New Pool Owner... New Pump vs New Motor

[momobetta]

Hello All,
I'm a relatively new pool owner, and am slowly learning as I go. I purchased a home with a 30 year old fiberglass pool 1 year ago, and muddled through my first season of pool ownership. By my calculations, it's a 25,000 gallon pool. It has one jet, and one skimmer/suction port. The suction line is about a 20 foot run, and the pressure line to the jet is 60ish feet (rough estimates). I purchased a home warranty for my first year, and used it to get the pool guy out a few times. I tried to glean as much as I could from him. The warranty also purchased me a brand new heater!

I have a burning question about my pump that I know you guys will be able to answer... My pump is an old Jacuzzi pump. The pool guy told me that the pump is from a period when Jacuzzi was turning out junk. It is a 2 HP pump, which the pool guy thought was a bit excessive. Anyways, I had some serious sticker shock when I saw my first few electric bills, and asked the pool guy about how to save some money. He told me that I should wait until my pump goes bad before I invest in anything. I have some cash saved, and don't mind a big one time payment if I'm going to save money month to month. The pump is noisy, and a $350 a month electric bill makes me sad. I'd like to make my pool investment for this summer a pump investment, but I need to know a few things.
1. Should I replace the entire pump, or just replace the motor? I read an article that mentions swapping an old motor for a newer 2 stage motor instead of plumbing an entire pump.
2. Will upgrading the pump save me a significant amount of money?
3. Judging by the stats above, was the pool guy right in thinking a 2HP motor was a little excessive? Could I downgrade?

Any advice would be greatly appreciated. I'm sure I've left out critical information. I'll fill you in if you ask for anything else. I'd look at my pump now, but I'm at work right now and in 100% Friday afternoon distraction mode.

[mas985]

First off, $350 per month is pretty high even for a 2 HP pump. This could partially be due to a run time issue. 2 HP pumps tend to turover a pool pretty fast so you really don't need more than a few hours per day in pump run time. So I am not sure how long you are running your pump now, but that is the first step.

As to your other questions:

1. That depends on the condition of the wet end. If it is in fairly good condition, you do have the option of just replacing the motor which is cheaper than the full pump.

2. Going from a single speed to a two or variable speed most definitely will save in energy costs.

3. Yes and Yes. But if you want to downsize the pump at the same time and parts are not available for the old pump, then you are probably better off going with a new pump. Downsizing an old pump requires changing the impeller and sometimes the diffusor so they would need to be available.



Some additional details might help too:

1. Pipe size.

2. Any other water features; spa, waterfall, deck jets, etc.

3. Current pump run time.

4. Electrical rate ($/kwh).

5. Current control system if you have one.

[momobetta]

Okay... Here is some of what you asked for...
Pipe size is 2". Sand filter. Everything is in good working condition.
There are no other features. It's a pretty plain set up. One suction port and one discharge.
I have been running the pump 8 hours per day. I'm basing this off of a book I purchased on pool maintenance. There were no calculations in the book, it just said that running the pump for 8 hours a day is a good rule of thumb.
The only control system I have is a mechanical timer. I have it running from 10:00 am to 6:00 pm. I am up against the mountains in salt lake city, so we don't get direct sunlight until the sun peeks over the ridge around 8:30 am in the summer.
I'm looking for my electric bill to give you a rate, but I should mention that the $350 electric bill was not only for the pool. It is for the whole house. I pay about $100-150 a month without the pool.
Some other things that you didn't ask for that might help...
The pump is a jacuzzi magnum force pump. Production date: July 1999.
The pump body (not the motor) says model: 2umf-s order number: 94027120
The motor says... Magnetek part number: 10-184950-22.

Hope this helps... Thanks again for the advice!

[mas985]

The pump model was helpful. That is a an uprated 2 HP which is equivalent to a full rated 1.5 HP pump. Full power draw for that pump is around 2.4 kw so running 8 hrs per day should be less than 580 kwh per month. But if your rates are around $0.11/kwh, you should be paying less than $64/month for the pump.

On 2" plumbing, your current pump is probably producing close to 90 GPM which would be a 3 hour turnover. So with 8 hours, you are turning over the pool over 2.5x which probably much more than you actually need.

Most pools need only 1 turnover per day so the first thing you could try is reducing your run time in half and see how the pool looks. The run time of a pump is mainly for removing debris from the water so mostly asthetics. As long as you have enough chlorine in the water, everything should be fine with a reduced run time.

As for a new pump, going with a 3/4 HP two speed would save even more energy. Taking into account both the lower power draw and slower turnover, a 3/4 HP pump will save you in energy costs close to 25% on high speed and 66% on low speed. Full speed turnover would be about 5.3 hours and low speed 10.6 hours. A Pentair Whisperflo WFDS-24 would be a good choice your setup.