Aquacal tech said my flow meter was in the wrong spot?

[anthony21078]

I plumbed in a new aquacal sq225 a little over a month ago. I placed the flowvis meter after the heater since it acts as a check valve/bypass. With fresh DE and the pump running at max 3400 rpm, the meter reads about 38gpm. Heater min/max flow is 30/70. My pump typically runs at 2100rpm which shows about 28-30gpm on the meter which activates the heater.

Aqucal tech said the optimal flow for this heater was 40-45gpm. He said I should have placed the flow meter before the heater inlet to get an accurate gpm. I explained the flow meter doubled as a check valve and acting as a bypass which he understood. However, he still stated in order to get the correct flow entering the heater I should add another flow meter at the heater inlet. Is this correct?

He also went on the check the water inlet and outlet temps at the skimmer and return jet.
2100 rpm - 9°
2400 rpm - 8°
2700 rpm - 7°
3000 rpm - 6°

The directions for this model regarding delta-t state 4-9° difference is optimal.

Where is the happy medium here? Should I be more concerned with achieving the optimal gpm of 40-45 gpm? Or, finding the correct rpm that puts the delta-t somewhere in the middle of 4-9°?

 

[ajw22]

If there is no other plumbing to divert the water then flow in = flow out and putting the Flowvis by the input or the output makes no difference.

Delta-T also makes no difference. Read Heater Maintenance - Further Reading

The heater puts out fixed amount of BTU's. A low flow rate absorbs more BTUs and has a higher temperature then a high flow rate absorbing less BTU's. The same amount of BTUs (heat) gets into the pool regardless of delta-t.

 

[PoolStored]

He said I should have placed the flow meter before the heater inlet to get an accurate gpm.

The flow is the same, before or after the heater.

You are fighting a little bit because the pump is a medium head pump. Would work better with a high head pump


You likely will not get to 40-45 with that pump.

There is "optimal" then there is acceptable. The flow is all about heat transfer. Below 30 or over 70 can damage the heater. Any flow in that range is fine.

The heater will heat, run it at 2400 and >30GPM, you should be fine.

 

[anthony21078]

The heater puts out fixed amount of BTU's. A low flow rate absorbs more BTUs and has a higher temperature then a high flow rate absorbing less BTU's. The same amount of BTUs (heat) gets into the pool regardless of delta-t.

I understand that. However, from the tech's standpoint, he said when using the optimal flow rate of 40-45gpm, it "places less stress on the compressor." Any truth to that?

The flow is the same, before or after the heater


You are fighting a little bit because the pump is a medium head pump. Would work better with a high head pump
View attachment 597749

You likely will not get to 40-45 with that pump.

There is "optimal" then there is acceptable. The flow is all about heat transfer. Below 30 or over 70 can damage the heater. Any flow in that range is fine.

The heater will heat, run it at 2400 and >30GPM, you should be fine.

I think the only way I could see increased flow without maxing out the rpms on this pump is to redo the entire pad plumbing. If I could figure out a way to remove several of those 90 bends I would see an improvement but I dont know if its worth the trouble.

I never heard of a medium vs high head pump until now. If both a high and medium head pump have the same hp, can a high head move more water at the same or lower rpm?

 

[PoolStored]

I think the only way I could see increased flow without maxing out the rpms on this pump is to redo the entire pad plumbing. If I could figure out a way to remove several of those 90 bends I would see an improvement but I dont know if its worth the trouble.

A couple 90s will not make a big difference. Your heater does...

I never heard of a medium vs high head pump until now. If both a high and medium head pump have the same hp, can a high head move more water at the same or lower rpm?

Exactly. So does a 3hp vs a 1hp. 3hp will move the same water at lower RPM.

 

[ajw22]

I understand that. However, from the tech's standpoint, he said when using the optimal flow rate of 40-45gpm, it "places less stress on the compressor." Any truth to that?

I don’t see any science or engineering behind that comment.

The compressor acts on the refrigerant and has no contact with the water flow. The only connection between the two is with the heat exchanger and I cannot see how a bit more water flow and heat exchange can materially effect the compressor.

I think the only way I could see increased flow without maxing out the rpms on this pump is to redo the entire pad plumbing. If I could figure out a way to remove several of those 90 bends I would see an improvement but I dont know if it’s worth the trouble.

It is not.

I never heard of a medium vs high head pump until now. If both a high and medium head pump have the same hp, can a high head move more water at the same or lower rpm?

Yes.

Water flow is not just about horsepower but also impeller design.

 

[anthony21078]

You guys have any recommendations for a high head pump?

 

[PoolStored]

Do you have any automation?
Do you have 115V or 230v to the pump?

 

[anthony21078]

Do you have any automation?
Do you have 115V or 230v to the pump?

No automation
230v

 

[PoolStored]

Waterway defender 2.7, pentair intelliflo, Hayward tristar vs 950.