Is there an advantage to a 2 speed or variable speed

[chem geek]

Correct. If you run double the amperage through a single wire vs half the amperage through two wires, there will be a difference in motor startup. Think of a table saw wired with 110 vs 220. Which one starts up quicker?

This isn't the situation in a pump where you switch the configuration from parallel for 110V input to serial for 220V input. In both situations, you have "two wires" or windings. The difference is whether you connect them in series or in parallel.

As you can see from my post above, the amperage through each winding (wire) is the same in both scenarios, even though the incoming amperage is twice as high in the 110V case. It is the amperage in the winding that matters for (resistive) power consumption, heat, and torque, not the amperage coming into the pump.

 

[mas985]

Richard,

I agree with everything you posted except for this statement.

Only the wiring to the pump as well as the wiring in the pump to the windings is affected by the difference in total incoming current.

The windings are split at the terminal block in the motor so technically, there is no wire which is carrying twice the current inside the motor except for the wire coming from the breaker box.

But the important piece of information is that the windings themselves carry exactly the same current with 220v vs 110v. So heat loss is the same, efficiency is the same and start up torque and speed is the same.

 

[RobbieH]

OK, now, how inefficient is this pump compared to what's out there today?

 

[JasonLion]

RobbieH, impossible to say with any precision without seeing the pump curve. As a general rule a two speed pump saves up to 50% on electricity when run on low.

 

[mas985]

RobbieH,

If you are interested in looking at the cost savings in detail, I have a spreadsheet in my sig "Pump Modeling Tools" which allows you to compare the lifetime costs of various pumps including the one you have. Let me know if you need any help with that but it usually requires over $0.12/kwh before a variable is more cost effective. It depends on the configuration and any extra controllers that inflate the cost.

 

[douglee25]

I agree 100% with the Ohm's law illustrations. (SeriesQ's (in series - same amperage), ParV (in parallel - same voltage)... that's how I used to remember it in school)

I guess what I'm not being clear about is that the wiring to the motor (not inside) has double the amperage through it when wiring it with 110v. If you wire the same motor with 220v, the wiring to the motor (not inside) has half the amperage through it. The losses are in the wiring coming to the motor and in that case, I have seen a difference in how the motor responds when wired 110 vs 220. That's all I was trying to convey to the OP. I apologize if I was unclear.

Doug

 

[RobbieH]

RobbieH, impossible to say with any precision without seeing the pump curve. As a general rule a two speed pump saves up to 50% on electricity when run on low.

There's a chart on this PDF, which is for the newer model of the system I have. It would be F for my 1.5 hp model. It says it is "more efficient" than the one I have, but who knows how much or where (electricity vs. flow).

 

[RobbieH]

RobbieH,

If you are interested in looking at the cost savings in detail, I have a spreadsheet in my sig "Pump Modeling Tools" which allows you to compare the lifetime costs of various pumps including the one you have. Let me know if you need any help with that but it usually requires over $0.12/kwh before a variable is more cost effective. It depends on the configuration and any extra controllers that inflate the cost.

I found the spreadsheet, sure looks like it's there. I have a lot to learn though!