Johnston Boiler

Top quality boiler manufacturing since 1864!

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Resources

Everything you need to know.

Home > Resources > Product Knowledge > Boiler Trim

Boiler Trim

A. Component Overview –General Trim Items Fig 2.1, Fig 2.2

Johnston Series PFT Boilers generally include the following trim items. Where the word “steam” is indicated, the device commonly applies to steam boilers only.

Low Water CutoffStops the burner on a low water condition. Burner restarts when normal water is achieved.Feedwater modulating control valve (steam)On signal from level controller, modulates open/close to allow condensate to flow into boiler.
Aux. Low Water CutoffStops the burner on a low water condition. Burner restarts when normal water is achieved, and manual intervention is involved (manual reset).Quick opening blowoff valve (steam)Lever handled valve piped to bottom of boiler to allow quick discharge of condensate and contaminants.

Optional:

Boiler Level Controller (steam)

Signals feed water valve to modulate open/close as necessary to maintain proper water level.Slow opening blowoff valveWheel handled valve piped to bottom of boiler to allow slow discharge of condensate and contaminants.
Optional: Boiler High Water Alarm (steam)Signals the operator of a high level in the boiler. If desired, could stop the burner as well.Continuous blowoff control valve (steam)Position indicating hand wheel needle valve to meter the discharge of condensate at the top of the boiler.
Operating Limit ControllerRestricts the boiler from over pressure or temperature. Stops the burner on high condition, restarts when boiler returns to normal.Continuous blowoff control valve (steam)TDS manual control. Position indicating hand wheel needle valve to meter the discharge of condensate at the top of the boiler.
High Limit ControlRestricts the boiler from over pressure or temperature. Stops the burner on high condition, restarts when boiler returns to normal and manual intervention is involved (manual reset).Automatic continuous blowoff system (steam)TDS automatic control. Controller, electric valve and conductivity probe. Controller opens/closes valve on basis of input signal from probe.
Modulating press or temp. controllerSignals burner to adjust firing rate on the basis of the boilers current operating pressure/temperature.Steam non-return valve (steam)Combination stop/check valve to isolate and back flow prevention.
Pressure or combination press altitude gaugeDirect reading gauge located close to the limit controls. Boiler monitor.Steam stop valve (steam)Stop gate valve to isolate boiler.
Low Fire Hold limit controlRestricts the burner from firing above “low” prior to water temperature achieving set temperature.Sight glassVisual indication of water level.
Safety Relief valve(s)Boiler shell mounted device to vent excess steam/water when boiler pressure/temperature is exceeded.Tri-cocksWhen opened, gives secondary indication of water level.

 

Follow Links Below to Reference Trim Location

Steam Boiler Trim

Water Boiler Trim

 

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  • Green Technologies
  • Why choose JBC?
  • Education & Training
  • Customer Installations
  • Photo Gallery
  • Factory Tour
  • Products
  • 509 Series Boiler
  • XID Scotch Marine Boiler
  • 358 Series Boiler – Ohio Special
  • 309 Series Boiler
  • WHR Series Boiler
  • Burners
  • Ancillary Equipment
  • Resources
  • General
  • Product Knowledge
  • Contact Us
  • Johnston Boiler
  • 300 Pine Street
    P.O. Box 300
    Ferrysburg, MI 49409-0300
  • P (616) 842-5050
  • F (616) 842-1854
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