Determining if I should upgrade the plumbing

[East_Akl_Neil]

Hi

I am trying to work out if it is worth upgrading the old 32mm (1 1/4") plumbing that I have on my 35yo (give or take I'm guessing) pool. I currently have a suction leak somewhere around the skimmer that I can hear when I vacuum the pool, (or I put my hand over the suction port,) but expect it to get worse over time. I don't see air coming out the return, but the lint basket on the pump does have air in it, and there are large amounts of air after backwashing. I am also getting some sand in the pool after vacuuming, but that is a question for another thread. I don’t think that would take too much to fix the leak, but I am thinking am I going to be throwing good money at a now bad solution?

Here is my current setup to the best of my knowledge I only took over the place a few months ago so don’t know the history, and am new to all this pool stuff. All pipe work initially 32mm until it gets to the Pad, where it goes to 40mm. It is a simple solution with a single outlet at skimmer that goes to a single return via the pump & filter. (No heater/chlorinators etc, yet.)

Skimmer with unused main drain inlet and used suction outlet. No main drain in the pool.
Elbow at 0.2m down (approx 0.7m underground)
4.9m Straight
Elbow
1.5 Straight
Elbow
0.9m Up
Elbow
0.2 Into Garage
Threaded joiner to
Elbow
0.3m straight adapted to 40mm pipe using several adaptors & Joiners
Elbow
Butt join to Pump inlet
0.19 straight out of pump
45 Elbow
0.12 Straight
Elbow
0.07 Straight into Filter
0.2 Straight out of Filter
Elbow
0.34m Straight
Elbow
0.18 Straight
Elbow
0.49 Straight
Elbow
Adapted to 32mm Thread join
0.3 Straight out of Garage including adaptor above
Elbow
0.7 Straight down into ground
Elbow
1.5m Straight
Elbow
2.4m Straight
Elbow
0.2m Straight into pool return
No eye in return

What I am thinking of.

Joining the 2 outlets of the skimmer to the same return using
2x 32-40(or 50)mm adaptor, 3x Elbows, 1x T, Couple of short straights
4.5m Straight
Elbow
1.4 Straight
Elbow
1.0 Straight
Elbow
0.3 Straight into Garage then straight into Pump inlet
0.19 straight out of pump
45 Elbow
0.12 Straight
Elbow
0.2 Straight into Filter
0.07 Straight out of Filter
Elbow
Joiner/50mm Adaptor
0.6 Straight out of Garage (Including Straight and joiner)
Elbow
1.0 Straight
Elbow
1.5 Straight
Elbow
2.4 Straight
Elbow
0.2 Straight adapted to existing 32mm Return
Maybe fit eye in return

Pump is a Hurlcon E170 Single Speed Pump.
Pump is rated at 170L/m @ 8m Head (See links in Sig for Web Pages and PDF info).
I measured the pump power draw at 770watts (with a Watt Meter,) but is rated at 850w.
Pump is a 0.75hp.
Unknown Vacuum as Pump does not have any drains drilled & Plugged, but I do have a gauge.
Clean filter pressure is 9PSI.
Filter is a Astral FT55.
Unknown multiport valve on Filter
The filter is rated at 160L/m.
Using the pressure and the assumptions on the Hydraulics 101 thread, I suspect that I am getting approx 11m of head, which using the pump curve (located on the brochure) gives me approx 100L/m.

So the question I really have is should I upgrade the existing plumbing and if I do, should I go for 40 or 50mm? Doing the job should not be too hard as it is all tiled in the area. And if I do this, am I going to increase my flow to a point that I have too much for my filter to handle? I have to make sure that this upgrade makes $$$ sense as once I convince myself I have to turn around and convince the financial controller (Wife).
I'm currently pricing up the costs of the parts if I make the upgrade, but need some calculations to confirm that it is going to be worth doing.

Attached is photo of Pad for reference.

As it is coming into spring here, am thinking that I should do something before our season kicks into gear.

 

[jblizzle]

Your current setup up certainly leaves something to be desired. Only having 1 small suction line and 1 small return line to a single outlet is certainly going to limit your flow rate. The single outlet is really going to be your limiting factor.

I think running a 50mm suction line (from 1 or both holes) and a 50mm return line could give a good flow rate increase. If you put an eyeball on, you will want the largest outlet you can find. Using the larger pipe should not be much increase in cost and bigger is certainly better than too small.

Hopefully Mark will swing by here and offer his expert advice.

 

[mas985]

A couple of questions:

I did not see a head curve in the manual link that you gave. Where is it?

How did you get to 11 m head loss?

How high is the filter pressure gauge above the water level?

 

[East_Akl_Neil]

I'm at work now but I estimate that the pressure gauge is about 1m above the top of the water in the pool. The head curve was in the Brochure, go figure, I have cut and paste in here for easier reference.

I got to the 11m head loss by using the formulas in the Hydraulics 101 - Have you lost your head? thread, and some interpretation of the information, I could be totally wrong.

 

[mas985]

I was more interested in how you got the suction side because I don't really address that if you don't have a suction measurement. Pressure side should be about 7.5 m of head loss and for your setup, the suction is probably 30% of the return but that is just a guess so total head should be around 9.75 m. Replacing only the pad plumbing would reduce that some but I can't be entirely sure if it would lower it enough to be above the filter limit or not.

I might be able to give you a better idea, if I can get a little more information about the setup. I know you gave me all the information in the post above but I am bit lazy so could you summarize as follows:

# Suction 90s
# Suction 45s
# Suction Tee branch/flow
Total Length of suction line
Pipe size

# Pad 90s
# Pad 45s
# Pad Tee branch/flow
# and size of any valves
Total Length of Pad line
Pipe size

# Return 90s
# Return 45s
# Return Tee branch/flow
Total Length of return line
# Return eyeballs and diameter of the eyeball
Pipe size

Also repeat the same list with the changes you would like to make. BTW using the second port on the skimmer without a second line won't help much.

 

[East_Akl_Neil]

There is mention of how to calculate suction based on pipe size and pressure, so I just made come creative measurements based on that. Going by your numbers I was not too far off with my estimation. I'd like to know what the suction reading on the pump is but to get it will involve drills, taps, plugs and time. None that I have at the moment to achieve the reading. Maybe in a month or so when I have a couple of hours, and have gathered the parts. I'm not sure if upgrading just the pad is going to achieve anything much as it is currently 40mm. The existing suction and returns are 32mm so they I would suspect are the main restriction in flow.

Existing Setup
The Suction and return lines I am guessing at this time as they are underground and I don't want to dig them up to find out unless I replacing/repairing them. The layout and numbers would make most sense so I have made those assumptions. I have also de-marked the pad at the 40mm plumbing, and the Suction/Return at 32mm pipework sizing.

Suction
5 x 90's
7.5m Straight

Pad
6x 90's
2.19m Straight
1 x 45's

Return
4 x 90's
4.8m Straight



Proposed Setup
I have de-marked the pad at the point where the pipe comes out of the ground, but before it goes into the shed. Given that it will make little/no difference to join the 2 skimmer drains, I'll forget that idea. Would it make much difference if I swapped one of the 90's on the suction and return lines for 2 x 45's?

Suction
3 x 90's
5.9m Straight

Pad
4 x 90's
6.27m Straight
1 x 45's

Return
3 x 90's
4.1m Straight


HTH

Neil

 

[mas985]

Sorry, which pipe/fittings were you planning to up size. Just the pad?

Also, how many eyeballs and the size?

And 2x45s are about the same as a 90.

 

[East_Akl_Neil]

I was thinking of doing the whole lot in 40mm which is the same as what the pad is currently, however it would be nice to know what the difference, if any, would be if I went for 50mm instead. Was thinking of just one eyeball at this time, at whatever size was appropriate for the 40/50mm pipe size. (I haven't investigated them as yet.)

 

[mas985]

But what do you currently have for eyeballs in the pool?

 

[jblizzle]

first post says no eyeball into the pool from the single outlet.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[East_Akl_Neil]

When the temp gets up, the eyeballs in the pool will be attached to the swimmers in the pool otherwise there is none at this time.

 

[mas985]

Sorry about the eyeballs, I missed that one.

But I am having a bit of trouble with this setup. If I model the plumbing as described, I get a filter pressure much lower than you have indicated (~6.5 PSI). To get 9 PSI, I would need to triple the filter head loss. So this means I am not modeling something correctly or the filter gauge is bad.

One problem could be the pipe size. Do you have the exact pipe I.D.? Are they the same as 1.25", 1.5" & 2" Schedule 40 sizes? This can make a big difference in the calculations.

Also, I know you don't have any eyeballs but does the pipe narrow at all entering the pool? That can cause high pressure.

One suggestion is to forget all this and go ahead and up size the pipe. If the flow rate becomes an issue, you can always reduce it with a smaller eyeball or get a bigger filter.

 

[East_Akl_Neil]

I dont have the exact id at this time as I am yet to cut any of the pipe. Ill cut a piece of suction when I fix the minor leak at the skimmer, but up intill then its the best guestimation I can do based on the OD of the pipes. There is the posibility that something strange is going on underground that I dont know about as yet.
Ill have a look at the retun in an hour or so when I get outside thismorning.

I cant afford to just replace the plumbing, unless there is good $$$ reason to do so. I do want to do it, but unless something breaks, or I'm going to save lots then there are other thing to do that are higher on the list of bugeted expences.

Gague should be good, looks quite new, and does go back to 0 when off.

Could there be something wrong with the filter as I do believe I am getting some small abounts of sand back through the return, but have not felt it as yet due to the pool being too cold to get into. That may be throwing the pressure readings off a small bit.

 

[jblizzle]

Upping the pipe size will result in higher flow rates, which might allow you to shorten the pump run time ... it may not be a money saver as you seem to be looking for.

If you want to save money on electricity, change to a 2-speed pump and run on low speed ... then the size of the plumbing is not even a factor at the lower flow rates. Sure the larger pipe would still give higher flow rates even on low speed, but not likely to save you more money.

 

[mas985]

Certainly filters can have problems but then I would be interested in the history of the filter/system. Did it always run at 9 PSI or did it ever read lower when it was first installed? If you don't know the history of the system, it can be hard to know for sure.

Also, normally replacing the piping underground is rarely worth the effort and cost. Replacing pad piping is usually always worth it. But as Jason points out, a two speed pump would probably save you much more than a piping change.

 

[East_Akl_Neil]

Just checked and return is 30mm. The OD of the pipes are 36mm so it is all likley that they may be even smaller than 32mm ID.

So with the increased pipe size, what would the projected flow rates be.

Dont have a clue what the history is, or what it was when new.

 

[mas985]

Just checked and return is 30mm. The OD of the pipes are 36mm so it is all likley that they may be even smaller than 32mm ID.

Are both the return and suction pipes 30 mm ID?

Also, what is the ID of the pad pipe?

And, what is the ID of the planned pipe and are you planning to replace all of the pipe?

Accurate ID measurements are very important. A 10% diameter error results in a 60% head loss error so it makes a big difference. If these are standard pipes, they should have standard dimensions. I just don't know what they use down under. Are they rated like schedule 40?

 

[East_Akl_Neil]

I honestly cant say what the suction and return ID sizes are. The pad is 40mm ID given the numbers on it, and I would guess that it is schedule 40.

 

[mas985]

There is a table in the following document that might help you identify what type and size pipe you actually have.

http://www.plasticsystems.co.nz/booklet ... feb06s.pdf

Note that the label on the pipe is actually much smaller than the ID of the pipe. The pipe should also have a rating starting with PN.

 

[East_Akl_Neil]

The image above shoes the skimmer on the right, the return in the middle below the white bottle, and the pump pad is in the garage behind the leaf rake. If you look carefully you can see the pipes going through the wall painted the same colour. (It's not the white one to the left.)

I've had a close look at the elbows, and have found some info on them.

The ones at the pad are iPLEX Novakey uPVC Pressure fittings. The 90's info page is here. Model 801.40.90. The fittings are a PN18, the combination is not listed in the table of your attachment.

The older ones are a bit more harder to figure out, and all the wording on the fittings says that they are 32mm Garnite Slon waste pipe.

The other thing that could be throwing the pressure readings off is there is a very small suction leak at the skimmer. Not enough to cause any visible air at the return during normal operation, but will cause visible air when I am vacuuming after a shot while.

With the problems you are having with the numbers I am beginning to think that there is something else wrong in the suction line. Or something has been lost down the suction at some point in the past and is causing some suction to be lost.

Question. If there was sand coming out of the filter and back into the pool, would that make any difference to the readings? I think I have a small amount of sand coming out the return, but the water is too cold to go in and get some. It looks like it from the surface. (Water is crystal clear thanks to BBB )