... what is inside?

There is the metal covering, probably some insulation under that, then what? A metal tank?

I keep passing a place that is installing instant hot water heaters, and there are always a bunch of discarded tank-type units stacked out front. I was just wondering if there is something usable inside.

Sue, once a scrounger, always a scrounger

A whole lotta boom?

Er, I dunno. I assumed it was just a heating element in a bottle, surrounded with a bit of insulation and then wrapped in a sheet metal skin.

But that's just a guess. But the video is great. :-)

Google turned up this.

-john

There's an inner metal tank. Depending on whether it's gas or electric, there's either a flue running up the middle to the chimney(gas) or some electric elements inside. Of course there's also a cold inlet and hot outlet pipe. And there's an anode, which is a metal spike designed to attract any corrosive salts or chemicals in the water so they don't attack the other parts.

And, at the bottom of the tank, there is a layer of built-up sediment from the water and decaying anode. Some tanks have an access vent to clean out this sludge periodically. I don't know of anyone who actually does this, though. But the anode should be checked and replaced every couple of years.

See: http://home.howstuffworks.com/water-heater.htm

The anodes can be used for some cool looking metal sculptures.

The anode is magnesium, which you could use for firestarter after taking a file to it. But if it's all gunked up, I don't know how good it would be...

The anode is really gnarly looking- like barnacles on a piling.
Running down the center is a steel rod.
While you *could* make a firestarter out of it I'd regard buying a dedicated firestarter as a very cheap way of buying out of the trouble of doing anything with the rod.

I keep one or two around to show people how they can make their water heater last forever. (change it before it's fully consumed by corrosion and the steel of the tank is completely protected from corrosion)

It also does a fine imitation of the dreaded BOHICA.

Okay, I guess I won't volunteer to take any off their hands...

Thanks for the info, guys!

Sue

Parents get them a strip them down to the internal tank, then cut the top and bottom off and weld a couple together length wise to make culverts to put under roads. You don't have to bury them as deep as the thin sheet metal from a store bought one because they are much stronger.

Eugene, what (approx.) is the size of the internal tank of a standard 40-gal water heater? Length, diameter? How thick is the wall?

Ack! HOT water heater! What other kind of water heater would you find?! Redundency in everything, eh?

Sue

The insulation around the tank is only a couple inches thick so estimating the whole water to be close to 24" diameter, the internal tank is around 20". The steel is pretty thick, I remember he had to cut it with a torch. The tank is only a few inches shorter than the height of the outside also, gas being a little shorter since there is the burner under.

The tank in a water heater is a pressure vessel and a fairly substantial piece of steel or fiber reinforced plastic. An old water heater that isn't leaking, decommissioned for other reasons, makes a good water storage tank. If you route you water through it you will always have an extra 20 to 40 gallons of fresh water on hand.

If it is a steel tank it can make a nice grill. One issue in this is a steel tank will have glass fused to the inside. This can make working the steel more hazardous, wear safety glasses, and slightly more difficult. Of curse a plastic tank is useless as a grill. Then again a plastic tank is far less likely to leak and makes a better holding and/or pressure tank. I have seen a new one used in a solar water heating system because the water heater was less expensive than the holding tank.

The electric ones usually have deeply dished bottoms.
If you cut the bottoms off they make fairly good watering bowls and stuff like that, if you cut the tank lengthwise they make bigger waterers or feed troughs.
The steel tanks are thick enough to make fairly good stoves with.