Help me select a new pump

Users who are viewing this thread

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
Yesterday I replaced our 30 year old pressure tank. I figure our pump probably isn't far behind, so I thought I would start doing my research now.

Our current pump is a Grundfos 5S05-13, 1/2 HP, 230V. I placed it about 60' down the well when I originally installed it back in 1991.

According to the well report from 1987, the well is 6" round, 97 foot deep, with a static level of 35 feet. Bailer test of 5 GPM with a 39 foot draw down after one hour.

I have a new 52 gallon pressure tank with a 30/50 switch.

I would like another Grundfos pump, though I would prefer to get a 120V pump so it would be easier to connect to a generator during a power outage. It would also be nice to eliminate the external control box.

I've looked at the Grundfos 5SQ05-180-115V which seems comparable, but I don't really understand all the pump curves, head, etc. to know which size pump to select.

When replacing the pump can I reuse the existing black poly pipe and wiring, or should I plan to replace those too?

Will I be able to manually lift the pump out of the well now that it has water filling 60' of 1" pipe?

Our current well seal is made of cast iron and is very rusty. Most of the new ones I see are made of plastic. Are they reliable?

Finally, would it be a bad idea to buy a pump and have it sitting around on a shelf until the old pump fails? Or would it be better to proactively replace the 30 year old pump? We've never had a problem with the pump, but ours is 30 years old and I don't know how long they typically last. I'm guessing it will probably just fail with no warning signs it's going bad?
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
When it comes to pumps, if it ain't broke, don't fix it. You can't buy a pump as good as one made 30 years ago. That 5 GPM pump working with an 80 gallon tank that holds 25 gallons of water hasn't cycled very much in all those years compared to many other systems.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
I would like another Grundfos pump, though I would prefer to get a 120V pump so it would be easier to connect to a generator during a power outage. It would also be nice to eliminate the external control box.
Since you have a control box, you might want to preventively replace the start capacitor. Those are cheap if you are not in a hurry. They are non-polarized electrolytics, so will degrade.
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
It would take the 5SQ05-270 to equal the 7 GPM you are getting from the 5S05-13. The 5SQ05-180 will only do about 4 GPM. Pumps can be stored for a long time, but motors not so much. The SQ has an oil filled motor with ball bearings, and it is not good for ball bearings to sit in the same spot for long periods of time. Turn the motor with your finger a couple times a year and they will probably be OK. But the SQ might be better than a 4" motor like on the 5S05-13. They don't have ball bearings, but are water cooled and lubed and the water leaks or evaporates out of the motor over time.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
When it comes to pumps, if it ain't broke, don't fix it.

Yeah, that has been my general viewpoint as well. At the same time, I don't want to be in a situation where our pump dies and we're without water for 2-3 weeks waiting for a new pump to be delivered.

Do well pumps give any sign that they are failing? Or do they just stop pumping all at once?
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
It would take the 5SQ05-270 to equal the 7 GPM you are getting from the 5S05-13. The 5SQ05-180 will only do about 4 GPM.

My 5S05-13 is a 1/2 HP pump. The 5SQ05-270 is a 3/4 HP pump and 240V (I want 120V if possible).

If I'm reading the pump curve chart correctly, the 5SQ05-180 will do 5GPM with a 180 foot head. I don't understand the total head calculation completely, but 60 foot up the well, 10 feet above ground, and maybe 10 feet in losses would only be about 80 feet of head. Seems like the 5SQ05-180 would be more than enough. What am I missing?
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Head is a measure of pressure where 1 psi = 2.31 ft. So your 10 ft of head for "losses" would be only 4 psi, and you're not going to push much water through your house's pipes with 4 psi. Try 50 psi, or 115 ft of head, for distribution within the house.

[And I don't know enough to know if that 50 should be 40 or 60 or what. I guess if you want to use a 40/60 pressure tank, then you might want to use 70 psi, so you can be sure of developing 60 psi at the pressure switch. So make that 160 ft of head for distribution.]

Cheers, Wayne
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
The 5SQ05-270 is a 3/4 HP pump and 240V (I want 120V if possible).
5SQ05 is 1/2 hp.

Grundfos 5SQ05-180-115V part 96160165 runs on 12o.
5SQ05-180-230V part 96160132 runs on 24o.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
I appreciate the feedback, but I'm still confused. My current 5S05-13 pump works well, I just want something comparable, preferably with 115V power instead of 230V.

I'm also confused about calculating my total head. If my pump is 60ft down in the well, and I add 115ft for distribution as Wayne suggested, wouldn't that put my total head around 175 feet? If so, wouldn't the 5SQ05-180 be the proper pump (pump curves state 5gpm at 200ft head)?
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
You are correct. The -180 will give you 5 GPM, the -230 will give you 6 GPM, and the -270, which my old book shows to still be a 1/2HP will do 7 GPM and is more like the 5s5-13 you have now. 115V takes twice the amperage of a 230V motor and is usually harder to start from a generator.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
The -180 will give you 5 GPM, the -230 will give you 6 GPM, and the -270, which my old book shows to still be a 1/2HP will do 7 GPM and is more like the 5s5-13 you have now. 115V takes twice the amperage of a 230V motor and is usually harder to start from a generator.

All of the places selling Grundfos pumps online list the -230 and -270 as 3/4 HP pumps? The -180 is the biggest 1/2 HP pump listed.

Can you clarify how total head is calculated? I assume I would count the 60' from the pump to the top of the well. Where I get lost is how to calculate what I need to include above ground for pipe losses and full pressure at the sinks. I've got a 30/50 pressure switch, so 50 psi should be the max I'm working with, right?

My current 5S05-13 has worked well, but I didn't select it. It's what the store had in stock when I first set up our well. I don't know that I necessarily need the equivalent pump. That's why I need to better understand how to calculate the total head so I can select the right pump. There's no reason to buy more pump than I need.

I've been leaning towards a 115V pump as 240V generators tend to be bigger and costlier. However, I haven't needed a generator in 30 years so I'm probably overthinking something I'll never use. A 240V pump would certainly be more efficient on a daily basis.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
I'm also confused about calculating my total head. If my pump is 60ft down in the well, and I add 115ft for distribution as Wayne suggested, wouldn't that put my total head around 175 feet?
Wayne suggested adding 115 ft for the pressure head, and not friction, which is low. If you call that distribution, then yes. For friction, you could add 5 psi (which is probably high), or you could use a pipe pressure drop calculator. http://www.pressure-drop.com/Online-Calculator/ is complex, but lets you model in elbows, pipe size changes, and more. Pressure drops add. With a CSV add maybe 3 psi at 7 gpm. https://cyclestopvalves.com/pages/csv1a-specifications
Can you clarify how total head is calculated? I assume I would count the 60' from the pump to the top of the well. Where I get lost is how to calculate what I need to include above ground for pipe losses and full pressure at the sinks. I've got a 30/50 pressure switch, so 50 psi should be the max I'm working with, right?
Assuming you stay with 30/50, you want good flow when the water pressure is at 30 psi. You want reliable but slower flow at 50. You want to have enough margin that the pump will not deadhead at 55 or 60, even if the pump is only pumping 1 gpm. This would allow component drift.

Also, assuming your well and pump support it, you could adjust your pressure switch to 35/55 or 40/60. I set mine to 38/58, although vs when it was set to 30/50 I did not notice a difference. If you change the pressure switch, adjust the precharge also.

If the casing is big enough, it is good to use a flow inducer sleeve. Cheap and homemade.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
Assuming you stay with 30/50, you want good flow when the water pressure is at 30 psi. You want reliable but slower flow at 50. You want to have enough margin that the pump will not deadhead at 55 or 60, even if the pump is only pumping 1 gpm. This would allow component drift.

Whoosh!!! Right over my head. :)

Pump is 60' down in well.
Pressure switch is 30/50.
Tank is 52 gallon.
Piping is 1" diameter and about 100 feet to the house.

What is my calculated total head?
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
Can you clarify how total head is calculated?

2.31' of head is the same as 1 PSI. A 30/50 switch gives and average of 40 PSI, which is the same as 92' of head. You pump maybe set at 60', but is only lifting from the actual water level. If the pumping level is say 30' and you want 40 PSI working pressure, that is a pumping head of only 122'. Add to that your pipe friction losses and you have your Total Dynamic Head or TDH.

You also have to make sure the pump can make more than enough head or pressure to reach the pressure switch cut off point of 50 PSI, which is the same as 115' of head. If you don't know the pumping level, figuring the depth the pump is set is worst case scenario. At 40 PSI working pressure that would make the total head 152' on the pump. But, to be sure the pump can make enough pressure to reach the pressure switch cut off point of 50 PSI from max depth, it needs to be able to produce more than 175' of head.

The 5SQ05-180 builds about 275' max head, which is good, and would give you about 6 GPM at 152' of head. The 275' of head available would also let you turn up the pressure switch to 40/60 if you wanted, as that is a more common pressure setting these days.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
The 5SQ05-180 builds about 275' max head, which is good, and would give you about 6 GPM at 152' of head.

Thank you for clarifying. That makes more sense.

I've been looking at the Grundfos pumps since that's what I have now and it has lasted 30 years. They do tend to be rather expensive though. Are there other/better pump brands you would recommend?
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Pump is 60' down in well.
Pressure switch is 30/50.
I would look for two points:
40 ft down and 6 gpm and 30 psi . This reflects normal operation while backwashing a backwashing filter or otherwise drawing 6 gpm for a while. If I read your drawdown test correctly, your well dropped from 35 ft to 39 ft at 5 psi.

40 ft of head: 40 ft
30 psi in ft: 70 ft
Allowance for friction: 12 ft​
So I total that to 122 ft. for general use

60 ft down and 1 gpm and 50 psi plus some margin to make sure the pump turns off. IMO, having the pump deliver less flow as you are about down to the pump is not bad. I would like to see less gpm delivered if I was heading for running the well dry.
60 ft of head: 60 ft
55 psi (50+margin) in ft: 127 ft
Allowance for friction: 2 ft​
So I total that to 189 ft. for worst case running the well dry. I want over 1 gpm flow in that case. With low flow, the friction goes way down.

These are my opinions that are not based on experience, and there are other very valid views.
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
Grundfos pumps are my favorite as well. There probably won't be anything wrong with your 30-40 year old one when it stops pumping water. You can usually put 2-3 motors on a Grundfos pump before the pump end fails. Motors are a different story. Yours will have a Franklin motor from that long ago. I believe Franklin makes the best motor, but not a good pump. Grundfos makes an excellent pump, but not such a good motor. You certainly do not want a 2 wire Grundfos or a 115V. 230V, 3 wire only with the Grundfos motor if you go that way.

Like I said earlier, the SQ is a different animal. It maybe fine, but I doubt they will last 30-40 years spinning 10,700 RPM like the 3450 RPM 4" pumps do. I have a regular 4" Grundfos pump and motor I installed in 1982 that is still working. Not replacing it until it quits, then may just replace the motor.
 

Anthony W

New Member
Messages
26
Reaction score
2
Points
3
Location
Washington State
The product selector on the Grundfos web site recommends either the 5SQ05-180 or the 10SQ05-160. Which do you think would be best for my situation? They seem to be about the same price.
 

VAWellDriller

Active Member
Messages
539
Reaction score
111
Points
43
Location
Richmond, VA
The 5SQ05 better matches well yield based on what you mentioned earlier. If you have had good luck with a 5gpm pump for so long I'd stick with that. To answer earlier questions, that pumping equipment is not very heavy...should be very easy to handle by yourself. The plastic well seal will be just fine for your application. You could reuse the old pipe and wire, but you could replace it ALL with all new fittings for about $200...might as well start off fresh in my opinion.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks