Aeotec Heavy Duty Smart Switch: Bypass?

[sejtam]

I have one of these which I want to use to control and measure my Storage Water heater

The Switch itself has no mechanical override switch that could be used to turn on the heater
should my Zwave network fail for some reason.

I wonder whether it is possible to wire it in parallel to a mechanical switch , using a DPDT switch?
yea it would not monitor usage when in use but that would be acceptable when the network is dead.

This would be for 240V Singapore


I really think Aeotec should have made this with a manual switch or added two contacts
to wire in an external control switch..