Correct technique to purge air via the relief valve

[plnewb]

When I need to purge air from the system, like the filter, I open the relief valve at the back of the filter with the pump running until water starts to spray out of the open relief valve.

This doesnt feel correct though and makes me wonder if I am doing something wrong.

I was taught this technique by my uncle who liked to take shortcuts but would never teach me the correct technique

 

[mknauss]

I open the relief valve at the back of the filter with the pump running until water starts to spray out of the open relief valve.

Correct.

 

[1poolman1]

When I need to purge air from the system, like the filter, I open the relief valve at the back of the filter with the pump running until water starts to spray out of the open relief valve.

This doesnt feel correct though and makes me wonder if I am doing something wrong.

I was taught this technique by my uncle who liked to take shortcuts but would never teach me the correct technique

There is really no need to purge the air from a filter. The air relief screen/tube in the tank is above the level of the grids so water will force air out every time the pump is moving water, its automatic. On your filter it should be on top of the manifold. Some aftermarket DE manifolds have a screen or series of very small holes built in that serve the same purpose. Even if you open the filter for cleaning, all the air now in the tank/system will be removed once the system starts moving water unless the screen/tube is plugged. It takes a lot to plug an air-relief screen.

Even with a suction leak, any air that the pump might suck in will be forced out of the system as it is running before it forces water in the filter below the level of the grids/cartridges and interfere with filtration. That's one of the first complaints people have, "I see air returning to my pool."
Main reason for that external air relief is to be sure there is no residual air-pressure in the tank before opening it. That can be very dangerous.

As pool system age they often develop very minor leaks that allow air into the system when the pump is off that don't show up as a water leak when it is running. That allows air to enter every time the system stops its cycle and it is removed every time it re-starts.

All that being said, if you are more comfortable doing so, it won't hurt anything.