The Pick Variable Flow Heater is an instantaneous steam injection heater designed for heating water and water-miscible products. It uses direct steam injection to heat liquids, offering efficient and precise temperature control.
Function Description:
The Pick heater operates by injecting steam directly into the liquid being heated. This process is instantaneous, meaning the liquid is heated as it flows through the unit. The system is designed to provide accurate temperature control over varying flow rates. A circulating pump creates a high rate of water flow through the heating chamber and over the temperature control sensor, allowing the temperature controller to track changing conditions and maintain accurate outlet temperature regardless of water flow. The heater is suitable for applications requiring the heating of water or water-miscible products, with installation, maintenance, and troubleshooting procedures largely unaffected by the nature of the liquid.
Important Technical Specifications:
- Heater Models: The manual references various models, including 6X7, 6X10, 6X25, 6X50, 6X75, 6X100, 6X150, 6X200, 6X350, and 6X500, indicating a range of capacities.
- Cleaning Solution Capacity: The manual provides approximate cleaning solution capacities for different heater models, ranging from 1 gallon for 6X7/6X10 to 55-97 gallons for 6X500, with larger heaters' capacities depending on associated piping size.
- Steam Valve Operation: The steam control valve should ideally be open at least 20% during operation to prevent vibration, bounce, flutter, or hammer. If operating below this minimum turndown, a dual steam valve assembly or a smaller steam valve may be required.
- Air Pressure: The filter regulator for the air supply should be set at 20 psi.
- Relief Valve Setting: The relief valve must be set to relieve at a pressure between the water and steam pressures, approximately 15 psi above the water pressure. It should not be set above the steam pressure.
- Steam Leakage: Maximum leakage rate should not exceed 0.01% of full open valve capacity (ANSI CLASS IV).
- Water Pressure vs. Steam Pressure: The water pressure must be less than the steam pressure, ideally at least 20 psi less, for proper operation and to avoid temperature variations and vibration.
- Injection Tube Fasteners: Specific bolt sizes and quantities are provided for different heater models (e.g., 1/4-28 Shoulder Bolt for 6X7, 1/4-28 x 5/8 for 6X10, 1/4-28 X 3/4 for 6X50).
- Outlet Housing Clearance and Weight: The manual lists clearance dimensions ('D') and weights for outlet housings, ranging from 10 inches / 25 lbs for 6X10 to 35 inches / 725 lbs for 6X500. This information is crucial for safe disassembly.
- Temperature Controller: The standard temperature controller has a calibration set screw and a sensitivity adjustment screw (proportional adjustment).
Usage Features:
- Instantaneous Heating: Provides on-demand heating of liquids.
- Variable Flow: Designed to maintain accurate temperature control across varying liquid flow rates.
- Temperature Control: Utilizes a temperature controller and sensor to regulate steam injection and maintain a set outlet temperature.
- Safety Features: Includes warnings about handling hot liquids/steam, proper use of cleaning solvents, and safe disassembly procedures. The relief valve prevents overheating and pressure spikes.
- Installation: Assumes a vertical-up flow orientation for installation. Proper piping connections, including dielectric unions for dissimilar metals, are emphasized.
Maintenance Features:
- Cleaning: Regular cleaning of the injection tube and internal components is necessary to remove lime deposits, especially when heating hard water above 120°F. The frequency depends on water composition, operating time, and temperature. A significant drop in hot water temperature indicates a need for cleaning.
- Cleaning Solutions: Inhibited dilute muriatic acid is widely used. Cleaning solvents must be FDA approved for potable water service and should not attack copper-bearing alloys.
- Cleaning Procedures: Detailed instructions are provided for internal cleaning without disassembly, as well as for cleaning the injection tube after removal.
- Disassembly and Reassembly: Comprehensive instructions are given for disassembling and reassembling the heater, including specific steps for different models (6X7 vs. 6X10 through 6X500). Special attention is paid to the injection tube, which is a critical component.
- Injection Tube Inspection: The piston within the injection tube must move freely. Inspection for mineral deposits, burrs, and foreign material is crucial.
- Replacement Parts: New stainless steel bolts and flexlock nuts are required for reassembly of the injection tube spring stopper. Replacement gaskets are also needed for housing reassembly.
- Troubleshooting: Extensive troubleshooting tables are provided to address common issues such as insufficient heating, noisy operation, low water flow, overheated discharge, and discolored water. These tables link observations to probable causes and suggested actions, with page references for detailed service instructions.
- Pump Service: Basic checks for pump flow direction, rotation, and coupling tightness are outlined. Detailed pump repairs refer to a separate service sheet.
- Relief Valve Service: Instructions for setting the relief valve to ensure proper operation and prevent steam discharge into downstream piping.
- Steam Control Valve Service: Addresses issues like steam valve leakage and adjustment of the steam valve opening pressure. Warnings are given against using valve positioners due to potential vibration and poor temperature control.
- Temperature Controller Service: Instructions for calibration and adjustment of standard Pick temperature controllers, including checking air pressure, sensitivity, and linkage. Repairs for standard controllers are typically performed at the factory, with rebuilt units available for exchange. Optional controllers have separate manuals.
- System Isolation: Procedures for isolating the heater to diagnose whether vibration issues originate within the heater/supply lines or the hot water distribution system.
- Technical Assistance: Pick Heaters, Inc. provides assistance and replacement parts. Users are advised to provide heater and valve nameplate information when seeking support.
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