PVC sizing confusion

[september]

I will have my pool installed in a few weeks. 12x24 Doughboy with a 1hp Hayward xstream cc10092stl pump/cartridge filter that has 1.5" input/output and a 150k btu Hayward h150fdn heater that has 2" input/output so I am a bit confused on what proper size PVC piping will be needed in this setup?
Pool will have 1 return/1 skimmer. Should they run 1.5" pvc pipes from pool to the pump/filter then 1.5" with a 2" adapter to the heater and then another adapter 2" to 1.5" back to the pool? Or 2" PVC everywhere with reducers for 1.5" where needed?

 

[september]

I will have my pool installed in a few weeks. semi inground 12'x24'x52" Doughboy with a 1hp Hayward xstream cc10092stl pump/cartridge filter that has 1.5" input/output and a 150k btu Hayward h150fdn heater that has 2" input/output so I am a bit confused on what proper size PVC piping will be needed in this setup?
Pool will have 1 return/1 skimmer. Should they run 1.5" pvc pipes from pool to the pump/filter then 1.5" with a 2" adapter to the heater and then another adapter 2" to 1.5" back to the pool? Or 2" PVC everywhere with reducers for 1.5" where needed?

 

[ajw22]

1.5" pipes and reducing to 2" at the heater will work fine.

 

[Richard320]

Calculating flows is beyond me. But look carefully at that pump and filter. Sometimes the fittings are dual-sized - ID fits 1.5", OD is the same as 2" so you can use a coupling on the outside. If so, you could use 2" throughout.
Let's see what @JamesW has to say

 

[JamesW]

I would do 2" everywhere and reduce as needed.

I would definitely not do a single speed pump.

I would go two speed or variable speed.