Main Eco Compact Expansion Vessel 7L 7683801 Replacement Part

This main eco compact expansion vessel 7l absorbs system pressure changes as water heats up, helping the boiler run safely and steadily. Over time, the internal diaphragm can fail or lose charge, which may cause pressure to rise, discharge pipe dripping, frequent pressure drops, or repeated lockouts. Replacing the correct expansion vessel helps restore stable pressure control and reduces nuisance shutdowns.

Compatibility :

• Eco Compact System: 15, 18
• Eco Compact Combi: 25, 30

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 the expansion vessel do in a Main Eco Compact boiler?
It absorbs expansion in the heating water as it warms up, keeping system pressure stable.

2. Signs the expansion vessel is faulty?
Pressure keeps rising, PRV/discharge pipe dripping, frequent re-pressurising, pressure dropping after heating, or lockouts.

3. Is 7683801 suitable for both combi and system models?
Yes fits Eco Compact System 15/18 and Combi 25/30 (see compatibility list above).

4. Do I need an engineer to replace it?
Yes boiler components should be fitted by a qualified heating engineer (Gas Safe in the UK).

5. Will a new expansion vessel stop pressure loss?
If the vessel is the cause, it usually restores stable pressure; if not, check for leaks, PRV issues, or air in the system.