Water Heater internal wiring??

[popbigguy]

My house has a ground well Geo unit that heats and cools the house. The geo unit also heats water to heat the basement floor and to warm the master bathroom floors. There is a 80 gal thermal storage tank for the floor heating leg of the system and it has a 4,500 KW electric back up. When it's really cold in the Winter, the geo unit is running some much that it can't keep up with heating the water for the floor heat leg, so I run the electric back up heater. But sometimes even that back up heater gets behind. I'd like to change the heating element to a 5,500 KW. From the main panel to the hook up to the storage tank, is 10ga wire with a 30 Amp breaker. The internal wiring on the tank, from hook up to the thermostat to the element is 12ga wire. So,,, a 5,500KW out of the question??? I thought about changing the wiring, but they're foam spayed in, don't budge. And why do companies use 12ga wire for the internals??

 

[nadogail]

Companies have been known to pinch pennies for greater profits; thinner wire = lower cost = greater profits.
Someone figured out that they could get adequate life out of the heater with their specified heater elements and the 12 gauge wire. The NEC only applies to the wiring to the heater, not the wiring within it.
I have yet to see a water hater fail because of the internal wiring; usually they get changed because the tank leaks or an element fails on an old tank. Plumbers make money changing water heaters; if they change the heating element in on old tank they know they get blamed for the eventual failure of the heater from old age.

A little low order math, 5500 watts and 240 volts, calculates to almost 23 Amps.

You could ask the heater manufacturer for an opinion and they, most probably, will tell you that changing the elements will violate the warranty. If it were my house I would probably change the element myself and not open this can of worms with the manufacturer.

Any technical advice you get from me is guaranteed to be worth exactly what you have paid me for it.

 

[428PI]

I've had a short wire to an element start to burn up. Caught it before it caught the foam on fire. Replaced the element and wiring and it's been ok for over 10 years now. Original elements don't last very long. Higher quality aftermarket elements last a lot longer with longer warranty.

 

[wssix99]

How do you know the water heater will be able to take the extra heating? (aside from a potential wiring issue)

Have you looked at options to increace the output of your geo unit? Sometimes, installers go short on glycol and throttle down the performance to save some bucks...

 

[Milton Shaw]

If you can access the elements through the service plates, why not just run the wire externally in wire mold/conduit and a couple of boxes. Make sure you wire the thermostats correctly and they need to be sized for the larger elements also.