Using Pool Pump to Blow Out Lines?

[NullQwerty]

Hey folks,

Just curious...If you lower the water level below the skimmer and returns, and then turn on the pump, shouldn't that blow out the lines for you (actually it'll suck the water out)? The water from the skimmer and returns should shoot out the returns until it's clear, no?

Or another option would be disconnect the tube from the pump to the filter and then turn on the pump...The water from the skimmer line should shoot out the front of the pump, no?

Is this an ok way to clear out your lines?

Thanks!

[ChuckD]

Don't think so.
The pump will only push, or pull, until the prime's lost which would be the first significant amount of air in the impeller. After that happens it's just spinning; it won't push or pull air.

This would still leave significant amounts of water in the lines. Air needs to be forced thru to displace it.

[Poconos]

Chuck is right. I want to add something else because there have been many posts and questions about using an air compressor to blow lines. For all but a main drain it isn't a good idea. An air compressor usually supplies a low volume at a high pressure. This could be fine for a main drain where the pipe going to the drain is at a steep slope. You would tend to push all the water out the drain and no water would settle in the pipe. A main drain is a specific case where you are trying to displace possibly an 8 foot column of water and you need more pressure than a shop-vac can develop. If you have long horizontal runs like to the returns, you want a high volume of high velocity air to try and move as much water out the pipes before you plug the returns. If you use a low volume and low veloity you could leave some water that could settle at low spots and possiby freeze and break a pipe. Depends on how it freezes. Think about the analogy of using a leaf blower to clear puddles off a flat slab of something. When I blow my returns I let the things bubble vigorously for probably 10 minutes before plugging. Back to the original question about the pump. Both shop-vacs and pool pumps are centrifugal pumps. One is designed for liquid and the other for air. Motor speed on a pool pump is usually 3450 RPM (single speed) while a shop vac is many thousands of RPM, probably over 10,000. Never measured one. Same with a vacuum cleaner motor/pump. The much higher motor speed is necessary because of the lower density of air versus water. Hope this sheds a little more light on the situation of blowing lines.
Al

[NullQwerty]

Makes sense guys....Thanks for clearing that up!