IntelliFlo VSF issues

[gregorym59]

New pool owner so I apologize in advance for using any wrong terminology. Pool was originally built about 20 years ago. Recently advised by our pool service company that we ought to replace our pump due to bearings going out (it was making a very loud whining kind of noise). Previous pump was a 4-year old Pentair WhisperFlo WF26 (single speed, 3,450 rpm). Pool company provided following options: Replace existing pump motor, replace existing pump with same model, replace existing pump with IntelliFlo VSF (explained opportunities for cost savings due to variable speed / variable flow capability). We went with the VSF and it was installed about three weeks ago. We also replaced two Pentair valve actuators (on suction and return lines) and check valve internals (return lines). We previously replaced the heater (AquaCal SQ225), added a Pentair EasyTouch control system, and had the pool resurfaced.

Now to the issues. This past week we used the heater for the first time with the new pump. The heater failed with flow fault codes (I was not in town at the time; pool being used by family guests). Our guests informed our service tech of the issue (same tech that installed the pump), and he told them the heater wasn't getting enough flow and to crank up the pump speed. When they informed me of this I checked out the system remotely via the ScrenLogic app. The data indicated the pump was running at 2,750 RPM and pushing only 21 GPM. They had cranked the pump up to max (3,450 RPM) and it was only pushing 28 GPM (still not enough flow for heater; the heater requires a flow range between 30 and 70 GPM). I followed up with the service tech and he told me it is a heater issue! For the past 16 months the heater worked fine with the former pump, and given that it is a fairly new heater (16 mos) this made no sense to me, so I have been trying to figure out why there is a flow issue. I looked at photos I had taken before and after and notice that the plumbing from the pump to the filter had been changed; it is now a longer run and has an additional 90 elbow. Can this be a contributing factor? Note, the manual heater bypass valve is in the same position it was with the old pump. Any other insights as to why the pump seems to be pushing about half the GPM that it ought to be pushing at specific RPMs?

I also spoke reached out to the owner of the pool company and his response to me was that "the new pump will int be capable of reaching the published maximum GPH (I believe he meant GPM) due to the pre-existing suction and return plumbing size." I also share that this was the same pool builder that built the pool originally 20 years ago, so my follow up question to him will be why suggest a pump that can't reach spec due to existing plumbing conditions, but that's another story!

Thanks.

 

[pjt]

The handle on the 3-way diverter valve after your filter needs to be adjusted so all the flow goes to the heat pump (it's restricting flow as depicted in your photo). For the bypass, you also need a check valve between the heat pump output and the tee fitting.

What is the purpose of the check valve on the spa return line?

If things are going to get replumbed, this would be an excellent opportunity to install a SWG between the tee and the pool/spa diverter valve, as well as remove the trichlor tab feeder. In that case, you can remove both the check valves you have installed right now.

 

[ajw22]

Your plumbing is fine. Just close the heater bypass and then adjust the pump speed.

Your heater bypass valve is bypassing too much flow. You need to close the bypass and send most if not all flow to the heater, That bypass valve was needed with your old pump to not exceed the maximum flow for your HP since the pump was not adjustable. With your VS pump the bypass should be totally closed and adjust the pump speed so you don't exceed the HP maximum flow rate.

Both of your CV's are necessary. The spa return CV to keep the spa from draining down to the pool when the pump is off. The CV before your chlorinator is necessary to prevent acidic water from backflowing to the equipment when the pump is off.

 

[Jimrahbe]

Greg,

I agree with everyone else about adjusting your heater by-pass..

Another thing is your filter. If you just had your pool resurfaced, it could be very dirty, which will decrease the flow. When was the last time your "Dinky" Florida Filter was cleaned??

An extra few 90's will not any appreciable difference. Your plumbing is fine.

Thanks,

Jim R.

 

[gregorym59]

Greg,

I agree with everyone else about adjusting your heater by-pass..

Another thing is your filter. If you just had your pool resurfaced, it could be very dirty, which will decrease the flow. When was the last time your "Dinky" Florida Filter was cleaned??

An extra few 90's will not much any appreciable difference. Your plumbing is fine.

Thanks,

Jim R.

Thank you!

 

[gregorym59]

Your plumbing is fine. Just close the heater bypass and then adjust the pump speed.

Your heater bypass valve is bypassing too much flow. You need to close the bypass and send most if not all flow to the heater, That bypass valve was needed with your old pump to not exceed the maximum flow for your HP since the pump was not adjustable. With your VS pump the bypass should be totally closed and adjust the pump speed so you don't exceed the HP maximum flow rate.

Both of your CV's are necessary. The spa return CV to keep the spa from draining down to the pool when the pump is off. The CV before your chlorinator is necessary to prevent acidic water from backflowing to the equipment when the pump is off.

Thank you. I appreciate everyone educating me!