Saving electricity - replacing an old pump/motor

[pauster]

Hi Mark,

now what happens in 1 1/2 inch pipe where it supposedly gets ugly beyond the 42 gpm ? If I had over 60 gpm going through that pipe today the velocity of the water could be detrimental to the piping ?

Just looking at the smallest pumps availabe - I was aiming for about 40 gpm at 40 ft of head. Most pumps go beyond that.

Of course if I am getting more than 40 gpm today (say 60 gpm) then my new head at 40 gpm would be lower: 40 / (60/40)^2 - right ? So head at 40 gpm is around 17.8 ft ?

Patrick

[mas985]

Hi Mark,

now what happens in 1 1/2 inch pipe where it supposedly gets ugly beyond the 42 gpm ? If I had over 60 gpm going through that pipe today the velocity of the water could be detrimental to the piping ?

Theoretically, it could slowly wear out the interior of the pipe but I have never heard of a case.

Just looking at the smallest pumps availabe - I was aiming for about 40 gpm at 40 ft of head. Most pumps go beyond that.

Of course if I am getting more than 40 gpm today (say 60 gpm) then my new head at 40 gpm would be lower: 40 / (60/40)^2 - right ? So head at 40 gpm is around 17.8 ft ?

Right so most single speed pumps will be well beyond that. But as the calculations showed earlier, multi-speed pumps at lower speeds should be in that range. Target a 3/4 HP 2-speed or multi-speed pump and you should be OK. The Whisper flow 3/4 HP I did the calcs for earlier should be about 33 GPM at low speed.

Also, sometimes it is good to have a high speed to mix up and distribute chemicals before a quick swim.

Patrick

See above for answers

[pauster]

Hi Mark,

I have your your input for some more extrapolations ... so for a sanity check (another one )

Pentail IntelliFlo

GPM Ft head KW gpm / kw (assume about const. efficiency per manuf info)
85 86 2.9478 29
65 50.7 1.318 49
50 30 0.600 83
45 24.3 0.437 103
40 19.2 0.307 130
35 14.7 0.206 170
30 10.8 0.130 231
25 7.5 0.075 333
20 4.8 0.038 521
15 2.7 0.016 926


Pentair 2 speed

high = 3450 rpm: 65 GPM, 1.676 kW, 39 gpm/kw
low = 1725 rpm: 35 GPM, .54 kW, 65 gpm/kw

The Pentair 2 speed would save me $208 per season, the Intelliflo $372 (see attched zipped Excel spreadsheet)

So it's just a question of how much the pumps cost and how long it takes to pay for itself.

I found the pentair for $421 online plus say $130 for a 2 speed switch - does that sound reasonable ?

If I can get the Intelliflo for $900 (supposedly, but I have to confirm with the dealer) then it makes more sense, if it costs more, the Pentair is what I'll use - but I'd have to run 230V to the pump (.

Thanks again for your patience !

Patrick

[mas985]

I thought the Intellifo only had 4 RPM settings, you are showing 10. Are there more than the head curves show?

Also, remember that these calculations are approximations so I would not expect less than 10% error. You may be splitting hairs when it comes to costs.

I understand you want to save the most money but the Intelliflo is relatively new pump so it is not well time tested and has many more parts to fail. Keep that in mind when doing a cost benefit analysis.

You might want to query the forum again to see if anyone has one.

[pauster]

H iMark,

Pentair sells the IntelliFlo (part no 11012) http://www-1.pentairwater.com/jwcs/w...egory_rn=29151

and the IntelliFlo 4 160 (part 11013) http://www-1.pentairwater.com/jwcs/w...egory_rn=29151.

The former has a built in timer etc. The latter can store 4 different speed thay you preset. One of Pentair's manual references a smaller IntelliFlo 4 100 but nobdoy seems to have seen it.

The only reference I could find on this forum was

http://www.poolforum.com/pf2/showthr...ght=IntelliFlo

http://ths.gardenweb.com/search/nph-...Pools+%26+Spas has some info (and I think I have seen posts from you, too) but nothing conclusive ...

I'll ask on a separate thread

Patrick