Worcester Bosch
Worcester Bosch Expansion Vessel Greenstar CDi 87186849450
At a glance
- Part type: Expansion vessel
- Also known as WB87186849450, 1030991
- This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.
Showing prices
£131.35
£109.46 ex. VAT · VAT at 20%
Available to order · 3 working days
Available to order · 3 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 Worcester Bosch expansion vessel is a sealed tank fitted within the boiler casing on Greenstar and CDi appliances. It holds a charge of air that acts as a cushion against the pressure rise created as water heats and expands through the closed heating system. By absorbing that expansion, the vessel keeps system pressure within a workable band and reduces stress on the boiler's internal components.
Signs this part needs replacing
- System pressure drops repeatedly and the filling loop has to be used often
- Water discharges from the pressure relief valve as the boiler heats up
- The pressure gauge climbs sharply once the burner fires
- Water weeps from the air valve on the vessel
- The boiler locks out or shuts down on low system pressure
Before you order
- Check the appliance GC number and serial number against the compatibility list before ordering.
- Cross-reference the alternative numbers 1030991 and WB87186849450 if the original label is unreadable.
- A gasket or seal may be needed when refitting the vessel connection.
- This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.
Mechanical
| Part type | Expansion Vessels, Tanks & Cylinders |
|---|---|
| Length | 0.1mm |
| Width | 0.1mm |
| Depth | 0.1mm |
Compliance
| Manufacturer part number (MPN) | 87186849450 |
|---|---|
| GC number | J04-509 |
| Barcode / EAN | 4051516200763 |
| Commodity code | 8403 90 00 00 |
| GPC classification | Household Boilers/Furnaces/Tank Water Heaters Replacement Parts/Accessories |
| Alternative numbers | WB87186849450, 1030991 |
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| WORCESTER GREENSTAR 25SI COMPACT LPG | 47-406-51 | 47-406-51 | — | — |
| WORCESTER GREENSTAR 25SI COMPACT NG | 47-406-50 | 47-406-50 | — | — |
| WORCESTER GREENSTAR 25Si ErP COMPACT LPG | 47-407-74 | 47-407-74 | — | — |
| WORCESTER GREENSTAR 25Si ErP COMPACT NG | 47-406-73 | 47-406-73 | — | — |
| WORCESTER GREENSTAR 27I COMPACT SYSTEM LPG | 41-406-14 | 41-406-14 | — | — |
| WORCESTER GREENSTAR 27I COMPACT SYSTEM NG | 41-406-13 | 41-406-13 | — | — |
| WORCESTER GREENSTAR 27i ErP SYSTEM COMPACT LPG | 41-406-59 | 41-406-59 | — | — |
| WORCESTER GREENSTAR 27i ErP SYSTEM COMPACT NG | 41-406-58 | 41-406-58 | — | — |
| WORCESTER GREENSTAR 28 CDI COMPACT LPG | 47-406-45 | 47-406-45 | — | — |
| WORCESTER GREENSTAR 28 CDI COMPACT NG | 47-406-44 | 47-406-44 | — | — |
Showing 10 of 58 compatible appliances.
Fitment listings are a guide, not a guarantee. Plant-room assemblies get modified on site more often than not. Send us the GC number off the data badge and a photo of the existing valve and we will confirm before anything is dispatched.
Documents & drawings
Everything we hold for this part. Where a document exists but we don't hold it, the technical team will source it from the manufacturer — usually the same working day.
manual
WORCESTER appliance manual — GREENSTAR 25SI COMPACT LPG (GC 47-406-51), GREENSTAR 25SI COMPACT NG (GC 47-406-50), GREENSTAR 30 SI COMPACT LPG (GC 47-406-53), GREENSTAR 30 SI COMPACT NG (GC 47-406-52)
manualmanualWORCESTER appliance manual — GREENSTAR 25Si ErP COMPACT LPG (GC 47-407-74), GREENSTAR 25Si ErP COMPACT NG (GC 47-406-73), GREENSTAR 28Si ErP COMPACT, GREENSTAR 30Si ErP COMPACT LPG (GC 47-406-76), GREENSTAR 30Si ErP COMPACT NG (GC 47-406-75)
manualmanualWORCESTER appliance manual — GREENSTAR 27I COMPACT SYSTEM LPG (GC 41-406-14), GREENSTAR 27I COMPACT SYSTEM NG (GC 41-406-13), GREENSTAR 30I COMPACT SYSTEM LPG (GC 41-406-16), GREENSTAR 30I COMPACT SYSTEM NG (GC 41-406-15)
manualmanualWORCESTER appliance manual — GREENSTAR 27i ErP SYSTEM COMPACT LPG (GC 41-406-59), GREENSTAR 27i ErP SYSTEM COMPACT NG (GC 41-406-58), GREENSTAR 30i ErP SYSTEM COMPACT LPG (GC 41-406-61), GREENSTAR 30i ErP SYSTEM COMPACT NG (GC 41-406-60)
manualmanualWORCESTER appliance manual — GREENSTAR 28 CDI COMPACT LPG (GC 47-406-45), GREENSTAR 28 CDI COMPACT NG (GC 47-406-44)
manualmanualWORCESTER appliance manual — GREENSTAR 28CDi ErP COMPACT LPG (GC 47-406-78), GREENSTAR 28CDi ErP COMPACT NG (GC 47-406-77), GREENSTAR 32CDi ErP COMPACT LPG (GC 47-406-80), GREENSTAR 32CDi ErP COMPACT NG (GC 47-406-79), GREENSTAR 36CDi ErP COMPACT LPG (GC 47-406-82), GREENSTAR 36CDi ErP COMPACT NG (GC 47-406-81)
manualmanualWORCESTER appliance manual — GREENSTAR 32CDI COMPACT LPG (GC 47-406-47), GREENSTAR 32CDI COMPACT NG (GC 47-406-46), GREENSTAR 36CDI COMPACT LPG (GC 47-406-49), GREENSTAR 36CDI COMPACT NG (GC 47-406-48)
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