Chlorine injection tube location? Before or after pool pump? Pressure or vacuum side

[mystrwizard]

I have purchased a Stenner pump and am about to start hooking it up, but not sure where to locate the injection point of the chlorine? Should it be before the pump where the pump is pulling the water? at the pump somewhere? or after the pump? If attached before the pump, there will be a bit of vacuum pulling the chlorine, if after the pump, Im guessing there will be a sort of pressure pushing the chlorine back into the injection tube?

Any thoughts would be greatly appreciated!

Reese

 

[Bama Rambler]

Put it somewhere on the discharge of the filter, preferably after all other equipment.
Not that it matters in the placement, but did you get the low pressure or high pressure pump?

 

[Isaac-1]

Also remember that chlorine will outgas, so to avoid potential air lock in the line you want to keep them running upward to the injection point as much as possible.

 

[1502tuley]

I have purchased a Stenner pump and am about to start hooking it up, but not sure where to locate the injection point of the chlorine? Should it be before the pump where the pump is pulling the water? at the pump somewhere? or after the pump? If attached before the pump, there will be a bit of vacuum pulling the chlorine, if after the pump, Im guessing there will be a sort of pressure pushing the chlorine back into the injection tube?

Any thoughts would be greatly appreciated!

Reese

Do you currently have an in-line chlorine feeded (a puck feeder)? If so, you can move the water inlet to the upper hole (you will have to get the longer feed hose for this though), and screw the chlorine injection valve into the lower hole. This is how I did mine. You don't have to drill anything, and it made for a really clean install. Here's the thread where I learned about doing it this way. http://www.troublefreepool.com/threads/51224-Another-happy-peristaltic-pump-injector. Notice the first and second pics in the thread.

 

[mystrwizard]

Put it somewhere on the discharge of the filter, preferably after all other equipment.
Not that it matters in the placement, but did you get the low pressure or high pressure pump?

I ended up getting model 45MPHP10, I guess that is high pressure.

 

[Bama Rambler]

I asked because the HP units come with an injection check valve so even if the tubing or pump tube split the water won't flow out.

Also remember that chlorine will outgas, so to avoid potential air lock in the line you want to keep them running upward to the injection point as much as possible.

Since the Stenners are peristaltic pumps you don't have to worry about the outgassing issue.

 

[Patrick_B]

Is there a downside to putting it in the suction side of your system with a Stenner? I can think of possiblilities why it would be, but don't some do this into the drain plug on the pump basket? I was going to ask about this in my own thread but it seems pertinent here.

Also, Stenners don't need head on their suction side do they?

Since you mention it Dave, how do the Stenners overcome gassing when injecting to pressure sides? I've dealt with LMI lots and lots, but never Stenners.

 

[Bama Rambler]

The only real downside to injecting it in the suction side of the pump (and it's not just limited to the Stenners) is that if the tubing/fittings spring a leak, it would introduce air into the system and possibly cause the pump to lose prime.

Peristaltic pumps in general don't need head on the suction side.

It's all in the way peristaltic pumps move the fluid. They will actually pump air. Not very efficiently, but they will. Since they use a progressively moving cavity it doesn't stop the flow if some gas gets into the system.

 

[Patrick_B]

Well, I wasn't thinking of that, but thanks, that is a good thought for sure. I was afraid there could be enough vacuum to pull bleach through the pump uncontrolled. I guess the vacuum isn't strong enough.

Thanks for all the info Dave, I appreciate it.

 

[JasonLion]

As a general rule chlorine injection is always after everything else. Injection pumps with high flow rates (rare) could raise the FC level enough to cause a risk to the heater if the injection point is before the heater. There is also some risk of voiding your heater warranty even if the FC level could never get high enough to make any difference.

 

[Bama Rambler]

... I was afraid there could be enough vacuum to pull bleach through the pump uncontrolled....

If there were enough vacuum it would "suck" the pump tube flat before it would pull anything through the pump past the rollers.

And as Jason said, there are other reasons for not injecting on the suction side.

And as a side note; the LQ (Liquidator) only works by utilizing the suction to draw the chlorine/water mixture out of the vessel. So it's the exception to the rule.

 

[Patrick_B]

Thanks guys. I clearly wasn't thinking it through. I'll have PB cut in a T for me when he plumbs my equipment pad.