A 30 g vermiculite sachet inside the utensil drawer, not on the worktop

The drawer is the only closed volume this room gives you

Kitchen air is interrupted constantly — by the extractor, by the window, by cooking itself — and any plan sized to the room has to fight all three. A drawer is different. It is a closed volume of roughly 0.05 m3 with a high open-close frequency but a very small air exchange per cycle. A sachet in that environment reads as "right every time it opens" rather than "never quite there".

This is the only plan in the register that works on an event-based read instead of a spatial one, and the test changes with it. The question is not whether you can smell it standing in the kitchen; it is the two seconds after the drawer opens.

Vermiculite rather than silica, for humidity reasons

Drawer humidity tracks cooking and measures between 45% and 58% over a week. Vermiculite loses less of its oil-holding capacity as humidity rises than silica does, which flattens the output curve. Silica in the same drawer absorbs moisture and then releases it again, producing the familiar pattern of a faint day followed by an overpowering one.

Load is 14%, below the 18% used in the entryway sachet. Drawer lining paper, napkins and wooden utensils all sit against the sachet for months at a time, and a higher load puts visible oil marks on all three.

Installation: side wall, never flat on the bottom

1. Take the drawer out and wipe the inside dry. Any film of oil or water kills the adhesive pad.
2. Fix the sachet to the upper third of the drawer's side wall, not flat on the base.
3. The side position keeps the sachet above the contents so nothing presses on it, and air moving along the wall on opening gives a stronger read for the same load.
4. If the drawer holds wooden utensils or a bamboo board, move the sachet to the outside face of the drawer instead and let it release through the gap.

Laying it flat on the bottom is the most common mistake. The contents block most of the release area and the transfer risk roughly doubles.

Twenty-eight days, and why not to refresh

30 g at 14% load gives a 670-hour window. Because the drawer is closed most of the time the real release rate is lower than an exposed sachet, and the measured life is 28 days, dropping to 24 in a household that opens the drawer constantly.

Refreshing is not recommended here. Vermiculite steepens its release curve after a second oil load — heavy for three days, then a sharp fall — and a drawer needs consistency per opening far more than it needs the CNY 10 a refresh saves. Replace the sachet whole.

Cost: CNY 10 a month

CNY 10 a sachet, replaced every 28 days, is CNY 10 a month and the cheapest plan in the register. The seven-reed plan for the same kitchen runs CNY 34, and the CNY 24 difference buys 22 m2 of room-level coverage that a kitchen cannot use during the hours it is actually occupied.

Diagnosis

• Nothing at all. The sachet is being pressed by cutlery, or the non-woven outer is clogged with cooking oil. Move it to the side wall or replace the outer.
• Very strong on day one, faint after. Filler has been sealed a long time and the surface load flashes off first. Normal; it settles to steady state around day four.
• Oil spots on napkins. Load too high, or the sachet is being compressed. Drop to a lower load and put it back on the side wall.
• A wooden spoon smells of it. Wood absorbs. Move the sachet to the cabinet side of the drawer and let it release through the gap.

Assembly, in order

1. Pick the filler for the room — Vermiculite holds its release when the air is damp; silica beads pull moisture in and go quiet. Between a bathroom and a wardrobe the same pouch behaves like two different products.
2. Place it side-on, never flat — Stand the pouch against a side wall or hang it. Lying flat on a drawer floor, the lower face is against the wood and half the surface does no work at all.
3. Squeeze it once a month — Squeeze the pouch once a month to break up the filler. It costs nothing and it is the difference between an even curve and a flat final fortnight.
4. Refresh twice, then replace — Add one to two millilitres of oil, close the pouch in a bag and shake for a minute. After the second refresh the filler stops holding and the whole pouch should be replaced.

Code SACH · very large surface area to volume ratio, so output is low per gram but extremely even

What it costs to keep running

Running cost	CNY 10
One fill lasts	28 d
Refill cycle	28 d
Coverage	3 m2
Refill and replacement	30 g vermiculite-filled sachet, non-woven outer, adhesive pad

Failure diagnosis for L2

What you notice	What caused it	What to change
Clear at the desk, gone by the door	The rung is working exactly as specified. L2 is not meant to reach the far wall.	If the doorway has to read, change rung rather than dose. Adding units to an L2 set-up produces an L2 with a hot spot, not an L3.
One side of the room reads, the other does not	The carrier is sitting in the moving air, so the scent is carried past the near seating before it can build	Move it out of the draught and keep 1.5 m clear of any vent. Position fixes shape; oil only fixes amount.
It reads noticeably louder after dark	Cooling air drops toward the floor and takes the layer with it, concentrating it at seat height	Raise the carrier 20-30 cm for the evening, or accept it as the shape of the rung and set the position for the evening hours.

Same room, other rung

• A 7-reed diffuser placed 2.4 m from the hob in a 9.8 m2 kitchen (L3 · 40 d)

Open the rung card — L2 · Close range

This record went live on 2026-10-05. Records dated later in the register are not listed anywhere on the site until their date arrives.