Pressure issues with Equipment Upgrades

[My_Hoosier_Pool]

Good Morning TFP,
I live in Indiana and am excited to get started on a new pool project once the weather breaks....assuming it ever breaks. I am installing a Pentair Thermalflo heat pump and a hayward sp3400vsp pump. The heat pump will be an addition while the pump will just replace the Hayward single speed pump which is on its death bed. Both new units have 2" unions. My inground pool has 1 1/2" pipes. The sand filter I have is 1 1/2" unions.
My runs are less than 60 feet. The longest run is the skimmer line which is 51 feet. I know I will need to use reducers in my piping, but since I am in planning mode, I'd like the Forum's expertise to know where they should be fitted. Feedback can be conceptual or precise. I would like to maximize the cost savings with the variable speed pump but I am aware of the pressure requirements of the heat pump. I don't want to set up a system that trips off the heat pump (due to low pressure) just because my design was poor or ineffective. Any help would be greatly appreciated!

Tony

 

[jblizzle]

Welcome to TFP!!!

I am a little unclear what you are looking to change. To minimize head loss and increase flow rate at a given pump RPM, I would suggest increasing your equipment pad pipe size to 2" (especially an 90s) as much as you can. That said, there is no need to start from scratch, I would just use 2" on anything you happen to be messing with.

Even if you left everything at 1.5", the pump and heater will work just fine.

Note that heaters generally work best at higher flow rates, so that is counter to trying to save money on electricity by lowering the pump speed. Although generally you are likely best off running the pump as low as you can and still make the heater happy.

Also note that with the limited pipe size, you will not want to run the pump at full speed, so you should limit the maximum speed that is allowed.

 

[My_Hoosier_Pool]

Thanks for the initial feedback. Hopefully I can articulate my ideas and requested feedback a little better. My existing piping is 1 1/2". The new equipment will have 2" unions but the sand filter (existing) and bypass value have 1 1/2" unions. I will need to increase the pipe size and eventually reduce the pipe size before returning to the pool. I need some help with where to put these connections.
Or, I can accept feedback saying that the 1/2" changes won't matter that much since my runs are 1 1/2" and head loss is negligible. It just seems like increasing piping to 2" and then reducing it and then increasing it again is going to negatively impact my pumps effectiveness.

 

[jblizzle]

Increasing to 2" and decreasing back to 1.5" where needed will not hurt you ... it will have lower head loss than if you leave everything at 1.5".

"Pump Effectiveness" is kind of an odd term ... because basically the more water you move, the more money it is going to cost to run. So, there is not real optimum.

I would suggest running 2" for as much as you can. What is the bypass valve? Most pool 3-way valves can accept 1.5" or 2" pipe.

 

[My_Hoosier_Pool]

I will strongly consider just upgrading the pad to 2". That would solve the majority of my questions and concerns. I think your comment about the 90 degree turns is key. I don't have an over-abundance of space available to me. The pipes will turn several times before moving back to the return.
I will most likely reduce the new 2" pipe down to move through the sand filter and reduce it after the chlorination before the return to the pool.
Thanks Jason!