Lochinvar GAS HEATER FOR COMMERICAL POOL APPLICATIONS Adjusting Differential Air Pressure

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Installation and Service Manual

Combustion Air Fans

Both the 500,000 - 750,000 Btu/hr models and the 990,000 - 2,070,000 Btu/hr models use a fan-assisted combustion process. The 500,000 - 750,000 Btu/hr models have one fan

and the 990,000 - 2,070,000 Btu/hr models use two fans to supply combustion air to the burners.

Fan Cleaning

Check each combustion air fan every six months. Clean the fan as required when installed in a dusty or dirty location. Oiling is not required.

Combustion Air Fan Adjustment
The combustion air fans are factory pre-set and should not
need adjustment in most cases. Follow the steps below to
adjust the fan if a continuous Low Air status code occurs.	Figure 53 – Loosening Fan Transition Box Screws

Note: On the 500,000 - 750,000 Btu/hr models the air shutter is adjusted on the side of the fan duct as depicted in Figure 52. On the 990,000 - 2,070,000 Btu/hr models the air shutter is adjusted on the rear of the fan duct as depicted in Figure 54.

1. Check for proper installation and draft in the venting system. Correct as required.

2. The following pressure settings are for installations up to 4000 feet altitude. Contact the factory for high altitude air pressure settings.

Adjusting Differential Air Pressure

The following is a recommended method for setting the differential air pressure (P) for each fan.

LESS	AIR

EAIR

R

O

M

Figure 54 – Adjusting Air Shutter 990,000 - 2,070,000 Btu/hr Models

Set-Up Procedure

Beside the fan duct is an air pressure switch with a large and a small tube delivering pressure from points inside the pool heater (see Figure 55). The pressure in the large tube is the chamber pressure. The pressure in the small tube is the burner pressure. They act together to make the pressure switch. By disconnecting the caps from the tees in the pressure switch hoses and connecting them to either side of a manometer, you can read the differential pressure to the switch.

AIR SHUTTER

Figure 52 – Adjusting Air Shutter 500,000 - 750,000 Btu/hr

The left pressure tapping connection on the manometer connects to the tee in the tubing from the pool heater front chamber and the right pressure tapping connection on the manometer connects to the tee in the small tubing from the burner.

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Contents GAS Heaters for Commercial Pool Applications Commercial Pool Heaters Unpacking General Product InformationCommercial Pool Heaters Product Identification Base for Combustible Floors Clearances from Combustible ConstructionCombustion Air Filter Freeze ProtectionCombustion Air Options InstallationCombustion Air from Interior Space Exhaust FansVenting Support General InformationVertical Vent Termination Clearances and Location Table B Sidewall Vent Termination Clearances and LocationLength of Air Inlet Pipe Combustion Air Inlet PipingSidewall Air Inlet Combined Air Inlet Points Vertical Rooftop Air InletConventional Negative Draft Venting Vent System OptionsNegative Draft Flue Outlet Piping Masonry Chimney InstallationsCommon Venting Systems Inspection of a Masonry Chimney Vertical DirectAire VentingSidewall Venting Vent KitsVenting of Flue Products Sidewall Venting Termination Sidewall FanSidewall Venting Without Fan Masonry Chimney Installation TABLE-E Horizontal DirectAire VentingDirect Venting Flue Pipe Materials Horizontal DV Venting TerminationCombustion Air Inlet Piping Air Inlet Piping Materials Length of Air Inlet PipeSealing Type-B Doublewall Vent Pipe or Galvanized Vent Pipe Vertical Rooftop Air Inlet Combined Combustion Air Inlet PointsOutdoor Vent/Air Inlet Location Outdoor Installation Venting3-Way Valve Cover Installation Combustion Air Fan Adjustment for startupGas Pressure Test Outdoor Vent Cap KitGas Piping Connecting Gas Piping to the Pool HeaterGas Train and Controls Venting of Combination Gas Valves Combination Gas ValvesChecking Gas Supply Pressure TABLE-JTable K Multiple Unit Installations Gas Supply Pipe SizingMeasuring Net Manifold Gas Pressure Gas Manifold Pressure AdjustmentPumped Automatic Bypass Auxiliary Mixed Water Limit ControlWay Valve Cover Heater is Within 15 Feet of Pool Piping Heaters are within 15 feet Perpendicular of Pool Piping Relief Valve Water Flow SwitchAutomatic Chlorinator and Chemical Feeders Service Indicator Option Pump Purge Delay OptionWay Automatic Bypass Valve Wiring TABLE-M Terminal Strip Connection OptionsLighting Instructions OperationTo Turn Off Gas To Pool Heater Pre-Start ChecklistStarting the Filter System Operation Error Messages Displayed by the Temperature Controller Programming ModeHot Surface Igniter and Ignition Control Module Diagnostic Status IndicationHot Surface Ignition Control Module Ignition Module Lockout FunctionsTABLE-N Access to Internal Control PanelIgnition and Control Timings TABLE-O Water ChemistryTest Recommended Level TABLE-PCirculating Pump Pipe Size RequirementsMinimum Pump Performance Heat ExchangerFlue Gas Passageways Cleaning Procedures High Water Temperature Limit ControlAppliance Area Water Circulating PumpHeat Exchanger Cleaning Burner Removal and CleaningElectrical Combustion and Ventilation AirFan Cleaning Adjusting Differential Air PressureCombustion Air Fan Adjustment Set-Up ProcedureServicing Hot Surface Igniter and Ignition Module Adjustment ProcedureIgnition System Checkout Sequence of Operation Glossary Prepurge Wiring BOX Connections Wiring BOX Connections Ladder Diagram Control BOX Connections Commercial Pool Heaters Appendix a View Menu Item Menu Description Appendix B