Chat with Sunniva on WhatsApp
Skip to Content
Storage
300 · 400 · 500 L

Glass lined tanks — enamel fused to steel at 900 °C

Vitreous enamel fused to steel at 900 °C, CFC-free polyurethane insulation, an Incoloy 800 element and a magnesium anode. Built to pair with a heat pump, a solar collector, gas, or to stand alone.

hot out cold in Enamel lining, fired at 900 °CCFC-free PU insulationMagnesium anodeIncoloy 800 element Section — schematic, not to scale

A tank is not a heat pump, so there is no COP or ambient range here. What matters is the lining, the insulation and the corrosion protection — and how well it pairs with the machine in front of it.

Is this the right range for you?

Two minutes here saves a wasted quotation. The boundaries below are the published ones, not sales judgement.

Yes, if all of these are true

  • You need storage to pair with a heat pump or solar
  • Your water is hard, or corrosive, or both
  • You want a tank that lasts as long as the plant
  • 300 to 500 litres covers your storage

Look at another range if

Applications

Where this range is normally installed.

Heat pump systems
Solar thermal
Gas water heating
Standalone electric

Key features

What is inside the cabinet, and why each of them is there.

Vitreous enamel fused at 900 °C

Not a coating that is painted on. The glass is fired into the steel, which is why it does not chip off in service.

Magnesium sacrificial anode

Corrodes so the tank does not. Replaceable, and the single cheapest thing you can do to double a tank's life.

Incoloy 800 element

Resists scaling and pitting far better than a standard element in hard Indian water.

CFC-free polyurethane insulation

Standing loss is what a tank costs you every hour it is not being drawn from.

Available in 300, 400 and 500 litres

Benefits

What this range does for the building, rather than what is in the box.

It is the tank that fails, not the machine

In most hot water installations the storage vessel is the first thing to go. The lining and the anode are what decide when.

Pairs with any source

Heat pump, solar, gas or electric — or several at once.

Sized properly, it makes the machine smaller

A heat pump is sized on the day's energy, not the peak draw. The tank rides the morning rush. Undersize it and you pay for a bigger machine.

How much storage do you actually need?

Our commercial hot water calculator sizes the tank alongside the machine — two to six times the hourly output, the rule printed on every Sunniva datasheet. Below two times the machine short-cycles; above six you pay to keep water hot that nobody draws.

And what every Sunniva heat pump gives you

True of the whole range, not just this one.

  • Up to 75 % off water heating against electric, LPG or PNG
  • Quick payback and strong return on investment
  • The longest product life of any common water-heating technology
  • Silent operation
  • Hot water round the year, independent of sunlight
  • Lower carbon emissions
  • Negligible maintenance cost
  • Saves space against a boiler or a solar-thermal field

Common questions

The ones our engineers are actually asked.

Why does the lining matter so much?
Hot water plus dissolved oxygen plus steel is a corrosion cell. Vitreous enamel fired into the steel puts glass between the two. A painted or sprayed coating chips; a fired one does not.
How often should the anode be replaced?
Inspect it every two years. In hard or high-chloride water it may need replacing sooner. It costs very little and it is what keeps the tank alive.
What size tank for my heat pump?
Two to six times the machine's hourly output. Our calculators size it for you alongside the machine, because getting it wrong is the commonest reason a correctly sized heat pump appears to underperform.

Manuals and related ranges

Performance figures are published test data at the stated conditions and are not a guarantee for a specific installation. Draw-off pattern, pipe runs, water quality, static head and local code all affect the final selection — confirm with Sunniva Encon LLP before ordering.

© 2026 Sunniva Encon LLP. The design and code of this page are our copyright. Results are indicative and offered in good faith — the method is set out above. Confirm the final selection with us before ordering.