Unvented cylinder vs thermal store: how they heat water differently

What matters most with unvented cylinders and thermal stores

• Thermal stores pass mains water through an internal heat exchanger coil
• Unvented cylinders store and deliver mains water directly
• Thermal stores integrate multiple heat sources readily
• Unvented systems need dedicated safety and relief devices
• Coil sizing in a thermal store affects instantaneous flow rate

Unvented cylinders and thermal stores: the short technical version

Because a thermal store never delivers its own stored water to a tap, there is no requirement for the pressure and temperature relief devices that unvented cylinders need, which can simplify some installations. Thermal stores can also combine multiple heat sources, such as a boiler and a solid fuel stove, more easily. Recovery performance and instant multi-outlet capability tend to favour a well-sized unvented cylinder for typical family bathroom use.

Where we deal with this

• Blagdon (BS40) · 9 mi
• Long Ashton (BS41) · 12 mi
• North Bradley (BA14) · 11 mi
• Bruton (BA10) · 13 mi

Questions we get asked

Which gives better shower flow?

A correctly sized unvented cylinder typically delivers stronger simultaneous flow than a small thermal store coil.

Do thermal stores suit stoves with a back boiler?

Yes, they are a common way to combine a stove and a boiler safely.