Secondary Boiler Controller (SBC) prom HV2s, HD2s

This allows sites with multiple independent boilers to be controlled on one SeaChange network. Whilst most of the features available on the current boiler controller are supported there are some important exclusions so please read this carefully to avoid quotation errors.

The SBC is registered to the Main Boiler Controller as an independent heat source, up to 20 heat sources are supported. The main boiler must be in configuration mode to register heat sources. Note VT Controllers are also registered as heat sources so the total number of VTC and SBC must be 20 or less.

The SBC can be any of the currently supported boiler types, VT output or DHW output, automatic sequence, high/low, fixed sequence.

The SBC gets it’s outside air reading from the Main Boiler controller so the fourth analogue input is not used. The SBC therefore only supports 3 plot channels.

The Secondary Boiler Controller can NOT have pump changeover modules or VT controllers registered to it. The SBC will support up to three cascade modules so the maximum number of boilers can be eight. Note however that if all the boilers need to have ‘lockout’ or ‘disable’ supported then only six boilers can be accommodated, the first two boilers do not have the requisite inputs.

The registration process is the same as for VT Controllers, Put the main boiler controller into config, register the SBC, the first one registered will be called heat source 2, the main boiler being heat source 1. Put the SBC into config and then register the zones which will be supplied by this heat source. The zones will first be registered to the main boiler to be allocated a zone number (network address) and will then (approx 5 second delay) have their heat source variable updated by the SBC. Trim signals from the zone will thus be directed to the secondary boiler. The top ‘error’ LED flashes to indicate that the heat source has been updated, red for heat sources, yellow for cool sources, on controllers with a display ‘HTSC 2’ is presented. Changing the heat source variable at the zone using the config variables is all that is required to reallocate a zone to an alternative heat source.

The Main Boiler controller has a MODE config variable which when set to 1 ensures that the zone which is presenting the highest trim signal, will drive it’s actuators to 100% thus ensuring a valid circuit is available at all times when the boilers are running. This mode also opens actuators to dissipate heat from the boilers at boiler shut down. This mode of operation is NOT available on Secondary Boilers, the config variable MODE is present but forced to a value of zero. Look carefully at the boiler circuit and ensure that the water has somewhere to flow if all the actuators close at once. Boilers with VT valves, bypass circuits or shunt pumps will be OK.

When looking at the parameters on a zone controller the FLOW presented is the flow temperature for the Main boiler. There is currently not enough memory in the zone controller to correct this at present.

DHW controllers may be registered to a SBC but the ‘electric’ output option will not work exactly as intended in that the DHW controller will be monitoring the main boiler Flow temp not the Secondary Flow temp.