Viessmann Vitocrossal 200 CM2 Series Gas-Fired Condensing Boiler

Product Overview

The Vitocrossal 200 CM2 Series is a high-efficiency, gas-fired condensing boiler featuring a pre-mix modulating cylinder burner. It is designed for natural gas or liquid propane gas and utilizes an Inox-Crossal heat exchanger made of high-grade SA 240-316 Ti stainless steel. This boiler is suitable for operation without a low limit on boiler return water temperature and is intended for closed loop hot water heating systems with a maximum supply water temperature of 210°F (99°C) and a maximum operating pressure of 75 psig.

Available models include CM2 Series 186, 246, and 311, with heating inputs ranging from 663 to 1112 MBH (194 to 326 kW).

Note: Product illustration may not be exact.

Benefits at a Glance

• Inox-Crossal heat exchanger surface made of high-grade SA 240-316 Ti stainless steel for high operational reliability and long service life.
• Easy dispersal of condensate through vertical gas flues, preventing condensate concentration.
• Increased self-cleaning effect due to smooth stainless steel surfaces.
• Highly efficient heat transfer and high condensation rate achieved through turbulated heat exchanger surfaces and counterflow of boiler water and hot gases.
• Efficiency up to 98% through intensive condensation.
• Flue gas temperature is approximately 9 - 27°F (5 - 15°C) above boiler return temperature.
• Clean combustion via perfect match of burner and boiler, low combustion chamber loading, and straight-through combustion chamber.
• Easy handling in boiler rooms due to particularly low build height and weight.
• Simple installation and wiring with Viessmann prewired plug-in system.
• Coordinated Viessmann system technology components (heating boiler, system control, hot water storage tank) ensure seamless integration.
• All components are design-matched for quick installation.
• Pre-mix cylinder burner offers environmentally-friendly operation with a modulation range from 20 to 100%.
• Hydronic connections can be fitted from above.
• Economical and safe heating system operation with Vitotronic digital control system, offering communication capability and tailored control strategies.
• Standard LON BUS for integration into building management systems.
• Particularly quiet operation.
• High altitude operation up to 10,000 ft. (3000 m) with simple electronic adjustment.

Performance Graphs

Boiler Efficiency vs. System Partial Load

This graph illustrates boiler efficiency (Y-axis) as a function of system partial load (X-axis). It shows multiple curves representing different design supply/return temperature combinations, such as 194°F/158°F (90°C/70°C) Curve 1.8, 104°F/88°F (40°C/30°C) Curve 0.5, and 167°F/140°F (75°C/60°C) Curve 1.4.

Boiler Water/Supply Temperature vs. Outdoor Temperature

This graph plots Boiler Water/Supply Temperature (°F/°C) on the left Y-axis against Outdoor Temperature (°F/°C) on the X-axis. A secondary Y-axis on the right indicates a related value. Multiple curves represent different room set-point temperatures.

Boiler Efficiency Curve vs. Return Water Temperature

This graph shows Boiler Efficiency (%) on the Y-axis against Return Water Temperature (°F/°C) on the X-axis. It displays efficiency curves for various partial loads (20%, 40%, 60%, 80%, 100%).

Boiler Flue Gas Temperature Curve vs. Partial Load

This graph plots Flue Gas Temperature (°F/°C) on the Y-axis against Partial Load (%) on the X-axis. Five curves (A-E) are shown, each corresponding to a specific supply/return temperature difference, ranging from 176°F/140°F (80°C/60°C) for curve A down to 104°F/68°F (40°C/20°C) for curve E.

Pressure Drop vs. Flow Rate

This graph illustrates the pressure drop (in "w.c. and mbar) on the Y-axis against flow rate (in m³/h and GPM) on the X-axis. It indicates a linear relationship suitable for fully pumped hot water heating systems.

Altitude Derating

A graph shows Burner Input (%) on the Y-axis versus Elevation (Feet Above Sea Level) on the X-axis. It illustrates input capacity derating at higher altitudes, with a -15% derate at 5000 ft and a total -18% derate at 10,000 ft after electronic altitude adjustment.

Cutaway Section

A cutaway diagram reveals the internal workings of the Vitocrossal 200 boiler. Labeled components include: (A) Inox-Crossal heat exchanger surface made from high-grade SA 240-316 Ti stainless steel, (B) Highly effective thermal insulation, (C) Water-cooled stainless steel combustion chamber, (D) Wide water passageways with low pressure drop for good natural circulation, (E) Fully modulating pre-mix cylinder burner, and (F) Vitotronic control unit.

Technical Data & Specifications

*1 Tested to AHRI, BTS-2000 Testing Standard Method to Determine Efficiency of Commercial Heating Boilers.

*2 Add 1½ in. (40 mm) when using seismic mounts (optional accessory).

*3 Optional low NOx certified by SCAQMD Natural Gas models available.

Altitude Operation Note: For operation up to 4,999 feet, derate input capacity by 3%/1000 ft. For operation from 5,000 to 10,000 feet, with electronic altitude adjustment, derate input capacity by an additional 0.6%/1000 ft. for a total derate of 18%.

Boiler Water Content and Heat Exchanger Surface

Operating Parameters

Boiler Connections

Flue Gas Values

Dimensions

* Add 1½ in. (40 mm) when using seismic mounts (optional accessory).

Recommended Minimum Service Clearances

To enable convenient installation and maintenance, observe the stated clearance dimensions. Maintain minimum clearances where space is tight.

*¹ Clearance may be reduced to zero in multi-boiler installations, provided the side panel removal is not required. Note: Burner, boiler control, condensate trap, venting, and heat exchanger are accessible from front and rear.

*² Clearance for vent pipe installation.

Minimum Clearances to Combustibles

Mechanical Room Requirements

• Avoid air contamination by halogenated hydrocarbons (e.g., sprays, paints, solvents, cleaning agents).
• Avoid very dusty conditions.
• Avoid high levels of humidity.
• Protect against frost and ensure good ventilation; otherwise, the system may suffer faults and damage.
• In rooms with potential halogenated hydrocarbon contamination, operate the boiler only in balanced flue mode.

Cylinder Burner Specifications

Cylinder Radiant Burner Diagram Legend: (A) Boiler door, (B) Air pressure switch 1, (C) Fan, (D) Burner display and programming unit, (E) Gas valve with gas pressure switch, (F) Gas supply pipe, (G) Burner test firing valve, (H) Cylinder burner assembly, (I) Ignition electrodes, (J) Ionization electrode, (K) Gas pipe, (L) AC-EMI suppression filter device, (M) Ignition unit, (N) Thermal insulation block, (O) Manual shut-off valve, (P) Venturi mixing pipe, (Q) Air pressure switch 2, (R) Burner control sub-base, (S) Servomotor and burner inlet damper (for models 246 / 311). Note: Solenoid valve (choke valve) for CM2 model 186 is not shown.

Standard Equipment

• Boiler body with fitted mating ANSI flanges and gaskets, fitted protective crate, and flue gas collector collar.
• 1 thermal insulation
• 1 cylinder burner
• 1 boiler control unit (see boiler control alternatives)
• 1 boiler coding card
• 1 technical documentation

Installation Fittings Included:

• Low water cut-off
• Safety header (with 75 psig pressure relief valve, air vent, and pressure gauge)
• Drain valve
• Product documentation
• Combustion air intake kit
• NG to LPG conversion kit

Boiler Accessories

• Motorized flue gas damper (for cascade venting system). Refer to common venting flue vent damper Installation Instructions.

Boiler Control Alternatives

For single boiler systems:

Vitotronic 300 (type GW6B) Single Boiler Operating Mode: Outdoor reset control for stand-alone operation, modulating water temperature, and mixing valve control for up to 2 heating circuits. Also supports additional Vitotronic 200-H, type HK1B for 1 or 3 additional heating circuits.

For single-boiler or multiple-boiler installations:

Custom control panels for residential or commercial applications are designed and manufactured by Viessmann to meet specific requirements. These can integrate features like pool heating, hot tub heating, snow melting, telephone tie-in, and Building Management Systems integration.

For multi boiler systems (up to 8 boilers CM2):

Vitotronic 300 (type GW6B) Lead boiler + Cascade Operating mode: Outdoor reset control for cascade operation with a Vitotronic 300 GW6B in lag boiler mode, supporting up to 2 heating circuits with mixing valve and additional Vitotronic 200-H, type HK1B for 1 or 3 additional heating circuits.

Vitotronic 300 (type GW6B) Lag boiler Operating mode: For modulating boiler water temperature, used in conjunction with a Vitotronic 300 GW6B in lead boiler + cascade mode.

System Design Considerations

Condensate Disposal

Domestic drainage systems should use materials resistant to acidic condensate, such as stoneware, hard PVC, PVC, PE-HD, PP(s), ABS/ASA, stainless steel, or borosilicate pipes.

The amount of condensate and flue gas temperature can be read from graphs. Condensate pH is between 3 and 4. If neutralization is required, contact Viessmann for a neutralization tank. Treated condensate (pH 6.5-9) can be disposed of into the wastewater system.

Condensate drains must be inspected, routed with a gradient, include a P-trap, and be made of corrosion-resistant materials. Avoid galvanized or copper/black iron materials. Install a P-trap to prevent flue gas escape.

Venting Options

PP(s) (Polypropylene) flue gas/fresh air systems for sealed or room air dependent operation are tested to ANSI Z21.13 - CSA 4.9 standards and certified with the Vitocrossal 200. Special stainless steel, single-wall venting (UL listed for category IV) is also an option. Venting can be horizontal or vertical.

Combustion Air Supply

The boiler must not be located in areas with chemicals like chlorine, bromine, fluorine, bleach, refrigerants, paint, hair spray, or cleaning solvents. Ensure adequate ventilation and fresh combustion air. Avoid dusty conditions, high humidity, and frost risk.

For marine environments, use room air dependent vent systems to minimize corrosion from sea spray and humidity.

The boiler requires clean fresh air. Follow Natural Gas Installation Code CAN/CSA-B149.1 or B149.2 (Canada) or National Fuel Gas Code ANSI Z223.1 (USA) for provisions.

Water Quality

Consider boiler feed water treatment in areas with high mineral content or hardness. For freezing protection, use antifreeze specifically made for hot water heating systems (do not use automotive silicate-based). A 40% antifreeze mix provides freeze-up protection to -10°F (-23°C). Do not exceed 50% mix ratio.

The pH value of heating water should be between 8.2 and 9.5.

Oxygen Diffusion Barrier

The warranty does not cover pressure vessel failure from corrosion caused by underfloor plastic tubing without an oxygen diffusion barrier. Viessmann recommends using tubing with a barrier or separating it from the boiler with a heat exchanger.

Boiler/Burner Start-up

Vitocrossal 200, CM2 boilers with Viessmann cylinder burners do not require a specific start-up procedure by Viessmann.

Sound Attenuation

Consult a professional engineer for noise attenuation advice. Noise from the boiler system can transfer to adjacent rooms. Additional protective measures may be needed at the design stage. Subsequent noise reduction measures can be extensive and costly.

Airborne Noise Attenuation

Boilers may have silencer hoods or sound-insulated ventilation housings. For larger systems, sound-insulated channels for ventilation air may be necessary. Flue gas silencers are typically required for higher noise protection. Assessment of noise emission and sound pressure level is recommended during planning.

Anti-vibration Measures

Anti-vibration supports can be used to combat noise. Consider the total system weight when sizing supports. Flexible couplings can physically separate combustion equipment from the building. Insulate braces or hanging arrangements against sound/vibration transmission.

Warranty

The warranty does not cover damages from: operation with contaminated fill/feed water, contaminated combustion air, or exposing the boiler to pressures/temperatures exceeding its certified rating. Refer to the warranty sheet for details.