Skip to main content
Skip to main content
Product title:

Harman Differential Pressure Sensor Vacuum Switch: 3-20-6866-AMP

Product rating:
Product price:
$27.99

A $12.00 Savings over the OEM

Product SKU ! 3-20-6866-AMP
Product MPN ! 3-20-6866
Product availability: In Stock
Bullet point features

Frequently Bought Together

Total Price: $50.97

Description

A pressure switch is often referred to as a vacuum switch. This sensor is looking for airflow within the stove to close the circuit to the feed system and the igniter. If your stove is feeding pellets, your pressure switch is ok. For the switch to work properly, the hopper and the front door must be making a tight seal. Almost all of the time, the switch is good but there is an air leak or point of failure somewhere else within the stove. For example, a clogged vent or burnt-out combustion blower motor.

This switch is calibrated to close the ignition and feed circuit at .10 WC PF.

See our Helpful hints and instructions for troubleshooting information.

Vacuum Switch Visual Note: The manufacturer of all OEM and AMP switches has made a design change. The switch received may appear different, but will work the same.



Replacement For Part Numbers:

  • 3-20-6866
  • 3-20-9301
  • 3-20-3433
  • SRV8320-003

View Compatible Models

UPC: 652174670475

Compatible Models

    Harman

  • Absolute 43
  • Absolute 43-C
  • Absolute 63
  • Accentra 52i
  • Accentra 52i TC
  • Accentra Cast FS
  • Accentra Insert
  • Advance
  • Allure 50
  • Allure 50-CE
  • HF60
  • P35i
  • P35i-C
  • P38
  • P38+
  • P43
  • P43-C
  • P61-A
  • P61-C
  • P61A
  • P68
  • P68-C
  • PB105
  • PC45
  • PF100
  • PF120
  • XXV
  • XXV TC

Technical Specs

Normal Position Open
Closed Position .10 WC

Instructions

Install Instructions For Harman Differential Pressure Sensor Vacuum Switch: 3-20-6866-AMP

The switch is located in the rear of the stove. There is a white wire coming from the controller to one side of the switch and there are two light blue wires connected at the terminal on the other side of the switch. These light blue wires run to the igniter and to the feed motor. To change the switch, disconnect the white wire and double blue wires from the switch, disconnect the air tube, replace the switch and then connect the wires and tube back to the switch.

Troubleshooting

If the stove is not feeding and you are getting a vacuum error, 99.99% there is usually nothing at all wrong with the switch. The switch is simply sensing an airflow problem and is doing the job it was designed to do. The switch is normally open, which means no power can flow through the switch until the switch senses enough airflow to close the contacts.


The most important thing to know about the pressure switch is:


  • if there is a problem with the switch, the stove's feed system will not dispense pellets because the auger motor is not getting power.
  • unlike most brands, there is no vacuum error code on Harman Pellet Stoves


Common things that cause the switch to remain open are:


  • Excessively Dirty Stove
  • Clogged vent
  • Burnt out of worn out combustion blower
  • Door Gaskets: poor seal on stove door or ash pan door
  • Door Handle: Handle mechanism is broken and the door cannot close properly
  • Bad Hopper Gasket
  • Missing hardware or broken latch on hopper lid
  • Ash pan must be in stove to create proper air flow
  • Combustion motor cover must be installed and seated properly
  • Fines collection box cover must be installed and tightly sealed
  • Units with a hopper lid switch, the switch can fail
  • Units that take the pressure reading from inside the hopper (early versions of the XXV, Accentra and Accentra Insert) can have a broken filter at the end of the vacuum hose or the vacuum hose may have fallen off the end mount
  • Accentra Inserts - Hopper lid can be hinge bound and not seating



Warranty

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 Information

This Item Qualifies For Free Shipping With Orders Over $49!

HOLIDAY UPDATE
Due to the upcoming Christmas and New Years holidays, shippers will not be picking up on the dates below. Additionally, packages may take longer to arrive than expected. We appreciate your understanding and patience during this time.

  • USPS: No pickup on Dec 24th, Dec 25th, and Jan 1st.
  • UPS: No pickup on Dec 24th (except NDA and 2nd Day), Dec 25th, Dec 31st (except NDA and 2nd Day), and Jan 1st.
CANADA UPDATE

Due to the ongoing Canada Post postal workers' strike, we are forced to suspend all ordering to Canada. Please be advised that any shipments that did not clear U.S. customs by November 15th will be delayed until Canada Post is fully operational. We appreciate your understanding and patience during this time.

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: 12PM, Saturday: 10AM, Sunday: No Shipping), orders placed after our cutoff time are shipped the next morning.

Do You Offer Express Shipping?

Yes! Please note the shipping times are based on business days, weekends and holidays do not count to the delivery date. Please see our expedited ship time schedules here.

How Does Free Shipping Work?

Most orders over $49 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.

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 Hawaii?

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.

Shipping Time Estimations

For information on shipping time estimations, see the Shipping Information & Transit Times on the shipping page.

Learn More About Our Shipping Information
Jump back to product information tab navigation

Description

A pressure switch is often referred to as a vacuum switch. This sensor is looking for airflow within the stove to close the circuit to the feed system and the igniter. If your stove is feeding pellets, your pressure switch is ok. For the switch to work properly, the hopper and the front door must be making a tight seal. Almost all of the time, the switch is good but there is an air leak or point of failure somewhere else within the stove. For example, a clogged vent or burnt-out combustion blower motor.

This switch is calibrated to close the ignition and feed circuit at .10 WC PF.

See our Helpful hints and instructions for troubleshooting information.

Vacuum Switch Visual Note: The manufacturer of all OEM and AMP switches has made a design change. The switch received may appear different, but will work the same.



Replacement For Part Numbers:

  • 3-20-6866
  • 3-20-9301
  • 3-20-3433
  • SRV8320-003

View Compatible Models

UPC: 652174670475

Compatible Models

    Harman

  • Absolute 43
  • Absolute 43-C
  • Absolute 63
  • Accentra 52i
  • Accentra 52i TC
  • Accentra Cast FS
  • Accentra Insert
  • Advance
  • Allure 50
  • Allure 50-CE
  • HF60
  • P35i
  • P35i-C
  • P38
  • P38+
  • P43
  • P43-C
  • P61-A
  • P61-C
  • P61A
  • P68
  • P68-C
  • PB105
  • PC45
  • PF100
  • PF120
  • XXV
  • XXV TC

Technical Specs

Normal Position Open
Closed Position .10 WC

Instructions

Install Instructions For Harman Differential Pressure Sensor Vacuum Switch: 3-20-6866-AMP

The switch is located in the rear of the stove. There is a white wire coming from the controller to one side of the switch and there are two light blue wires connected at the terminal on the other side of the switch. These light blue wires run to the igniter and to the feed motor. To change the switch, disconnect the white wire and double blue wires from the switch, disconnect the air tube, replace the switch and then connect the wires and tube back to the switch.

Troubleshooting

If the stove is not feeding and you are getting a vacuum error, 99.99% there is usually nothing at all wrong with the switch. The switch is simply sensing an airflow problem and is doing the job it was designed to do. The switch is normally open, which means no power can flow through the switch until the switch senses enough airflow to close the contacts.


The most important thing to know about the pressure switch is:


  • if there is a problem with the switch, the stove's feed system will not dispense pellets because the auger motor is not getting power.
  • unlike most brands, there is no vacuum error code on Harman Pellet Stoves


Common things that cause the switch to remain open are:


  • Excessively Dirty Stove
  • Clogged vent
  • Burnt out of worn out combustion blower
  • Door Gaskets: poor seal on stove door or ash pan door
  • Door Handle: Handle mechanism is broken and the door cannot close properly
  • Bad Hopper Gasket
  • Missing hardware or broken latch on hopper lid
  • Ash pan must be in stove to create proper air flow
  • Combustion motor cover must be installed and seated properly
  • Fines collection box cover must be installed and tightly sealed
  • Units with a hopper lid switch, the switch can fail
  • Units that take the pressure reading from inside the hopper (early versions of the XXV, Accentra and Accentra Insert) can have a broken filter at the end of the vacuum hose or the vacuum hose may have fallen off the end mount
  • Accentra Inserts - Hopper lid can be hinge bound and not seating



Warranty

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 $49!

HOLIDAY UPDATE
Due to the upcoming Christmas and New Years holidays, shippers will not be picking up on the dates below. Additionally, packages may take longer to arrive than expected. We appreciate your understanding and patience during this time.

  • USPS: No pickup on Dec 24th, Dec 25th, and Jan 1st.
  • UPS: No pickup on Dec 24th (except NDA and 2nd Day), Dec 25th, Dec 31st (except NDA and 2nd Day), and Jan 1st.
CANADA UPDATE

Due to the ongoing Canada Post postal workers' strike, we are forced to suspend all ordering to Canada. Please be advised that any shipments that did not clear U.S. customs by November 15th will be delayed until Canada Post is fully operational. We appreciate your understanding and patience during this time.

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: 12PM, Saturday: 10AM, Sunday: No Shipping), orders placed after our cutoff time are shipped the next morning.

Do You Offer Express Shipping?

Yes! Please note the shipping times are based on business days, weekends and holidays do not count to the delivery date. Please see our expedited ship time schedules here.

How Does Free Shipping Work?

Most orders over $49 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.

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 Hawaii?

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.

Shipping Time Estimations

For information on shipping time estimations, see the Shipping Information & Transit Times on the shipping page.

Learn More About Our Shipping Information

Customer Reviews

Based on 10 reviews
100%
(10)
0%
(0)
0%
(0)
0%
(0)
0%
(0)
S
Stephen H.
Harman XXV parts purchase

I ordered a combustion fan and distribution fan, sensor and a pressure switch. Parts are high quality, most likely same as oem. With the info available on this site I was able to trouble shoot and select the right parts. Parts that fit several models came with instructions on how to wire. Great experience and my Harman XXV is back to nearly silent operation and works properly again.

P
Paul L.
vaccum switch, igniter

Parts were as ordered, fast service

D
Deborah S.
Vacuum Switch, 3-20-6866-AMP

haven't installed it yet but sure it will be fine. shipping was quick.

N
Nathan r.
Direct replacement

Fantastic to have my stove up running again. Fast shipping.

G
GDS
Pressure Switch

I appreciate that you carry all the necessary parts for woodburning pellet stoves. Your website is easy to navigate and finding parts that I need is a breeze.

12

QUESTIONS & ANSWERS

If your question does not concern this specific product, use our contact form

Have a Question?

Be the first to ask a question about this.

Ask a Question

Customer Reviews

Based on 10 reviews
100%
(10)
0%
(0)
0%
(0)
0%
(0)
0%
(0)
S
Stephen H.
Harman XXV parts purchase

I ordered a combustion fan and distribution fan, sensor and a pressure switch. Parts are high quality, most likely same as oem. With the info available on this site I was able to trouble shoot and select the right parts. Parts that fit several models came with instructions on how to wire. Great experience and my Harman XXV is back to nearly silent operation and works properly again.

P
Paul L.
vaccum switch, igniter

Parts were as ordered, fast service

D
Deborah S.
Vacuum Switch, 3-20-6866-AMP

haven't installed it yet but sure it will be fine. shipping was quick.

N
Nathan r.
Direct replacement

Fantastic to have my stove up running again. Fast shipping.

G
GDS
Pressure Switch

I appreciate that you carry all the necessary parts for woodburning pellet stoves. Your website is easy to navigate and finding parts that I need is a breeze.

12
Liquid error (layout/theme line 255): Could not find asset snippets/iStock-notify-me.liquid