Lochinvar Domestic water heaters, Domestic Water Heaters 90,000 500,000 Btu/hr Models

Page 46

Installation & Service Manual

7Domestic water heaters

Domestic Water Heaters 90,000 - 500,000 Btu/hr Models

This section applies only to those units used to supply direct fired domestic hot water and installed with a storage tank(s). The use of a properly sized pump and the control of water velocity, as explained in the Water Velocity Control section, are important for correct operation of your hot water heater.

This section contains specific instructions for those units used to supply domestic hot water. All warnings, cautions, notes and instructions in the general installation and service sections apply to these instructions. Water heaters are designed for installation with a storage tank. The use of a properly sized pump and the control of water velocity, as explained below, is important for correct operation of your water heater.

Water Velocity Control

IMPORTANT - To ensure proper velocity through the heat exchanger, it is necessary to regulate the temperature rise across the heat exchanger from inlet to outlet. This must be done on initial installation and periodically rechecked. With the correct temperature rise across the heat exchanger, you may be assured of the proper velocity in the tubes. This will yield long life and economical operation from your water heater. Excessive lime build-up in the tube is a result of too little velocity in the tubes. Excessive pitting or erosion in the tube is caused by too much velocity through the tubes. Care should be taken to measure temperature rise and maintain a velocity as follows:

1.The pump must run continuously when the burners are firing.

2.With the pump running and the water heater off, the inlet and outlet thermometers should read the same temperatures. If they do not, an adjustment must be made to your final calculation.

3.Turn the water heater on and allow time for the temperature to stabilize. Record the difference between the inlet and outlet temperatures. This difference will be the “temperature rise.”

4.Compare the temperature rise on the heater with the required temperature rise in Table 7A. Should adjustment be needed, proceed as follows:

If the temperature rise is too high, the water velocity is too low. Check the following:

1.Check for restrictions in the outlet of the water heater.

2.Be sure all valves are open between the water heater and the tank.

3.Check the pump to be sure it is running properly and that the pump motor is running in the proper direction.

4.Be sure the circulation pipes between the water heater and storage tank are not less than 2" diameter for a single unit installation.

5.Common manifold piping for multiple unit installations will require larger minimum pipe sizes to tank tappings to ensure proper flow. See Table 7B on page 47.

6.Multiple unit installations may also require a larger circulating pump to achieve the specified flow against the increased head loss of multiple unit common manifold piping.

If the temperature rise is too low, the water velocity is too high. Adjust as follows:

1.Slowly throttle the valve on the outlet side of the water heater until the temperature rise is steady at the required temperature rise as noted in Table 7A.

2.Sustained high water velocity and low temperature rise may result in pitting or erosion of the copper tubes in the heat exchanger. This is a non-warrantable failure. Temperature rise must be properly adjusted to achieve the specified flow rate.

Required Temperature Rise

Temperature rise is based on the hardness of the potable water to be heated. The temperature rise specified is for water with a hardness of 5 to 25 grains per gallon. The total dissolved solids shall not exceed 350 ppm.

TABLE - 7A

REQUIRED TEMPERATURE RISE

 

Btu/hr

Flow Rate

Temperature Rise °F

 

 

INPUT

GPM

 

 

 

 

 

 

 

 

90,000

30

5

 

 

 

 

 

 

 

135,000

30

7

 

 

 

 

 

 

 

180,000

30

10

 

 

 

 

 

 

 

199,999

30

11

 

 

 

 

 

 

 

225,000

30

12

 

 

 

 

 

 

 

270,000

30

15

 

 

 

 

 

 

 

315,000

30

17

 

 

 

 

 

 

 

360,000

30

20

 

 

 

 

 

 

 

399,999

30

22

 

 

 

 

 

 

 

500,000

30

28

 

 

 

 

 

 

46

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Contents Models 90,000 500,000 Btu/hr Contents Please read before proceeding Checking equipmentCodes Ratings Copper-fin =B=R RatingCopper-fin Specifications Copper-fin How it works Gas connection pipeModels CWN270 Front View Model CWN399 Front View 422 Determine unit location Location of unitDetermine boiler location 3Combustion Air Direct from Outside6Combustion Air from Outside Single Opening Minimum Recommended Combustion AIR Supply to Equipment Room Conventional Negative Draft Venting System VentingVent Pipe Sizes Venting Vertical Vent Termination Clearances Less from Ridge From Parapet WallSidewall Venting Masonry Chimney InstallationVent Materials NumberAutomatic Vent Damper 7CB with Vent Damper and Vent Damper Terminal BlockGas Connection Gas connectionsGas Supply Gas Pressure Test Manifold PressureInstall Piping to Control Gas PipingGas Manifold Pressure Adjustment Procedure Clockwise to raise regulator gas pressure, counterclockwiseChecking Gas Supply Pressure 4Gas Supply PressureVenting of Combination Gas Valves Combination Gas ValvesTwo Stage Burner Control System Hydronic piping Water Flow Switch if equippedRelief Valve Minimum Required Flow For Heating Boiler Typical Heating Boiler InstallationsLow Water Cutoff if equipped General Plumbing RulesSystem Temperature Rise Chart Piping of the Boiler SystemWater Connections Heating Boilers Only Heat Exchanger Pressure Drop ChartCirculator Pump Specifications Circulator Pump RequirementsPrimary/Secondary Boiler Piping Three Way Valves Boiler Flow RatesPrimary / Secondary Piping 4Primary / Secondary Piping of a Single BoilerNot to Exceed 4 Pipe DIA or MAX. of 12 Apart 8Multiple Boilers Zoned with Circulators Power Venter Connection to Terminal Strip Terminal Strip WiringBoiler Operating Temperature Control Electrical connectionsPump Wiring for a Heating Boiler Temperature AdjustmentOperating Temperature Control Maximum SET Point Determination Locating Temperature ControlTemperature Control Settings Maximum Set Point DeterminationMulti-Purpose Temperature Sensor Temperature Control SensorsInlet Water Temperature Sensor Outdoor Air Temperature SensorInstallation of a Remote Sensor Boiler Application Outdoor Air Reset OptionInstallation of a Tank Sensor Water Heater Application Additional Temperature Controls Blocked Vent and Flame Roll-Out / Flame Interlock Switch Manual Reset High Water Temperature Limit ControlStart-up Pre-start ChecklistInitial Start-up Lighting Instructions 1Gas Valve 90,000 270,000 Btu/hr ModelsSafety Shutoff Test For Standing Pilot Ignition System To Turn OFF GAS to ApplianceOperating Instructions Freeze Protection Safety Shutoff Test for Spark Ignition Pilot SystemIntermittent Pilot Spark Ignition System F9/M9 To Turn Off Gas to ApplianceWater Treatment Freeze Protection for a Heating Boiler System if requiredDomestic water heaters Required Temperature RiseRequired Temperature Rise Domestic Water Heaters 90,000 500,000 Btu/hr ModelsSoftened Water Systems Water ChemistryPump Operation 1Single water heatersingle tank 2Single water heatermultiple tank 3Multiple water heatersingle tank Minimum Pump Performance Remote Sensor InstallationThermostat Settings Heat Exchanger5Danger Warning Thermal Expansion Water Flow Switch if equippedPressure Only Relief Valve Cathodic ProtectionOwner maintenance Maintenance and annual startupService technician See the User’s Information Manual for instructionsMaintenance Check Expansion Tank Check Relief ValveCombustion Air Adjustment Check All WiringCheck Control Settings Perform Start-up and ChecksHeat Exchanger / Burner Access Inspect and Clean BurnerInspection and Cleaning Procedure Inspection of Heat Exchanger Waterways Pilot Flame Adjustment ProcedureClear Area Water Circulating PumpReview with owner Gas Train and ControlsTroubleshooting Pilot or replace Wiring Diagram F1 Unit DiagramsSchematic Diagram F1 Unit 90,000 270,000 Btu/hr ModelsWiring Diagram F9 Unit Schematic Diagram F9 Unit315,000 399,999 Btu/hr Models Diagrams Diagrams Page Revision a ECO #C06290 initial release CFA-I-S Rev a 09/10
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