HELP can't blow out main drain

[lilhall]

I typically use a 4.25 HP shop vac but for some reason I cant get the main drain to blow out. I tried everything do you think I just need a larger HP vac.My compressor does not seem to produce enough air to get it to bubble. The pool ones are too much money for 10 mins a year. Any help will be appreciated.


Drain is in about 9' water

 

[Catanzaro]

Make sure everything else is isolated before attempting again. If not, you will have to work with an air compressor. Have you been successful in the past with the man drain? If so, what did you do different? Shop Vacs do not produce a lot of air.

 

[PoolguyinCT]

If yes to Catanzaro questions. Remove filter from the shop vac.

* what’s too much money is a cracked main drain pipe

 

[C4ST]

Have you checked to see if any of the pool stores near you rent blowers? A pool store in my area rents blowers for a relatively small amount--$10 to $20/day as I recall.

 

[JamesW]

Most shop vacs can't generate enough pressure to blow out a 9 foot (108 inches)deep main drain.

Most top out at about 60 inches. A few industrial ones can get close. This one can hit 105 inches.

Shop-Vac 10 Gallon* 3.0 Peak HP** Two-Stage Industrial Heavy Duty Wet Dry Vac | Shop-Vac

A compressor can do it if the line is isolated. It just takes a little while.

Be careful with a compressor because it can generate dangerous amounts of pressure if everything isn't set up correctly.

 

[Catanzaro]

If yes to Catanzaro questions. Remove filter from the shop vac.* what’s too much money is a cracked main drain pipe

Never thought about the filter as this will create resistance. Also, depending on the filter you have, place on recirculate, or bypass the filter when clearing the lines. This year, I have to try my filter to see if the main drain will budge. I will try later and report back.

- - - Updated - - -

Most shop vacs can't generate enough pressure to blow out a 9 foot (108 inches)deep main drain. Most top out at about 60 inches. A few industrial ones can get close. This one can hit 105 inches. Shop-Vac 10 Gallon* 3.0 Peak HP** Two-Stage Industrial Heavy Duty Wet Dry Vac | Shop-Vac A compressor can do it if the line is isolated. It just takes a little while. Be careful with a compressor because it can generate dangerous amounts of pressure if everything isn't set up correctly.

Thanks James. I just looked at my Rigid (WD1956) wet vac (16 gallon & 6.5 peak HP). Maybe this will work and I will give it a try over the next few days to a week.

 

[JamesW]

Note:Shop vacs are really not designed to generate pressure. The sealed pressure is the maximum suction they can generate, which means how far they can lift water, not push it down.

The sealed pressure is probably how far they can push down water, but the pressure generates heat and might burn up the motor.

In most cases, a shop vac won't be suitable for blowing out a main drain.

A compressor will work, but it takes longer and won't work if there are any air leaks.

Compressors can build up a lot of pressure. So, you have to be careful not to over pressurize the system.

 

[Pool_Medic]

A cyclone is a darn good investment.

 

[Catanzaro]

A cyclone is a darn good investment.

It sure is and should be split amongst friends. I help close 4 other pools (no charge), but get taken care of with liquor, food, etc. It kind of pays for itself. Also, my shop vac (wrong adapters) did not works so far. I am going with 2 hoses to see if I can purchase a reducer from 2" to 1.5", then remove the filter and give it another go. The issue is now that the hose will be about 12' and some resistance or volume will be lost. My Rigid is a good shop vac, and I will report back by the end of the week if this works.

 

[JamesW]

It really comes down to how much pressure the vac can generate.

Blowing out a main drain is similar to having a straw in a drink. If you blow into the straw, air will go into the straw and push out the liquid. If you put your finger over the end of the straw, the air is trapped in the straw and the liquid is kept out.

If you blow into the straw, you can stop at any point and that's where the air will stay. For example, you can push the liquid down 1 inch, 2 inches etc.

A wet dry vac is unlikely to be able to push water down 8 or 9 feet. It might be able to get the water pushed down 4, 5 or 6 feet.

As long as the skimmers and returns blow, the water left in the main drain line should be deep enough to keep it from freezing.

So, you don't really need the main drain to blow as long as you're sure that the water is pushed down deep enough.

A compressor also works if everything is done correctly.

The volume flow rate doesn't matter as long as the system is airtight. Just take precautions to avoid over pressurizing.

Also, doing a quick search, I was able to find blower rentals at general rental places. Example.

POOL LINE BLOWER Rentals New York City Metro Area NJ, Where to Rent POOL LINE BLOWER in Hillsdale New Jersey, Ridgewood, Franklin Lakes, Westwood, Paramus, Wyckoff, NYC

 

[Catanzaro]

Also, doing a quick search, I was able to find blower rentals at general rental places. Example.

POOL LINE BLOWER Rentals New York City Metro Area NJ, Where to Rent POOL LINE BLOWER in Hillsdale New Jersey, Ridgewood, Franklin Lakes, Westwood, Paramus, Wyckoff, NYC

James, I own the Cyclone, but always want to see if other methods work. Wow, $18 for 4 hours.

It literally takes me 12-15 minutes to clear out 8 returns, 2 skimmers and the main drain.

 

[lilhall]

I ended up buying the cyclone, it took five minutes and did a great job. next year will be easy as I wont be wasting time with wetvacs. thank you all that replayed.