Variable speed motor/pump worth it?

[bfr57]

Just had my third 2hp motor go out over a 6 year period. The last was a locally rebuilt single speed motor that lasted barely 2 years. I'm considering a variable speed motor/pump combo like the Pentair Intellichoice VS3050, but they are definitely pricey compared to a $250 replacement motor. Of course the salesmen tell you they last years and years and pay for themselves in about 2 years, but what is reality? The only thing I really have that needs the extra power would be my solar heating and Creepy. Of course it sounds like I have to buy a controller in order to keep the solar demand and motor/pump in sync which is another $500! Are these variable speed units worth replacing or just stick to a regular single speed motor on a timer?
Any others to compaer with Pentair?

 

[Puffin]

mas985 has some spreadsheets to help you do a cost comparisons. But the general feeling here seems to be it depends on the price of electricity in your area. If your electric rates are very high then they can be worthwhile. However if your electricity is inexpensive, it can take a long time to recoup the higher cost of the pump and a 2 speed pump would probably be a better bet.

This is only looking at it from monetary perspective. There have been comments that suggest the tuneability/versatility of the pump is worth considering as well. Obviously the value of that is subjective and would depend on your needs.

 

[mas985]

It really depends on several things but for most people, a two speed pump will be more cost effective over the long run than a VS pump. Also, it is even harder to make case if you just replace the motor with a two speed. You get most of the saving without much up front costs.

But in my sig under "Pump Modeling Tools" is a spreadsheet which allows you to do side by side comparisons of your old pump agains a new pump and/or your old pump with a two speed motor. But unless you pay a lot for electricity, replacing just the motor with a two speed motor is likely to be your best bet.

However, if you need the multiple speed of a VS for various functions, then the cost differences are less meaningful.