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Valve Boxes / Manifold Boxes

Top-end valve boxes are Quazite with a slip-resistant surface. More inexpensive options for a valve box are skimmer lids or PVC grating.

With metal lids on outdoor pools, the designer must watch the color and coating. The sun will heat all aluminum lids, so they must be coated with non-slip rubber of a light color. All features should have a control valve.

Valve boxes should be either a bronze Zurn or made with a slip-resistant PVC frame and lid. Skimmer lids are also an inexpensive, but not as attractive option.  Pan-filled valve boxes (similar to surge tank access hatches) should be used on high-end facilities.

A “feature relief line” should also be considered when multiple features are supplied from a single pump. The intent of this line is to bleed off any flow when features are turned off.  This will allow the feature pump to continue operation at its design point on its pump curve.  The feature relief line should be sized to accommodate 100% of the feature flow and be piped to the closest pool wall and be covered with a properly sized square PVC grate.

There are several criteria to be determined when implementing the valve boxes and of these the major factors are the quantity of valves to be concealed, and location of valve box.

 

  • Example
  •  sample facility has two main recreational bodies of water: an indoor and outdoor leisure pool. The natatorium incorporates a mid-sized play structure, several ground effects, a vortex, hydrotherapy bench jets, a current channel, and a waterslide.  The outdoor facility has similar features.  The indoor pumps are housed within a single filter room offset from the leisure pool.  The outdoor mechanical is being served from two different locations:  the filter room and feature pump pit.  The hydraulic data is summarized in the following table.
  Circuit Feature Flow Rate Pipe

Size

Combined Flow Rate Pump to Feature Central Feature Distance from Center
Indoor              
Play Structure 1 650 6” - 150 - 25
Bubblers 1 270 4” - 125 Yes 0
Tea Cup 1 130 3” - 130 - 5
Spray rings 1 50 2” 900 90 - -35
Vortex 2 600 6” - 220   -20
Hydrotherapy 2 300 4” 900 240 yes 0
Current Channel 3 1000 8” 1000 250 n/a n/a
Waterslide 4 700 6” 700 400 n/a n/a
               
Outdoor              
Play Structure 1 750 6” - 150 -  
Spray Bars 1 150 3” - 125 Yes  
Curvy Cool 1 75 2” 975 130 -  
Hydrotherapy 2 650 6” - 60 Yes  
Vortex 2 1150 8” - 80    
Waterfall 2 200 3” - 65    
Haystack 2 300 4” 2400 75    
River #1 3 1200 8” 1200 105 n/a 165
River #2 4 1200 8” 1200 150 n/a 115
Waterslide “A” 5 600 6” - 30 Yes 0
Waterslide “B” 5 800 6” 1400 50 - 20

 

  • Quantity:
    • When determining the quantity of valves boxes, the designer must first consider the number of valves or features to be controlled at a single point. It is reasonable to assume that being able to shut-off and/or control features at a single point in the deck is advantageous and provides a level of simplicity to the pool operator.  However, there is a price to be paid for the ease of operation.  The overall size of the valve box does become large and will adversely affect the attractiveness of the deck and/or natatorium.  To combat the overall size issue with the valve box, the designer must set a proposed maximum limit of 6 linear feet for a single valve box and lid.
    • This configuration will allow for two 10” or 12” diameter valves to be placed or up to three 8” diameter valves within the confines for the box. Of course, any combination of valve box sizes could be installed provided there is adequate service clearance and the maximum footprint limit is not exceeded.

 

  • Example continued
    • Referring to the sample facility, circuit #1 from the indoor facility has four pipes branching from a single pump feed: 6”, 4”, 3”, and 2” pipes. The butterfly valves require a separation distance of 19”, 13”, 13” and 11”, respectively.  In addition, a service clearance of 8” is required.  This puts our single circuit valve box cover at approximately 54” wide which is under the maximum length requirement.
    • Referring to the sample facility, outdoor pool circuit #2 has four pipes: 8”, 6”, 4”, and 3”. This configuration requires a minimum of 80” length which exceeds the maximum limit.  This valve box should be reconfigured.
  • Location
    • The valve box location contains several important factors which the designer should consider distance from the pump to the main feature, a centralized location among the features controlled, and location available for the valve box to be installed.
    • First, the distance from the pump to the main feature should be considered. The placement of the valve box should be approximately 2/3 the distance or greater of the most critical piping run.
    • Referring to the sample facility indoor circuit #3, the current channel, the main run length is 250 feet. The 2/3 rule would place the valve box at 166 feet or greater from the current channel pump. In reality, the valve box, if provided, for the current channel can and should be placed closer to the current channel.
    • Secondly, the valve box should be placed within a centralized location or closer to the most critical branch. The centralize location is fairly straight forward in its description, the valve box should be set in a place close to the feature or features which it is controlling. The critical flow branch is the feature that either requires the most amount of water or the pressure drop is critical to the feature’s performance.
  • Example continued
    • The sample facility, indoor circuit #2 is the vortex and hydrotherapy seating area. From the chart, we see the combined flow (900 GPM), and the approximate distance from the pump (230 feet).  The hydrotherapy bench is the critical branch due to the pressure requirements of the hydrotherapy nozzles even though the vortex flow requirement is double the amount of water.  Therefore, the valve box should be located closer to the hydrotherapy bench than the vortex.
    • Finally, the location where the valve box will be installed, and finish are important. In an outdoor facility, there may be more likelihood to locate the valve box off the deck or in a low visibility area.  This affords the designer some latitude to select lower costing valve box lids: solid PVC, or an extruded grating.  The strict spatial constraints of the natatorium mandate the valve box lids should be located closer to the pool shell or controlled feature.  The designer should give special consideration for the valve box to be less obtrusive and blend into the natatorium.  This can be achieved by indicating valve boxes with either a recessed or a pan filled lid to match the surrounding finishes.  The owner and architect should be made aware that this option comes at a premium.  The solid or grate style valve box lids can be installed in a natatorium, but these will affect the overall appearance.

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