Crown Boiler 24-07, 24-11, 24-10, 24-08, 24-12, 24-06, 24-05, 24-09, 24-03, 24-04 Boil MIN Delay

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ASHRAE Fundamentals for the area closest to the installation. This value has a default of 10°F, and is adjustable between –60ºF to 32ºF.

e.WWSD – The Warm Weather Shut Down feature is used only when the outdoor reset feature

is selected. (OUTDR DESIGN = ON) If the outdoor temperature rises above the WWSD value, WWSD will be displayed. If a demand for heat is generated when the control is in the WWSD mode, the boiler will be disabled. The default for the WWSD is 70ºF, but is adjustable from 35ºF to 100ºF.

f.MIX MIN – This represents the minimum mix target supply temperature when the outdoor reset feature is selected. (OUTDR DESIGN = ON) This is the lowest temperature the controller is allowed to use as a MIX TARGET temperature. During mild conditions, if the RTC calculates a MIX TARGET below the MIX MIN, the target will be adjusted to match the MIX MIN setting.

g.MIX MAX – This represents the highest temperature allowed as the MIX TARGET temperature when the outdoor reset feature is selected. (OUTDR DESIGN = ON) If the RTC calculates a MIX TARGET higher than the MIX MAX, the MIX TARGET will take the value of the MIX MAX. Typically, this is set between 200ºF and 220ºF. The temperature must be set below the lowest permissible temperature for any system related component affected by boiler supply water.

h.OPEN DELAY – This value represents the number of seconds required for the actuator to open through 90 degrees of rotation. Leave in default value of 50 seconds.

i.BOIL MIN – This is the minimum boiler return temperature allowed. The minimum value has been set to 135ºF, adjustable to as high as 230ºF. The RTC will control the diverting valve while maintaining a minimum BOIL MIN temperature. Setting should remain at 135ºF unless a higher minimum boiler temperature is required.

j.BOIL MIN DELAY – This represents the time (in seconds) required for warm-up during an initial cold start. This prevents the counter from including cold start warm up time in the total boiler operation time below 135ºF. This grace period is provided for every heat demand cycle until 135ºF has been sensed at the return sensor. Once the return sensor has sensed a return temperature reading of 135ºF, after the heat demand cycle has initiated, the grace period is terminated. The warm up time includes a 90 seconds of pre-purge time. Use the values in Table V for the correct application.

k.PUMP DELAY – Pump delay represents the time (in seconds) for pump purge (boiler

Table V: Boil Min Delay Settings

Boiler

BOIL MIN DELAY

Model

(Seconds)

 

 

24-03

540

 

 

24-04

460

 

 

24-05

410

 

 

24-06

370

 

 

24-07

360

 

 

24-08

340

 

 

24-09

320

 

 

24-10

310

 

 

24-11

300

 

 

24-12

290

 

 

circulator purge) after a heat demand cycle. This minimizes the amount of boiler temperature overshoot at the end of a boiler cycle. During the pump purge the diverting valve will continue to operate and prevent low return water temperatures from entering the boiler. At the end of the pump purge period the diverting valve will be immediately closed. The default PUMP DELAY is set to 30 seconds.

l.UNITS – The temperature units can be changed to either Fahrenheit or Celsius. The default temperature unit is Fahrenheit.

4.ERROR MESSAGES – Error messages are shown on the LED display. The function in error will be shown as a black background label in the LED.

Most of the errors indicate an open or short circuit, connected to the RTC. The RTC Installation and Maintenance Manual identifies common errors. Cycle through the error messages and repair as required.

a.Return Sensor Error – If the return water temperature sensor has been damaged or omitted, the BOIL item will be displayed as either a “short” or “open” circuit. This will force the mixing device (i.e. 3-way valve) to run at a fixed 30% open position. The system may not receive enough heat nor will it be fully protected, however a significant change will be obvious to occupants and/or operators.

b.Operation Below Minimum – If the return sensor has been damaged or omitted, and the return water is allowed to return to the boiler below 135ºF, the BOIL MIN field will be displayed along with ERR. The failure must be identified and repaired immediately since the boiler

has been operating in a condition that fosters premature boiler failure.

5.COMPONENT EXERCISE - The RTC will exercise

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Contents Series Page Important Information Read Carefully Page Page Table of Contents Table of Contents Section I General Information Boiler RATINGS/DATA Locate the Unit Section I General InformationChimney or Vent Boiler FoundationVents Faults & Suggestions Assembly of Sections Manual DRAW- UP Section II Cast Iron Block AssemblyNipple Gauge Series 24 Section Arrangement Draw-Up Rods Alternating Pattern Manual Draw-up Center Section Channel Block Position Partial Block Draw-Up Hydraulic Draw-Up of Sections Canopy with Rear Flue Outlet Damper Assembly Section III Installation InstructionsBare Boiler Assembly Avoid Breathing Fiber Particulates and Dust Left Side Canopy Intermediate Bracket Inspect ALL Boiler Seals Mount Rear Observation Port Cover Refer to FigureSeries 24 Jacket Assembly Boiler Models 24-03 thru Mount Burner Adapter Plate to Burner Mounting Plate Burner Mounting Plate Refer to Figures 16Purpose of Tappings Steam Boilers Steam Trim Steam Boilers Install Steam Trim This Is Intentionally Left Blank Purpose of Tappings Water Boilers Water Trim Burner Installation Water Boilers Install Water TrimBoiler Piping Heating Applications Page Parallel Piping Conversion Recommendation 1 Use when Recommendation 2 Use when Recommendation 3 Use when Page Page Page BMounting Elevations M&M 150, 64 Float Low Water Cut-offs Schematic Tankless Heater Piping 24-08 24-09 CCW Open to System Return Temperature Control and ComponentsWater Boiler Pressure Relief Valve Hook-Up Typical Boiler Wiring with RTC Front Typical Boiler with RTC Return Sensor Rear Section IV Operating Instructions Always Inspect Installation BeforeStarting Burner Fill Heating System with WaterFlame Failure Boil MIN Delay Check Operation of High Limit Control Test ControlsBoiler and System Cleaning Steam Boiler Boiler and System Cleaning Water Boilers Oxygen Corrosion Frequent Water AdditionClean the Boiler Flueways Section V Service InstructionsMaintenance of LOW Water Cutoff Devices Operation General Maintenance ConsiderationsOIL Burners Section VI Burner SpecificationsSection VII Repair Parts & Carton Contents Series 24 Master Parts List Section VII Repair Parts Jacket Carton Bare Boiler Assembly Section Joiner Carton Assy Rear Target Wall Carton Standard Steam Trim Carton Assy RTC Carton with Outdoor Reset Tankless Coil Components Boiler Water Section Viii Appendix Page Mechanical Page Mechanical Electrical Page Page Page Page Page Page Page Page Series 24 Boiler Circulator Selection Taco 20F Differential Boiler Recirculation Grundfos Circulating Pump Way Boiler Recirculation Bell and Gossett Circulating Pump Way Boiler Recirculation Armstrong Circulating Pump Way Application Appendix C Valve and Actuator Mounting InstructionsService Record PN 980417 S24 12/05
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