I'm looking for a digital timer for my hot water (3000W / 13A element), as with Flick power is cheaper overnight. I already have a Theben TR 608 Top2 for my underfloor heating timer (data sheet here), from memory it was around $100. Apparently saving a guy $5 per week / $250 / year.

I've seen a reference to someone using something like this, which is $30. Any reason not to use one of those?

Obviously I'm going to check with my regular electrician (my neighbor) before I buy anything, interested in thoughts first, especially from people who are qualified in this area.

Notes: new cylinder, with a cylinder wrap (probably unnecessary, had it for the old one), well insulated older house, two people living here, with the water heater turned off the hot water would last us around 36 hours regular use.

Update: you can see my estimated savings from this on this post.

UPDATE: according to the Ministry of Health residential hot water must be kept at 60 degrees or above at all times to prevent the growth of Legionella Bacteria. This bacteria can prove fatal. My current thought is heating water only at night could increase the changes of catching the bacteria. Instead I may look at turning off the hot water cylinder during periods of typical high load (7-9am and 5-8pm), but will likely leave it on other times. That's a shame, as I think it was contributing to decent power and money savings.