Service of Steam Generator AT and 3T
1. DESCRIPTION OF STEAM GENERATOR
The Printed Circuit Assembly (the “PCA”) provides the basic functions necessary to produce steam. The PCA controls makeup water, provides a water level permissive for powering the elements and provides raw DC power for the system.
The PCA also provides regulated non-interruptible 12 VDC power for the generator control, 5 VDC for the temperature sensor. It also provides the interface circuitry between the control and the PCA. The control provides the room temperature control loop, power switching for "soft steam" and an adjustable steam bath timer.
2. MAINTENANCE OF STEAM GENERATORS
Whenever the generator is opened, inspect for any evidence of water leaks. Inspect the wiring for any evidence of overheating. Check all electrical connections for tightness.
Flush monthly, or more often, depending on local water conditions.
- The generator should be cool.
- Press the ON/OFF button. The control should light.
- Open the manual drain valve (if installed) and manually open the Autodrain valve by moving the lever until it latches.
- The unit will drain without heating the water.
- Allow the water to run for a full 10 minutes, then press the ON/OFF button. The control light should turn off.
- Allow the unit to drain completely. When the water stops, close the drain valves.
3. REPAIR OF GENERATORS
- ELEMENT REPLACEMENT:
(refer to diagrams 11 & 12) Disconnect power from the unit. Drain the tank. Remove the front and HEATING ELEMENT ACCESS covers. Note the wire connections. (See diagram) Remove the element wires. Using a hot water element socket, remove the element. To install a new element, mount a new element gasket on the element. Clean the element port and add a light coat of Rectorseal No. 5 pipe thread compound or equivalent to the threads. Insert and hand tighten the element-gasket combination. Notice the element end orientation as shown in diagram. Tighten the element until the orientation is the same as diagram, ± 15°. The gasket should be set and tight but not deformed to a rounded or bulbous appearance. If the drain valve was removed reinstall it. Reconnect the wiring. Test the unit per SECTION 7: OPERATIONAL TEST. Check for leaks at the element. Replace the front and HEATING ELEMENT ACCESS covers. (Replace with factory supplied elements only)
- PRINTED CIRCUIT REPLACEMENT: (refer to diagrams 14 - 16)
Printed circuit assembly (PCA) removal and replacement must be performed in the following sequence: any other method can damage the PCA.
IMPORTANT: The PCA’s contain static sensitive devices. Static electricity may damage PCA’s. Handle accordingly.
Disconnect power from the unit. Note and tag the positions of all wires that plug into the printed circuit assembly mounted relays. Remove all the wires from the relays. When removing these wires, pull on the connector, not the wire. Note the blue wire connected to the shortest of the triple pronged water level probe. Disconnect all three wires from the water level probe. Remove PCA from all seven standoffs by pinching the tops. When it is completely disconnected, it may be lifted out of the enclosure. To install the board, reverse this procedure. The wire lugs must fi r tightly onto the relay tabs! Test the unit per SECTION 7: OPERATIONAL TEST.
IMPORTANT: The blue wire connected to MAX on the PCA must be connected to the shortest of the three level probes, the black wire (MID) to the long probe with black tubing and the white wire (MIN) connected to the longest probe with white tubing.
- WATER SOLENOID REPLACEMENT:
Disconnect power from the unit. Turn the water supply OFF. Disconnect the water supply from the water solenoid valve. Remove the front cover. Remove the two blue wires from the water solenoid valve. Rotate the self-tightening hose clamp so it can be loosened with a pair of pliers. Squeeze the clamp and move it down towards the shelf and off the valve outlet tube. Remove the two 1/4" - 20 hex head bolts and lock washers that attach the valve to the chassis. Pull the valve off the rubber fi ll hose. To install the valve, reverse these instructions. Test the unit per SECTION 7: OPERATIONAL TEST.
- LEVEL PROBE REPLACEMENT: (refer to diagram 13)
Disconnect power from the unit. Remove the front cover. Note where the blue wire is connected to the triple pronged water level probe. Disconnect all three wires from the water level probe. Using a 1-1/4" (32 mm) box wrench, remove the level probe. Install a new level probe. Use Tefl on Tape on threads of probe if required. Tighten until the bottom of the plastic nut is 6,4 to 9,5 mm above the top of the port. Reattach the three wires. Test the unit per SECTION 7: OPERATIONAL TEST.
IMPORTANT: The blue wire connected to “L” on the PCA must be connected to the shortest of the three level probes, the black wire to the probe with black tubing and the white wire to the probe with white tubing.
IMPORTANT: The level probe may be extremely tight. Damage to the insulation or chassis may result unless the tank is properly blocked or supported during probe removal or installation. It may be necessary to completely disconnect and disassemble the generator.