I work on residential and light commercial, split systems and rtus mostly under 10 tons.
I use the drain dawg, the drain kat, a wet vac and occasionally a water hose (on rtus after cleaning the condenser coils). It all depends on the situation.
I prefer blowing it out with the drain dawg but it's not alway practical especially in medical clinics with split systems and shared drains terminating under bathroom sinks. A wet vac is essential then.
I'd like to see a clean out tee above the p-trap. Makes blowing out most systems easy.
Just cap the vent and blow away.
A wet vac or drain kat can work just as well if it's easy to access the drain end and are a godsend if unable to cut into the drain due to access issues..
Just cap the vent and clean out first and uncap the vent afterwards.
“I am for doing good to the poor, but...I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it. I observed...that the more public provisions were made for the poor, the less they provided for themselves, and of course became poorer. And, on the contrary, the less was done for them, the more they did for themselves, and became richer.”
― Benjamin Franklin