Question about pipe size specified in Engineering Doc vs what the PB used

[essbase]

Hi,

I have a pool/spa combo that was built in Florida over the last year and has had many issues along the way.... Thanks so much for all the help and answers provided during this journey.

I need some direction on another issue. The pool/Spa has a 3hp VS motor. at higher RPMs it starts cavitating unless it is pulling from more than one suction pipe. In example, in SPA mode the suction 3 way valve closes off the Main Drain and Skimmer, so it only pumps water from the Spa drain. When this happens and the pump is above 2750 rpm it sounds like gravel is in the pump. Same thing if only the Main Drain is open to the pump. I am not sure if I am reading the Engineering Doc correctly, but it appears to specify 2-1/2" pipe for the Branch, Trunk, Spa Suction lines. The lines that the PB ran are all 2". Can someone take a look at the attached Engineer's Calcs and tell me if they ran too small of pipe? I think that's the case but also wonder why the inspector didn't catch the issue if so. Thanks so much for everything!

 

[ajw22]

Yup, the documents say 2.5" pipe should be used.

Town inspectors look if the construction meets the building codes. They don't check what is constructed versus the engineering documents for items that the building codes do not specify.

Post pics of your equipment pad and your spa showing the drains.

@mas985 my have some thoughts.

 

[essbase]

Yup, the documents say 2.5" pipe should be used.

Town inspectors look if the construction meets the building codes. They don't check what is constructed versus the engineering documents for items that the building codes do not specify.

Post pics of your equipment pad and your spa showing the drains.

@mas985 my have some thoughts.

Thanks Allen... Here is a picture of the Suction valves and a clip of the drains. I have 2 of these drains in both the Spa and the Pool. Thanks Again!

 

[Jimrahbe]

ESS,

We need to know exactly which pump you have..

Also, we'd like to see several pics of your equipment pad.

In the Spa mode, almost every system I have seen is set up to suck all the water from the spa using a single pipe. So, it would be odd, if your pump can't run at full speed in that configuration.

Thanks,

Jim R.

 

[Jimrahbe]

I have 2 of these drains in both the Spa and the Pool.

ess,

Not really.. You have two drain covers, but they are connected together and only have one pipe leading back to the equipment pad.

Thanks,

Jim R.

 

[Newdude]

Here's mine, upside down. The feed pipe goes in the middle.

 

[essbase]

ESS,

We need to know exactly which pump you have..

Also, we'd like to see several pics of your equipment pad.

In the Spa mode, almost every system I have seen is set up to suck all the water from the spa using a single pipe. So, it would be odd, if your pump can't run at full speed in that configuration.

Thanks,

Jim R.

Hi Jim,

I am not there or I would snap a picture of the pad. This is the pump that is installed:
3.95THP 230V INTELLIFLO VSF VARIABLE SPEED & FLOW PUMP (PUR-10-1662)

• Product # : PUR-10-1662
• Mfg : PENTAIR WATER POOL AND SPA INC
• Mfg # : 011056

 

[essbase]

Yup, the documents say 2.5" pipe should be used.

Town inspectors look if the construction meets the building codes. They don't check what is constructed versus the engineering documents for items that the building codes do not specify.

Post pics of your equipment pad and your spa showing the drains.

@mas985 my have some thoughts.

Allen,

I am in Florida and I think the FL building code included the Ansi specs 7 & 15 for pools... Some of the requirements in the code are hard to specifically understand. but even if they do require it, I am not sure which pipe sizing they would apply from the Engineering docs. Would it be based on the Ansi spec calcs vs what the Engineer specified... (seems like if references smaller pipes and then specifies 2.5". Probably need to call the Engineering firm that the PB used and ask that question. Thanks!

 

[JamesW]

It says that you have 4 spa jets at 10 gpm for a total of 40 gpm in spa mode.

Is that what you have?

 

[Jimrahbe]

ess,

There are thousands of those pumps (011056) that are out there running pools and Spas, and my 'pull it out of my rear' guess is that most of them are installed with 2" plumbing. Since I don't remember anyone else having this same problem, I really doubt that the pipe size is the cause of your issue.

Something else is a foot...

Thanks,

Jim R.

 

[ajw22]

I am in Florida and I think the FL building code included the Ansi specs 7 & 15 for pools... Some of the requirements in the code are hard to specifically understand. but even if they do require it, I am not sure which pipe sizing they would apply from the Engineering docs. Would it be based on the Ansi spec calcs vs what the Engineer specified... (seems like if references smaller pipes and then specifies 2.5". Probably need to call the Engineering firm that the PB used and ask that question. Thanks!

The ANSI calculations demonstrate that your pool meets the minimum requirements. No pool should be built to those minimum standards.

This page specifies what the engineer wanted installed.

As others have said many folks, including me, have the 011056 pump running fine with 2" suction. 2.5" suction will provide a bit better hydraulic efficiency but 2" pipe will be able to keep up with the pump.

The VSF pump will display the flow rate. It would be helpful to know what the pump is displaying for flow at various RPMs.

When you are at the house we can help you diagnose your problem further. But the use of 2" pipe is not what I would go after the pool builder for.

Do you have any pics of the pool during construction? Particularly pictures of after rebar and plumbing but before gunite?

 

[Jimrahbe]

ess,

I see that you are in Florida, the land of the dinky filters...

I suspect your problem is either a very small filter or the filter is dirty from construction and plaster debris.

Thanks,

Jim R.

 

[essbase]

It says that you have 4 spa jets at 10 gpm for a total of 40 gpm in spa mode.

Is that what you have?

James,

Yes I think that is correct. There are 4 Waterway straight body jets.

 

[essbase]

ess,

I see that you are in Florida, the land of the dinky filters...

I suspect your problem is either a very small filter or the filter is dirty from construction and plaster debris.

Thanks,

Jim R.

Jim,

Its a 150 sqft filter. I have cleaned it very often... Daily for the first couple of weeks. However, they didnt balance the pool water after plastering so the Calcium levels were really low. I have white deposits all over the glass tile and have been told the surface of the pool is rough because of this. I finally got them to add calcium and get the level up from 75 to 300 about a month after plastering. Wonder if that could cause issues with the filter flow.

 

[essbase]

The ANSI calculations demonstrate that your pool meets the minimum requirements. No pool should be built to those minimum standards.

This page specifies what the engineer wanted installed.

As others have said many folks, including me, have the 011056 pump running fine with 2" suction. 2.5" suction will provide a bit better hydraulic efficiency but 2" pipe will be able to keep up with the pump.

The VSF pump will display the flow rate. It would be helpful to know what the pump is displaying for flow at various RPMs.

When you are at the house we can help you diagnose your problem further. But the use of 2" pipe is not what I would go after the pool builder for.

Do you have any pics of the pool during construction? Particularly pictures of after rebar and plumbing but before gunite?

Thanks Allen
I will check the GPM tomorrow. Here are some shots of the pipes

 

[JamesW]

For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.

Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm

The document says 102 gpm for spa mode which would indicate that the suction should be 3".

How long is the pipe for the suction?

How many 90s in the suction line?

You will probably need to get a vacuum gauge to measure the suction if you think that the pump is cavitating.

 

[JamesW]

Yes I think that is correct. There are 4 Waterway straight body jets.

So, how much actual flow do you want for the spa?

Why are you running the pump at full speed?

Check the pump to see what the flow and system pressure are as reported by the pump at different speeds.

 

[essbase]

For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.

Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm

The document says 102 gpm for spa mode which would indicate that the suction should be 3".

How long is the pipe for the suction?

How many 90s in the suction line?

You will probably need to get a vacuum gauge to measure the suction if you think that the pump is cavitating.

Hi James when I say cavitating... It seems to vibrate/growl and I can see turbulence (lots of what look like tiny bubbles) through the clear basket cover on the pump when I set the only suction on to the SPA or the Main Drain. In pool mode I can set the 3 way between the Main and Skimmer in the middle and it runs clean. If its on the main drain only it starts the cavitation. I am going to measure the length tomorrow and compare to the engineering. I think the Spa drain line has 8 - 90s ( its the one in the picture that comes out under the center of the Spa and runs into 2-90s runs a couple of feet and goes back down through 2 more 90s)... I think the Main Drain has 5 or 6. More than what they listed on the Engineering.

 

[JamesW]

The document says to use 2. 5" pipe, so the builder should have used 2.5" pipe.

With 2" pipe, you can possibly get cavitation at full speed.

 

[essbase]

So, how much actual flow do you want for the spa?

Why are you running the pump at full speed?

Check the pump to see what the flow and system pressure are as reported by the pump at different speeds.

Not running at full speed (3450) I like it at about 2900... Start to see cavitation at 26-2700 or so.