Skip to content
Contact Us Privacy & Policy Return & Refund Policy Shipping Policy Terms & Services FAQ
Free Shipping in Selected Areas | Quality You Can Trust | Secure Checkout
Free Shipping in Selected Areas | Quality You Can Trust | Secure Checkout
Main 300 Litre Indirect Unvented Hot Water Cylinder - 5135328 - Getplumb

Main 300 Litre Indirect Unvented Hot Water Cylinder - 5135328

by Main
SKU 5135328
£812.83 - £812.83
£812.83
£812.83 - £812.83
£812.83

Free Local Shipping

Free Local Shipping on orders over £100. Standard delivery to most UK postcodes within 2-3 working days. Express options available at checkout.

Contact Us

Give Us A Call +44 118 958 8882 Our team is here to help. We will provide expert advice on specifications, compatibility, and delivery options.

30-day Easy Return

30 days Easy Return — no questions asked. If you're not completely satisfied, send it back within 14 days for a full refund.

The Main 300 Litre Indirect Unvented Hot Water Cylinder (5135328) is a high-capacity, UK-manufactured stainless steel unvented cylinder designed to provide mains-pressure domestic hot water heated indirectly by a compatible gas, oil or system boiler. With a factory-fitted 3kW Incoloy 800 immersion heater for backup, this 300 litre cylinder is suited to large homes with three or more bathrooms, premium properties and installations with very high hot water demand.

The cylinder features a unique coil-in-coil heat exchanger with a 19kW rating for rapid heat recovery, while 50mm of factory-injected CFC/HCFC-free polyurethane foam insulation helps minimise heat loss. It is KIWA approved, Building Regulation G3 compliant and supplied with a 2-port motorised valve for primary over-temperature protection.

300L Capacity 19kW Coil-in-Coil 3kW Incoloy 800 Immersion 25-Year Inner Vessel Warranty
Capacity
300 Litres
Coil Rating
19kW
Maximum Flow
55 l/min @ 6 bar
ERP Rating
D

Applications & suitability

Large Homes

The 300 litre capacity is designed for larger domestic properties with substantial hot water requirements.

Multiple Bathrooms

Suitable for homes with three or more bathrooms and higher simultaneous hot water demand.

Indirect Heating

Designed to be heated through the integrated coil-in-coil heat exchanger by a compatible boiler.

Premium Installations

A high-capacity solution for premium properties and projects requiring substantial domestic hot water storage.

Key specifications

Product Code 5135328
Type Indirect Unvented
Nominal Capacity 300 Litres
Height 2065mm
Diameter Ø550mm (Cylinder) / 595mm (Base)
Weight Empty 58kg
Coil Rating 19kW
Coil Heat-Up Time 47 minutes
Recovery Time 35 minutes
Standing Heat Loss 2.52 kWh/24h
ERP Energy Rating D
Operating Pressure 3.5 bar
Expansion Vessel 24 litre (Supplied)
Connections 22mm Compression / ¾" BSP

Installation & compatibility

Boiler compatibility: Designed for indirect heating via a compatible gas, oil or system boiler connected to the cylinder's coil-in-coil heat exchanger.

Installation: The cylinder is supplied with a 24 litre expansion vessel, T&P relief valve, 2-port motorised valve, pressure reducing valve and factory-fitted controls. Installation should be carried out in accordance with applicable unvented cylinder requirements.

Design & performance benefits

300L High-Capacity Storage

Provides substantial stored hot water capacity for large properties and high-demand domestic installations.

19kW Coil-in-Coil Heat Exchanger

The stainless steel coil-in-coil heat exchanger provides a 19kW rating for indirect cylinder heating.

50mm Polyurethane Insulation

Factory-injected 50mm CFC/HCFC-free polyurethane foam insulation helps minimise heat loss.

Backup Immersion Heating

A 3kW Incoloy 800 immersion heater provides backup electric heating when required.

Additional installation features

Supplied Expansion Vessel

A 24 litre expansion vessel is supplied as part of the cylinder installation package.

Motorised Valve

A supplied 2-port motorised valve provides primary over-temperature protection.

KIWA & G3 Compliant

KIWA approved and Building Regulation G3 compliant, with CE marking as specified.

Ideal for

The Main 300 Litre Indirect Unvented Hot Water Cylinder is ideal for large homes with three or more bathrooms, premium properties and domestic projects with very high hot water demand. Its 300 litre storage capacity, 19kW coil-in-coil heat exchanger, backup Incoloy 800 immersion heater and 3.5 bar operating pressure make it a high-capacity indirect hot water solution. It pairs with the Main Eco Compact System or Main Eco Elite System boilers for a complete domestic hot water installation.

Specifications

BrandMain
Part Number5135328
Capacity300 litres
Height2065mm
Diameter550mm
Weight (empty)58kg
Weight (full)358kg
Standing Loss105W
Reheat Time47 mins
Primary Coil Rating19.0kW
ErP Energy ClassD
Power240V
ModesIndirect Heating (Boiler Coil) + Electric Immersion Backup
MountingFloor Standing
FinishWhite thermoplastic / coated steel
DimensionsH 2065 × Ø 550 mm
Warranty25 years inner vessel, 1 year parts & labour

Compare products

{"one"=>"Select 2 or 3 items to compare", "other"=>"{{ count }} of 3 items selected"}

Select first item to compare

Select second item to compare

Select third item to compare

Compare