12th November                 Software release notes

Boiler Controller BV2t1 pre release development issue

These new features have been added to the Boiler controller and will be tried out on a lead site before being incorporated in the next issue of firmware. The DHW priority will apply to both types of Boiler Controller VT and DHW

Please Email comments to Mervyn before the end of the month

1. Add VT setpoint limit, config variable MXVT maximum VT added. This allows a limit lower than the Boiler Maximum Flow to be made on the setpoint for the VT control loop. This is intended to be used to limit the temperature in radiator circuits in schools etc. The default limit is set to 60 C. Without this limit the VT circuit is able to reach the Max Boiler Flow setting during 'warm up'
2. Add feature to restrict the VT valve opening when the Boiler Return Temperature is below the Minimum Return. This feature has been added to improve the 'backend protection' provided by our controllers. While the Return temperature is below the minimum required the flow through the VT circuit is restricted to enable the Return temperature to rise more quickly and thus reduce the time in which the cold parts of the boiler are subjected to corrosive condensation. This feature must only be enabled on Boilers with a shunt path for the Boiler flow back to the return. This is set using a new config variable VLIM default value 100% (limit inoperable). The VT valve opening will be limited progressively as the return temperature falls below the Minimum Return temperature. An example will hopefully clarify this
   • Min Return set to 40
   • VLIM set to 0%
   • If the Return temperature is 30, the VT valve will be held closed at 0% (VLIM)
   • If the Return temperature is 40 the VT valve will be free to open fully.
   • Between these values the limit varies linearly between 0% and 100% so at 35 return the VT valve is limited to 50% opening. This proportional section always operates for the first 10 degrees below Min Return.
   • VLIM defines the extent of the restriction on the VT valve, if set to 30% say then regardless of how low the Return temperature falls the VT valve will be able to be opened to 30%.

 













12th November                 Software release notes

1. Add Domestic Hot Water priority. This allows demands from DHW Controller(s) to disable the Heating outputs so that in situations where the boilers are undersized and where there are large demands for hot water, e.g. Nursing Homes the DHW is able to recover quickly by using all the boiler capacity for DHW, (at the expense of the heating demands). This feature is enabled by setting DHWP to 1 (default is 0). This will then switch off the VT pump or the Heating output (DHW version) whenever the DHW controller is calling for heat. Pump changeover modules used for Heating (type 2) will also be switched off.