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Vaillant 203031 Piston (Green)

Vaillant

Vaillant 203031 Piston (Green)

Green piston, part number 203031, manufactured by Vaillant for MAG 350/9 W and MAG 350/9 XW appliances.

At a glance

  • Also known as 1377104
Manufacturer part no.
203031
Showing prices

£9.60

£8.00 ex. VAT · VAT at 20%

Available to order · 7 working days
Available to order · 7 working days
Not certain it's the right part? The technical team verifies fitment before dispatch — no charge, and it stops a second trip.Call the technical teamSend a technical question

Same-day dispatch

Ordered by 4pm Mon–Fri, 10:30am Sat.

30-day returns

Unused, in original packaging.

What it is

The Vaillant 203031 Piston (Green) is a piston component manufactured by Vaillant for use in the MAG range of gas appliances. It forms part of the internal valve or water section assembly, where it moves within its bore to control the passage of flow through the appliance. The piston is identified by its green colour coding.

Signs this part needs replacing

  • Hot water output becomes inconsistent or drops away during use
  • The appliance fails to respond correctly when a hot water tap is opened
  • The piston shows scoring, swelling or deposits that prevent free movement in its bore
  • Water or gas flow through the valve section is restricted or erratic
  • Intermittent operation that traces back to a sticking piston

Before you order

  • Confirm the appliance model matches one of the fitments listed above
  • Check the existing piston colour coding against the green piston specified here
  • Verify the part number 203031 against the marking on the component being replaced
  • Inspect the piston bore and associated seals for wear before refitting

Not sure which part?

Search by part number, product name or brand — our technical team confirms fitment before anything is dispatched.