Pool Systems Introduction

Systems for pumping, filtering and chemical treatment ensure that pool water is sanitary, clear and warm.

As illustrated in the Process Flow Diagram, water exits the pool via the drain and/or gutters. A surge tank balances the flow from both sources. An intake pipe near the bottom of the surge tank feeds a strainer basket that is used to catch large debris (such as leaves) prior to entering the main pump. The main pump forces water into a bank of sand filters. Filtered water then proceeds to enter multiple "loops" for chemical monitoring, heating (via the boiler) and chlorination. Finally, water is returned to the pool via small outlets at the base of the gutter tray.

Surge Tank

The surge tank fundamentally supports the gutter system, which captures surface water and absorbs of waves formed within the pool. The water on the surface has the potential to be the dirtiest in the pool. Debris (such as leaves, pollen), algae spores and oils (from skin, sun screen lotion) collect on the surface. The sun's UV rays break down disinfectant (chlorine) most at the surface. It is important that this water be collected with priority.

When the flow from the gutters is not sufficient (due to water level and/or a lack of waves), additional flow from the drain is required to maintain the surge tank level. This is typically handled via a modulation valve on the drain inlet to the surge tank, controlled by a level monitoring mechanism (such as a float). When a modulation valve is not present, flow much be restricted on the drain return and the pool level must be maintained to ensure some amount of gutter return is present.

Key Observations

When the surge tank is too low, this is typically due to one of more of the following reasons:

• The pool water level is too low (when a drain return modulating valve is not present). Fill the pool.
• The drain return modulating valve is malfunctioning, if present. Service the valve.
• The main pump flow rate is too high. Reduce the outlet flow rate (only after ensuring that other conditions are not present).

When a drain return modulating valve is not present, it is important that the drain return is restricted (the valve is partially closed). Otherwise, flow from the drain will potentially prevent adequate flow from the gutter return. In an ideal case, the surge tank should always have a modulating valve on the drain return.

Filters

Four Pentair Triton II Commercial silica sand-filled filter tanks operate in parallel to capture particles in the water that passes through. As particles accumulate, flow is restricted. This is indicated by an increase in pressure.

Maintenance

Periodic back-washing is required when filter tank pressure exceeds a threshold.

The filter sand should be replaced every 5-10 years. In a marcite pool, the filter sand should be replaced following the cure period of a new marcite coating (as the process releases a large number of particles, clogging the sand filters).

Boiler

The boiler is a natural gas fired 1,200,000 BTW/hr RBI LW1200 (as-built RBI drawing #42-2112).

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.

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.

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.