If your hot water system is outdated, inconsistent, or struggling to meet your household’s demand, you might be wondering whether an unvented cylinder is the right upgrade. It’s a common recommendation from heating engineers — but is it always necessary?
In this article, we’ll break down exactly what an unvented cylinder is, who really benefits from it, and when it’s worth the investment.
💧 What Is an Unvented Cylinder?
An unvented hot water cylinder is a pressurised tank that stores hot water and feeds it directly from the mains water supply. That means you’ll get high-pressure hot water straight to your taps, showers, and baths — no need for a cold water storage tank in the loft.
They’re typically made from stainless steel, come insulated, and are heated via either a system boiler or immersion heater.
✅ The Advantages
There’s a reason unvented cylinders are popular in modern plumbing installations:
- Consistent water pressure: You can run multiple outlets (e.g. kitchen tap + shower + bath) at the same time without pressure dropping.
- Cleaner installation: No need for loft tanks — great for bungalows, flats, or loft conversions.
- Hygienic water storage: Since it’s sealed from external contamination, the water stays cleaner and safer.
- Efficient reheating: Modern units heat up fast and retain heat well, saving on energy bills.
❌ When You Don’t Need an Unvented Cylinder
Not every property benefits from one — and in some cases, it’s the wrong choice.
You likely don’t need (or want) an unvented cylinder if:
- Your mains water pressure is weak – It relies entirely on strong incoming pressure. If yours is poor, you’ll need a booster or accumulator.
- You live alone or use minimal hot water – A combi boiler may be a simpler and more efficient solution.
- You don’t have space – Though more compact than older systems, they still need installation room, venting clearances, and access.
💰 Cost vs Value: Is It Worth It?
An unvented cylinder installation usually costs £1,200–£2,000, depending on brand, size, and complexity. While this is a higher upfront cost compared to combi boilers, it’s often worth it for:
- Large households (3+ people)
- Homes with multiple bathrooms
- Upstairs/downstairs layouts needing even pressure
It also adds resale value to a home, especially in newer developments or family homes where hot water performance is a selling point.
🧠 Engineer’s Tip
We always recommend pressure-testing your mains supply before considering an unvented system. If your incoming pressure is below 1.5 bar, you’ll either need a booster set — or to consider alternatives.
🛠️ What Are The Alternatives?
- Combi boiler – Ideal for small homes with one bathroom. Instant hot water, no tank, very space-efficient.
- Vented cylinder – Good for low-pressure mains properties. Uses a loft tank for gravity-fed pressure.
- Thermal store – Stores hot water in a different way and can serve large properties with biomass or renewable energy inputs.
📞 Final Word: Book a Free Pressure Test
The key to choosing the right hot water system isn’t guessing — it’s testing. We offer a free home visit to test your pressure, inspect your current setup, and recommend the most efficient, long-term solution for your property.
👉 Ready to upgrade your hot water system?
Click below to request a quote or book your pressure check.