Spunding Valve Care: The 30-Second Habit That Keeps It Accurate

The spunding valve is what turns a sealed fermenter into a pressure vessel you can actually control. It is also the one fitting on the tank sitting directly in the path of rising krausen. Look after it and it holds your set point season after season — and looking after it takes a rinse and a few minutes, not a workshop.

Setting it: with gas flowing, not on a dead tank

The ball knob on top sets the pressure the tank is allowed to hold, and the scale engraved on the column shows where you are — 0 to 2.2 bar on the BrewTaurus valve. Gas escapes only once the tank beats that setting, and the built-in gauge shows what the tank is actually doing.

One rule matters more than the rest: set it with gas flowing. Pressurise to a known figure first, then wind the knob down until the valve just begins to bleed. A set point dialled in on an unpressurised tank is a guess, and it is the most common reason a valve seems to hold the wrong pressure.

Why a valve that was fine starts opening late

Fermentation pushes foam and a fine mist of beer up into the valve. While it is still wet, it rinses away in seconds. Left to dry, it becomes a thin sticky film on the sealing surfaces, and the seal then needs a little more pressure before it lifts.

You notice it as a change in rhythm rather than a failure. The gauge creeps past your set point, and when the valve does open it lets go more abruptly than it used to — sometimes hard enough to throw whatever has collected in the clear cup. Nothing is broken. The valve is telling you it is overdue a clean.

The 30-second habit that prevents almost all of it

Rinse the valve straight after the batch, while the residue is still soft. Vent the tank, take the valve off the tri-clamp port, empty the clear cup and run hot water through everything before it dries. Half a minute at the end of a brew day, and there is nothing left to harden onto the sealing surfaces.

This single habit does more for a spunding valve than any cleaning routine you can carry out once the residue has set.

The proper clean

1. Depressurise the fermenter completely before touching the valve. Never open a fitting that is still holding pressure.
2. Note where the knob sits on the scale, then back the adjuster fully off so there is no tension on it.
3. Take the valve off the port and remove the clear cup. Wash it separately — warm water and a soft cloth, no scourers.
4. Soak the valve in warm PBW or an oxygen-based cleaner at roughly 40–50 °C for 15 to 20 minutes.
5. Soft brush only. Never anything abrasive on a sealing surface — a scratch there does not polish out.
6. Rinse, dry, reassemble and reset the pressure under gas as above.

Clean and back together, the valve should start bleeding close to your set point and hold steady while it vents, instead of creeping past it and releasing in one go.

Three habits that add years

• Keep krausen out of it. Leave 20–25 % headspace and run a blow-off for the first two or three days, fitting the spunding valve once high krausen has dropped. This is the whole game.
• Ramp the pressure, do not jump to it. Start around 0.3–0.5 bar through peak fermentation and raise the set point as activity slows. At the peak, a warm ferment makes CO₂ faster than any valve bleeds it off smoothly.
• Store it with the adjuster backed off. Ten seconds at the end of a brew day, and nothing sits compressed for weeks between batches.

If a clean does not settle it

A spunding valve is a serviceable fitting, not a sealed unit — the clear cup, for instance, is a standard spare part. If yours still will not hold steadily after a proper clean, write to us at info@brewtaurus.com with a short video of what it is doing, and we will work out which part it needs.

Our spunding valves: 1.5" Spunding Valve with pressure gauge and gas port and the 1.5" TC Spunding Valve.