Well pump, pipe, wire decisions

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mikerjj

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Hello -

I have learned so much from the contributors to this forum - especially grateful to consistent contributors and moderators I see replying often and those that have come back to finish their threads after their projects.

Background - purchased a house (plus a small cottage on the same lot) in 2020 with two wells. It took me a few years to unravel which well was which due to conflicting information, funky drawings, and just tracking down some of the records not on file with the county. Cutting that part of the story short, I found out my PVC lined well, which is prone to running dry during high demand (I measured recovery at 0.33 gal/minute) is my older (1991) more shallow well.

My newer (1995) deeper well is steel cased (6in). What we've figured out is that this newer well has a significantly higher recovery rate - it was declared a "good well" by a local driller I had do an inspection, but that it has an iron bacteria problem and that I just need to shock it every 6 months. The pump I pulled out was a 2018 mfg'd Goulds and was locked up. Driller declared the pump dead. First 6 inches of pipe above the check valve was plugged solid with iron bacteria sludge. The house sat on the market for 4 months - I'm thinking that sitting, along with not shocking it lead to the locked up pump.

We pointed out a lack of water when we first looked at the house (insert lessons about well inspections here). They said it was a bad pressure tank, replaced it and the water worked. In retrospect, I think they replaced the pressure tank and switched both the cottage and the house over to the older well. The line and wire to the cottage run through the house crawlspace, so this was an easy T to make.

The original driller of the deeper well retired, but another nearby driller has their logs. They have two records with the below specs for my lot number and same original customer name - note that the older PVC lined well is only 145ft deep and that record was registered with the county. To my knowledge, I don't have a 3rd well, so I'm not sure which of this is actually correct

Date: 8/30/1995 Depth: 497' Casing: 51' Flow: 3.5 gpm Date: 10/10/1995 Depth: 408' Casing: 63' Flow: 2.0 gpm

I pulled 400ft of poly from the hole, spliced at about 150 down. I recorded the waterline at around 56 ft. The driller recommended I just replace the poly and the wire - especially because the wire was apparently the wrong kind. He also suggested (knew I was going to install myself) I set at 300' with poly as that would give me far more reserve than I have now and be less pipe to deal with, but this was more of an off-hand suggestion.

Thoughts, some of which might conflict:
- I have grid tied solar. In the event of a grid down/unreliable grid future, I'd like a softer start in place now. I see Cary's (and Franklin's) recommendation is to run thinnest allowable gauge for the length to get a softer start without the extra complexity.
- On current well/pump - When the house tub is being filled, hardly any water available. Thinking 15gpm peak would be nice for those edge cases, but this likely directly conflicts with the previous point. Consider positive displacement pump? Probably also conflicts with reliability goal?
- I already have a CSV valve and I prefer simple to the VFD options overall, but I would really like some remote telemetry (gpm, gallons pumped, time running, etc) and control (remote on/off) without introducing a future point of failure I'm afraid of with a VFD, especially if we have supply chain issues again. Recommended add-ons to add remote telemetry and control?
- I do not yet have Cycle Stop Sensor, but planning to get one. Have been somewhat confused on what the non-VFD control boxes I've see do since my current well operates with out one. I'm guessing same as a Cycle Stop Sensor or Littlefuse, but proprietary?

Questions are
- What depth do you think I should set the pump at given this info? Once I make that decision, I'll then need to make decisions on pump, and wire gauge, and maybe the poly.
- Tools - I'm going to rent a pump puller when I install and have a helper. I pulled myself using a tractor, helper for the last 200ft, rigged up pulley and a yard tractor. I had no idea when I pulled it (before I tracked down the record) I was going to end up with 400ft or I would have never started with such a setup.
- Seems like a Kwik Klamp would be prudent now and for the future. This seems like it might be nicer and kind of auto-engaging preventing accidental drops? - https://deanbennettsupply.com/products/47368/8871-Pipe-Holder-For-Drop-Pipe-DBS1502

Thanks in advance for anyone taking the time to read!
 

Valveman

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With static water level of 50'-60', setting the pumps at 300' will give you about 350 gallons stored in each well. With normal house use being less than 300 gallons per day, I would think you have plenty in one well, plus a back up. Iron can be a problem. You may want to consider using a Sulfur Eliminator. They aerate the water in the well continuously and eliminate the need for chlorine. You may want to talk to the guy who makes them. I would think as long as you have extra hole below the pump for the stuff to fall into, they would work well. Probably have to have the well bailed out after a number of years, but maybe not.

Stagger the pressure switch settings like the primary well at 40/60 and the secondary well at 30/50. With a Cycle Sensor and a Cycle Stop Valve on each pump the primary well should have time to recover while the secondary well is completing a watering event that uses more than 350 gallons.

Two Subs same system plain (1).jpg
 

mikerjj

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Thank you - up until now, I had been thinking of pulling the pump from the lower producing well and keeping it and that well as a backup - I thought leaving the pump in but not using it could result in it getting clogged like the other one did. However, this two pump setup seems like I could put a smaller pump in the deeper well and still meet gpm demand and redundancy. In power outage, I could supply just one pump from generator and still feed both house and cottage right?
 

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Thank you - up until now, I had been thinking of pulling the pump from the lower producing well and keeping it and that well as a backup - I thought leaving the pump in but not using it could result in it getting clogged like the other one did. However, this two pump setup seems like I could put a smaller pump in the deeper well and still meet gpm demand and redundancy. In power outage, I could supply just one pump from generator and still feed both house and cottage right?
Yep.
 

Fitter30

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Thank you - up until now, I had been thinking of pulling the pump from the lower producing well and keeping it and that well as a backup - I thought leaving the pump in but not using it could result in it getting clogged like the other one did. However, this two pump setup seems like I could put a smaller pump in the deeper well and still meet gpm demand and redundancy. In power outage, I could supply just one pump from generator and still feed both house and cottage right?
Pumps are sized by head pressure ( feet of lift ,lenght of pipe ,the size and gpm). Small well pump might not be able to pump that head. Look at this pipe clamp also carry 1" just for poly.
 

mikerjj

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Thank you - so....

Pipe selection: 330 feet of head (pump at 300ft, additional 30ft of pumping height) would be approximately 142.89 psi + 60psi for pump pressure == 202 psi, so I would think I should use #250 poly, but would like validation

Pump brand/line: It seems Grundfos SQ series is often recommended - or would you recommend the SP series? Any others you would recommend?

Pump sizing: I'm really not sure on this one. My current thinking is that a 10SQ07-240 might be a good size. I was originally thinking of 10SQ15-330 but 1) seems like having the gpm drop as water level approaches the level of the pump would be somewhat protective? 2) I like the idea of lower power draw of a smaller pump which is especially feasible if we have 2 pumps in service (I want to keep the house and cottage on the same supply because the house has backup generator, but cottage does not).

I'm not sure if it would be better to size lower (10SQ07-200) so that it wasn't possible to pump the well dry - but that seems like the pump would burn up if running too far to the left on the pump curve?

But with a static head 60ft, that isn't even on the pump curve for the 10SQ07-240 - does that just mean it would be quite inefficient?
 

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The SQ has the 5 second soft start thing. The SP does not. The SQ would also be less weight for setting by hand. If setting at 300' the 10SQ07 would work. But it is a weak producing well, so I would install a 10SQ10-330 pump at 400' to have an extra 150 gallons of storage. With 50 PSI for the house and 50' of lift, the 10SQ10 will still have enough back pressure to prevent upthrust, especially if you use a Cycle Stop Valve. The back pressure from a 10SQ10-330 will be about 219 PSI. So, the 250# pipe would be fine. Just use extra long brass barb fittings with two good hose clamps each. Tape over the hose clamps to prevent rusting.

The SQ comes with a good built in check valve, which is the only one needed. The PK1A kit with a 10 gallon size tank would be all the controls needed. A little poly pipe, a few fittings, and some wire (THHN type) will finish the job.

Set up both wells the same way and stagger the pressures with one at 50/70 and the other at 40/60. Using a Cycle Sensor for each pump will protect them from running dry. When/if the first well runs dry, the Cycle Sensor will shut if off, the pressure will drop to 40 and the second pump will come on. Setting the Cycle Sensor for say and hour to recover means after 60 minutes the first well pump will come back on, the pressure will increase to 60 PSI, which will shut off the second well.
 

mikerjj

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I'll be renting an Easy Riser to assist with setting the pump this time and will of course have extra hands this time - so I'm less concerned with the weight now. Soft start is nice - but with two wells, I have options as to which one to put on the generator, so I'd like to understand the compromises between the SQ and SP beyond weight. I see the SP turns and *much* slower and has stainless impellers. Is one likely to last much longer than the other?
 

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The SP is a very long lasting pump. I have a 1982 model still working everyday. The SQ does spin like 10,700 and has composite impellers. But it was introduced in 1999 and has far exceeded my expectations. I doubt the SQ will last as long as the SP, but I probably won't be around long enough to know the difference. :)

With any pump it is the number of cycles that determines how long it will last. Eliminate the cycling and even cheap pumps will last a long time.
 
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