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Glow-worm Control Thermostat S800850

Glow-worm

Glow-worm Control Thermostat S800850

Two-pin control thermostat for Glow-worm Ultimate FF boilers, used to set and regulate boiler flow temperature.

At a glance

  • Appliance family: Glow-worm Ultimate FF
  • Also known as 1336468
Manufacturer part no.
S800850
Showing prices

£52.82

£44.02 ex. VAT · VAT at 20%

Available to order · 1 working day
Available to order · 1 working day
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 S800850 is a two-pin control thermostat manufactured by Glow-worm. It is fitted to boilers in the Glow-worm Ultimate FF family and regulates the boiler's heating flow temperature in response to the setting on the control knob. The thermostat switches the boiler on and off to hold the selected temperature.

Signs this part needs replacing

  • The boiler does not respond when the control knob is turned up or down.
  • Heating flow temperature drifts well above or below the setting on the dial.
  • The boiler short-cycles or fails to fire on a call for heat.
  • The control knob turns loosely with no resistance or click.
  • Heating output is intermittent despite a steady demand.

Before you order

  • Confirm your boiler model against the fit list above.
  • Check the existing thermostat has a two-pin connection.
  • Isolate the electrical supply to the boiler before removing or fitting any component.
  • Verify the part number S800850 on the existing component where visible.

Not sure which part?

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