Raypak 902B Hydronic Heating, Temperature & Pressure Gauge, Pump Selection, Cold Water Starts

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Failure to exceed 105ºF (41ºC) within 7 minutes may result in the premature failure of the hot surface ignit- er, remote flame sensor, burners and heat exchanger. It can cause operational problems, bad combustion, sooting, flue gas spillage and reduced service life of the vent system. The bypass allows part of the heater discharge water to be mixed with the cooler heater return water to increase the heater inlet temperature above 105ºF (41ºC). This precautionary measure should prevent the products of combustion from con- densing in most installations. Warranty claims will be denied when condensation occurs.

Cold water operation issues are applicable to both cold water start and cold water run applications. Cold water operation for 7 minutes or less on start-up is acceptable. Where cold water starts will last longer than 7 minutes or where cold water operation is con- tinuous, provisions must be made to mix higher temperature outlet water with the colder inlet water and thereby raise the inlet temperature to at least 105ºF (41ºC) within the 7-minute time limit.

Cold Water Starts

Frequent (more than once a week) cold water starts, wherein the inlet water temperature remains below 105ºF (41ºC) for more than 7 minutes, must have cold water start protection. Known protection methods con- sist of mixing heated outlet water with the inlet water with a bypass to raise the inlet to 105ºF (41ºC) or high- er. Once the system is heated up and has return water temperatures of 105ºF (41ºC) or higher, the mixing of outlet water with inlet water is no longer needed and the bypass can be shut off. If the bypass is not shut off as the system heats up, the outlet temperature may continue to climb and actuate the high limit, thereby shutting down the heater. Thus an automatic valve system, such as a three-way proportional valve or a modulating two-way valve to control the bypass, should be utilized.

NOTE: Individual and multi-boiler Cold Water Start systems require the use of a 20°F ∆T boiler pump.

Cold Water Run

Cold water run differs from cold water start in that the system water entering the heater remains below 105ºF (41ºC) continuously. Typically, this is the case in swim- ming pool heating and water source heat pump applications as well as some others. If the system water is kept in a narrow temperature range, a perma- nent manual bypass can be employed and manually adjusted to achieve an inlet temperature of 105ºF (41ºC) or higher. An injector pump arrangement may also be utilized to keep the heater loop at or above 105ºF (41ºC). An injector pump approach has the added value of being able to adjust to changes in the system water coming back to the heater take-off.

NOTE: To ensure proper operation, use 20°F ∆T boiler flow rates when designing the heating system loop pump.

Temperature & Pressure Gauge

The temperature and pressure gauge is factory- mounted in the in/out header.

Hydronic Heating

Pump Selection

In order to ensure proper performance of your heater system, you must install a correctly sized pump. Ray- pak recommends using a 20°F ∆T as design ∆T. (∆T is the temperature difference between the inlet and out- let water when the heater is firing at full rate). If a ∆T of larger than 20°F is necessary, see Table H and Table I for flow rate requirements.

Model

10°F

T

20°F

T

30°F

T

40°F

T

Min. Flow

 

Max Flow

 

No.

gpm

 

P (ft)

gpm

 

P (ft)

gpm

 

P (ft)

gpm

 

P (ft)

gpm

P (ft)

T

gpm

P (ft)

T

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

302B

50

 

3.3

25

 

0.8

N/A

 

N/A

N/A

 

N/A

20

0.5

25

90

9.8

6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

402B

67

 

5.8

34

 

1.4

22

 

0.6

N/A

 

N/A

20

0.5

34

90

10.0

7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

502B

84

 

9.1

42

 

2.3

28

 

1.1

21

 

0.6

21

0.6

40

90

10.4

9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

652B

N/A

 

N/A

55

 

4.1

36

 

1.8

27

 

1.1

27

1.1

40

90

10.8

12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

752B

N/A

 

N/A

63

 

5.7

42

 

2.6

32

 

1.5

32

1.5

40

90

11.3

14

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

902B

N/A

 

N/A

76

 

8.3

50

 

3.8

38

 

2.2

38

2.2

40

90

11.7

17

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Notes: 1. Basis for minimum flow is 20 gpm or 40°F ∆T. Basis for maximum flow is 90 gpm. Flow switch will not operate if flow is less than 20 gpm.

2.Rear-mounted pumps may provide higher flow rates on smaller models than the system requirements.

Table H: Heater Rates of Flow and Pressure Drops

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Contents Installation & Operating Instructions Deletions None Contents Pay Attention to These Terms Before Installation Installations at ElevationProduct Receipt Model IdentificationComponent Locations Component Locations BackGeneral Information Time/Temperature Relationships in Scalds General SafetyWater Time to Produce Serious Temp Burn Installation Installation CodesEquipment Base StackingOutdoor Installations Indoor InstallationsClearances Ft 91 cm within a Combustion and Ventilation Air Indoor UnitsReversing Air Filter Direct VentInstallations Conventional Combustion Air SupplyTruSeal Combustion Air All Air from Inside the BuildingCanadian Installations Water PipingGeneral Reversing Water ConnectionsRelief Valve Piping Hydrostatic Test Cold Water OperationTemperature & Pressure Gauge Hydronic HeatingPump Selection Cold Water StartsPressure Drop in Feet of Head Feedwater Regulator PipingAir-Separation/Expansion Tank Three-Way ValvesPotable Water and Space Heating Pool HeatingAutomatic Chlorinators and Chemical Feeders Winterizing Your HeaterPool/Spa Water Chemistry Water HardnessPH of Water Total Dissolved SolidsGas Supply Gas Supply ConnectionModel Table K Maximum Equivalent Pipe LengthGas Supply Pressure Electrical Power ConnectionsField-Connected Controllers Check the Power Source Field Wiring ConnectionMaking the Electrical Connections Stage Tankstat Venting Flue Exhaust TeeModel Diameter Order Number Appliance CategoriesSupport of Vent Stack Vent Terminal LocationCanadian Installations InstallationsChanging the Flue Outlet Venting Installation Tips Venting ConfigurationsInstallation Natural Draft Vertical Venting CategoryTermination Common Venting SystemCertified Vertical Venting Combustion Air Air Inlet HeightHorizontal Through-the-Wall Venting Category Horizontal Through-the-Wall Venting CategoryDirect Vent Horizontal Through- the-Wall Model Certified Maximum Combustion Air InletVenting EquivalentDirect Vent Vertical Direct Vent VerticalControls Outdoor InstallationFreeze Protection Heater Sequence of Operation Models 302B-902BExternal Lights Color Indication Ignition Module Code ConditionHigh Limit Manual Reset Flow SwitchHigh and Low Gas Pressure Switches Low Water Cut-Off OptionalUDB Fault History UDB Diagnostic BoardPump Time Delay Table R UDB Fault Messages 87%-Efficiency Boilers Special Instructions Water PipingVenting Appliance Categories Model 10F 20F 30F Min. Flow Max Flow GpmVent Terminal Location Vertical Venting CategoryCondensate Management Certified Maximum Combustion Air Air Inlet Model Venting 752BE Combustion Air 902BE 30’ 80’Direct Vent Horizontal Through- the-Wall ABS Cpvc Wiring Diagram START-UP Pre Start-upMain Burner Adjustment Blower AdjustmentStart-Up Safety Inspection Leak Test Procedure Dual-Seat Gas ValvesFollow-Up Pilot Turn-Down TestPost Start-Up Check Leak TestLighting Instructions OperationTo Turn Off Gas To Appliance Troubleshooting StepSuggested Minimum Maintenance Schedule MaintenancePreventive Maintenance Schedule Weekly Semi-AnnuallyAnnually As RequiredAppendix Inside Air ContaminationLimited Parts Warranty HI Delta Types H and WH Limited Parts Warranty HI Delta Type P START-UP Checklist for FAN-ASSISTED Raypak Products Important Instructions for the Commonwealth of Massachusetts
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302B, 902B specifications

Raypak is a prominent name in the heating industry, particularly known for its advanced technology and robust design in residential and commercial heating solutions. Two of their notable models, the Raypak 302B and 402B, exemplify innovation and efficiency in hydronic heating systems, designed to meet diverse needs while ensuring optimal performance.

The Raypak 302B and 402B are high-efficiency boilers that utilize gas-fueled systems. The 302B model has a heating capacity of 302,000 BTU/h, while the 402B boasts a maximum capacity of 402,000 BTU/h. This range of heating output makes these models suitable for a variety of applications, from residential heating needs to larger commercial spaces that require a reliable heat source.

One of the standout features of the Raypak 302B and 402B is their use of fire-tube heat exchanger technology. This design promotes efficient heat transfer and allows for lower emissions, thus minimizing the environmental impact. The fire-tube design also contributes to a longer lifespan and reduced maintenance costs, making these boilers a cost-effective solution over time.

Equipped with advanced control systems, the Raypak 302B and 402B ensure precise temperature regulation and improved energy usage. The digital display provides real-time feedback and diagnostics, enhancing user experience and simplifying troubleshooting. These models are also compatible with various building management systems, providing users with versatility in integration to optimize building performance.

In addition to their technological advancements, these boilers are designed with user safety and convenience in mind. They include features such as built-in safety controls, easy access for service and maintenance, and a compact footprint to fit into tight spaces. Their robust construction ensures durability, which is crucial for systems that operate under high demand.

Moreover, both models have been engineered to succeed in various climates, making them reliable choices for users in diverse geographical locations. With their energy-efficient operation, reliable performance, and advanced features, the Raypak 302B and 402B embody quality and innovation in the heating market, ensuring comfortable environments while lowering energy costs and environmental footprints.
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