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Support of Expansion Tanks for Water Heaters - Often Overlooked

jar546

jar546

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Here's an educational summary of IPC code section 308.10 regarding the installation of thermal expansion tanks:
  • Code Requirement: Thermal expansion tanks must be supported in accordance with the manufacturer's instructions.
  • Support Restrictions:
    • The piping that connects to the tanks cannot be used as a support mechanism for the tanks.
    • Tanks should be supported independently of the connecting piping.
  • Manufacturers' Instructions:
    • Installation instructions from manufacturers might not specify how to mount their tanks.
    • For larger tanks equipped with a floor mounting flange, the method of mounting is typically clear.
  • Supporting the Tanks:
    • If no specific mounting instructions are provided, the method of support is left to the discretion of the installer.
    • The tanks must be supported, not necessarily fastened, unless there is a risk of them being displaced by external forces such as bumping.
  • Seismic Considerations:
    • In regions requiring seismic safety measures, similar strapping methods used for water heaters (as per Section 502.4) might be advisable for thermal expansion tanks, although the code does not explicitly require this for expansion tanks.
  • Additional Considerations:
    • Tanks often include a fitting for air pressure adjustment, indicating the need for accessible mounting.
    • Given that thermal expansion tanks may need periodic replacement, their mounting location should be chosen to facilitate maintenance and replacement activities.
  • Location of the Tank:
    • Typically located near the water heater due to their role in managing pressure from heated water.
    • The tank can be placed elsewhere, provided there are no check valves or backflow preventers between the tank and the heater that could block the pressure relief path.
 
The kicker is that the code says to follow manufacturer's instructions and that thermal expansion tanks shall not be supported by the piping.

The manufacturers vary widely and some require almost nothing in the way of support.
 
I could feel okay calling out something that looks like those pictures. everything ive inspected so far(i'm a year in) has just been a single vert pipe. fancy home builders put on supports though
 
Couldn't the tank manufacture been made to design its own supporting system, like some welded on legs?

Kind of asking the plumber to be creative with pipe strapping aren't we?
 
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