Replacing 1 hp pump with a 1.5 hp - change impeller?

[jperiod]

The pool store says my sta-rite dyna-glas 1 hp pump has bit the dust. The bearings are bad and they said since it's made of "pot metal", the casing can't handle the replacement bearings and will just cause the new set to go bad within a few months. The impeller also broke and it needs a new seal.

Someone gave me their old whisperflo 1.5 hp pump a few years ago and I asked the store about hooking that up to my exisiting sand filter instead. They said I could if I retrofit it with a 3/4 impeller. Then they said if the motor ever goes, just replace the motor with a 3/4 hp at that time. Does this all make sense?

I couldn't find GPM on my sta-rite to compare to the whisperflo pumps online. My filter says it max flow rate is 62 GPM but I saw somewhere online where it says the flow rate is only 44 GPM if you have 1.5" pipe.

Thoughts?

 

[scooperhsd]

Unless you ARE replacing the 1.5 HP motor with the .75, changing the impeller is unnecessary - you should be able to just plumb it in and wire it up and you should be OK. It is a bit too much pump with only 1.5 inch plumbing, but you should still be ok.

 

[jperiod]

Really? It won't blow or overwhelm the rest of my system? I don't have a dedicated suction line to my pool vac. It runs out of a "vac mate" in the skimmer. I seem to remember this being a factor in my conversation with the guy at the store (which is a mom and pop shop, not a silly chain with kids working). He also said our state had some law requiring dual speed or 3/4 hp or less.

 

[mas985]

Someone gave me their old whisperflo 1.5 hp pump a few years ago and I asked the store about hooking that up to my exisiting sand filter instead. They said I could if I retrofit it with a 3/4 impeller. Then they said if the motor ever goes, just replace the motor with a 3/4 hp at that time. Does this all make sense?

Makes perfect sense and I would recommend the same but I might go one step further and recommend a 2 speed motor when the current motor dies. It isn't absolutely necessary but downsizing the impeller now would still save quite a bit in energy costs so I think it would be worth doing.

 

[scooperhsd]

The California law is Title 20 - max horsepower for a single speed pump is 1 HP. For a larger HP, it needs to be 2 or more speeds, defaulting to spending most of the time on low speed.

I don't know how the law would regard to replacing one pump with another for this.

It's not that I am against replacing the impeller, it's just that I don't believe in spending money unless it's necessary. If it is a legal requirement to use the 3/4 HP impeller - go ahead - You'll just be running it lighter, and saving money on running the pump.
I would also be prepared to be buying a new pump (depending on the condition of that whisperflo) - I'd at least test it before I replaced the impeller.

 

[jperiod]

Someone gave me their old whisperflo 1.5 hp pump a few years ago and I asked the store about hooking that up to my exisiting sand filter instead. They said I could if I retrofit it with a 3/4 impeller. Then they said if the motor ever goes, just replace the motor with a 3/4 hp at that time. Does this all make sense?

Makes perfect sense and I would recommend the same but I might go one step further and recommend a 2 speed motor when the current motor dies. It isn't absolutely necessary but downsizing the impeller now would still save quite a bit in energy costs so I think it would be worth doing.

Like what difference in cost? I run it 6-8 hours/day and my electric bill is $400 during summer and only $90-100 in the winter (which only seems like a differnce in A/C). It might cost me about $130 to replace impeller/seal/gaskets. Is it really worth it now? I'm wondering if it will just hook up and run even though it's sat dry for 4-5 years?

 

[scooperhsd]

Although I said I would test the whisperflo before replacing the impeller, let me throw this out at you -

Around 1997, the wife and me did a bathroom remodel. what had been in the master bathroom was a "hydrotherapy" tub, that was powered with a Hayward Powerflo II 3/4 HP pump (with no strainer) (and keep in mind that our house was built in 1983). I kept that pump as a "maybe someday" and left it in storage, until last summer. Around the 1st of July 2011, my pump at that time (a Hayward Superpump 1.5 HP) died (probably motor failure of some kind, but I never really looked into it). I pulled this now 28 year old Powerflo II pump out, hooked up the plumbing, primed through the pump's outlet, then connected the power. It worked just fine for 2 weeks until my present pump arrived and I got it plumbed in and working. I went ahead and got a strainer assembly from a vender on Amazon, and I'm seriously considering using that Powerflo II pump next year. Nothing wrong with my current pump, just interested to how well it will work for an entire season.

Sometimes it's nice to have a spare pump...

 

[mas985]

Like what difference in cost? I run it 6-8 hours/day and my electric bill is $400 during summer and only $90-100 in the winter (which only seems like a differnce in A/C). It might cost me about $130 to replace impeller/seal/gaskets. Is it really worth it now? I'm wondering if it will just hook up and run even though it's sat dry for 4-5 years?

A 3/4 HP Whisperflo will use about 1600 watts on high speed and a 1.5 HP Whisperflo (I am assuming they are both full rated), will use about 2200 watts so about a 27% savings in energy costs. Accounting for the flow rate difference in turnover it is about 20% savings. BTW, impellers are pretty cheap so it shouldn't take long to pay it off but it depends on what you pay for electricity.

Also, for a 16k pool, you probably don't really need that much run time. I run my pump 4 hours per day, 2 on high, 2 on low, and I have a bigger pool and smaller pump.