In the case of the OP's Nova, we're talking about a heater for the water bath and its associated temperature control circuitry.
...What would happen if I tried using the Nova at 50hz. Blow up ? Catch Fire ? Fry?...
Actually, on Nova's (The Imagingwarehouse) website they specifically state that the unit is not compatible with 60 hz
IMPORTANT NOTE:-
EUROPEAN & WORLD Customers (excluding USA and Canada) - A UK 3 Plug is fitted as standard to all our equipment but an optional European 2 Pin Plug adaptor can be purchased to assist you to connect to your electrical supply.
USA & CANADA Customers - Unfortunately, this product is unsuitable for use in the USA & Canada owing to highly sensitive electronic microchip controls which require a 230 volts 50Hz electrical supply. Although a step up transformer can be used to create 230volts from 110volts, the standard frequency of 60Hz also has to be converted to 50Hz in order for the unit to work. You can use a frequency converter but they tend to be expensive.
link
Unless you're planning to use it for color, leaving it unplugged and using it at room temperature is probably fine. I have an older quad with a US-compatible heater, which I keep set for 68° F. It's handy in the winter here, but not truly necessary even then.
If you are handy with electronics, especially micro-controllers, it might be possible to dissect the heater and replace the temperature control portion.