Are thinking about a hot water HEATER tank or a hot water BOILER tank?
They are quite different critters.

I certainly would not consider a used one for the project. They usually
have enough accumulated corrosion to make them pretty weak.

Keep in mind that a failure in a hot water tank results in a small
pressure leak and then just drips. The compressed air tank has a large
amount of stored energy, they can fail catastrophically.

VW Golf Cart wrote:
Hi, not really related to the topic, but thought someone should have some
knowledge on the subject.

I have a compressor, but the tank is too small. Just wondering if I can
retro fit the compressor on Hot Water Boiler tank? They are rated at 150psi
wp and 300psi tp.

Am I way off here or could this be accomplished??

I am a welder, so welding it up wouldn't be a problem.

Thanks