What's the difference between nominal and actual size?

Nominal size (e.g., 16x25x1) is the rounded "marketing" size printed on most filters and HVAC slots. Actual dimensions (e.g., 15.5 x 24.5 x 0.75 inches) are the exact physical measurements. They refer to the same filter — manufacturers make filters slightly smaller than nominal so they slide cleanly into the HVAC slot without binding.

How do I find out what size filter my furnace uses?

Pull out your current filter. The size is usually printed on the cardboard frame (16x25x1, 20x25x1, etc.). If no size is printed, measure the slot opening with a tape measure — the nominal size should be ½ inch larger than your slot dimensions in each direction.

Which MERV rating should I pick?

For most residential properties, Merv 11 is the sweet spot. Merv 8 is budget-friendly basic filtration; Merv 13 is high-end filtration that works in modern HVAC but may strain older systems. See our complete MERV guide for help choosing.

What if my furnace uses a custom or odd size?

We currently stock the 80+ most common nominal sizes. If your filter slot uses a non-standard size, contact us — we may be able to source it.

What kind of filters does Filterflow ship?

Pleated synthetic furnace filters with a recyclable beverage-board frame. All filters meet ASHRAE 52.2 standards for their MERV rating.

How does the subscription work?

Pick the filter size and MERV rating for each unit you manage. Filterflow ships a fresh filter to each unit's address on your chosen cadence (monthly, every 2 months, or every 3 months). You're billed at each shipment.

Is there a fee to cancel?

No. Cancel anytime from your account dashboard. No commitments, no fees, no questions asked.

Can I pause a subscription?

Yes. Pause for a specific number of months or indefinitely. Resume anytime. Useful for vacant units or seasonal properties.

Can I change the filter size or MERV mid-subscription?

Yes. Update size, MERV, cadence, or shipping address in your account. The next shipment will reflect your changes.

How much does it cost?

Pricing varies by filter size and MERV rating. Subscription pricing is typically 10–15% less than one-time purchase. Multi-unit discounts apply when you manage multiple subscriptions from one account.

Can I order one-time without subscribing?

Yes. Every product offers a one-time purchase option alongside subscription. Subscription is just cheaper and means you don't have to think about reordering.

Will the SMS reminders annoy my tenants?

One short text per month, sent the day the filter arrives. We've optimized message timing and tone — most tenants appreciate the heads-up. They can reply STOP at any time to opt out of messages.

What does the SMS message say?

Something like: "Hi [Name] — your monthly furnace filter just arrived. Quick 2-minute swap when you get a chance. Reply DONE when installed, or tap this link to confirm: [link]."

What if my tenant doesn't install the filter?

We send one polite follow-up text after a few days. If the install still isn't confirmed, you (the landlord) get notified so you can follow up directly. No tenant-chasing required on your end.

Do I need to give Filterflow my tenant's phone number?

Yes — that's how the SMS reminder works. We treat tenant contact info as confidential and never share it. Tenants can opt out of messaging without affecting the subscription.

What if there's no tenant — the unit is vacant?

Pause the subscription, or update the unit's "occupied" status in your dashboard. When occupied, you can update the tenant contact info anytime.

How long does shipping take?

Typically 3–5 business days from US warehouses. You'll receive a tracking link via email and the tenant gets one via SMS.

Where does Filterflow ship?

All 50 US states plus DC. We don't currently ship internationally.

Is shipping included in the subscription price?

Yes. Free shipping on all subscription orders. One-time orders have flat-rate shipping calculated at checkout.

Can I ship to multiple addresses from one subscription?

Yes — that's the whole point. Each unit in your dashboard has its own shipping address. Filters ship directly to each tenant's address; you're billed in one consolidated charge.

What if a filter arrives damaged?

Email support with a photo within 14 days. We'll ship a replacement at no charge.

Can I manage multiple properties or units?

Yes. Add as many units as you need from your account dashboard. Each unit has its own size, MERV rating, shipping address, and tenant contact. All managed in one place, billed together.

Is there a multi-unit discount?

Yes. Pricing tiers automatically apply based on the number of active unit subscriptions in your account. The more units, the lower the per-unit price.

Can I add a property manager or co-owner to my account?

Multi-user accounts are on our roadmap. For now, you can share account credentials with a co-manager or contact us about a managed account if you're operating at scale.

How are properties organized in the dashboard?

Group units under a property name (e.g., "Maple Street Apts"), then within each property add individual unit subscriptions. View all units at a glance, including filter status, last shipment date, and install confirmation status.

How do I update billing info?

From your account settings → payment methods. Changes apply to all future shipments.

Still have questions?

If you don't see your question covered above, we're happy to help.