Since a hot water heater is also a holding tank, I don't really understand your question.

Can you give us some more information on what you are trying to do?

Yes, you can.

Is there anything else different I would have to do? Other than not hooking up heating elements and connecting thermostat to the boiler. I can get the water heater today at half the price or wait a week for the bradford white ast 40-6 storage tank.

Not really. Since it is used for Storage Tank than make sure you connect HOT water only. That's all...

Hi Tony...

Just out of curiosity... exactly what are you doing here? Are you using an old tankless coil for hot water and then storing it in the water heater tank?

Please let us know the details so we can be sure you don't miss anything... like a temperature and pressure relief valve... these are very important for safety!

Back to you...

Mark

Sure you can! Is the "storage tank" a working heater and will you be using the elements? Here are the two ways to hook them up, (see images). Depending on your needs what's your pleasure? Cheers, Tom