Siphon trick or foolish user?

[drewstar]

Well I had a productive weekend.  Part of the "honey-do" list included a water change out.  (4 months of the old water. It held up well, IMHO).

I decided to give the "super Siphon" trick a try but I had no luck.

I used a 10' leanght of pool vac hose (1 1/2 -2" dia) and tried to get a siphon going by holding one end up to a jet on high.

I had no luck!    I've done this on my pool with a garden hose, is the vac hose too large?  

finally I ended up using the drain plugs and my 1/2 hp quick pump.  

[Tatooed_Lady]

maybe the 10' wasn't enough length to keep things moving through that hose?

[drewstar]

maybe the 10' wasn't enough length to keep things moving through that hose?

I originaly would think a shorter run of house would be easier?  But then again, a longer leagth, once the water is flowing would create an appropriate vacuum. No?

I am thinking the vac hose, at 2" dia was a bit too  large. I'm thinkning yea, either longer hose at this dia or a smaller dia at this leagth?  Can anyone confirm my half assed sceince?  What's the largest sized hose that others have used successfully?

[wmccall]

Does your spa inject air into the water?  I've not tried this technique yet, but if I did, I would turn off the air injection thinking it might break the siphon.

[drewstar]

Does your spa inject air into the water?  I've not tried this technique yet, but if I did, I would turn off the air injection thinking it might break the siphon.

Nope. No air.

[Drewski]

Hey Bud:

For a siphon to work correctly the suction end must be higher than the drain end AND the hose must support vacuum pressure. The higher it is, the better the flow.

I use a wet-vac to help with this process. I connect 2 wet-vac hoses with an adapter, plug the end into my wet vac, have my kid hold the suction end in the bottom of the tub and turn the vac on. When water hits the vac I pull the hose out and put it under my foot. I have a 6 HP Home Depot “Rigid” vac, so it REALLY sucks! Generally, in about 15 minutes, my 500 GAL tub is almost empty. Sometimes I lose suction toward the end, but can regain it if I'm careful. I also use the wet vac to suck out the remaining water and blow out the heater water and water in the plumbing using the vac in reverse.

Been doing this for 2+ years now and it works GOOD, usually no more than 30 minutes from beginning to end...

Drewski

[Zep]

1/2 HORSEPOWER SUBMERSIBLE WATER PUMP
This 1/2-horsepower submersible pumps up to 2000 gallons per hour and makes a great sump pump.

Current bid: US $33.99

[drewstar]

Drewski....Hmmm.  Maybe I'll try my wet vac next time.   The hose was higher than at the drain side.  


Zep, 2000 gallons per hour?  

Damn!

I have this, it's 1/2 hp and rated for about 600 gph.  Cost? $150.  (Yes Bonie,  it's a CRAFTSMAN. )

Why is one 1/2 horse pump dumping 3x the water than the other, and apperently significanlty less money?    

[Snyper]

1/2 HORSEPOWER SUBMERSIBLE WATER PUMP
This 1/2-horsepower submersible pumps up to 2000 gallons per hour and makes a great sump pump.

Current bid: US $33.99

I have one exactly like that, got it from eBay, perhaps the same guy. Works like a dream. I can drain my spa in less than 10 minutes.

[anne]

I used a 10' leanght of pool vac hose (1 1/2 -2" dia) and tried to get a siphon going by holding one end up to a jet on high.

 

The hose is rigid, right? Otherwise no vaccuum.

Also, the larger the diameter of the tube, the more "flow" you'd have to create from the jet to get the syphon started. Maybe the jet is not "strong" enough for that hose. Try a bigger (higher volume, not pressure) jet? I dont know at what point the length of the hose affects the vaccuum created, but I do know that you need more volume water per second for a larger diameter hose to create a syphon.  

[drewstar]

The hose is rigid, right? Otherwise no vaccuum.

Also, the larger the diameter of the tube, the more "flow" you'd have to create from the jet to get the syphon started. Maybe the jet is not "strong" enough for that hose. Try a bigger (higher volume, not pressure) jet? I dont know at what point the length of the hose affects the vaccuum created, but I do know that you need more volume water per second for a larger diameter hose to create a syphon.  

I think you are right about the pressue. I'm not following you on the hose ridgidness.  hwo would that affect the vacuum?


hey....if  my hose is rigid or soft is between me and Mrs Drewstar.  
 

[anne]

I think you are right about the pressue. I'm not following you on the hose ridgidness.  hwo would that affect the vacuum?


hey....if  my hose is rigid or soft is between me and Mrs Drewstar.  
  

Whoa, not trying to get personal, just trying to help! I'm sure your hose is rigid enough to do the job

As far as emptying a tub (that was the topic, right?) I just meant that the hose has to hold its shape- like a garden hose compared to a firemans hose.  His water hose! If the hose is too soft, it'll collapse with the negative pressure created bythe vaccuum, and the bigger the diameter of the hose, the more likely that is to be a problem. I should have said "thick walled" rather than "rigid".

[dirtrubber]

http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=45019   I have one from here works great a little cheaper

[jsimo7]

On my last water change I used a 1 1/4 cheap pool hose 25' lenth put it all in the tub and filled it with the jets in the water. I put a pair of vice grips on the end to hold it at the bottom and held my hand over the other end and pulled that end out and it started running and drinned in about 30-40 min. My tub sits about 1 foot above where I could get the lower end of the hose

[Brewman]

As mentioned earlier, a siphon works only when the discharge end of the hose is lower than the input end.  
And the farther below, the better the flow.  
Air entering the hose anywhere along it's length will cause the flow to slow down or even stop.  
I've started thousands of siphons, it's very common in brewing.  After a while you just develop a knack.

It will be trickier to get a 2" siphon flowing than a garden hose.  More area to deal with.   You need to make sure the hose is almost full of water.  Try dunking the entire hose in the spa, until bubbles stop coming out, keep one end in the water, move the other end to where you want, making sure the water doesn't all pour out and let go once the far end is lower than the spa end.  If done properly, it has to work.  
The jet pump method will work too, as long as enough water is pumping through the hose.