics Selection of the antifreeze solution for closed loop systems require the consideration of many important factors, which have long-term implications on the performance and life of the equipment. Each area of concern leads to a different best choice of antifreeze. There is no perfect antifreeze. Some of the factors to consider are as follows (Brine = antifreeze solution including water): Safety: The toxicity and flammability of the brine (especially in a pure form). Cost: Prices vary widely. Thermal Performance: The heat transfer and viscosity effect of the brine. Corrosiveness: The brine must be compatible with the system materials. Stability: Will the brine require periodic change out or maintenance? Convenience: Is the antifreeze available and easy to transport and install? Codes: Will the brine meet local and state/ provincial codes? The following are some general observations about the types of brines presently being used: Methanol: Wood grain alcohol that is considered toxic in pure form. It has good heat transfer, low viscosity, is non-corrosive, and is mid to low price. The biggest down side is that it is flammable in concentrations greater than 25%. Ethanol: Grain alcohol, which by the ATF (Alcohol, Tobaco, Firearms) department of the U.S. government, is required to be denatured and rendered unfit to drink. It has good heat transfer, mid to high price, is non-corrosive, non-toxic even in its pure form, and has medium viscosity. It also is flammable with concentrations greater than 25%. Note that the brand of ethanol is very important. Make sure it has been formulated for the geothermal industry. Some of the denaturants are not compatible with HDPE pipe (for example, solutions denatured with gasoline). Propylene Glycol: Non-toxic, non-corrosive, mid to high price, poor heat transfer, high viscosity when cold, and can introduce micro air bubbles when adding to the system. It has also been known to form a slime-type coating inside the pipe. Food grade glycol is recommended because some of the other types have certain inhibitors that react poorly with geothermal 17

18 Section 6: Antifreeze Selection & Charging systems. A 25% brine solution is a minimum required by glycol manufacturers, so that bacteria does not start to form. Ethylene Glycol: Considered toxic and is not recommended for use in earth loop applications. GS4 (Potassium acetate): Considered highly corrosive (especially if air is present in the system) and has a very low surface tension, which causes leaks through most mechanical fittings. This brine is not recommended for use in earth loop applications. Notes: 1. Consult with your representative or distributor if you have any questions regarding antifreeze selection or use. 2. All antifreeze suppliers and manufacturers recommend the use of either de-ionized or distilled water with their products. Caution: Use extreme care when opening, pouring, and mixing flammable antifreeze solutions. Remote flames or electrical sparks can ignite undiluted antifreezes and vapors. Use only in a well ventilated area. Do not smoke when handling flammable solutions. Failure to observe safety precautions may result in fire, injury, or death. Never work with 100% alcohol solutions. Antifreeze Charging Calculate the total amount of pipe in the system and use table 3 to calculate the amount of volume for each specific section of the system. Add the entire volume together, and multiply that volume by the proper antifreeze percentage needed (table 4) for the freeze protection required in your area. Then, double check calculations during installation with the proper hydrometer and specific gravity chart (figure 14) to determine if the correct amount of antifreeze was added. Table 3: Antifreeze Percentages by Volume Minimum Temperature for Freeze Protection Type of Antifreeze 10F (-12.2C) 15F (-9.4C) 20F (-6.7C) 25F (-3.9C) Procool (Ethanol) 25% 22% 17% 12% Methanol 25% 21% 16% 10% Propylene Glycol 38% 30% 22% 15% All antifreeze solutions are shown in pure form not premixed. 18

19 Section 6: Antifreeze Selection & Charging Table 4: Pipe Fluid Volume Type Size Volume/100 ft. U.S. Gal. Copper 1" CTS 4.1 Copper 1.25" CTS 6.4 Copper 1.5" CTS 9.2 HDPE.75 SDR HDPE 1" SDR HDPE 1.25" SDR HDPE 1.5" SDR HDPE 2" SDR Additional component volumes: Unit coaxial heat exchanger = 1 Gallon Flush Cart = 8-10 Gallons 10 of 1 Rubber Hose = 0.4 Gallons NOTE: Most manufacturers of antifreeze solutions recommend the use of de-ionized water. Tap water may include chemicals that could react with the antifreeze solution. Figure 14: Antifreeze Specific Gravity Specific Gravity Freeze Protection (deg F) Procool Methanol Propylene Glycol 19

20 Section 7: HDPE Pipe High Density Polyethylene Pipe (HDPE) All earth loop piping materials should be limited to only polyethylene pipe underground. Copper, brass, galvanized, or steel pipe or fittings should not be used. For fusion applications, the HDPE pipe must meet IGSHPA (International Ground Source Heat Pump Association) cell classification requirements (see below). The water well industry uses similar black HDPE 160 psi rated pipe. However, this pipe does not allow for fusion joints. Below are the specifications for the proper geothermal HDPE pipe: 1. All pipe and heat fused materials shall be made from high density, extra-high molecular weight PE 3408 resin. 2. The cell classification shall be C as specified in ASTM D Extruded pipe shall conform to the requirements of ASTM D Socket fittings shall conform to the requirements of ASTM D-2683 and rated for pressure equivalent to SDR-11 pipe. 5. Wall thickness of pipe shall be in tolerance of the specifications of 160 psi and SDR-11 for heat fused pipe & fittings. A hundredth of an inch accuracy while fusing in a difficult position can be almost impossible to attain in the field. 2. The socket fusion joint is 3 to 4 times the cross sectional area of a butt fusion joint in sizes under 2, and therefore tends to be more forgiving of operator skill level. 3. Joints are frequently required in difficult trench conditions. The smaller the socket fusion iron is, the more mobile the operator will be, which will provide less incentive to cut corners during the fusion procedure. Once the pipe diameter gets over 2, socket fusion loses its advantages, and butt fusion is typically the method of choice. Butt fusion requires a different fusion machine, which is larger and less maneuverable. All technicians doing fusion joints should be certified by the pipe manufacturer as well as IGSHPA. Please see the pipe manufacturers and IGSHPA tables and specifications for all fusion procedures. Note: Earth loop systems require a hydrostatic test of psi before backfilling to test for leaks. Do not use an air test for leaks on an earth loop system. Pressure drop calculations Pipe Fusion Methods The three basic types of pipe joining methods that are used for earth coupled applications are socket, butt, and side saddle fusion. In all processes the pipe is melted together with the fitting to form a joint that is even stronger than the original pipe. Although when any of the procedures are performed properly the joint is stronger than the pipe wall, the preferred method for 2 and smaller diameter pipe is socket fusion because of the following: 1. Allowable tolerance of mating the pipe is much greater. According to general fusion guidelines, a 3/4 SDR11 butt fusion joint alignment can be off by no more than 10% of the wall thickness (0.01 in.). 20 When designing the earth loop and selecting the proper flow center, a pressure drop calculation must be done to calculate how much pumping power is needed for proper flow through the heat pump and loops. In general, if basic loop design rules are followed, systems of 3 tons or less would require a one pump flow center, and system from 3.5 to 6 tons would require a two pump flow center. As a precautionary measure a loop pressure drop calculation should be performed for accurate flow estimation. The pressure drop must include the following components: 1. Heat pump at design flow rate 2. Hose kit (maximum 10 ) 3. Supply and Return header piping

21 Section 8: Flow Center Selection 4. Circuit piping (only one if piped in parallel) 5. Antifreeze Once the pressure drop of the system has been calculated at design flow rate, review the flow center pump curve to select a flow center that matches design criteria. There are many options with flow centers from one pump, two pump, three pump, four pump, and size pumps from UP26-99F to UP26-116F. The following pages include pressure drop tables for the pipe and the flow center pump curves. Note: Enertech Mfg has software available to assist in calculating the pressure drop of an earth coupled system along with flushing requirements. Figure 17: Grundfos Pump Curves Legend 3 - UP UP UP UP UP Ft. of Head Flow Rate (U.S. GPM) 21

22 Section 8: Flow Center Selection Table 5: Procool (Ethanol) Antifreeze (30 F EWT): 22% by Volume Solution of Procool - freeze protected to 15 F Flow Rate 3/4" SDR11 1" SDR11 1-1/4" SCH40 1-1/2" SCH40 2" SCH40 US GPM 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 Table 6: Methanol Antifreeze (30 F EWT): 21% by Volume Solution of Methanol - freeze protected to 15 F Flow Rate 3/4" SDR11 1" SDR11 1-1/4" SCH40 1-1/2" SCH40 2" SCH40 US GPM 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

23 Section 8: Flow Center Selection Table 7: Propylene Glycol Antifreeze (30 F EWT): 30% by Volume Solution of Propylene Glycol - freeze protected to 15 F Flow Rate 3/4" SDR11 1" SDR11 1-1/4" SCH40 1-1/2" SCH40 2" SCH40 US GPM 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 Table 8: Water Water -- No Antifreeze (50 F EWT) Flow Rate 3/4" SDR11 1" SDR11 1-1/4" SCH40 1-1/2" SCH40 2" SCH40 US GPM 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