Dometic Vacuflush Question

I am back with the same problem.

Having the same hammering problem again. Started right off when I used the head after sitting for 12 days. Had son and grandson with us but we explained how to use it. Anyway I ran about 10 full bowels of water through, I know DW is using plenty of water. Others say they are. Tried another 10 full bowels of water through it later but still have a hard hammering the last 10-15 seconds of the cycle. Everyone is holding down he flush for a 15 count.

Advice and ideas welcomed again.

Thanks. Right after I posted this it started again. We increased the water level a bit and the hold down time a little and all seems back to normal. We/ thought we were doing right but some insight helped. Thanks

RedRollingRoadblock wrote:
Just got a new Bounder that has the Dometic VacuFlush we are on the shakedown cruse now. Last night after the flush as it is doing its thing the last thing was a knocking sound. Sounded just like someone knocking/slapping on the door. Did it about five times then no more.

I was thinking maybe a blockage, the DW tends to be shy with the water and ran a few full bowels through. Cannot find anything in the manual. Ideas?

No worries, it is the sound that comes with that type of toilet, I have the same. Normally last maybe 30 seconds or so, unless your at a high elevation. As the other fella suggested, hold the pedal down 3 seconds, I do 5 just for good measure.

Tell your wife to do her business then hold the foot pedal down while counting to three then slide or take her foot off the pedal quickly. This will allow enough water in for the flush. If you have low pressure or are using the water pump, count to five.

Having completely disassembled the vacuum pump, I can tell you there is nothing that would 'knock' unless the motor is loose and banging against something else. However, at least in ours, we occasionally get a 'knock' when not enough water is used. It seems to be due to the acoustics of the space rather than the pump itself. Easiest way to check is to watch it when someone flushes.

Water pressure maybe combined with trapped air?