Possible black tank vent issue.

[coffeediver]

I have a 2010 Big Country that has been permanently parked on a concrete pad on my property with a cover, deck and septic tank. I removed the original toilet and replaced with a standard home toilet but flushing is creating a vacuum in the tank so after a day or so it will not flush properly unless I drain it first which relieves the vacuum. I do not know if this unit has a roof vent. I don't do well with ladders.
Should this have a roof vent that should prevent the vacuum?

Barry

 

[Roller4tan]

The Tank is vented. You should not leave the dump valve open. Liquids flow out, solids remain and will pile up under the down pipe, or block vent pipe. Since you say you are on a permanent spot, it might make more sense to remove the black tank and plumb directly to your septic.
To check your tank vent for obstructions, find a friend who can run a water hose into the vent to see if the pipe fills.