DON'T DO IT! First, the water heater tank is 20 years old. You don't know what condition it is in on the inside. It may be (probably is) partially rusted through and therefore weakened.

Secondly, water heater tanks are not intended for this application. As hj points out, air tanks should be tested to ASME specs. Just because it might hold 110 psi now does not mean it is safe. It could be in a condition that barely holds 110 and on the verge of failure.

If the tank blows, it could cause serious injury and property damage. The volume of air that it would contain would explode like a bomb. Unlike pressurized water which looses its pressure immediately upon a small release, air will continue to expand and can throw fragments across the room and through walls.

DON'T DO IT!

- John Scates

: Hello, I replaced my 20 year old 40G gas water heater. The old one was not leaking, I just wanted something more efficient. I would like to use the old tank as a pressure tank for a compressor I am building. I have the pump which is currently attached to a 10 gallon tank but would like to upgrade to a 40 gallon tank. An old water heater tank seems like it will work. I removed the outer jacket and insulation from the steel tank. I would be pumping air into this tank to a maximum pressure of 110 PSI. Since a T&P valve is rated higher that that, I figured that my project would work. Do you have any thoughts or suggestions on my idea?
: Thanks,

: Delta

• Re: Converting an old water heater tank to air pressure. Delta 23:50:29 05/29/03(0)