No image available
+5% Tax • Shipping calculated at checkout.
U.S. Duties/Taxes, if applicable, may be due at time of delivery.
Pickup available at 75 Blue Mountain St #3
Usually ready in 24 hours
This high-performance differential air pressure switch is a vital safety component for HVAC systems and air handling units. Designed to function as an air proving switch, it monitors the pressure difference across blowers, filters, or coils to ensure proper airflow is maintained during operation. By detecting changes in air pressure within a range of -40 to 15, it prevents the system from running under unsafe or inefficient conditions, such as a blocked vent or a failing motor. This switch is a common replacement part for heating and cooling equipment that fails to trigger ignition or experiences frequent safety shutdowns due to airflow detection errors.
Our team is happy to help you verify compatibility before you order. We'll confirm it fits your specific furnace model.
1-778-759-9864Mon–Sat 8AM–5PM PT · Or email parts@bcfurnace.com
Compatible parts and related replacements
Yes, the 021-870 is a genuine OEM, or a factory replacement manufacturer approved part. We source all Air Pressure Switches from authorized distributors to ensure exact-fit compatibility. This Air Pressure Switch is backed by our 100% compatibility guarantee — if it doesn't fit your furnace, we'll make it right.
The easiest way is to match the part number (021-870) with your furnace model number. Visit the homepage and enter your model number in the search bar — our system will show all compatible Air Pressure Switches for your specific unit. You can also call our technicians at 1-778-759-9864 for free compatibility verification.
Most Air Pressure Switches including the 021-870 ship within 1–2 business days from our warehouse. We ship across Canada and the United States, and worldwide, with tracking on every order. For urgent furnace repairs, contact us at 1-778-759-9864 for expedited shipping options.
Yes! Local pickup is available at our Coquitlam, BC location: 75 Blue Mountain St #3. Air Pressure Switches orders are usually ready within 24 hours. Call us at 1-778-759-9864 to confirm the 021-870 is in stock before visiting.
Still not sure this is the right part? Call 1-778-759-9864 and we will check your model number with you.
The model number is on the rating plate inside the furnace door.
Looking for more Air Pressure Switches?
