Should I Switch Form 1 1/2" To 2" Pvc Pipes?

[Gavin]

will my filter pressure go down if I switch to bigger pipes? my pressure gauge reads around 23psi normally. will it read lower if I use 2" pipes instead of 1 1/2"?

Thanks.

[chem geek]

The answer depends on why the pressure is high. If I assume that you have cleaned your filter and don't have any major obstructions (i.e. blocked returns), then yes using larger diameter pipes will lower the pressure and increase flow rates (GPM). Even more importantly, it will probably let you use a variable speed or flow pump or even a 2-speed pump on low speed which will save you a lot of money on pump electricity costs. Normally the pipe going to the returns from the pump is 2", though may get split into separate 1.5" pipes for each return if there is more than one. For the suction side from the skimmer and floor drains, it's typically separate 1.5" pipes from each, or if combined then 2". Having 1.5" on output is low unless the entire system is much smaller which doesn't sound like your situation given the high PSI.

The inside area of 2" pipe is 1.65 times higher than 1.5" pipe. The head loss using 1.5" pipe is over 3 times higher than using 2" pipe at the same GPM, though with a fixed speed pump the GPM is higher using 2" pipe. See this thread for more detailed info.

[Gavin]

Thanks Chem geek. I acid washed the filter the other day so its clean. I have 3 suction lines: main drain, skimmer and vacuum. They are 1 1/2". I think the return is 1 1/2"...will need to double check that. my pump and filter is about 2ft above the pool if that makes any difference in pressure?

btw I pay $1,600 per year in electrical cost to run the pump 8hrs per day. not much but if I install solar I'll save some money. I could use that $1,600 on a vacation.

[chem geek]

I lowered my pump electricity cost from $1400 to $700 per year by switching to a variable flow (Pentair Intelliflo) pump replacing a 1 HP pump and a 3/4 HP booster pump for a pool cleaner (I now use The Pool Cleaner with a valve that switches the main pump to it when cleaning at night over a dedicated line). I have solar so need a high flow rate part of the time; otherwise I would have saved even more.

[Gavin]

I lowered my pump electricity cost from $1400 to $700 per year by switching to a variable flow (Pentair Intelliflo) pump replacing a 1 HP pump and a 3/4 HP booster pump for a pool cleaner (I now use The Pool Cleaner with a valve that switches the main pump to it when cleaning at night over a dedicated line). I have solar so need a high flow rate part of the time; otherwise I would have saved even more.

Thats not bad savings. you have solar heating for the pool?

btw I guess the main thing is to make sure the return pvc line from the filter is 2". thanks will check that.

[quantumchromodynamics]

23 psi is pretty high. Most likely, your pump is oversized for your system. You would probably benefit from a smaller two-speed or a variable speed pump. What size pump do you have and how many gallons is your pool?

[chem geek]

Thats not bad savings. you have solar heating for the pool?

Yes I do. I have 12 panels needing 4 GPM each so that's 48 GPM with long pipe runs. That's what uses up most of the electricity at around 1500 Watts. When the solar is off and I'm at 26 GPM the power usage is only 275 Watts. My electricity rates are high at around 32 cents per kilowatt-hour.

[Gavin]

23 psi is pretty high. Most likely, your pump is oversized for your system. You would probably benefit from a smaller two-speed or a variable speed pump. What size pump do you have and how many gallons is your pool?

I have a 15,000 gal pool and 1hp pump and a EC65 hayward de filter. but the pump and filter is like 2ft above pool water level if that makes any difference. I was told by someone it might. however I need to check my return pipe to make sure its 2" like Chem geek suggests.

[Gavin]

Thats not bad savings. you have solar heating for the pool?

Yes I do. I have 12 panels needing 4 GPM each so that's 48 GPM with long pipe runs. That's what uses up most of the electricity at around 1500 Watts. When the solar is off and I'm at 26 GPM the power usage is only 275 Watts. My electricity rates are high at around 32 cents per kilowatt-hour.

That is high. like ours round here. I thought electricity in the states was cheaper.

[quantumchromodynamics]

I have a 15,000 gal pool and 1hp pump and a EC65 hayward de filter. but the pump and filter is like 2ft above pool water level if that makes any difference. I was told by someone it might. however I need to check my return pipe to make sure its 2" like Chem geek suggests.

23 psi for a 1 H.P pump on an EC-65 is too high. I have seen many such setups with 1.5-inch pipe and the pressure is usually right around 10 psi. The fact that the filter is 2 feet above the water will not have any significant effect on the pressure. It will actually lower the pressure reading by about 1 psi.

You should try to determine why your pressure is so high. You should also consider switching to a two speed pump when this pump needs to be replaced.

[chem geek]

That is high. like ours round here. I thought electricity in the states was cheaper.

It depends on the state (and the utility company) and the tier (% above baseline) based on total electricity usage. PG&E, which services northern California is expensive.

[quantumchromodynamics]

How many return fittings do you have that return water to the pool?

Do the returns have eyeball fittings?

If yes, what is the inside diameter of the eyeball fittings?

It could also be a bad pressure gauge. Does the gauge go to zero when the pump is off? If you have any doubt about the pressure gauge, you should replace it.

[Gavin]

How many return fittings do you have that return water to the pool?

Do the returns have eyeball fittings?

If yes, what is the inside diameter of the eyeball fittings?

It could also be a bad pressure gauge. Does the gauge go to zero when the pump is off? If you have any doubt about the pressure gauge, you should replace it.

Thanks. I will check the pressure gauge. it might be bad as its very old.

I have 4 returns with regular size eyeball fittings.

I think I will replace the gauge anyway to be on the safe side. it is old.

[chem geek]

What is the service factor on your 1 HP pump? Is it 1.65? Also, how long is your pipe run from your pump to near the edge of your pool (where I presume the pipe splits to go to multiple fittings)?

23 PSI is 54 feet of head on the pressure side. The dynamic head may be 51 feet assuming a 3 foot height of the filter gauge above the pump. To get to this amount of dynamic head, you would have to have the equivalent run length as follows depending on the GPM (remember that the fittings and the filter itself add to the equivalent run length):

30 GPM 1000 feet

40 GPM 600 feet

50 GPM 400 feet

60 GPM 285 feet

70 GPM 215 feet

Figuring suction head at around 22% of dynamic head (in your situation of possibly 1.5" pipe for return to the pool and 3 1.5" suction equivalent to around a single 2.3" pipe), that's no more than 11 feet of suction head so 62 feet of total dynamic head. For a typical 1 HP pump, that's around 55 GPM and around 350 feet of equivalent pipe length for the return which does seem a little high unless your pump isn't close to your pool (remember that fittings and filter add to the equivalent length).

[EDIT] I corrected an error below -- from this thread I see that with solar off I had around 90 GPM according to the pump curve and my estimate of suction losses and I saw 15 PSI on the gauge. [END-EDIT]

I know that in my own pool when I used to have a Jandy HHP 1 HP (1.65 SF) pump, I had around 15 PSI (35 feet of head) with 2" pipe for return to the pool (though split at the pool going to 3 separate returns) and two separate 1.5" pipe for suction (so roughly equivalent to one 2" pipe). The flow rate, based on the pump curve, was around 90 GPM. The Jandy CL340 cartridge filter has around 1 PSI head loss and the gauge may add 1 PSI or so due to its height so that's 13 PSI net for pipe and fittings. My equivalent pipe length in this situation on the return side was around 270 feet while actual distance from the pump to the pool edge is only around 50 feet. So your pressure reading seems a bit high, but is still possible if your pipe runs aren't a lot shorter.

Richard

[Mark]

With 1.5" plumbing it really doesn't take much to get to 23 PSI. If I assume a full rated 1 HP pump with 2x1.5" suction lines and 1x1.5" return line with 30' runs and no heater, typical number of fittings, I get can easily 23 to PSI. Flow rate is 70 GPM @ 67' of total head (193' total equivalent length of 1.5" pipe).

[quantumchromodynamics]

23 psi still seems high. I think that the pressure gauge should be replaced and the eyeballs should be removed to see what effect that has.

[chem geek]

With 1.5" plumbing it really doesn't take much to get to 23 PSI. If I assume a full rated 1 HP pump with 2x1.5" suction lines and 1x1.5" return line with 30' runs and no heater, typical number of fittings, I get can easily 23 to PSI. Flow rate is 70 GPM @ 67' of total head (193' total equivalent length of 1.5" pipe).

Mark, do you have some reference source (preferably online) for loss curves for fittings or for their equivalent length of pipe (if that works)? I was never able to find anything more than this link that is great for pipe fittings (elbows, valves, T's, etc.), but not for actual returns/inlets, floor drain, skimmer.

[Mark]

Mark, do you have some reference source (preferably online) for loss curves for fittings or for their equivalent length of pipe (if that works)? I was never able to find anything more than this link that is great for pipe fittings (elbows, valves, T's, etc.), but not for actual returns/inlets, floor drain, skimmer.

Generally, I perfer to use friction coefficients (K) instead of equivalent lengths since friction coefficients are independent of pipe diameter and easier to remember, although after the analysis, I sometimes determine the equivalent length for the whole setup just for reference. Here is one table I use for friction coefficients but the table you linked to should be pretty close as well.

Eyeballs and skimmer inlets are pretty easy as you can just use a K=1 with the actual orifice diameter. In fact, I model spa jets this way as well and it comes out pretty close to what I measure in my own setup. As for odd ball fittings not shown in tables, I have done some calibration calculations on my own pool and came up with a total K value for the entire pool both suction and return. I tend to use this aggregate number in most cases since most pool owners really don't know much about the number and types of fittings used except for maybe the pad. I can also improve the model accuracy if I know the filter pressure and/or the pump suction. I also have a general model for each type of filter.

[Gavin]

Thanks for the info guys.

Yep return is 1 1/2"

I think i need to really clean the flex tubes well. Maybe some suntan lotion is clogging it up. I will take it down tomorrow and soak it in acid and water for a few minutes. would 15minutes in 50/50 acid/water be too long?

Thanks.

[quantumchromodynamics]

I recommend that you clean the Flex-Tube Assemblies first with one cup tri sodium phosphate (TSP) to five gallons of water or one cup dishwasher detergent to five gallons of water. Remove the fingers from the assembly before cleaning.

Then, if the Flex-Tube Assemblies have a coating of calcium carbonate, iron, or other minerals, soak them in a solution of one part muriatic acid to twenty parts water until all bubbling stops.

I don't really like to use acid for cleaning. I think that you should avoid it if you can. If you do use it, I recommend that you keep the soaking time as short as possible.

If the Flex-Tube Assemblies are really bad, you should replace them.

22a Part Number = ECX1031 Flex-Tube Assembly 13 3/8” (EC65) (120 required)

[Pool Clown]

Possibly save some time:

Take the filter assembly out and Reassemble the filter tank, run it, and see if the pressure drops way down, before you (have to) mess with the cleaning chemicals.

[Gavin]

Possibly save some time:

Take the filter assembly out and Reassemble the filter tank, run it, and see if the pressure drops way down, before you (have to) mess with the cleaning chemicals.

that sounds like a plan. Thanks I'll do that.

if pressure drops then I know it is the filter assembly thats clogged up and will do what Quantum said. Thanks guys!

[quantumchromodynamics]

If you do that, you're still going to need to remove the Flex-Tube Assemblies, because the EC-65 requires the tube sheet assembly to properly seal. http://www.haywardnet.com/products/Manuals...s/Manual257.pdf

As Richard (chem geek) asked, what is the S.F (service factor) of your pump? If it is higher than 1.0, then the pump is over sized for that filter. That filter has a design flow rate of 54 gpm.

If you can, remove the eyeballs to see what effect that has.

Also, did you get a chance to replace the pressure gauge?

[Gavin]

If you do that, you're still going to need to remove the Flex-Tube Assemblies, because the EC-65 requires the tube sheet assembly to properly seal. http://www.haywardnet.com/products/Manuals...s/Manual257.pdf

As Richard (chem geek) asked, what is the S.F (service factor) of your pump? If it is higher than 1.0, then the pump is over sized for that filter. That filter has a design flow rate of 54 gpm.

If you can, remove the eyeballs to see what effect that has.

Also, did you get a chance to replace the pressure gauge?

Thanks. yeah I see what you mean. also I still would have to bolt it all back on which takes me time. best just to go ahead and clean it with TSP and water.

haven't had a chance to change the gauge yet. I will check that S.F. number thanks.

the eyeballs are pretty good size. I've moved them around and can get my finger in them easy.

[Pool Clown]

Gavin, Has the pressure always been high? Or is this something that has happened recently?