furnacefiltersize.com
Furnace filters for small landlords (1–20 doors).
Second Nature’s PM product is built around property-management-system sync and resident-benefits packing. Consumer pricing in a June 2026 This Old House review: $10–$26 per filter, free shipping, one MERV per shipment. That stack is overkill under ~20 doors and often under ~50. This page is for owners who will never buy resident-benefits software.
The failure mode
Each unit has a different slot; the super buys a case of 20x25x1; half of them rattle. The fix is a unit → size → MERV → cadence list, not a subscription brand.
- Mixed-size cases: Filterbuy and Nordic Pure will ship mixed sizes. Amazon S&S will not mix well. FiltersFast is for the two doors that have Aprilaire/Carrier cabinets.
- Cadence: 1-inch pleated every 60–90 days (Carrier/Trane); media 6–12 months. Turnover / pets / smoking units: 30 days. Put that on the unit card, not a building-wide 90-day rule.
- Liability: do not put MERV 13 1-inch in older PSC apartments. Default landlord 1-inch spec: MERV 8 or 11. MERV 13 only in 4/5-inch cabinets or where a tech has said the blower will take it. Link: 1-inch MERV 13 (draft).
- No inventory: we generate a CSV/print checklist and affiliate the order. We do not warehouse 12 SKUs.
Spreadsheet template
Columns: Unit | Address | Slot location | Nominal size | Cabinet part | MERV cap | Cadence | Merchant.
Download CSV template (4-door example) Same example, generated in the browser
Pack-out example: 4 doors, three sizes
| Unit | Size | MERV cap | Cadence | Merchant |
|---|---|---|---|---|
| #1 hallway grille | 16x25x1 | 11 | 60–90 days | Filterbuy mixed case |
| #2 basement slot, pets | 20x25x1 | 11 | 30–60 days | Filterbuy mixed case |
| #3 closet, Aprilaire 2210 | OEM 213 | 13 | 12 months | FiltersFast |
| #4 odd return | custom 17.50 × 22.25 × 1 | 11 | 60–90 days | Filterbuy custom (non-returnable) |
CTA: Filterbuy mixed/odd primary; FiltersFast for cabinet SKUs; Amazon only for doors on 16x20x1 / 16x25x1 / 20x20x1 / 20x25x1.
Add a unit (nothing is saved on our server)
v1 stores rows in this browser via localStorage, then you download CSV. Fill unit / address / slot if you want those columns; occupancy defaults to landlord in your head — set it on the finder too.
Reminder: one ICS file with staggered dates is still a to-do; for v1 use the first-of-the-month ICS or download a staggered 4-door example ICS. We do not run an email list.
Finder · odd / custom · cabinets · cadence matrix.