Originally Posted by toskeysam
The vacuum break is likely an attempt to provide a code-compliant apparatus that would protect a potable water system hooked up to supply the flush water. A single check valve does not meet a code requirement for this service. The combination comes close.
Boxster,. No water to the spray head in the tank was what started this.
If the check valve hadn't been installed backwards on the vacuum / anti siphon valve and the water supply plumbed to outlet instead of the inlet it would have been spraying water everywhere behind freezer.
I agree about the code requirement but there is no fresh water to contaminate when the hose is disconnected.