Help on pump prime of Pentair intelliflo variable speed pump

[yangcha1]

Chris,

This one looks better than the one from amazon. Thank you for your information. I wish I had known it earlier.

PRAHER 2IN MIPxSKT UNION WITH PR200903


I found this Praher part...ought to work fine at about half the cost of the Pentair parts. I actually only need one since the output of my IntelliFlo goes to my filter and that has its own (proprietary) union.

 

[gtemkin]

The root of this problem is that there are 2 types of pipe threads (actually there are even more than just 2).

The 2 most common types are tapered and straight pipe threads. Tapered are far and away the most common and seal by interference between the male and female thread; that interference occurs across multiple threads.

Straight threads have no taper and therefor do not seal by interference. They need a separate sealing means, such as an o-ring. Both tapered and straight use the same thread count so they look almost identical, but they are not.

Pump manufacturers often use straight threads on their pumps, that's why many of the fittings for pump attachment have o-ring sealing. Using a straight thread prevents damage to delicate plastic housings by not stressing the housing from the wedging effect of tapered threads.

Unfortunately, marketing departments at many pump manufacturers don't know the difference between a tapered and a straight thread so their literature often incorrectly show the threads as NPT (National Pipe Tapered) when in fact they are straight pipe threads.

When you put a tapered pipe fitting into a straight pump housing you end up trying to seal on a very tiny fraction of the threads, and that's why so many people have problems with that connection and have to resort to tape and sealant and standing on their heads to stop a leak there.

Generally, always use an o-ring style fitting, as supplied by the manufacturer at a pump inlet and outlet and you won't have problems.

 

[yangcha1]

Very educational information. Thanks.

The root of this problem is that there are 2 types of pipe threads (actually there are even more than just 2).

The 2 most common types are tapered and straight pipe threads. Tapered are far and away the most common and seal by interference between the male and female thread; that interference occurs across multiple threads.

Straight threads have no taper and therefor do not seal by interference. They need a separate sealing means, such as an o-ring. Both tapered and straight use the same thread count so they look almost identical, but they are not.

Pump manufacturers often use straight threads on their pumps, that's why many of the fittings for pump attachment have o-ring sealing. Using a straight thread prevents damage to delicate plastic housings by not stressing the housing from the wedging effect of tapered threads.

Unfortunately, marketing departments at many pump manufacturers don't know the difference between a tapered and a straight thread so their literature often incorrectly show the threads as NPT (National Tapered Pipe) when in fact they are straight pipe threads.

When you put a tapered pipe fitting into a straight pump housing you end up trying to seal on a very tiny fraction of the threads, and that's why so many people have problems with that connection and have to resort to tape and sealant and standing on their heads to stop a leak there.

Generally, always use an o-ring style fitting, as supplied by the manufacturer at a pump inlet and outlet and you won't have problems.

 

[Agent99]

Interesting. You'd think the engineering department would make sure that the literature for their pumps stipulate tapered or straight threads in their systems. I'm going to shoot my Pentair buddy this very question about the threads in the IntelliFlo pump. He is an old hat tech guy who seems to know quite a bit.

- - - Updated - - -

I don't think pipe dope is necessary for this kind of union. It may mess up with the o-ring. Remember to lubricate the o-ring thoroughly before installation.

Pipe compound won't mess up the o-ring since the o-ring seals to the pump body and the compound seals within the threads. Good point with the lube...just make sure it is silicone based and not petroleum (like vaseline...never use vaseline).

 

[Agent99]

Well I've confirmed that the threads on the IntelliFlo are straight threads. I think I'm picking up some appropriate unions and redoing my plumbing. I don't have any leaks but I don't like the idea of using PVC pipe nipples (that are tapered) in a straight thread. Pentair ought to simply include the unions as part of the pump sale I think.

 

[gtemkin]

Well I've confirmed that the threads on the IntelliFlo are straight threads. I think I'm picking up some appropriate unions and redoing my plumbing. I don't have any leaks but I don't like the idea of using PVC pipe nipples (that are tapered) in a straight thread. Pentair ought to simply include the unions as part of the pump sale I think.

Yes, knowing how common tapered pipe threads are and how uncommon straight pipe fittings are, you would think they'd make a small effort to point out that leaks or damage could occur if standard tapered pipe fittings are used.

My cynical side thinks they intentionally want home installers to fail. On the other hand, it wouldn't surprise me if many professional installers were unaware of the thread distinctions, or have rationalized there's no problem using NPT fittings as long as they can keep them leak free for the warranty period.

 

[gtemkin]

...and one last thing. Below are the specs, as shown on Pentair's website, for the Intelliflo 011018 that the original poster installed. You can see under the heading for Port Size, the letters NPT.

If you check the specs for all their "flo" pumps, they say the same thing. This is not to single out Pentair. Most all the pump manufacturers mis-state their pump threads.



IntelliFlo Variable Speed Pool Pump
Product Model Voltage Full Load Amps kW HP SF SFHP Port Size (NPT) Carton Wt (Lbs.)
011018 IntelliFlo Variable Speed Pump 230 16 3.2 3 1.32 3.95 2 in. x 2 in. 45

 

[Agent99]

oops

 

[Agent99]

Yes, knowing how common tapered pipe threads are and how uncommon straight pipe fittings are, you would think they'd make a small effort to point out that leaks or damage could occur if standard tapered pipe fittings are used.

My cynical side thinks they intentionally want home installers to fail. On the other hand, it wouldn't surprise me if many professional installers were unaware of the thread distinctions, or have rationalized there's no problem using NPT fittings as long as they can keep them leak free for the warranty period.

The first guy I talked to at Pentair said his plumber uses Sch 80 CPVC pipe nipples along with teflon tape AND Permatex high-temp gasket sealer on all the threaded connections he makes. I've read time and again that mixing the tape and pipe dope is a bad idea...pick one or the other but not both.

The second guy I talked to said that, yes, the threads are straight and he doesn't know anything about the literature saying NPT. ???

ANYWAY...back to picking up the correct unions and redoing my pump plumbing! Ugh....

Now I'm concerned that the various links to other unions in this thread might have tapered threads instead of straight. Pentair has a union kit (357603) but they want around $70 for it!! It must have gold woven within it or something. Hmmmm...............

 

[gtemkin]

If it's got a flange that holds an o-ring, that's meant to seat on the pump body, it's likely a straight pipe thread fitting. If it has no o-ring flange, it's likely a tapered pipe fitting.

 

[Agent99]

Right. Good point. I knew that or more that I should know that as I was just edumacated on it 'n stuff.