The ability to change an existing sub-critical boiler over to an OT program is very limited.
"Common injection points are just after the condensate polisher and again at the deaerator outlet.
"[1] This forms a thicker protective layer of hematite (Fe2O3) on top of the magnetite.
This is a denser, flatter film (vs. the undulation scale with OT) so that there is less resistance to water flow compared to AVT.
[3] When OT is used, conductivity after cation exchange (CACE) at the economiser inlet must be maintained below 0.15μS/cm [4] this can be achieved by the use of a full-flow condensate polisher.