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Lesson 3 / 4 · Commercial Button Mushroom Operator

Room Mapping

One number for a whole room is an average of places where nothing is growing and places where everything is.

  • By the end you can lay out a repeatable set of measuring points.
  • By the end you can tell a distribution problem from a set point problem.
  • By the end you can link picked weight to position in the room.

Controlled room: how the air moves

Cooled, humid air drops from the overhead duct onto the beds, returns through the room, and 20 to 30 percent fresh air is mixed in. About 15 cm per second over the beds, 4 to 6 air changes an hour. Source: ICAR-DMR manual.

Perforated supply ductAHUcooling coilhumidifierreturnfresh air 20-30%
Supply airReturn airBeds

Read numerical examples with their source, method and crop context. They are not universal operating instructions. Historical prices are not current quotations.

Bed above air temperature1-2°Cmeasure both, not oneSource: ICAR-DMR manual, 2011
Air handling unit exit air14°Cto deliver 17 C at the bedSource: ICAR-DMR manual, 2011
Humidity band during cropping80-85%a corner outside it is a distribution faultSource: ICAR-DMR manual, 2011
Carbon dioxide during cropping1000-1500ppmcompare the far end with the unit endSource: ICAR-DMR manual, 2011
Air speed over the bed15cm per secondfeel for movement at every pointSource: ICAR-DMR manual, 2011
Illustration of an engineer and grower inspecting air handling and closed controls.
AI-generated teaching illustration · not field evidence
Connect the picture to the lesson

Check performance

Notice
Installed equipment must be checked against an agreed operating brief.
Understand
A component list is not proof of loaded-room performance.
Try it
Agree measurements, load conditions and acceptance tests before ordering.
See where this fits in the full workflow →

01A room is never one climate

Three published facts guarantee variation. The bed runs 1 to 2 C above the air around it. Air leaves the handling unit at 14 C to deliver 17 C at the bed, so it warms along its path. Air speed at the bed is limited to 15 cm per second, so the far end gets whatever is left.

Add a door that opens on to a warm corridor, tiers at different heights, and beds of different depth, and one room easily holds two climates.

The controller shows one number because it has one sensor. That number is a place, not a room.

02Make a nine point map

Take three positions along the room, near the unit, middle and far end, at three heights, bottom, middle and top tier. That is nine points.

At each point record air temperature, bed temperature, humidity, carbon dioxide if you have a meter, and whether you can feel air movement. Use the same instrument, the same person and the same time of day, because the comparison matters more than absolute accuracy.

Write the nine readings on a grid drawn in the room file, not on a loose slip, so the next crop can be compared with this one.

03What the map tells you

A spread of more than a degree or two between points, a corner sitting outside the 80 to 85 per cent humidity band, or carbon dioxide well above the 1000 to 1500 ppm cropping band at the far end all say the same thing: the room is not distributing what the machine is making.

That is a baffle, duct, deflector or loading problem. Changing the set point to fix it only moves the whole room, and usually makes the good end wrong as well.

Fix distribution first, then set points, then blame the equipment.

04Map the stages that matter

Map at least three times in a crop: at venting, during the first flush and during the third flush, when air changes drop from 6 to 4 per hour.

Keep the same nine points every time. A map that moves cannot be compared.

Then put the crop beside the climate. Record picked weight by position, not just by room. If the far end gives less weight at every mapping, you have evidence that survives an argument, and a target for the next shutdown. Photograph the grid sheet at the end of each crop and keep it with the room file.

Map one room this week

  1. Draw the room and mark nine fixed points, three along by three high.
  2. Read air and bed temperature and humidity at each point in one round.
  3. Note at every point whether you can feel air moving on your hand.
  4. Repeat at the same time of day on three days and average each point.
  5. Record picked weight by position for the same room.

Write in your farm diary: Grid sheet with nine readings per round, dates, instrument used, picked weight by position.

Mistakes that cost a crop

  • Trusting the controller sensor as if it described the whole room.
  • Mapping once, then never repeating it at the same points.
  • Changing the set point to fix a corner, which spoils the rest of the room.

Check yourself

Three questions, instant answers

  1. The far end of a room reads warm, dry and high in carbon dioxide. This is:

  2. Why keep the same nine points every time?

  3. Which pairing turns a map into evidence?

An editorial self-check, not a certificate. Answers are not stored, not even on this device.

Words used in this lesson

Room map
A grid of fixed points where the same readings are taken.
Spread
The difference between the highest and lowest reading in a room.
Baffle
A plate or sheet that redirects air inside a room.
Distribution
How evenly the room delivers what the machine produces.
References & further reading
Button mushroom cultivation and climate knowledge

Operating values require stage, strain, sensor and production-system context.

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The guide behind this lessonOpen the reference guide