Based on if the filters are in parallel or in series may change the proper backwash procedure.
Does nothing to address your flow rate concern. As a matter of fact the proposed filters may make your problem worse as the design flow rate is less than your current filters. Are the tanks leaking now? I’ve seen plenty of 20 year old fiberglass tanks that work just fine. Why not install unions (if not there currently) as a precaution to make future repairs faster and easier when needed.
While this may be an issue and should be addressed, repairing will do little to improve your flow rate concern.
Increasing pipe size to 3” may increase your flow rate. What size pipe is on the suction side of the pump coming from your pool to the pump?
The heat exchanger is a huge bottleneck to flow. I’d install a bypass with a metering valve that allows you to send just enough water to the heater to allow it to operate properly, while allowing the majority of the water to return to the pool without passing through the heat exchanger and impeding flow.
Can you describe the plumbing is a lot more detail and/or post a schematic of the entire plumbing system complete with all fittings, valves and basically anything that touches the water flow stream?
I doubt it. A 3" to 2" bushing does not have much head loss at all. The equivalent length of 2" pipe is less than 3'. At 120 GPM, this would be less than 0.6' of head which is not much at all and would not explain a lower flow rate. How much plumbing after the bushing and before the split to the filters is there?
Two filters in parallel would work just fine. They just need to be a TR100C or larger assuming the flow rate can reach specification.
Filter pressures run about 20 psi. I can post pics of those if necessary. Do you mean the height of the guage on the top of the filter relative to the water level?
Yes. Sometimes commercial pool equipment is below water level. I just wanted to make sure they were the same pressure which would indicate similar flow rates.
Some of the plumbing is below water level in the "pit". I did not include pics of that plumbing. The filters are definitely above water level.
That is what is limiting the flow rate to 120 GPM. Open that valve, and you will get higher flow rates.
I will try that. Should I expect the pressure on that guage to go up or down as I open that valve? I'm assuming that I am moving it to the right to open it all the way. Will doing so affect any other parts of the system? Pool company always seems to set that valve to maintain 30 psi at that guage. I assumed there was a reason for that.
The pressure will drop because you are reducing head loss and increasing the flow rate.
They may be limiting the flow due to the filters. Have you confirmed if they are TR140Cs? But even the TR140 should handle half of 170 GPM.
No it should not affect anything very much.
If you can get some better pics of the entire heating plumbing I can advise if there is a bypass with a metering valve. At this point it’s difficult to tell due to the pics.
Try this first….Mark is spot on and this may resolve your issue.
I opened that valve all the way. Pressure dropped about 5 psi. Flow did not change.
Yes.... it went down about 5 psi when I opened it all the way. I checked the flow meter and there was no change, so I put it back in the original position (where it was reading 30 psi).
So the pump pressure, gauge right after the pump, when down by 5 PSI but did the filter pressure(s) change at all? If flow rate went up, the filter pressure should have gone up. The pictures you showed, look like the filter pressure was reduced but that should not happen unless the valve was in the wrong position. Again, the gauge near the pump should decrease in pressure and the filter pressure(s) should increase.
