AERCO SWDW68 U-Tube Double-Wall Heaters w/ECS - Manual (Page 81)

Rev B Mar 2013 9-1
CHAPTER 9 DISASSEMBLY AND REASSEMBLY
9.1 INTRODUCTION
This chapter tells you how to disassemble your DW-Series heat exchanger, check it for tubing leaks,
reassemble it and put it back into service.
9.1.1 Tools required
• Torque wrench for 5/8" nuts
• Block and tackle or ratchet or winch hoist (for lifting the heat exchanger upper head assembly and
shell, or for lifting and moving the heat exchanger)
9.2 CHECKING FOR A TUBING LEAK
To check for a tube leak:
1. Shut down and drain the heat exchanger in accordance with 6.4.1, Steps 1 through 5.
2. Open the stop valves in the Steam Input line to introduce steam into the heat exchanger tubes.
3. If there is no flow from the leak detection tube
― whereas there had been a flow when the heat
exchanger was in operation
― the leak or leaks are in the outer wall (or walls) of the tubing. Similarly,
if there is a flow from the leak detection tube, the leak or leaks are in the inside wall (or walls) of the
tubing. When either type of leak occurs, it will be necessary to return the U-bend tube assembly or
the entire heat exchanger to AERCO for repair.
Step 12 explains how to disassemble the U-bend tube assembly from the heat exchanger, and
step 14 explains how to obtain instructions for returning equipment to AERCO for repair.
9.3 REMOVING THE HEAT EXCHANGER SHELL
Normally, there is no reason for the heat exchanger shell to be removed. However, if a leak has been
detected in the heat exchanger tubing, and it has been determined to be in the outer tubing walls (per
section 9.3, step 3), or if there is other valid justification for doing so, the heat exchanger shell may be
removed as follows:
1. If the heat exchanger has not already been shut down and drained, shut down and drain the heat
exchanger in accordance with 6.4.1, Steps 1 through 5.
Please refer to Figure 9-1.
2. Disconnect ALL EXTERNAL PIPING from the heat exchanger upper head assembly, including the
piping to the relief valve (1) and the water solenoid valve (2). Disconnect the Hot Water Output piping
(not shown) at the union or flange located beyond the outside diameter of the heat exchanger upper
head assembly.
3. Disconnect the Cold Water Input piping from the heat exchanger inlet pipe.
4. Disconnect any power supply wiring to the heat exchanger Control Box (4).
5. Disconnect the pressure gauge (5) from the Steam Input flanges (6).
6. Disconnect recirculation piping (7) at unions 26 and 27.