Pool Boiler
The boiler is a natural gas fired 1,200,000 BTW/hr RBI LW1200. Details are contained in RBI drawing #42-2112 (not published on the Wiki as it may be considered RBI proprietary).
Interlocks prevent the boiler from operating when the water level is too low, sufficient water flow is not present or the air pressure differential (as generated by the blower motors) is insufficient. Redundant over-temperature lock-outs (including those added by FFSC maintenance) prevent operation in the event that the temperature rises beyond a threshold.
Operation
The operation sequence below is based upon the procedure described in the LCD Series manual, with adaptations per the installation wiring.
Stage A: Demand for Heat
A demand for heat is satisfied when all of the following conditions are met:
- The measured temperature (via the temperature controller) has reached or fallen below the heat threshold.
- The normally closed (NC) Boiler Disable relay contact (part of the pool automation system) is closed, indicating that no fault is observed.
- The Low Operator relay contact (in the Johnson Controls C450CCN-3 module) is closed, indicating that the over-temperature bound has not been met.
At this point:
- The boiler time-delay relay TD4 (blower delay post-purge) is engaged, which immediately energizes contactor C1, turning on the boiler loop circulation pump.
- The automation system relay CR2110 is energized, which activates PLC input X10.
Stage B: Flow/Temperature Interlocks
The following interlocks must be satisfied to proceed:
- The High Temp latch is not set (in the Honeywell L4006E, with a reset pushbutton located on the front side of the boiler).
- The Water Flow switch is tripped, indicating that sufficient flow in the loop is present.
At this point:
- The boiler time-delay relay TD3 (pump delay post-purge) is engaged, which immediately energizes contactor C2, turning on the blower motors (low speed).
- The automation system relay CR2111 is energized, which activates PLC input X11.
Stage C
Control Interlocks
The list below includes interlocks with electrical interfaces only and is intended to align with the CSD-1. This table is for reference only; the CSD-1 should always be considered the master.
| Control/Device | ANSI CSD-1 Reference(s) |
Manufacturer | Model | Setpoint (align with CSD-1) |
|---|---|---|---|---|
| Low-Water [Fuel] Cutout | CW-110 CW-120 CW-150 |
ITT | PS-851-M-120 | N/A (not adjustable) |
| Forced Circulation | CW-200 CW-210(b) |
ITT | FS-251 | N/A (not adjustable) |
| Water Temperature | CW-410(b) | Red Lion | T4820219 | 82 °F |
| High Water Temp Limit | CW-210(b) | Johnson Controls | CC450CCN-3 | 180 °F |
| Combustion Air Switch | CF-220 | Cleveland Controls | AFS-1 | 0.5" WC |
| Purge Air Flow (Pre-Ignition) | CF-210 | UTEC | 1003-638A | 30 seconds |
| Flame Safeguard (Primary) | CF-310 CF-320 |
UTEC | 1003-638A | N/A (not adjustable) |
| Flame Detector (via RBI 3316-0327) |
CF-310 CF-320 |
UTEC | 1003-638A | 12 µA |
Maintenance
Regular inspections are mandated by the state and the insurance company. These inspections occur every three years. Prior to the official inspection, a Steam/Hot Water ASME CSD-1 form must be completed by a qualified technician. This form contains details about the boiler (identified by the state license and serial numbers), identifying key controls, their set-points and operation test results. Any issues found during the technician's inspection must be remedied before the document becomes acceptable as proof of compliance per Rule 27 of the State of Michigan Boiler Code.
Two copies of the CSD-1 should be kept by FFSC. One placed in a room near the boiler, another in a central filing location.
Troubleshooting
First, always ensure that the breaker and GFCI are not tripped, and that the power switch on the side of the unit is turned on.
If the boiler does not fire in response to a call for heat, the issue is likely related to an interlock or the ignition system. Verify that the low water sensor is reset; it can be tripped by air infiltration during filter back-washing. Ensure that the pump is operating. Verify that the covers are securely fastened; a loose cover leaks air and may not close the air pressure switches. Finally, check for the presence of spark and/or pilot light. This is visible via a small window on the lower-left of the unit.
The flame sensor unit is a consumable item and may need to be replaced at a regular interval (every two years?). If the pilot valve (PV) is open, but the main valve (MV) never opens, it is likely that adequate flame is not being detected. This can be verified by measuring the microamp current output of the flame sensor and should be done by a qualified technician.