400 Litre indirect unvented cylinder

 

Our 400 litre indirect unvented cylinder, or calorifier, is manufactured in stainless steel with proven technology and quality manufacturing processes and has the capacity to supply your mains pressure hot water demands for your bathrooms, showers, wet rooms, and hot water taps.

Conventional boiler fed

This indirect unvented cylinder is “indirect,” meaning that the cylinder has a coil within the inner cylinder that is a heat exchanger, which needs to be fed by a conventional boiler, be it electric, gas, or oil.

Being an unvented cylinder, you cannot use solid fuel traditional boiler as the heat source. You must use a vented cylinder for a solid fuel conventional boiler.

Unvented cylinder features of our indirect models

Our 400 Litre unvented indirect cylinder does not require an external expansion vessel, as it uses a patented self-sustaining internal air gap within the cylinder to account for the hot water expansion pressure that requires minimum to no maintenance.

 

 

Hot water heating performance

A 400l indirect unvented cylinder is suitable for larger domestic properties with 2 or 3 showers/2 baths properties or light commercial water heating applications.

As a general guideline, use the following average consumption values for hot water requirements per person per day:

• Low Consumption = 20–30 litres.

• Average consumption = 30–50 litres.

• High consumption = 50–70 litres.

Hot water heating times and recovery rates specification

The below heat exchanger coil output (kW) is based on a flow temperature of 85°C. If you require higher outputs, then please see our indirect high-recovery cylinder range.

The heat-up times, recovery times, and weights of our 400L indirect hot water cylinder—unvented model.

 

Download the –Indirect and direct hot water cylinders in stainless steel brochure from Flexiheat UK

Download the –  Installation and maintenance manual for Flexiheat UK indirect and direct hot water cylinders

Key features and benefits

These 400 Litre indirect cylinders are made from highly corrosion-resistant duplex-grade stainless steel, ensuring a long product life and minimal maintenance (25 year warranty for domestic use and 5 year warranty for commercial use).

No sacrificial anode is required for this stainless steel 400 litre indirect unvented cylinder.

We manufacture and certify our indirect cylinders in accordance with the BBA, CE, KIWA, ISO, NSF WRC, and WRAS independent approvals.

400 Litre indirect cylinders with superb manufacturing standards and proven capable technologies at competitive prices.

We use a stainless steel indirect heating coil (heat exchanger) to speed up heat recovery and enable high hot water flow rates.

We use 60 mm insulation to reduce heat loss on our 400 litre indirect cylinders – we use reduced heat loss manufactured factory-injected polyurethane foam insulation bonded onto our highly corrosion-resistant duplex stainless steel tank on our 400 Litre cylinder to minimise heat loss and running costs. This high-grade insulation is HCFC/CFC-free (ODP=0, GWP=1).

This 400 litre unvented hot water cylinder has an ErP “C” rating; they lose less heat, which is better for the environment.

It comes as complete with a 3kW immersion heater as standard. Incoloy construction provides long durability for this immersion heater.

The unvented kit, including a pressure relief valve, ensures a safe and efficient operation of this 400 Litre stainless steel indirect cylinder range.

We offer this 400 litre unvented indirect cylinder with either the standard 22mm pipework connections or larger 28mm for high flow rates for showers and baths in both residential and commercial settings.

Smaller space required and easier installation for our 400 litre unvented cylinder

Our 400 litre unvented indirect cylinder allows for installation in smaller spaces because it doesn’t require an external expansion vessel. On the left is our indirect unvented cylinder with no vessel installed, and on the right is an indirect cylinder with an external expansion vessel system, which requires a lot more space for the associated pipework, components and materials.

400 litre unvented cylinder dimensions 

Dimensions of our indirect unvented cylinder 400 Litres in capacity.

 

Dimension data in mm for the above specification diagram.

 

 

Immersion heater for top-up or backup DHW heating

Should the electric, gas, or oil conventional boiler fail, this 400 litre unvented cylinder has an immersion heater fitted to these indirect cylinders that allows for backup or additional hot water heating via electric power, just like direct models. Direct water heating models just use immersion heaters for the water heating of the unit.

Heat pump use?

This 400 litre unvented indirect cylinder range is designed to work with a conventional boiler, be it oil, electric or gas boilers, and have a heat exchanger suited to the higher hot water temperatures that these boilers can produce. With lower temperatures that heat pumps can produce, they require a larger heating coil to get the maximum heat transfer in indirect models, and is the same for solar thermal systems. We do a specific range for this application, which is listed here: hot water cylinders for heat pump systems

Contact us

For more details, check stock, lead time, delivery, cost, or purchase our 400 litre indirect unvented cylinder, which is one of the best and most competitively priced 400 Litre indirect cylinders on the UK market. They are manufactured in the United Kingdom from duplex stainless steel with quality manufacturing methods and a manufacturer 25 year warranty (for domestic use, 5 years warranty for commercial applications). Please contact our sales team on 01202 822221 or use our site email contact form.