Home > Plumbing Supplies Information > Plumbing Supplies Questions > ST-5 Water Heater Expansion Tank?

ST-5 Water Heater Expansion Tank?

A plumber came today to fix something, and he told me that I need to replace the water heater ST-5 expansion tank (I think it is 2 gallon size), since there is no air in there any more. The house was built in 2001. A friend of mine said he can do it for me. Questions: 1) What brand is a good brand to buy? I went to internet, it seems to point to Amtrol THERM-X-TROL ST-5 Expansion Tank, Model Number - ST-5. 2) Any plumbing supply company you recommend? I saw on ebay sell this brand for $32. Also at PlumberSurplus.com, sell it for $49 3) Do I need to buy any other accessories, when this tank is to be replaced? Such as connector or valve? What size? and what brand? 4) Anything else that I need to pay attention to? Thanks for your help!!

Public Comments

  1. should just screw on.. just pick one up at hd or lowes.. did he try to refill the tank with air? it could have a bad valve stem. read the label it should say what the pressure should be these are adjustable and could have been empty when installed
  2. You should be able to just buy a new one and screw the old one off. Amtrol is a good brand so you should be fine with that. Read the instructions for these tanks come preset from the factory. You wont need any other accessories except maybe teflon tape.
  3. this is a simple replacement but if you can drain some of the water out of the tank IE: drain valve then that's your fix by removing water you replace it with air and that's what you need for thermal expansion also I have seen these tanks at Home Depot