Harman (3-20-6866) Differential Pressure Sensor Vacuum Switch

We know that you want your purchase quickly, so we take every reasonable measure to ensure all orders are shipped within 1 - 2 business days from the date of purchase. In many cases, orders are shipped same day. Please note that we do not control courier delivery times, but all packages are sent expedited with one or more of the leading US based couriers (USPS, UPS, FedEx, etc). Tracking information is provided and is readily available via your order history.

Shipping & Returns

Please consult our shipping & returns terms for all questions related to shipping, returns, exchanges, refunds and warranty claims. We can also be reached directly by phone at 262-989-4882 or through email by contacting us directly.

Warranty Details

We believe you should feel safe when making a purchase from FireplaceBlowersOnline.com, which is why we offer a full 1 year warranty on all aftermarket blowers, fan kits and replacement parts. Please consult our product warranty page for additional warranty details.

Our warranty is a 1 year piece of mind that you're purchasing the most recognized aftermarket blower or fan kit available. We cover all parts and labor associated with the repair or replacement, we have incredibly fast turn around, and quite honestly the best customer service you'll find in the industry.

When we say we cover everything, we cover everything! Accessories like thermostats, rheostat variable speed controls, and power plugs are all covered under under our comprehensive 1 year warranty.

You pay no excess, less applicable return shippng fees, if you need to make a claim. Simply call us at 262-989-4882 or 262-989-4883 to make a claim with one our helpful associates or log into your account and request a return.

See below for additional information related to our products, their benefits and where they made.

Does it Fit?

Please consult the Compatibility section under Product Details in the Description tab. Or use the "Find Your Blower" tool located at the top of this page. If you're fireplace or model isn't listed, please contact us directly for additional installation support.

Installation Notes

Contractor installation instructions are provided with the the kit. Most kits are pre-wired for easy installation, but always consult with a professional if you experience problems during the installation. We're available by phone at 262-989-4882 to answer any installation questions you may have. You can also visit our helpful document center, where you can find installation manuals and videos related to this product. It's important to note that written instuctions can't always be provided for every model of fireplace, but we make every effort to provide OEM or our own instructions for your benefit. And for several of our products, we have helpful video installation tutorials that can help answer questions that written instructions along can not provide.

Assembled in USA

Our aftermarket fireplace blower kits are the culmination of years of our own research and development. It is designed in every sense to meet or exceed OEM specifications, which is why we back our claim with a comprehensive 1 year warranty. Don't be fooled by cheaper alternatives. Most of our competitors are simply overseas manufacturers or private label resellers.

All of our blower kits are assembled and tested in the USA (Racine, Wisconsin) and we make every reasonable effort to source parts, materials and supplies from US based manufacturers and suppliers. In fact, when you call us at 262-989-4882, you can speak with the person who will personally build and test your kit. Please be sure to compare our dimensions with your fireplace's available clearance and dimensions. While we provide instructions with each of our kits, the instructions can be limited due to the sheer number of fireplace manufacturers and fireplace models. We are always available by phone to assist or answer any questions you may have.

Here are some commonly asked questions we receive. If you don't see an answer to your question, feel free to contact us directly or use the Ask an Expert tool below for additional information. You can also consult our Frequently Asked Questions page for answers to additional questions.

Ask an Expert

• Can I install the blower myself?
  Yes, in most cases installation is a do-it-yourself job and requires little to no tools or experience. We're available by phone and email to support your installation, and we have a growing library of installation related content and videos available to you. You can find product related installation materials in our document center.
• How quickly do orders ship and where from?
  All orders are typically processed within 24 hours (1 business day) of receiving payment. Orders are shipped from us same day if placed before our shipping cutoff time (Monday - Friday: 1PM, Saturday: No Shipping, Sunday: No Shipping), orders placed after our cutoff time are shipped the next business morning. All orders are shipped from our Racine, Wisconsin location using a priority or expedited service with USPS or UPS. Courier selection is based on shipping location and delivery times can vary based on courier, service interuptions and location.
• Do you ship to Canada?
  Of course! We love our neighbors to the north and wouldn't leave you hanging. All Canadian shipments are made using a priority international service through USPS, FedEx or UPS. All orders are shipped within 1 - 2 business days. Delivery times can vary based on location, customs clearance and international courier (Canada Post) shipping times. For orders that can be shipped through FedEx, our preferred international courier, all duties and applicable taxes have already been paid!
• Do you ship to Alaska & Hawaii?
  Yes, although FREE shipping does NOT apply and no 2 or 3 day expedited service is available standard unless otherwise requested for and paid by the customer. Standard shipping is ground through UPS or USPS.
• Is there a warranty?
  Absolutely! We offer a comprehensive 1 year warranty from the date of purchase that covers the entire blower or fan kit, including all accessories and components. Please see our warranty for additional information pertaining to coverage and how to file a claim.
• How quiet are your blowers?
  This can be a difficult question to answer given the variables associated with blower noise. While we don't carry an official sone, dB or LP rating on our blowers, the blowers on their own are what we consider very quiet. We use extremely high quality Japanese sealed ball bearings and the construction of our blowers ensures smooth operation. However, noise from air movement, firebox resonation and room environment are all variables to consider. Remember that fireplace inserts are just metal boxes, so adding a blower that produces a significant amount of air flow, can give the impression that the blower is noiser than it really is. Some fireplace manufactures insulate their fireplaces better than others, which can also impact perceived noise. The addition of a variable speed controller or rheostat is an excellent way of controlling the RPM speed and air flow of the blower, thereby allowing for an effective method of reducing noise. Customers will often find a speed setting they're comfortable with. Others will prefer having control of the blower through a convenient wall-mounted variable speed dial. We would encourage you to watch some of our video content to get a better idea for how well the blowers are expected to perform and the noise you can expect from them.
• Can I make customizations to the blower kit?
  Yes, in many cases we can! We offer a variety of accessories, including variable speed controllers, thermostat sensors, remote controls, high temperature wiring and more. So if you need something slightly out of the box or would simply like to add an additional accessory, we can often times accommodate your request. The exception to this might be on some of our more complicated or fully integrated kits. These might include OEM kits or specialized blower kit assemblies that require a specific configuration.
• How does a blower's thermostat and rheostat work? Can I use a light dimmer switch?
  Thermostats, or limit switches, are heat sensitive sensors and are used in fireplace blower kit applications to automatically control when the blower turns on and off. They are most often used when a dedicated wall switch for the blower hasn't been installed or isn't available. However, they can still be used in home setups if a dedicated wall switch for the blower has been installed. In this case, the wall switch is left in the "ON" position and the thermostat sensor takes over control of the blower. Thermostat sensors come in several style, which will vary based on fireplace, installation location and temperature range.
  Rheostats, or variable speed controllers, are capacitance devices that regulate voltage and are what we refer to as TRIAC controllers. Voltage regulation is used to either reduce or increase the speed of the blower. A properly rated fan controller must be used in all fan kit applications. Light dimmers should not be used! While some light dimmers use TRIAC technology, they don't contain the necessary voltage regulation circuitry requied to operate an electric motor. Standard TRIAC light dimmers will cause fluctuations in current, which can damage an otherwise healthy electric motor. Newer light switches operate under a technology called VFD or Variable Frequency Drive. VFD devices control both voltage and frequency, which helps prevent light flickering, but most are not suitable for fan control. So it's important to use a variable speed control that is rated for fan and electric motor control. Both GE and Leviton have smart switches that are capable with fans, but must be used with a ZWave compatible hub in order to control them.
• How can I confirm this blower will fit my fireplace?

  Most fireplace manufacturers recommend the use of a specific blower kit in their fireplace. The blower or fan kit recommended by the manufacturer can typically be found in your owner's or service manual. You can also use our helpful Find Your Blower tool at the top of the page to match your fireplace's brand and model to the correct blower kit. And finally, you can also reference the Does It Fit section in the description of every blower kit we sell, which itemizes the brands and models that each blower kit or replacement blower is compatible with. If you don't see your brand or model listed, please reach out to us directy by clicking the Ask an Expert button below, and one of our expert staff will reach out to you with assistance.

  Ask an Expert

• What are the benefits of installing a blower?
  Adding a blower to a fireplace can signifcantly improve the heating efficiency of your fireplace! For additional information on the benefits of adding a fireplace blower, we would encourage you to read our How Does a Fireplace Blower Work? article.