Backwash procedure for pool with 2 filters

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JPMorgan said:
We definitely need a digital flow meter because the placement of the FlowVis flow meter in the pipe makes it very difficult to read. I'm assuming this flow meter would be a replacement for the current flow meter.... not an add-on to the system, correct? Does anyone have any experience with this type of flow meter? If we replace the current flow meter with this one and we get approximately the same reading (120 gpm), then we could definitely rule out the flow meter being the cause of the low flow rate, correct? I'm trying to rule out the simple things.... like a bad flow meter or valves not properly set before we start investing in bigger fixes. The proposals from the pool company that I posted earlier range from $5,000 to $14,000, so we want to be sure we are fixing things that are the real source of the low flow rate... not spending money on things that are unnecessary, i.e., new filters?????
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The F-1000 and F-2000 are not direct replacements for a Pitot tube style or the Vari-Flo flow meters meaning they will not “bolt in” to the existing holes. You would have to plumb them in the pipes in their own location. The F-1000 is battery powered, the F-2000 can be either battery powered or transformer powered. Both are complete independent meters, just plumb them in, (add power via batteries or transformer depending on model) and you should be set.
 
JamesW said:

Filter capacity?

We are currently getting about 100 gpm from our outdoor pool pump. I'm told the pump is capable of much more flow than that. The state regs say our pool should turn over every 6 hours, so that's 167 gpm required for our 60,000 gallon pool. We had the pump checked out and were told the...
www.troublefreepool.com www.troublefreepool.com

H2Flow Meter

We recently had some new equipment installed on our outdoor pool. After the equipment was installed the flow rate dropped from 170 gpm to 135 gpm. The pump is the same and only minor plumbing changes were made (from what I can tell). The installation primarily involved a new liquid chlorine...
www.troublefreepool.com www.troublefreepool.com
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I went back and re-read these old posts. Yes.... we are still dealing with this issue. The correct flow meter was installed last fall, but the system was shut down at that time. At start up this year, there was no improvement in the flow rate. We are evaluating proposals from the pool company to address this now. I included those proposals at the beginning of this post. One calls for replacing both TR-140C filters which I really don't think is necessary. So..... what I am trying to do here is figure out what the most likely cause of the low flow rate is before we start spending money on things that are unnecessary. Right now, the things that I think need to be ruled out in order of priority are:
  • Faulty Flow Meter (Fix: Install new digital flow meter to improve visibility/accuracy of flow rate reading and to see if rate increases)
  • Improper Position of Valves (Fix: Have pool company inspect and make sure all valves are set correctly)
  • Heater by-pass (Fix: If no bypass, install heater by pass)
  • Hydraulicly Inefficent Plumbing (Fix: Replace sections of plumbing that may be restricting flow.) (Recommended by pool company.)
  • Leaky MP Valves: (Fix: Not likely the cause of the problem, but should be addressed. Water flows out of backwash line in "Filter" mode. Replace spider gasket or install new MP Valve (recommended by pool comany)
  • Filters Restricting Flow Rate (Fix: Replace media (sand) in filters or replace both filters (recommended by pool company) Note: when filters are put in "Recirculate" mode, there is no increase in flow rate.
  • Pump not meeting required output (Fix: impeller was replaced less than 2 years ago. Consider new pump.)
Does this way of proceeding make sense? Anything I have missed that should be added? Any suggestions for a different way of proceeding, i.e., order in which to assess and fix things? Thanks.
 
When you turn off the pump do all gauges go to zero?

If so, the pump pressure and suction indicate that the flow rate is 180 GPM although one or more the gauges could be wrong.
 
Lake Placid said:
From what I can see, you have no bypass and metering system. All the water your pump is putting out is running through the heat exchanger and this is limiting your flow to what the heat exchanger can handle. It’s a bottleneck. Basically the bypass would be a pipe with a valve in the middle connecting the inlet and outlet pipes of the heater. You would also want valves on the inlet and outlet side of the piping before the heater but after the bypass. You can then tweak all three valves to restrict inlet and outlet flow to the heater to allow it to heat most efficiently while tweaking the bypass to increase flow back to the pool.
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Here are some pics that better illustrate the area in the plumbing where (I think) a bypass to the heater is installed.

1st pic... main return line
2nd pic... following the main return line
3rd pic... pipe coming off the return line going to heater with Valve #9 fully open
4th pic... section of the return line between pipe going to heater and pipe returning from heater with Valve #8 partially open
5th pic... pipe coming from the heater back to the return line with Valve #10 fully open

IMG_9186.jpgIMG_9187.jpgIMG_9188.jpgIMG_9189.jpgIMG_9190.jpg

I have seen the pool company adjust Valve #8 in order to maintain a 30 psi reading on the pressure side guage at the pump. I have never seen them adjust Valves 9 or 10. Is this the heater bypass you are referring to? Could playing around with those valves possibly increase the flow? Should I tempoarily shut off flow to the heater (Valve #9) and fully open Valve #8 to see if that affects the flow rate? Any precautions to take when adjusting these valves, i.e., should I turn off the heater first, adjust the valves slowly, which order to make the adjustments, leave Valve #10 open or closed, etc.? Thanks for any guidance on how to tweak these valves to increase flow (without breaking something). :)

Also, I notice that the suction line from the Main Drain is half closed. Is that common? Is this done in order to increase water flowing through the skimmers?
 
JPMorgan said:
Here are some pics that better illustrate the area in the plumbing where (I think) a bypass to the heater is installed.

1st pic... main return line
2nd pic... following the main return line
3rd pic... pipe coming off the return line going to heater with Valve #9 fully open
4th pic... section of the return line between pipe going to heater and pipe returning from heater with Valve #8 partially open
5th pic... pipe coming from the heater back to the return line with Valve #10 fully open

View attachment 648216View attachment 648217View attachment 648218View attachment 648219View attachment 648220

I have seen the pool company adjust Valve #8 in order to maintain a 30 psi reading on the pressure side guage at the pump. I have never seen them adjust Valves 9 or 10. Is this the heater bypass you are referring to? Could playing around with those valves possibly increase the flow? Should I tempoarily shut off flow to the heater (Valve #9) and fully open Valve #8 to see if that affects the flow rate? Any precautions to take when adjusting these valves, i.e., should I turn off the heater first, adjust the valves slowly, which order to make the adjustments, leave Valve #10 open or closed, etc.? Thanks for any guidance on how to tweak these valves to increase flow (without breaking something). :)

Also, I notice that the suction line from the Main Drain is half closed. Is that common? Is this done in order to increase water flowing through the skimmers?
Click to expand...
Let me get off my route and study your pics before you do anything. I’ll advise later this afternoon/evening.
 
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mas985 said:
When you turn off the pump do all gauges go to zero?
Click to expand...
Here are pics of the suction side and pressure side guages with the pump off. The suction side did not go to 0. What does that indicate? I also included pics of the pressure guages before and after each filter. Note... one of the filter guages on the return side of the filter did not go to 0. Does that tell me anything?

IMG_9192.jpgIMG_9191.jpgIMG_9193.jpgIMG_9194.jpgIMG_9195.jpgIMG_9196.jpg
 

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JPMorgan said:
Note... one of the filter guages on the return side of the filter did not go to 0. Does that tell me anything?
Click to expand...
That one is around 20 psi so I think it has an issue. Try tapping the dial with the pump off to see if the needle moves.

But the pump pressure and suction is behaving as it should so I think those values may be correct which means you might have higher flow rate than you think.

Another possibility is impeller is smaller than the original so the head curve is not the same as what I was using.
 
To confirm….

Valve 9 takes off from the return side of the pump and runs to the inlet side of the heater?
Valve 10 comes from the outlet of the heater to the return side of the pool?
 
Lake Placid said:
To confirm….

Valve 9 takes off from the return side of the pump and runs to the inlet side of the heater?
Valve 10 comes from the outlet of the heater to the return side of the pool?
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Yes. The Blue arrows on the Valve 9 pipe and the Red arrows (heated water) on the Valve 10 pipe also confirms this, correct?
 
JPMorgan said:
Yes. The Blue arrows on the Valve 9 pipe and the Red arrows (heated water) on the Valve 10 pipe also confirms this, correct?
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As best I can tell yes.

Valves 9 and 10 are the heater bypass valves. Valve 8 is the metering valve. As a test, turn the heater off. Open valve 8 all the way. Close valves 9 and 10. Observe any changes in flow. It should increase in theory.
 
Lake Placid said:
As best I can tell yes.

Valves 9 and 10 are the heater bypass valves. Valve 8 is the metering valve. As a test, turn the heater off. Open valve 8 all the way. Close valves 9 and 10. Observe any changes in flow. It should increase in theory.
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Should I open and close the valves in that order, I.e., after turning the heater off, open valve 8, then close valves 9 and 10? I can do this with the pump running, correct?
 
JPMorgan said:
Should I open and close the valves in that order, I.e., after turning the heater off, open valve 8, then close valves 9 and 10? I can do this with the pump running, correct?
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You can do it with the pump running. Mandatory to open valve 8 all the way first. It shouldn’t technically matter the sequence of the other 2, but closing 9 first will stop flow through the heater before closing the outlet side. You won’t put un-necssary pressure on the heat exchanger vs closing 10 first which would allow pressurized water to get trapped in the heat exchanger. Always close and open the valves slowly.

Reverse the sequence when opening. Open 10, then 9, then tweak 8. Although depending on what happens to flow with the heater bypassed, valve positions may need to be tweaked to get the desired flow rate.
 

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