There was no control of the domestic hot water coil circuit, continuously operated
The woodboiler was connected to bottom heat exchanger of hot water tank
The control pipe thermostats, relays did not work
Two diverter valves separated the gas boiler from expansion vessel
The woodboiler’s water thermostat and fluegas thermostat were broken
Woodboiler temperature gauge didn’t work
Woodboiler draught regulator was set too low
Pressure relief valve was installed at bottom point of system
The highest point of the buffer was not vented
The woodboiler output pipe was connected to the side of buffer
Expansion vessel pressure was set too high
The firewood was stored on the lawn without a cover
Hydraulic Schematic Diagram.
Use of PLC
made possible some extra features
Hot water production has priority. Space heating starts only after direct hot water reaches ~45°C. At his point space heating starts, but DHW heating stays on until reaches is maximum (60°C)
If there is no heat demand, and the bottom of the buffer is already hot, space heating starts to prevent system from over temperature
Hot water cylinder pasteurization is monitored continously. Should pasteurisation expire, hot water is produced with LPG boiler
