An air gap or a backflow preventer is needed on all fill funnels.
A backflow preventer for a 3” line is approximately $5000. Backflow preventers also need to be inspected every year (approx. $100/yr).
The design of a 6” air gap eliminates the need for a backflow preventer.
A splash collar is required so that water is not splashed on the mechanical room floor. The line needs to be throttled down so that the pool is not flooded. This is not required with the use of a backflow preventer. This especially becomes a concern with spas when you want to fill them quickly. Fill funnels should be sized with this in mind.
In instances where a fill funnel accepts water from multiple sources (i.e. domestic water and quick fill) the designer should increase the size of the fill funnel to accommodate the additional piping.
The fill funnel should have a fill line no less than 2” diameter. CH recommends a fill line of no less than 3” diameter. Slow closing is required to prevent water hammer. Manual fill is required at 5’ above the filter room floor. If the manual fill valve is 6’-8” above the floor, a chain operator is required.
Plumbing should provide the freshwater service line to the location of the funnel. The SPC will provide a solenoid valve to be installed by the Plumbing Contractor on a 1” bypass line at the location of the fill funnel. Fresh water service to the fill funnel should be sufficient in meeting the required fill times of the pools.
When the fill funnel cannot be located above the pool water surface elevation to allow for an air gap and ample head for gravity flow to the pool, a direct fill connection to the pool recirculation pump suction line can be designed. This requires a backflow preventer to prevent contamination of the domestic water system serving the facility.
Standard design of fill lines should terminate at the main drain in a skimmer pool. In gutter pools, the fill line should be taken to the surge tank.
The fill funnel piping sizes should be noted in the pipe schedule.
The fill funnel piping should be shown on the “Return Piping” drawing sheet.
The state of Michigan requires that all pools be designed to have a maximum initial fill time of 24 hrs.
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