The pool water is typically heated by means of either thermostatically controlled heat exchangers, which use the building’s central boiler or steam system as their heat source, direct-fired pool heaters, or recovered heat from the natatorium dehumidifier or two of the above. The respective heating systems must be capable of maintaining desired water temperature.
Lochinvar are "low NOX direct fired pool heaters" - they range from 88% to 97% efficiencies and they are NSF listed with cupronickel heat exchangers and bronze headers. Lochinvar has pool heater R & D division that is ongoing.
Raypak is as a lesser pool heater option although they are not as well supported or serviced but they do maintain an NSF listing. Raypak are also not as efficient as Lochinvar, as they are only 84% efficient at the top end. The heat exchanger is standard copper as opposed to cupronickel and they don’t have bronze headers, they are steel on their pool heaters so have a limited life.
Pentair Heaters "Power Max' are also available and are NSF listed. 82% efficient with copper heat exchangers, no bi pass pump with unit.
Pentair’s Master Temp 400 heater should not be used for commercial applications due to multiple failures at Crown Valley Teaching Pool.
Pool heaters need to be initially started and adjusted by an authorized pool heater representative.
'Pool Boilers' are atmospheric hot water boilers similar to Parker Boilers and are commonly seen in Arizona - these have 24" flues and require 3'-0" of clearances on all sides and run at 65% efficiency. They require medium pressure gas hook ups and a drain sump.
If the dehumidification system is being used to supply heat to the pool, then it often necessary to provide a backup heat source as the dehumidification may not be able to handle the entire load. The backup would normally be either a heat exchanger or a gas fired heater that requires a separate set of connection tees on the pool’s return line.
If there are more than one bodies of water in the system, the dehumidification will only be able to provide heat to one of the bodies.
Occasionally, stand-alone pool heaters are recommended so that building heating system boilers do not have to operate in summer. If there is a central steam or hot water system that will operate year-round, heat exchangers may be preferred.
Normally, a side stream of 20% to 40% of recirculation is heated, and then mixed into the pool recirculation.
Unless the capacity of the pool filter system is specifically designed to accommodate the heating system, then a booster pump may be necessary for conveyance of the pool water from the filter return line, to the heat source and return.
The heating system for a spa should be designed to heat the initial fill water in a relatively short time. Because of the high bather concentration in a spa and the small amount of water, the owner may choose to empty and refill the spa several times a week, or even once a day. Because of this, consideration should be given to designing the spa heating system for heating the initial fill water in approximately 4 to 8 hours (8 hours would typically allow the spa to heat up overnight). A cross fill from the swimming pool to the spa will reduce both the energy demand and the time required to heat the spa. Cross fill connections are not allowed in every state.
Interlock heaters to the pump so they do not stay on when the pump is off and therefore do not melt the pipe.
Make sure there is sufficient fresh outside air makeup, so they do not soot (Colorado Springs).
Heaters need to be de-rated for projects at elevations above 2000 feet from sea level. Heater de-rating is 4% for each 1000 ft above sea level.
Most health codes do not allow cross connections between pool systems. Separate heat loops/heat exchangers must be provided for each pool. If heat loops or heat exchangers are shared, water from multiple pools will be mixed. This creates the possibility of cross contamination between the various bodies of water. Shared heater piping also prevents the cross-connected pools from operating at different water surface elevations.
A dehumidification unit has only one influent and effluent connection, therefore each dehumidification unit should only be used to provide heat to one pool system in order to prevent a cross connection between multiple pools. (Additional heat exchangers can be added to the dehumidification unit effluent piping to deliver heat to other pools if required.)
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