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Honeywell A4021 Series Product Handbook

Universal gas valves. valve proving system.
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A4021 Series
The A4021 is a self--checking microprocessor based Valve
Proving System (VPS). The A4021 checks the effective clo-
sure of automatic shut--off valves by measuring the pressure
differential between two valves during the test sequence.
Subbase and pressure switch are required to complete the
When during the test sequence of the A4021 a failing valve is
detected, the A4021 will go into a non--volatile lock--out sta-
tus, generates an alarm and prevents a burner start--up.
The intended application is for gas fired power burners and
other large capacity gas firing installations, where according
to the European norm EN676 a valve proving system can be
used as an alternative for pre--purging the combustion cham-
ber. And for installations with or without pre--purge with a
capacity of more than 1200 kW.
EN2R--9023 9705R0--NE



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  Summary of Contents for Honeywell A4021 Series

  • Page 1 UNIVERSAL GAS VALVES A4021 Series VALVE PROVING SYSTEM PRODUCT HANDBOOK APPLICATION The A4021 is a self--checking microprocessor based Valve Proving System (VPS). The A4021 checks the effective clo- sure of automatic shut--off valves by measuring the pressure differential between two valves during the test sequence.
  • Page 2: Table Of Contents

    CONTENTS Application ..............General .
  • Page 3: General

    GENERAL Application (continued) there is a mounting bracket available (order separately) According the European standard EN676 a valve proving The A4021A can be used for both single and combination system can be used under certain conditions, as an valves with or without pilot valve. alternative for pre--purging the combustion chamber.
  • Page 4: Features

    FEATURES • Microprocessor technology • Automatic valve proving before heat demand, after heat--demand or during pre--purge possible. • Based on 7800 SERIES Burner Programmer safety • Different test--times (per valve) available by different technology O.S. numbers. − Dynamic relay test •...
  • Page 5: Description

    The A4021 valve proving system can be used with several pilot--valve configurations, like intermittent and interrupted Fig. 3. Valve proving post--configuration . pilot systems and 3--valve configurations as well. heat burner--controller Valve Proving System demand A4021 Series 7800 SERIES L.G.P.S. G.P.S. Pinlet Gas pressure switches C6058A Series burner...
  • Page 6 Table 2. Sequence timings for normal operation STANDBY State Description Time STANBY infinite start self--test + memory test < 2 manual reset V2 powered waiting for pressure to get low self test error + lock--out = OK ? wait valve 1 powered open valve 2 waiting for pressure to get high (5 sec.)
  • Page 7 Line voltage Heat demand Leak test Valve V1 POST Valve V2 CONFIG Vent valve (normally open) Leak test Valve V1 Valve V2 CONFIG Vent valve (normally open) Lock--out (Ignition controller) Reset ign. control. power--up start start lock--out reset burner controller start whithout valve proving ! heat--demand heat--demand...
  • Page 8: Specifications

    SPECIFICATIONS Mechanical Internal fuse: 5 A slow max. Power consumption Model Maximum 4.5 VA A4021A Electrical ratings Dimensions 4A, cos. ϕ 0.7 Valve outputs: Refer to Fig. 7. 1A, cos. ϕ 0.7 Vent valve output: For mounting bracket dimensions refer to Fig. 8. 4A, cos.
  • Page 9 Table 3. Connections for A4021A pre-- and post configuration with contact ratings Terminal Abbreviations Direction Description Ratings (220 (220 ... 240Vac/100 ... 120Vac, 240Vac/100 120Vac post depending on O.S. number) input Normally Open contact of the pressure n.a. switch (high pressure) RESET RESET input...
  • Page 10: Dimensional Drawings

    DIMENSIONAL DRAWINGS PG11 10 11 12 13 14 15 16 Fig. 7. Mounting dimensions of A4021A and subbase in millimeters 90° ∅ 4.5 (4x) ∅ 20 74.5 Fig. 8. Mounting bracket A4021A for VQ400 and VE5000 Series in millimeters. EN2R--9023 9705R0--NE...
  • Page 11: Safety Provisions

    SAFETY PROVISIONS A4021A external reset vent--valve H.D. LGPS pre--config. burner controller H.D. post--config. H.D. internal fuse input fuse 5 A slow post--config pre--config. int. power supply alarm = input micro--processor valve--1 valve--2 = external wiring = optional Simplified internal schematic and wiring diagram pre-- and post--test configuration. Fig.
  • Page 12: Calculations

    CALCULATIONS Calculate the maximum pipe length between two 1 1/2” safety General valves when an A4021A valve proving system is used with a The maximum allowable leak--rate (according the EN676 and test period (per valve) of 25 seconds. EN746--2) is 0,1 % of the maximum burner capacity. The test Given: Pi = 75 mbar time necessary to detect a falling valve is a function of:...
  • Page 13: Use Of Terminal

    INSTALLATION AND WIRING Wiring Installation 1. For proper subbase wiring, refer to Table 3. IMPORTANT Read these instructions carefully. Failure to follow 2. Disconnect the power supply from the main disconnect the intructions could damage the product or cause a before beginning the installation to prevent electrical hazardous condition.
  • Page 14: General Wiring Diagrams

    GENERAL WIRING DIAGRAMS Ignition controller Ignition controller pilot main main--valve valve heat--demand heat--demand valve output output output input input reset reset (ext.) (ext.) ALARM ALARM 4(N) 4(N) fuse fuse Valve Proving System Valve Proving System A4021A A4021A 6(N) 6(N) 5(N) 5(N) vent--valve vent--valve...
  • Page 15: Applications With Ec7850

    APPLICATIONS WITH EC7850 EC7850 (interrupted) (intermittent) flame-- ground signal C.V. SHTR ALARM P.S. lock--out switch flame--rod ign. LINE NEUTRAL EARTH open atmosphere H.D. vent-- EXTERNAL valve RESET L.G.P.S. gas supply burner ext. LINE V2IN V2OUT LGPS / HD RBHD VENT HD--OUT V1IN V1OUT...
  • Page 16 EC7850 with rectification amplifier (interrupted) (intermittent) flame-- ground signal C.V. SHTR P.S. flame--rod Lock--out switch ALARM ign. LINE NEUTRAL EARTH H.D. EXTERNAL L.G.P.S. RESET gas supply ext. LINE V2IN V2OUT LGPS / HD RBHD VENT HD--OUT V1IN V1OUT RESET ALARM A4021A G.P.S.
  • Page 17 STANDBY Modes TEST MODE RUN MODE ALARM MODE Timings (sec.) 25 * 25 * *= depends on OS # States Line voltage Heat demand Pressure (between V1 and V2 Valve 1 Valve 2 Operate burner Alarm output Power Alarm Valve 1 Valve 2 FAILING/ FAILING/...
  • Page 18: Checkout

    CHECKOUT The procedures described in this chapter are related to Final checkout of the installation A4021A. For adjustments on the other additional Set the appliance in operation after any adjustment and functionalities (e.g. pressure switch), refer to the included observe several complete cycles to ensure that all burner instruction sheet of the product in question in the package.
  • Page 19: Troubleshooting

    TROUBLESHOOTING General CAUTION If you encounter a error or fail on V1 or V2, refer to the instruction sheet of the valve. Use utmost care while troubleshooting the If you encounter other problems in the system, refer to the A4021A, line voltage is present on some of the Troubleshooting section in the instruction sheet for the terminals when power is on.
  • Page 20: Standards And Approvals

    STANDARDS AND APPROVALS − The product is designed according to the following standards: IEC 1000--4--2 (electrostatic discharges) − − (Pr)EN1643 IEC 1000--4--5 (surges) − − ENV 1954 IEC 1000--4--11 (voltage interruptions and decreases − − IEC 1000--4--4 (fast transient bursts) EN 60730 −...
  • Page 21: Ordering Information

    ORDERING INFORMATION • C6058A pressure switch. When ordering specify: • Model number • 1030002020 Mounting bracket for VQ400/VE5000 • Voltage • Replacement parts, if desired. Order separately: • ZL030001 Subbase. Table 6. Ordering information A4021A Series Valve Proving System. O.S. Number Rated Test time** Power...

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