The cylinder features 50mm CFC/HCFC-free polyurethane foam insulation to help minimise heat loss, while the stainless steel inner vessel provides durable construction. Supplied with an expansion vessel, T&P relief valve, pressure reducing valve, 2-port motorised valve and factory-fitted controls, it provides a comprehensive solution for domestic unvented hot water installations.
250L Capacity
Indirect Unvented
18kW Coil
25-Year Vessel Warranty
Capacity
250 litres
Coil Rating
18 kW coil-in-coil
Operating Pressure
3.5 bar
Insulation
50mm polyurethane foam
Applications & suitability
Large Homes
The 250-litre capacity is suited to larger domestic properties with higher hot water requirements.
Multiple Bathrooms
Designed for homes with multiple bathrooms and increased hot water demand across several outlets.
Boiler-Heated Systems
An indirect cylinder designed to be heated by a gas, oil or system boiler through its primary coil.
Domestic Hot Water
A mains-pressure unvented hot water solution for domestic applications requiring substantial stored hot water capacity.
Key specifications
| Product Code |
5135327 |
| Type |
Indirect Unvented |
| Nominal Capacity |
250 Litres |
| Height |
1752 mm |
| Diameter |
Ø 550 mm cylinder / 595 mm base |
| Weight Empty |
50 kg |
| Coil Rating |
18 kW |
| Coil Heat-Up Time |
40 minutes |
| Recovery Time |
30 minutes |
| Standing Heat Loss |
2.22 kWh/24h |
| ErP Energy Rating |
D |
| Operating Pressure |
3.5 bar |
| Expansion Vessel |
24 litre, supplied |
| Connections |
22mm compression / ¾" BSP |
Installation & compatibility
The Main 250 Litre is an indirect unvented hot water cylinder designed for connection to a compatible gas, oil or system boiler. The 18kW stainless steel coil-in-coil heat exchanger provides indirect heating, while the supplied 24-litre expansion vessel and factory-fitted controls support the unvented installation. The cylinder is supplied with a 2-port motorised valve for primary over-temperature protection.
Design & performance benefits
Coil-in-Coil Heat Exchanger
The 22mm stainless steel coil-in-coil heat exchanger has an 18kW rating and is designed for rapid heat recovery.
Stainless Steel Vessel
The high-grade stainless steel inner vessel is pressure tested to 15 bar and designed for durable hot water storage.
50mm Insulation
Factory-injected 50mm CFC/HCFC-free polyurethane foam helps minimise standing heat loss.
Backup Immersion
A factory-fitted 3kW Incoloy 800 immersion heater provides an electric backup heating option.
Additional installation features
Expansion Vessel
A supplied 24-litre expansion vessel forms part of the unvented hot water installation package.
Factory-Fitted Controls
Supplied with factory-fitted controls, pressure reducing valve, T&P relief valve and 2-port motorised valve.
Approvals & Compliance
KIWA approved, Building Regulation G3 compliant and CE marked as specified.
Ideal for
Large Domestic Properties
Homes requiring 250 litres of stored hot water for higher domestic demand.
Multiple Bathrooms
Properties with multiple bathrooms and several hot water outlets.
Boiler-Based Heating Systems
Suitable for indirect heating from compatible gas, oil or system boilers.
Main Boiler Systems
Pairs with Main Eco Compact System or Main Eco Elite System boilers for a complete domestic hot water solution.
The Main 250 Litre Indirect Unvented Hot Water Cylinder (5135327) combines 250-litre storage, an 18kW coil-in-coil heat exchanger, 3kW Incoloy 800 backup immersion and 50mm polyurethane insulation. With stainless steel construction, 3.5 bar operating pressure, KIWA approval and a 25-year stainless steel inner vessel warranty plus one-year parts and labour warranty, it provides a robust solution for larger homes with demanding hot water requirements.
