Corner Fireplace Insert with Cast Iron Door, Window Frames and Water Boiler Prity ATC W20 – 5 kW + 21.1 kW Water

Cast Iron on Every Side. Heat for the Whole House.

The Prity ATC W20 combines the cast iron door and cast iron-framed side windows of the Prity ATC with a 21.1 kW water heat exchanger — carrying most of the fire's energy straight into your central heating system, while 5 kW of radiant heat and three-sided visibility still warm the room it stands in directly.

Made in Bulgaria. EU Ecodesign compliant.

How Much Space Can It Heat?

Prity doesn't publish an official heated-area figure for the Prity ATC W20, so this is our own estimate, based on the heated-area-to-power ratio observed across comparable Prity models in our range (roughly 7.5 m² per kW). Here, that ratio applies to the unit's combined output of 26.1 kW — 5 kW radiating into the room plus 21.1 kW into the water circuit, which spreads its heat through radiators installed around the house rather than from the insert itself. Combined, that puts the Prity ATC W20 at approximately 195 m², depending on your home's insulation, radiator layout, and how the heating system is balanced.

Cast Iron Door and Window Frames: Heat Retention All Around

Cast iron absorbs heat progressively during combustion and releases it back slowly — long after sheet steel would have cooled. On the Prity ATC W20, that material isn't limited to the main door: the two angled side windows are cast iron-framed as well, giving the whole front of the insert the same slow, steady heat retention rather than just the central panel. Ceramic glass throughout keeps the fire visible from the front and both angles, kept clear by the secondary air wash system that runs fresh air across the inner glass surfaces during burning.

Corner Placement, Three-Sided Visibility

Like the rest of the Prity A range, the ATC W20 is shaped to fill a room corner, radiating heat across a wide arc of the room rather than throwing it in a single direction from a flat wall. The two angled side windows add to that — the fire stays visible from more of the room than a single front-facing pane allows.

A Water Heat Exchanger Built for Central Heating

The Prity ATC W20 delivers 21.1 kW to its water heat exchanger at nominal output, alongside 5 kW of direct radiant heat into the room. The water tank holds 34 litres, with a maximum working pressure of 1.25 bar and 1″ water connections for both flow and return.

This is a boiler-type appliance: it must be connected to a working central heating system before use, and should never be run dry or disconnected from your water circuit. Installation and commissioning by a qualified heating engineer is required.

Clean Combustion, Class A Efficiency

The Prity ATC W20 achieves a combustion efficiency (η) of 80% and a seasonal space heating energy efficiency of 71%, with an energy efficiency index of 106 — placing it in energy class A. Emissions at nominal output: CO at 1238 mg/Nm³, particulate matter at 26 mg/Nm³, NOx at 97 mg/Nm³, and OGC at 20 mg/Nm³ — all within EU Ecodesign limits.

Fuel consumption at nominal output is 8.2 kg of dry wood per hour, reflecting the load of heating both the room and your water circuit. Flue gas temperature is 227°C, with a mass flow rate of 21.6 g/s.

A Wide Firebox

The combustion chamber measures 870 mm wide, 585 mm deep, and 330 mm high — sized to sustain the longer, hotter burns a boiler system needs to keep up with central heating demand.

Important Installation Note

The Prity ATC W20 uses a Ø200 mm flue outlet and requires a minimum chimney draught of 12.1 Pa. Please confirm your chimney connection is compatible with this diameter before ordering. Its corner geometry with two glazed side panels means installation requires careful planning of the surrounding hearth structure on both adjoining walls. At 170 kg, this is one of the heavier inserts in our range — the unit needs a floor and framing capable of supporting the weight, and professional installation, including connection to your heating system, is required, not optional.

Overall dimensions: 1080 × 750 × 810 mm (W × D × H).

30 Years of European Engineering Behind Every Weld

Prity has manufactured solid fuel heating appliances in Gorna Oryahovitsa, Bulgaria, since 1995. With more than 250 production staff and a range refined across three decades, the company builds inserts that earn their place in a home for years. Every unit is manufactured to the relevant EN standards and independently verified.

Your Prity ATC W20 comes with a 24-month manufacturer's warranty.

Everything You Get

• 5 kW of direct radiant heat, plus 21.1 kW to your water heat exchanger (26.1 kW combined)

• Cast iron door and cast iron side window frames — heat retention around the whole visible face

• Corner-mounted design with two angled side windows — fire visible from more of the room

• 34-litre water tank, 1.25 bar maximum working pressure, 1″ water connections

• Class A energy efficiency with a seasonal space heating energy efficiency of 71%

• Combustion efficiency (η) of 80%

• Wide firebox: 870 × 585 × 330 mm (W × D × H)

• Fuel consumption: 8.2 kg of dry wood per hour at nominal output

• Overall footprint: 1080 × 750 mm

• Flue outlet: Ø200 mm — confirm chimney compatibility before ordering

• Net weight: 170 kg

• 24-month manufacturer's warranty

Box Contents

Insert body with cast iron door, cast iron side window frames, ceramic glass throughout, and integrated water heat exchanger, technical manual.

Use only dry, chemically untreated natural wood with a moisture content not exceeding 20%. Do not burn household waste, painted wood, plywood, or treated wood. This appliance must be connected by a qualified installer to a working central heating system before use — never operate it disconnected from your water circuit. Always consult a qualified installer before connecting the appliance to your chimney system, and before building the surrounding hearth structure for a corner installation. Note: this model requires a Ø200 mm flue connection and 1″ water connections.