Multiport (6-way) valve: all positions and functions explained
The multiport (6-way) valve controls which path the water takes through the sand filter. Once you know each position and its pitfalls, you operate the system safely and protect the spider gasket, the key wear part.
Design and mounting location of the multiport (6-way) valve
The multiport (6-way) valve – also called a multiport or backwash valve – sits on the sand filter and directs the water flow through different channels depending on the lever position. There are two designs: the top-mount valve on top of the filter tank and the side-mount valve on the side of the tank. Both work on the same principle.
Inside, a hand lever rotates a diverter disc over a rubberised spider gasket. In each detent position, the gasket’s star-shaped channels connect different ports with one another: the pump (supply), the filter tank, the pool return and the drain or waste connection. Depending on the model, the ports are designed as spigots or unions for d50 (DN 40) or d63 (DN 50) pipe.
The six positions in detail
Each position switches a different water path. The lever must always be felt to seat firmly in a detent – an intermediate position sends water uncontrolled into several paths at once.
| Position | Water path | Purpose |
|---|---|---|
| Filter | Pump → from above down through the sand bed → back to the pool | Normal operation, the water is cleaned |
| Backwash | Pump → from below up through the sand bed → to waste | Loosen the sand bed and flush out dirt |
| Rinse (clean rinse) | Pump → from above down through the sand bed → to waste | Let the sand settle, flush cloudy water out of the standpipe |
| Recirculate | Pump → past the filter → back to the pool | Circulation without filtration, e.g. when adding chemicals |
| Waste (drain) | Pump → past the filter → to waste | Lower the water level, vacuum coarse dirt directly |
| Closed | all paths blocked | Shut off pump and filter – only with the pump stopped |
Some valves also have a winter position, which does not switch a water path of its own but only relieves the gasket (see below).
Performing a backwash correctly
For beginners, backwashing is the most common reason to switch the valve at all. Here is how it goes in the correct order:
- Switch off the pump.
- Set the lever to Backwash.
- Switch on the pump and watch the sight glass – backwash until the water looks clear (usually 1 to 3 minutes).
- Switch off the pump and set the lever to Rinse.
- Run the pump briefly (about 20 to 30 seconds) until the sight glass is clear.
- Switch off the pump, return to Filter and switch the pump back on.
A typical beginner’s mistake is to skip the rinse. The cloudy water stirred up in the standpipe during backwashing then passes straight into the pool.
Closed and Winter positions: the most common sources of danger
Closed: In this position all paths are blocked. If the pump runs against the closed valve, pressure builds up abruptly. This can damage unions, solvent-cemented joints or the filter tank and overheat the pump. The Closed position is used solely for shutting off with the pump stopped, for example to clean the pump pre-filter.
Winter: Many valves have a winter position in which the lever is pressed down and parked between two detents. This lifts the spider gasket off its seats so that it is not permanently deformed over the winter. In this position, however, the valve does not seal – the system must then not be under pressure. Any residual water in the valve and filter should be drained before frost, otherwise the valve body is at risk of frost damage. These warnings are missing from many manuals, yet they are the most common cause of damage.
Switch positions only with the pump stopped
Basic rule: Never move the lever while the pump is running. Under pressure, the diverter disc presses firmly against the spider gasket. If the lever is then moved, the gasket shears across the edges of the seats, wears out prematurely or tears. In addition, switching under full load creates a pressure surge that stresses every pipe joint.
So with every change of position: first switch off the pump, then move the lever cleanly into the next detent, and only then switch the pump back on. The lever must audibly or noticeably click into place.
The spider gasket as a wear part
The spider gasket is the key wear part of the multiport (6-way) valve. It ages through pressure, chlorine and the mechanical stress of switching. Typical signs of wear:
- During filter operation, water runs continuously to waste – the gasket no longer cleanly separates the filter path from the waste path.
- The filter pressure no longer builds up properly.
Sand in the pool, by contrast, is not a typical sign of a worn spider gasket. It almost always points to broken filter nozzles (laterals), a cracked or leaking standpipe, or the wrong or too fine a sand grain size. You should check these causes first before replacing the gasket.
In many cases the spider gasket can be replaced on its own. If the housing is worn out or the ports are becoming brittle, a complete replacement valve is the more sensible choice. When buying, make sure you get the right design (top- or side-mount) and the right port size, d50 (DN 40) or d63 (DN 50).
Bill of materials
Example – please verify with a specialist. Parts and quantities depend on the installation; sizes shown are examples.
| Component | Size | Art. No. | KLN No. | Qty |
|---|---|---|---|---|
| Sand filter with 6-way valve | – | – | – | Top-mount or side-mount design; connection usually d50 (DN 40) or d63 (DN 50) |
| Replacement spider gasket | – | – | – | Matched to the valve type; central wearing part |
FAQ
Why does water run continuously to waste during filter operation?
Usually the spider gasket is worn and no longer cleanly separates the filter path from the waste path. Replacing the gasket or the whole valve fixes this.
Do I have to switch off the pump before every change of position?
Yes. Switching under pressure damages the spider gasket and creates a pressure surge. Always switch the pump off first, then move the lever, then switch it back on.
What is the Rinse position for?
After backwashing, it flushes the stirred-up cloudy water from the standpipe to waste before filtering back into the pool. Without this step, cloudy water gets into the pool.
What happens if the pump runs in the Closed position?
The pressure rises abruptly. This can damage the pipework, solvent-cemented joints, filter tank and pump. Only use the Closed position with the pump stopped.
What is the point of the valve's winter position?
It lifts the spider gasket off its seats so that it is not permanently deformed over the winter. The valve does not seal in this position, and any residual water should be drained beforehand.
This guide provides general technical orientation and does not replace professional planning. Safety-, electrical- and permit-relevant work must be carried out by qualified specialists.
