Zero-crossing or random turn-on SSR, to use with 220V heating element with PID?

Hi,

For a project, we (students) want to demonstrate the principle of PID to control the temperature of a room. Instead of using an entire room, we will make a "sample setup": namely a box with temperature sensor and a 220V AC heating element in it (probably coming from a hair dryer, or another home or kitchen appliance). And with a fan in it, to spread the temperature.

We will use an arduino, with the PID library, and we will connect that to a Solid State Relay (SSR).

However, it seems that we can use two types of solid state relays: zero-crossing or random turn-on... Which type should be chosen?

Thanks :)

So long as it works I don't suppose it matters for you application. Zero-crossing relays produce less radio interference and noise on the mains, so are in general preferred I think.