Pool Pump Replacement

[Ancala]

I have a 22k gal salt water IG pool / spa in Scottsdale Arizona with a spa spillway. There are also a couple of waterfalls on the side. There are two AO Smith ST1202 2 HP motors. One of them is for the pool/spa and the other is only for the waterfalls. The one powering the pool has died and needs replacing.

I've been researching and reading about pumps all morning and don't feel like I have any better idea of what to replace it with now than when I started.

2 speed? VS? I'm willing to pay more if it's worth the energy savings but I'm getting a lot of conflicting information about real world savings versus the extra cost of the VS (initial and maintenance).

Our power from APS (off peak) is about $0.12 to $0.14 kWh.

Suggestions?

[CarlD]

I don't know how much REAL savings a VS gives vs a 2-speed on low. 2HP sounds like 'way too much for a 22k pool, but I don't know if the spa requires the extra HP. Normally, 1HP would be sufficient. I just don't know enough about the spa options.

[mas985]

At those rates, you would probably be better off with a 2 HP 2 speed. Most of the savings comes from the lower speed so a VS will only give you slightly savings but the extra cost could make it many years before it breaks even with the two speed.

You can usually do even better with a two speed motor swap instead of buying an entire pump. Doesn't require plumbing changes either.

Also, with a spa I would not down size because you might be very disappointed in the jet pressure. Most 6-jet spa's require a 2 HP pump if running through a filter and heater.

[BigDave]

My 2 cents: You know the 2HP pump you had served your needs for the pool and spa. If you can get the same make / model pump in at 2 speed, 2HP version, you'd have the same performance when you need it and have the option of running it on low for filtering the pool and saving significant money. The 2 speed option on a pump should only be a fraction of the pump price where a VS will cost a few times more. I'd take an awful lot of $0.14 Kilowatt-hours to cover a $1000 price bump. Another factor to consider is reliability, 2 speed pumps are simple, time proven technology, VS (while potentially more efficient) pumps rely on sophistaced electronic controllers that can be destroyed by elctrical storms and power transients. I have a VS pump and I'm pretty happy with it but my selection was made to meet several different unknown operating conditions - you know a 2HP will work for your pool and spa.

[CarlD]

Thanks everyone for chipping in. I don't know much about the extra power reqs for a spa, but I do know that a 2 speed pump is an ABSOLUTELY worth-while investment.

[mas985]

Most two speeds consume about 1/4 the power on low speed as high speed but the flow rate is half of high speed. So to get the same turnover, which is not always necessary, the pump needs to run twice as long and you would end up saving about 50% in power over full speed. However, if you can maintain the same run time, you would save about 75% in power over full speed.

[PoolDoc]

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