ATTACK floor-standing indirect hot-water tank

30 years of development and manufacturing

ATTACK floor-standing indirect tanks

Models for different heat sources and hot-water capacities

ATTACK floor-standing tanks connect to an external heat source to prepare domestic hot water (DHW). The range includes OKC, OKH, NTR and SOL models with one or two heat exchangers and nominal capacities from 40 to 300 litres.

40 l

40 NTR

87 l

100 OKH NTR/HV
100 OKC/NTR/HV

113 l

125 OKC/NTR/Z
125 OKC/NTR/HV

115 l

125 OKH NTR/HV

148 l

160 OKC/NTR
160 OKC/NTR/HV

200 l

200 SOL/NTR

275 l

300 SOL/NTRR

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Category: Domestic hot-water tanks

Low NOxLow emissions

No electricityOperates without electricity

Enamelledtank surface

For differentheat sources

Discover ATTACK floor-standing indirect hot-water tanks

Suitable for external heat sources

Suitable for external heat sources

The indirectly heated wall-mounted tanks OKC, OKCV, OKH, NTR and SOL are available in capacities from 120 to 195 litres. They are designed to connect to biomass boilers, floor-standing boilers or wall-mounted condensing boilers using different energy sources to prepare DHW in residential and non-residential buildings.

Floor-standing design

A DHW tank heated by an external source

ATTACK floor-standing tanks connect to different heat sources. Depending on the model, they use one or two heat exchangers and have different connection layouts.

ATTACK floor-standing indirect hot-water tanks

ATTACK floor-standing tank models

Explore the tank models

Find out which heating appliances they are suitable for.

OKC NTR

Suitable for wood-fired boilers

The ATTACK tank with one heat exchanger is a dependable solution for preparing hot water with different heat sources. A special anti-corrosion coating helps protect the inner surface from pitting, while high-quality Covestro insulation reduces heat loss and running costs. DHW temperature control, a safety valve and a circulation connection support convenient, safe operation.

Ceramic electric heating element
One heat exchanger
Heating options: electricity or heat exchanger
Anti-corrosion coating resistant to hard and chlorinated water
High-quality insulation helps reduce heat loss and running costs

OKC NTRR/SOL

Suitable for wood-fired or gas boilers

The ATTACK NTRR/SOL tank is designed to make effective use of solar energy. Two heat exchangers sized for solar panels, anti-corrosion protection and a shape that supports better water stratification make it a versatile option, either as the main DHW tank or as a preheater for an existing tank.

Ceramic electric heating element
Two heat exchangers
The 1 m² heat-exchanger version is suitable for boilers using different fuels, including condensing boilers
Circulation connection
Anti-corrosion coating resistant to hard and chlorinated water
High-quality insulation helps reduce heat loss and running costs
Electric heating element included

OKC NTR/HV

Suitable for condensing boilers

The ATTACK OKC NTR/HV is a practical, economical way to prepare hot water. It has one heat exchanger and is designed to fit beneath a wall-mounted boiler; the connections are conveniently located in the top cover. An anti-corrosion coating protects the tank against hard and chlorinated water, while high-quality Covestro insulation helps keep heat loss and running costs low.

Ceramic electric heating element
One heat exchanger
Year-round hot-water preparation using heating water from a gas boiler
Anti-corrosion coating resistant to hard and chlorinated water
High-quality insulation helps reduce heat loss and running costs

OKH NTR/HV

Suitable for wood-fired or gas boilers

The OKH NTR/HV floor-standing tank has one heat exchanger and stores domestic hot water. Its special anti-corrosion coating resists hard and chlorinated water. High-quality insulation helps retain heat, reduce heat loss and lower running costs. This model is designed for installation beneath a wall-mounted boiler.

Ceramic electric heating element
One heat exchanger
The 1 m² heat-exchanger version is suitable for boilers using different fuels, including condensing boilers
Circulation connection
Anti-corrosion coating resistant to hard and chlorinated water
High-quality insulation helps reduce heat loss and running costs
Electric heating element included

Detailed specifications

Technical data

The current product page shows a technical table for the wall-mounted OKC/OKCV models, so that table is not used for the floor-standing tanks. The following values come from the technical table on page 39 of the ATTACK 2025 product catalogue, which is temporarily available in the migration database. The catalogue lists actual capacities; model names retain their nominal designations.

Parameter	Unit	40 NTR	100 OKH NTR/HV	125 OKH NTR/HV	100 OKC/NTR/HV	125 OKC/NTR/Z	125 OKC/NTR/HV	160 OKC/NTR	160 OKC/NTR/HV	200 SOL/NTR	300 SOL/NTRR
Capacity	l	40	87	115	87	113	113	148	148	200	275
Weight without water	kg	45	55	67	53	55	67	73	77	104	111
Heat-exchanger output	kW	23.2	24	32	24	32	32	32	32	19	29
Heat-up time via heat exchanger from 10 °C to 60 °C	min	10	13	13	13	13	13	16	16	34	33
Heat-exchanger surface area	m²	0.6	1.08	1.45	1.08	1.08	1.08	1.45	1.45	0.8	1.2