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Harman Red Thermister Exhaust Sensing Probe (ESP): 3-20-00844

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Product SKU ! 3-20-00844
Product MPN ! 3-20-00844
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Total Price: $124.98


This version of the ESP is the correct part for any model made after 2008. This updated ESP has red wires, as opposed to the previous probes which could have had black, yellow, or white wires. New Circuit boards are now sensing the condition of the differential pressure switch. (FIG 4) 

Notes for ordering replacement parts:

  • If you need a new probe: Order to match your existing probe. Red= #3-20-00844
  • Black, White, or Yellow Probe: Order the black Probe.
  • If you need a new board: Order using the part numbers included here.
  • If installing on a unit with an old probe = Dipswitch #5 “OFF”.
  • With new probe= Dipswitch #5 “ON”.
  • The DVC500 uses two probes, ESP and TCP(temperature control probe). They must be of the same color

This red ESP is used on all models manufactured after 2008 or any model in the list below with an updated controller:

Replacement For Part Number:

  • 3-20-00844

View Compatible Models

UPC: 652174715022

Compatible Models


  • Absolute 43
  • Absolute 43-C
  • Absolute 63
  • Accentra 52i
  • Accentra 52i TC
  • Accentra Cast FS
  • Accentra Insert (Post: 008241201)
  • Advance (Post: 008360001)
  • Allure 50
  • Allure 50-CE
  • DVC 500 (Post: 008065076)
  • HF60
  • Invincible Insert
  • Invincible RS
  • P35i
  • P35i-C
  • P38
  • P38+ (Post: 008190059)
  • P43
  • P43-C
  • P61-A (Post: 008085055)
  • P61-C
  • P61A (Post: 008085803)
  • P68 (Post: 008281295)
  • P68-C
  • PB105
  • PC45 (Post: 008055031)
  • PF100
  • PF120
  • XXV (Post: 008200828)
  • XXV TC

Technical Specs

High Temp Limit 572°F



Install Instructions For Harman Red Thermister Exhaust Sensing Probe (ESP): 3-20-00844

You must be careful not to bend an ESP probe if removing it for maintenance purposes. Bending the sheath of the probe will usually ruin the sensor. Likewise, when cleaning your stove, care should be taken to not bend the sensor when cleaning. Do not send brushes or vacuum tools through the stove blindly. Before cleaning your stove for the first time, find the ESP probe and make sure that it is not going to be in the way when cleaning. If it is, remove it from its mount prior to performing work.

Using a 1/4" socket, remove the mounting screw and remove the thermocouple from the stove. Trace the wires back to the control board and unplug the wires.

DIP Setting by Stove Model


The Control Board/ESP combination is responsible for all high limit safety control. There are 2 high limits, one normal operation high limit and one backup high limit. The control has an automatic diagnostic circuit that continuously monitors the ESP and Room Sensor for faults. If a fault should occur, the control sends a status alert and at the same time the unit goes down to minimum feed/ minimum burn as a safety condition.

In 2008 Harman changed the ESP probe for all units going forward. The change is notable by the color of the ESP wires, Black wires are Pre 2008 and Red Wires are Post 2008. THESE WERE ROLLING CHANGES AS NEW UNITS WERE MADE AND NOT ALL CHANGES HAPPENED JAN 1 2008.

  • For most units, dependent on the controller and/ revision, red thermocouples can be use in place of black thermocouples if the #5 DIP switch settings on the control board are set to 'ON', or 'UP'.

  • Black thermocouples have the #5 DIP switch setting 'OFF', or 'DOWN' however; red thermocouples are slightly larger in diameter than black ones and often will not fit into the mounting holes of black thermocouples on some units.

  • RED ESP wires cannot be cut and spliced.

  • Circuit board revisions ultimately dictate whether a black or red ESP should be used. See the chart below...