Need help selecting expansion chamber.......

I own a small 960 sq. ft home with our own well. It has a total of 10 outlets. My questions are as follows: I have noticed the pipe banging sometimes and water pressure fluctuates quite often through the house. Upon inspecting my water system, I notice the pressure tank is leaking. So I want to change it. I don't have much info on the pump other than it's a submersible(bottom of the well) and I thinks it pumps at 6-7 gpm, All I know are the approx. dimensions of the old cast iron pressure tank 32"ht x 22"wide. My problem is that's it's under the house with only entrance in through a crawl space from the outside. So size is a definate issue or I would go by one larger than I really needed.Would a 20gallon be large enough for such a small house. Thanks ahead for any info you give. Soc

If its really cast iron, save it as a museum piece. Unless its 3/4" thick, its probably not. Cast iron likes to blow up under pressure. You can get horizontal bladder tanks that will easily fit through that hole. You could start shopping at Graingers.com. Lots of tech info there also, and any other parts you might need.

Since you can't get a large one under the house you can have 2 or even 3 tied in together that will give you better service than just 1. Just a suggestion.