Worcester Greenstar Expansion Vessel 6L 87161055450 Replacement Part

This worcester greenstar expansion vessel 6l absorbs water expansion as your Worcester Greenstar heats up, helping keep system pressure stable. Over time the internal diaphragm can weaken, causing pressure to rise fast when heating, PRV discharge/drips, or repeated pressure drops and re-pressurising. Replacing the correct vessel restores proper pressure control, reduces nuisance lockouts, and helps protect the boiler from repeated over-pressure issues.

Compatibility :

• Greenstar i System: 12, 15, 18, 24 (NG & LPG)
• Greenstar i Junior HE: 24, 28 (NG & LPG)
• Greenstar i Junior HE Mk5 2013: 24, 28 (NG/LPG)
• Greenstar Si: 25, 30 (NG & LPG)
• i Junior RSF: 24, 28 (NG & LPG)

Important fitting advice

We recommend that all parts are fitted by a fully qualified Gas Safe registered engineer. If you need help confirming the right part, contact us our team has 10+ years of boiler spares knowledge and friendly chat support to help you quickly.

Delivery

At Boiler Spares Hub, we dispatch orders within 1 working day (Monday-Friday). Orders placed outside working days will be dispatched on the next working day. For delivery options available for this product, please add it to your basket or check our delivery options page.

Returns

We accept 30-day returns. Returns must be in an unopened, sealed box. If we find the item has been used or installation was attempted, we may refuse the return.

Frequently Asked Questions (FAQs)

1. What does an expansion vessel do in a Worcester boiler?
It absorbs pressure increases as heating water expands, keeping the system pressure stable.

2. What are the common symptoms of a failing expansion vessel?
Pressure rises quickly when heating, PRV/discharge pipe dripping outside, frequent re-pressurising, or pressure dropping after the boiler cools.

3. Does this fit both natural gas and LPG models?
Yes-compatibility includes both NG and LPG variants where listed (match your exact model).

4. If the PRV has been leaking, should it be replaced too?
Sometimes repeated over-pressure can stop a PRV resealing properly, so installers often check it during the repair.

5. Will the expansion vessel need pressure setting?
It’s pre-charged, but engineers typically check and set the charge pressure to suit your system before commissioning.