Quote:
Originally Posted by Mikesolar
What kind of tank is this?
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One of those "smart" storage heater that steps down a few degrees every time the bottom heater kicks on, then steps up some when upper heater has to kick in to tune the water temperature setting.
But 175kWh/year to feed the electronic board itself is absurdity.
On the board, you'll see four relays. They're all single pole normally open type (give power to coil, contacts close).
The outer two relays (contactors ) are energized whenever there is power and each switches each side of the line. The middle two acts as a power switch. One for the upper, one for the lower.
So, there's a considerable holding power for these heavy duty 30A relays. Standby power consumption is 20W 24/7.
When the heating element is on, it has to go through three relays. The controls loss into the air is probably ~50W range when the heater is on with three coils energized and 20A having to go through three relays.
The triple redundancy design is probably to compensate for the reliability issues of digitally controlled embedded system based design from becoming a liability claim.