Viessmann Vitodens 200-W B2HA Boiler
8 fault codes documented
157 Fault Alarm – DHW Recirc. Pump / Zone Circuit Pump Output Issue
The boiler's programming unit display may show a general "Fault message" or a specific code like 157. Code 157 indicates a problem related to the domestic hot water (DHW) recirculation pump or a zone circuit pump output, suggesting a pump malfunction or an electrical issue with its connection.
Boiler Not Level – Improper condensate drainage
The boiler must be installed perfectly level, both vertically and horizontally, to ensure proper draining of acidic condensate. If the boiler is not level, condensate can accumulate and cause operational issues or corrosion.
DHW System Imbalance – Short cycling or insufficient hot water
The domestic hot water (DHW) system may experience short cycling of the boiler or fail to provide adequate hot water. This can be due to an undersized DHW tank, an improperly selected pump, or insufficient water flow through the heat exchanger.
Gas Supply Pressure Out of Range – Not between 4 and 14 in.w.c. for NG, or 10 and 14 in.w.c. for LPG
The gas supply pressure to the boiler must be within specified minimum and maximum ranges (e.g., 4-14 in.w.c. for Natural Gas). Pressure outside this range can cause unsafe operation, inefficient combustion, or boiler shutdown.
Low System Pressure – Below 14 psi (1.0 bar) minimum
The boiler requires a minimum system pressure of 14 psi (1.0 bar) for proper operation. If the pressure drops below this threshold, the boiler may not function or may display an error.
Primary Circuit Flow Rate Out of Range – Exceeds max or falls below min
The boiler's primary circuit requires the system flow rate to be within specified maximum and minimum limits for efficient and reliable operation. Flow rates outside this range, or unknown flow rates, can cause system inefficiencies.
Corrosion Leaks – From underfloor plastic tubing without oxygen diffusion barrier
Using underfloor plastic tubing without an oxygen diffusion barrier directly connected to the boiler can lead to corrosion and leaks. This is explicitly stated as not covered under warranty. Oxygen ingress promotes corrosion within the heating system.
Water Quality Problem – High hardness/minerals or incorrect antifreeze
Poor water quality, characterized by high mineral content or hardness, can lead to scaling and corrosion within the boiler. Additionally, using unapproved or automotive silicate-based antifreeze can damage system components.