Remote Switching of Boilers

REMOTE SWITCHING OF BOILERS

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Where a boiler does not require a Pump Overrun, it is possible to use a Flow Switch to switch the boiler on and off, removing the need for wiring from the boiler to system wiring centre.

The flow switch should be fitted onto the boiler flow or return, and connect between a permanent live and the boiler switch live. When the primary pump starts water circulating, the flow switch will detect the flow of water and switch on the boiler.

One advantage to this method of switching is that it ensures that the boiler will not turn on if the primary circulating pump fails and there is no water flow.

If thermostatic radiator valves are used on all radiators, and if the flow switch is setup correctly and balanced, then this system can also reduce boiler cycling - the boiler will only switch on when a thermostatic radiator valve is open and calling for heat. It is imortant in this case to ensure that the by-pass is fitted around the pump and not accross the boiler flow and return, so that the boiler will not switch on when water is only flowing through the by-pass and not to any radiators.

In some situations, unwanted gravity circulation may cause the flow switch to activate and switch the boiler on. Fitting a check valve into the return to the boiler may prevent gravity circulation. The check valve acts as a restrictor preventing gravity circulation, but providing little opposition to pumped circulation. Care must be taken not to air lock the system.

IMPORTANT: THIS IS GENERALLY NOT ADVISED AS THE BOILER WILL GENERALLY NEED A SEPERATE ELECTRICAL ISOLATING SWITCH - IT IS PREFERABLE TO HAVE A SINGLE ISOLATING SWITCH FOR THE WHOLE SYSTEM.