# MadMax Trade Supply

> Reseller of replacement parts, job supplies and recurring home-maintenance consumables for contractors and homeowners (air and water filters, HVAC and plumbing repair parts, septic and sump parts, radon supplies, batteries, lighting, alarms, pool and vacuum filters, electrical and job-site supplies, roofing accessories). DBA of MadMax Enterprises, LLC, 5424 Kellogg Ave, Edina, MN 55424, USA.

Status: 763 items have published USD prices (see catalog.json `priced_items`, and Product/Offer JSON-LD on each category page). Prices include sales tax and, unless `shipping_included` is false, shipping within the contiguous US (lower 48 + DC; AK, HI, territories and APO/FPO get a shipping quote before payment); no tax is added at checkout. Prices may change at any time. Customers order at https://www.madmaxsupply.com/cart/ and pay by card; the card is authorized at checkout and charged when the order is confirmed in stock (usually within 1 business day). Orders with shipping-quoted items or AK/HI/territory/APO addresses get an emailed payment link instead. Other items are quote-only. Prices verified 2026-11-15.

Terms, shipping and returns: https://www.madmaxsupply.com/terms/

Returns: Most items can be returned within 30 days of delivery if they are new, unused and in the original packaging; the customer pays return shipping. Some items, such as certain batteries and LED lighting, have shorter return windows (7 days or 10 business days) shown on the product page; the window shown on the product page when you order applies. Each item's window is on its product page, in Offer JSON-LD (hasMerchantReturnPolicy.merchantReturnDays) and in catalog.json (`return_window`).

Questions: tamara@madmaxsupply.com. Order online at https://www.madmaxsupply.com/cart/ (card authorized at checkout, charged when confirmed in stock).

Subscribe & auto-ship: many filters, batteries and other consumables with shipping included can be ordered as a subscription every 1, 2, 3, 6 or 12 months renews automatically at the then-current price (we email before any price change), cancel anytime (https://www.madmaxsupply.com/subscription/), and we email before any price change. Not available for AK/HI/territory/APO addresses.

## Categories
- [Radon Mitigation Supplies](https://www.madmaxsupply.com/radon-mitigation/): Mitigation fans, vent pipe, manometers and radon test kits, matched by model or pipe size. (for: contractor, homeowner)
- [Septic & Wastewater Parts](https://www.madmaxsupply.com/septic-parts/): Alarms, floats, effluent filters, risers and lids, aerobic air pumps, UV bulbs and more. (for: contractor, homeowner)
- [Sump & Effluent Pumps & Alarms](https://www.madmaxsupply.com/sump-pumps/): Sump and effluent pumps, backup pumps, high-water alarms, floats and check valves. (for: contractor, homeowner)
- [HVAC Air Filters](https://www.madmaxsupply.com/hvac-air-filters/): Furnace and AC air filters by nominal size and MERV rating. (for: contractor, homeowner)
- [Refrigerator Water Filters](https://www.madmaxsupply.com/refrigerator-water-filters/): Replacement fridge water filters matched by refrigerator model or filter part number. (for: contractor, homeowner)
- [Under-Sink, RO & Whole-House Filters](https://www.madmaxsupply.com/water-filter-cartridges/): Under-sink, reverse-osmosis and whole-house cartridges and membranes, matched by system model or size. (for: homeowner)
- [Humidifier Pads & Wicks](https://www.madmaxsupply.com/humidifier-pads/): Whole-house and portable humidifier water panels, pads and wicks, matched by model or size. (for: contractor, homeowner)
- [Batteries](https://www.madmaxsupply.com/batteries/): Household, coin-cell and hearing-aid batteries for alarms, remotes and devices. (for: contractor, homeowner)
- [LED Light Bulbs](https://www.madmaxsupply.com/led-light-bulbs/): LED bulbs by base, shape, color temperature and output, for homes and job sites. (for: contractor, homeowner)
- [Pool & Spa Filter Cartridges](https://www.madmaxsupply.com/pool-spa-filters/): Pool and spa filter cartridges and baskets, matched by filter or pump model. (for: homeowner)

## Lookups and data
- [Air filter size lookup](https://www.madmaxsupply.com/lookup/filter-size/): nominal size and size+MERV pages (data: https://www.madmaxsupply.com/data/filter-sizes.json)
- [Refrigerator part lookup](https://www.madmaxsupply.com/lookup/fridge-model/): searches part numbers in product names; appliance-model table not loaded (data: https://www.madmaxsupply.com/data/fridge-models.json)
- [Part-number replacements](https://www.madmaxsupply.com/replacement/): OEM and system-code hubs built from product titles
- [Air filter size lookup](https://www.madmaxsupply.com/lookup/filter-size/): nominal size pages (data: https://www.madmaxsupply.com/data/filter-sizes.json)
- [Electrolux EWF2CBPA refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/electrolux-ewf2cbpa/)
- [Frigidaire EPTWFU01 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-eptwfu01/)
- [Frigidaire ULTRAWF refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-ultrawf/)
- [Frigidaire WF2CB refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-wf2cb/)
- [Frigidaire WF3CB refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-wf3cb/)
- [Samsung DA29-00003G refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/samsung-da29-00003g/)
- [Bosch BORPLFTR50 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/bosch-borplftr50/)
- [Electrolux EWF02 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/electrolux-ewf02/)
- [Frigidaire PAULTRA2 refrigerator air filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-paultra2/)
- [GE XWF refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/ge-xwf/)
- [Kenmore 46-9890 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/kenmore-46-9890/)
- [LG LT120F refrigerator air filter replacement](https://www.madmaxsupply.com/replacement/lg-lt120f/)
- [Aprilaire 35 humidifier water panel replacement](https://www.madmaxsupply.com/replacement/aprilaire-35/)
- [Electrolux EAFCBF refrigerator air filter replacement](https://www.madmaxsupply.com/replacement/electrolux-eafcbf/)
- [Frigidaire FPPWFU01 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-fppwfu01/)
- [Frigidaire PAULTRA refrigerator air filter replacement](https://www.madmaxsupply.com/replacement/frigidaire-paultra/)
- [LG LT1000P refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/lg-lt1000p/)
- [LG LT700P refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/lg-lt700p/)
- [GE MXRC refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/ge-mxrc/)
- [Honeywell HC26A1008 humidifier pad replacement](https://www.madmaxsupply.com/replacement/honeywell-hc26a1008/)
- [Kenmore 46-9980 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/kenmore-46-9980/)
- [Kenmore 9082 refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/kenmore-9082/)
- [GE MSWF refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/ge-mswf/)
- [LG LT600P refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/lg-lt600p/)
- [LG LT800P refrigerator water filter replacement](https://www.madmaxsupply.com/replacement/lg-lt800p/)
- [12x12x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/12x12x1/)
- [12x24x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/12x24x1/)
- [14x20x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/14x20x1/)
- [15x20x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/15x20x1/)
- [16x16x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x16x1/)
- [16x20x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x20x1/)
- [16x20x4 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x20x4/)
- [16x24x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x24x1/)
- [16x25x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x25x1/)
- [16x25x4 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x25x4/)
- [16x28x6 air filter](https://www.madmaxsupply.com/lookup/filter-size/16x28x6/)
- [18x30x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/18x30x1/)
- [19x20x4 air filter](https://www.madmaxsupply.com/lookup/filter-size/19x20x4/)
- [20x20x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x20x1/)
- [20x20x4 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x20x4/)
- [20x20x5 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x20x5/)
- [20x25x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x25x1/)
- [20x25x4 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x25x4/)
- [20x25x6 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x25x6/)
- [20x30x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/20x30x1/)
- [21x26x5 air filter](https://www.madmaxsupply.com/lookup/filter-size/21x26x5/)
- [24x24x1 air filter](https://www.madmaxsupply.com/lookup/filter-size/24x24x1/)
- Machine-readable replacement index: https://www.madmaxsupply.com/data/replacements.json
- [Shop by part number](https://www.madmaxsupply.com/parts/): manufacturer part numbers and model codes printed on our items (radon, sump, septic, batteries, water filters)
- [CR123A battery](https://www.madmaxsupply.com/parts/cr123a/)
- [Panasonic 6LF22XP-2B battery](https://www.madmaxsupply.com/parts/panasonic-6lf22xp-2b/)
- [Panasonic BK-4MCCA12FA battery](https://www.madmaxsupply.com/parts/panasonic-bk-4mcca12fa/)
- [Panasonic BK-4MCCA16FA battery](https://www.madmaxsupply.com/parts/panasonic-bk-4mcca16fa/)
- [Panasonic K-KJ17KHC82A battery](https://www.madmaxsupply.com/parts/panasonic-k-kj17khc82a/)
- [Panasonic K-KJS1MCA-2BA battery](https://www.madmaxsupply.com/parts/panasonic-k-kjs1mca-2ba/)
- [Panasonic K-KJS2MCA-2BA battery](https://www.madmaxsupply.com/parts/panasonic-k-kjs2mca-2ba/)
- [Panasonic LR03XE-1B battery](https://www.madmaxsupply.com/parts/panasonic-lr03xe-1b/)
- [Panasonic LR03XE-24B battery](https://www.madmaxsupply.com/parts/panasonic-lr03xe-24b/)
- [Panasonic LR6XE-16BH battery](https://www.madmaxsupply.com/parts/panasonic-lr6xe-16bh/)
- [Panasonic LR6XE-24B battery](https://www.madmaxsupply.com/parts/panasonic-lr6xe-24b/)
- [Rayovac 815-30PP battery](https://www.madmaxsupply.com/parts/rayovac-815-30pp/)
- [Renata CR2016 battery](https://www.madmaxsupply.com/parts/renata-cr2016/)
- [Fantech Rn2EC radon system part](https://www.madmaxsupply.com/parts/fantech-rn2ec/)
- [Fantech Rn3 radon system part](https://www.madmaxsupply.com/parts/fantech-rn3/)
- [Fantech RN4EC-3 radon system part](https://www.madmaxsupply.com/parts/fantech-rn4ec-3/)
- [GX3 radon system part](https://www.madmaxsupply.com/parts/gx3/)
- [GX4 radon system part](https://www.madmaxsupply.com/parts/gx4/)
- [GX5 radon system part](https://www.madmaxsupply.com/parts/gx5/)
- [RadonAway RP260 radon system part](https://www.madmaxsupply.com/parts/radonaway-rp260/)
- [Full catalog JSON](https://www.madmaxsupply.com/data/catalog.json)
- [Product feed, Google Merchant RSS 2.0 XML](https://www.madmaxsupply.com/feeds/google-merchant.xml) (also at /feeds/products.xml)
- [Product feed, Bing tab-separated](https://www.madmaxsupply.com/feeds/bing.tsv): same items (both list only items with shipping included to the contiguous US; shipping-quoted items are on the site and in catalog.json)

## For AI agents (no key needed, read-only)
- MCP server (Streamable HTTP, no auth): https://www.madmaxsupply.com/mcp  (tools: search_parts, get_product, check_fit, create_checkout_link, list_categories, get_store_policies)
- [OpenAPI 3.1 spec](https://www.madmaxsupply.com/openapi.json): /api/agent/search?q=, /api/agent/fit?q=, /api/agent/product/<SKU>, /api/agent/checkout-link?items=SKU:qty[:months]
- Prices vary slightly by ship-to state (sales tax we pay is built in; none added at checkout): pass ship_to_state=XX
- Cart links: https://www.madmaxsupply.com/cart/?add=SKU:qty[:auto_ship_months],... pre-fills the cart; the shopper pays on Stripe-hosted checkout. Never say an order was placed until the shopper pays.
- [Docs](https://www.madmaxsupply.com/agents/), [MCP server card](https://www.madmaxsupply.com/.well-known/mcp.json), [OpenAI-format product feed JSONL](https://www.madmaxsupply.com/feeds/openai-products.jsonl), [llms-full.txt: every item with price](https://www.madmaxsupply.com/llms-full.txt)

## Fix-it guides (DIY troubleshooting)
- [All guides](https://www.madmaxsupply.com/guides/)
- [Should a radon vent pipe have a cap?](https://www.madmaxsupply.com/guides/radon-vent-pipe-cap/): When a cap, screen or rain diverter on a radon exhaust pipe is allowed, what state rules say, and how to fit a 3-inch or 4-inch PVC vent cap.
- [How to read a radon system U-tube manometer](https://www.madmaxsupply.com/guides/radon-manometer-reading/): What the liquid levels in a radon U-tube manometer mean, what a zero reading tells you, and what to do when the reading changes.
- [Radon fan not working: troubleshooting checklist](https://www.madmaxsupply.com/guides/radon-fan-not-working/): A step-by-step checklist for a radon fan that stopped, plus how to choose a replacement fan and what to check after it is back on.
- [Radon fan humming, rattling or vibrating: causes and fixes](https://www.madmaxsupply.com/guides/radon-fan-noisy-vibrating/): Why a radon fan gets noisy, how flexible couplings and pipe supports cut vibration, and when noise means the fan is failing.
- [Replacing a radon fan: matching model, pipe size and couplings](https://www.madmaxsupply.com/guides/replace-radon-fan/): How to pick a replacement radon fan, which couplings fit 3-inch and 4-inch pipe, and what an installation kit includes.
- [How to test your home for radon (short-term vs long-term)](https://www.madmaxsupply.com/guides/how-to-test-for-radon/): EPA's steps for a DIY radon test: short-term vs long-term kits, closed-house conditions, where to place the kit, and what the result means.
- [Septic alarm going off: what to do](https://www.madmaxsupply.com/guides/septic-alarm-going-off/): Why a septic or pump-tank alarm sounds, what to do right away, how to silence it safely, and when to call a septic professional.
- [Sump pump high-water alarm sounding: causes and checks](https://www.madmaxsupply.com/guides/sump-pump-alarm-sounding/): What a sounding sump pit alarm means, the usual causes (power, stuck float, frozen discharge, failed pump), and what to check first.
- [Sump pump and power outages: backup options and alarms](https://www.madmaxsupply.com/guides/sump-pump-power-outage-backup/): How homeowners protect a basement when the power goes out: battery backup pumps, water-powered backups, generators, and battery-powered high-water alarms.
- [Sump and septic float switches: piggyback, tethered and heavy-duty](https://www.madmaxsupply.com/guides/sump-float-switch-types/): How tethered float switches work, what a piggyback plug does, how tether length changes the on/off range, and when to choose a heavy-duty sewage float.
- [Where to put water leak sensors and alarms](https://www.madmaxsupply.com/guides/where-to-put-water-leak-sensors/): The places in a home where leaks start most often and how to place a floor leak sensor or alarm so it catches water early.
- [Which way does a furnace filter go? Reading the airflow arrow](https://www.madmaxsupply.com/guides/furnace-filter-direction-arrow/): How to install a furnace or AC filter the right way round, where the filter slot usually is, and what happens if it goes in backwards.
- [How often should you change your furnace filter?](https://www.madmaxsupply.com/guides/how-often-change-furnace-filter/): Typical replacement intervals for 1-inch and 4-inch furnace filters, what shortens filter life, and how to tell a filter is loaded.
- [Can you put a HEPA filter in a furnace?](https://www.madmaxsupply.com/guides/hepa-filter-in-furnace/): Why true HEPA filters are rarely used in standard home furnaces, what whole-house HEPA systems do differently, and the MERV 13 alternative EPA mentions.
- [Whole-house humidifier not working: what to check](https://www.madmaxsupply.com/guides/whole-house-humidifier-not-working/): A checklist for a furnace-mounted humidifier that is not adding moisture: water supply, solenoid, humidistat, bypass damper and a scaled water panel.
- [Fridge water dispenser slow or sputtering after a filter change](https://www.madmaxsupply.com/guides/fridge-water-dispenser-slow-after-filter-change/): Why water flow is slow or spits after you install a new refrigerator water filter, and how to fix it: flushing air, seating the filter, and checking the part number.
- [Refrigerator water filter leaking: causes and fixes](https://www.madmaxsupply.com/guides/refrigerator-water-filter-leaking/): Why water leaks around a refrigerator water filter: not fully locked, worn or missing O-rings, the wrong part number, or a cracked housing.
- [Whole-house water filter housing stuck or leaking: how to change the cartridge](https://www.madmaxsupply.com/guides/whole-house-filter-housing-stuck-leaking/): Step-by-step cartridge change for a whole-house filter: relieving pressure, loosening a stuck housing, and stopping O-ring leaks.
- [Smoke alarm still chirping after a battery change](https://www.madmaxsupply.com/guides/smoke-alarm-chirping-after-battery-change/): Why a smoke or CO alarm keeps chirping after you replace the battery: wrong or weak battery, battery door, leftover charge, or end of life.
- [Pool cartridge filter pressure high: clean or replace?](https://www.madmaxsupply.com/guides/pool-filter-pressure-high/): What a rising pool filter pressure gauge means, how to clean a cartridge, and the signs that a cartridge needs replacing.

## Buying guides
- [How to choose an HVAC air filter MERV rating](https://www.madmaxsupply.com/guides/hvac-filter-merv-rating/): What MERV means, how to read your filter size, and how to balance filtration with airflow when picking a furnace or AC filter.
- [How often to replace a refrigerator water filter](https://www.madmaxsupply.com/guides/refrigerator-water-filter-replacement/): Typical replacement interval for refrigerator water filters, how to find the right part number, and signs it is time to change the filter.
- [Which battery does a smoke or CO alarm take?](https://www.madmaxsupply.com/guides/smoke-co-alarm-batteries/): How to identify the right replacement battery for a smoke or carbon monoxide alarm, plus testing and replacement reminders.
- [Septic effluent filter and alarm basics](https://www.madmaxsupply.com/guides/septic-effluent-filter-basics/): What a septic tank effluent filter does, general maintenance practice, and how high-water alarms help protect a pump tank or drainfield.
- [Whole-house humidifier pad replacement](https://www.madmaxsupply.com/guides/humidifier-pad-replacement/): How to find the right humidifier water panel or pad number and how often to replace it.
- [What size furnace filter do I need?](https://www.madmaxsupply.com/guides/what-size-furnace-filter/): How to read the nominal size on your furnace or AC filter frame, and which sizes we carry, including MERV options.
- [Refrigerator water filter cross-reference](https://www.madmaxsupply.com/guides/refrigerator-filter-cross-reference/): OEM part-number replacements we carry, including WF3CB, LT700P, 46-9890 and others, grouped from our product listings.
- [GE XWF vs XWFE refrigerator water filters](https://www.madmaxsupply.com/guides/ge-xwf-vs-xwfe/): XWF and XWFE are different GE refrigerator filters. We list XWF replacements and the genuine GE XWFE separately and never treat one as a substitute for the other.
- [Mini-split filter finder (Mitsubishi, Fujitsu, Daikin)](https://www.madmaxsupply.com/guides/mini-split-filter-finder/): A model-to-filter table for the Mitsubishi, Fujitsu and Daikin mini-split filters in our catalog, taken from the product titles.
- [Hayward pool filter cartridge cross-reference](https://www.madmaxsupply.com/guides/hayward-pool-filter-cartridges/): Hayward housing models and OEM cartridge numbers (including SwimClear C2030 / CX481XRE) as they appear in our product listings.
- [Waterdrop RO replacement filters by system](https://www.madmaxsupply.com/guides/waterdrop-ro-replacement-filters/): Replacement sets we carry for Waterdrop systems such as G3P600, G3P800, G6A8 and X12-PRO, grouped from our product titles.
- [Sump and septic high-water alarms](https://www.madmaxsupply.com/guides/sump-alarm-buying-guide/): Wi-Fi, 12V and float-switch high-water alarms we sell, grouped from the product names — for sump pits and septic or grinder tanks.

## Company
- [About](https://www.madmaxsupply.com/about/)
- Contact: tamara@madmaxsupply.com