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


A $70.00 Savings vs the OEM

SKU 3-20-00844-AMP
MPN 3-20-00844
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Frequently Bought Together


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

    Compatible Models


    • Absolute 43
    • Absolute 43-C
    • Absolute 63
    • Accentra 52i
    • Accentra 52i TC
    • Accentra Cast Free Standing
    • Accentra Insert
    • Advance
    • Allure 50
    • Allure 50-CE
    • DVC 500
    • Furnace & Boiler Systems
    • HF60
    • Invincible Insert
    • Invincible RS
    • P35i
    • P35i-C
    • P38
    • P38+
    • P43
    • P43-C
    • P61
    • P61-C
    • P61A
    • P68
    • P68-C
    • PB105
    • PC45
    • PF100
    • PF120
    • Pellet Pro II
    • XXV
    • XXV TC

    Technical Specs

    High Temp Limit 527°F



    Assembly Instructions For Harman Red Thermister Exhaust Sensing Probe (ESP), 3-20-00844-AMP

    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


    Harman Product Update: November 18, 2008 PDF Link

    1. If a Red probe is mistakenly used on an old board, the board will read it as an exhaust temperature of around 470° F at room temperature. Therefore, The Combustion and Distribution Blowers will be running immediately.
    2. If a Red probe is used on a new board without dip-switch #5 “ON”, the board will read it as an exhaust temperature of around 470° F at room temperature. Therefore, The Combustion and Distribution Blowers will be running immediately.
    3. If an old probe is used on new board with dip-switch #5 “ON”, the board will read it as an exhaust temperature of 572°F, and will show a “3 blink” status within 30 seconds. The Combustion and Distribution blowers will run as if in an over temperature condition.
    4. If there is insufficient draft, the circuit board will not send power to the feed motor or igniter, and the indicator lights will not be illuminated. However, it will increase the voltage to the combustion blower, in an attempt to improve the draft.
    5. If there is insufficient draft, the Combustion blower will not shut off during shut down, Regardless of ESP temperature. This is especially noticed if a door or hopper lid is left open during shut down.
    6. On the PC45, (3-20-05887), the five hour shut down timer has been eliminated with the use of a red probe.
    7. Make sure the feed motor is properly connected, including the terminal crimps and grounding wire. If not, the software may react as though there is insufficient draft, because the sensing device on the board is receiving a small amount of voltage through the feed motor circuit that should be diverted to ground.


    Unfortunately, sometimes products do not work like they are supposed to. We offer a 90 day warranty on manufacturer defects. Some manufacturers make this a very simple and easy process unfortunately others do not. Items must be used in accordance with the manufacturers guidelines to qualify for warranty replacement. Please be advised that warranty claims for these parts may take up to 4 weeks for processing, and customers must cover shipping.

    Shipping Info

    This Item Qualifies For Free Shipping With Orders Over $99!

    When Will My Order Ship

    All orders are typically processed within 24 hours of receiving payment and are shipped from us same day if placed before our shipping cutoff time (Monday - Friday: 1PM, Saturday: 10AM, Sunday: No Shipping), orders placed after our cutoff time are shipped the next morning.

    How Does Free Shipping Work?

    Most orders over $99 qualify for free shipping! Orders which ship for free are shipped with either USPS or UPS based on our discretion. If you are using a PO box, free shipping orders will always go USPS.

    Is Expedited Shipping Available?

    We offer both overnight and two day air shipping services for all orders placed within the Continental United States. For information on shipping cut-off times, go to our shipping page.

    Do You Ship To Canada?

    We ship to Canada! We estimate USPS to take 4-10 days once receiving your package from us. We do not offer expedited shipping of any kind to Canada. Please allow an extra 2-5 days for all shipments to Canada. Free shipping is not available to Canada.

    Do You Ship To Alaska Or Hawii?

    We ship to both Alaska and Hawaii! We do not offer next day or two day shipping to Alaska or Hawaii. Free shipping is not available to Alaska or Hawaii.

    Do You Ship Outside The US Or Canada?

    Unfortunately, at this time we do not offer international shipping other than to Canada.

    If you wish to calculate shipping for an item which does not qualify for free shipping, or if you would like the cost to expedite your order, please do the following. Add the item you want to order to your cart and click here to be taken to the cart page where you can enter your country, state / province, and zip code for an estimate.

    Shipping Time Estimations

    For information on shipping time estimations, see either the Shipping Information & Transit Times on the cart page, or go to our shipping page.

    Read More About Our Shipping Information

    Customer Reviews

    Based on 10 reviews
    It does what it's supposed to do.

    Fit perfectly, fixed the status code and the insert stove seems to work like new. Might be because I also did a tear down and compete cleaning while it was out but who cares, the part fit and worked as it should for less than a third the price.

    Harman Red Thermister Exhause Sensing Probe

    It worked as expected

    Harman pellet stove parts

    Nice and easy transaction, part well packaged and arrived in a timely manner. Installed and working fine.

    Harman P43 ESP

    New item was a perfect fit.
    Stove was pulsing off and on with no status light code. Figured this would be the first place to start. Replace the probe and stove is running like new


    Great price and fast international shipping .I will defiantly be ordering again


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