Gledhill ES 150L Direct Unvented Cylinder: The Complete Buyer’s Guide (2026)
Gledhill ES 150L Direct Unvented Cylinder
If you’re searching for a reliable 150-litre electric hot water cylinder, the Gledhill ES 150L Direct Unvented Cylinder (SESINPDR150) is one of the best value options available in the UK. Built from highly corrosion-resistant Duplex stainless steel and designed to deliver mains-pressure hot water, it offers dependable performance for modern homes without requiring a boiler-fed heating coil.
Whether you’re replacing an ageing cylinder, upgrading to an unvented system or specifying a cylinder for a new installation, this guide explains everything you need to know before buying.
What Is the Gledhill ES 150L Direct Unvented Cylinder?
The Gledhill Stainless ES 150L Direct Unvented Cylinder, model SESINPDR150, is an electrically heated hot water cylinder designed to store and supply hot water directly from the incoming mains water supply.
Unlike an indirect cylinder, this model uses two factory-fitted 3kW immersion heaters to heat the stored water. This makes it ideal for properties that rely on electricity for domestic hot water rather than a gas or oil boiler. It has a nominal capacity of 150 litres and an actual water capacity of approximately 149 litres.
Why Choose the Gledhill ES 150L Direct Cylinder?
The Stainless ES range has been designed to offer a balance of quality, performance and affordability.
Key benefits include:
149-litre actual hot water capacity
Two 3kW immersion heaters
Duplex stainless steel construction
Mains-pressure hot water
40mm high-performance insulation
Compact 530mm diameter
No cold water storage tank required
Up to 25-year manufacturer cylinder warranty (subject to terms)
WRAS, WRC and NSF approved design
Suitable for modern domestic installations
Who Is the Gledhill ES 150L Suitable For?
The 150L Direct model is ideal for:
Two and three-bedroom homes
Small to medium-sized families
Flats and apartments
Electric-only properties
Homes without a boiler-fed hot water cylinder
Holiday homes
Annexes
Replacement installations
Its larger capacity compared with a 120L cylinder makes it well suited to households with greater daily hot water demand while still offering a compact footprint.
What Is a Direct Unvented Cylinder?
A direct unvented cylinder heats water using electric immersion heaters instead of a heating coil connected to a boiler.
Cold water enters directly from the mains supply before being heated and stored inside the cylinder. When a hot tap or shower is opened, hot water is delivered at mains pressure.
Benefits include:
Better shower performance
Faster bath filling
Stronger tap flow
No loft tank
Cleaner water supply
More usable loft space
The final water pressure will always depend on the incoming mains water pressure and flow available at the property.
Duplex Stainless Steel Construction
One of the standout features of the Gledhill Stainless ES range is its Duplex stainless steel inner cylinder.
Compared with traditional copper cylinders, Duplex stainless steel provides:
Excellent corrosion resistance
High strength
Long service life
Reduced maintenance
Reliable performance under pressure
This robust construction is one reason why the Stainless ES range is widely specified for domestic installations.
2 x 3kW Immersion Heaters
The SESINPDR150 includes two factory-fitted 3kW immersion heaters.
This arrangement provides flexibility, allowing installers to configure the cylinder for different heating schedules or off-peak electricity tariffs where appropriate.
The upper immersion can provide a smaller amount of hot water more quickly, while the lower immersion heats the full cylinder capacity.
Excellent Mains-Pressure Hot Water
Unlike gravity-fed systems, the Gledhill ES 150L connects directly to the mains water supply.
This can provide:
Powerful showers
Faster bath filling
Strong kitchen tap performance
Better hot water flow throughout the property
To achieve these benefits, the property should have suitable incoming water pressure and flow rate.
Energy Efficiency
The cylinder uses 40mm factory-applied insulation to reduce standing heat loss.
Benefits include:
Better heat retention
Reduced reheating frequency
Improved energy efficiency
Lower running costs compared with poorly insulated older cylinders
The Gledhill ES Direct range carries an ErP Energy Rating of C.
Technical Specification
Specification Details
Manufacturer Gledhill
Model SESINPDR150
Nominal Capacity 150 Litres
Actual Capacity 149 Litres
Type Direct Unvented
Heat Source Two 3kW Immersion Heaters
Material Duplex Stainless Steel
Height 1012mm
Diameter 530mm
Maximum Working Pressure 6 Bar
Maximum Inlet Pressure 12 Bar
Pressure Reducing Valve 3 Bar
Insulation 40mm
Energy Rating C
What Comes in the Box?
The Gledhill ES 150L Direct is supplied with:
2 x 3kW immersion heaters
1 x Expansion vessel
1 x Temperature and pressure relief valve
1 x 3 Bar inlet control group
1 x Installation guide
These components help simplify installation for qualified installers.
Installation Requirements
The Gledhill ES 150L Direct should always be installed by a suitably qualified installer experienced with unvented hot water systems.
Before installation, the installer should confirm:
Incoming mains pressure
Flow rate
Available installation space
Electrical supply
Discharge pipe routing
Compliance with Building Regulations
Manufacturer installation instructions
Correct installation is essential for safety, performance and warranty compliance.
Direct vs Indirect Cylinder
Direct Cylinder
Uses electric immersion heaters.
Ideal for:
Electric-only homes
Flats
Apartments
Holiday properties
Homes without a boiler
Indirect Cylinder
Uses a heating coil connected to a boiler.
Ideal for:
Gas boiler systems
Oil boiler systems
Traditional central heating
Selecting the correct cylinder depends on how your property heats domestic hot water.
Frequently Asked Questions
Is the Gledhill ES 150L Direct suitable for a family?
Yes. The 149-litre capacity is suitable for many small to medium-sized households, although the ideal cylinder size depends on occupancy and hot water usage.
Does it include immersion heaters?
Yes.
The SESINPDR150 is supplied with two factory-fitted 3kW immersion heaters.
Does it require a cold water storage tank?
No.
Because it is an unvented cylinder, it connects directly to the mains water supply.
Can it improve shower pressure?
Provided the property has suitable mains pressure and flow, an unvented cylinder can provide significantly better shower performance than many older gravity-fed systems.
Can it work with Economy 7?
Yes.
Many installers connect direct cylinders to off-peak electricity tariffs using suitable controls where appropriate.
What is the actual capacity?
Although sold as a 150-litre cylinder, the actual stored water capacity is approximately 149 litres.
Why Buy the Gledhill ES 150L from SNH Tradecentre?
When you order from SNH Tradecentre, you benefit from:
Competitive online pricing
Fast delivery to Mainland England
Genuine Gledhill products
Expert plumbing and heating advice
Secure online ordering
Technical product information
A trusted independent plumbing merchant established in 1969
A full range of Gledhill Stainless ES cylinders and accessories
Whether you’re a homeowner, landlord or professional installer, SNH Tradecentre offers dependable service and competitive prices.
Final Verdict
The Gledhill ES 150L Direct Unvented Cylinder is an excellent choice for households that need reliable electric hot water without relying on a boiler. With its 149-litre capacity, twin 3kW immersion heaters, Duplex stainless steel construction and mains-pressure performance, it delivers an impressive combination of quality, efficiency and value.
For homeowners looking for a durable replacement cylinder or installers specifying a modern electric unvented system, the SESINPDR150 is a dependable option backed by Gledhill’s proven manufacturing expertise.