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mleman
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# Posted: 29 May 2023 08:01am
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Hi Everyone,
I'm building an off-grid cabin and am having trouble with water pressure. I'm hoping someone here might be able to offer some sage wisdom!
Current setup: 1/2 hp Flotec jet pump pulling from a lake and pushing 175' with a 20' rise through 1" poly pipe to the cabin. The pump is about 20' from the lake, with maybe a 4' rise. The pressure tank and 20/40 pressure switch are located at the cabin.
With this setup, I'm only able to get up to ~27 psi at the cabin, even though the pressure gauge on the pump is reading a steady 40 psi, so something needs to change. The pump is an older garage sale find, so I plan on replacing it with a new one.
Is it possible that the pump is worn, and a new one of the same size would suffice, or would I be better off going up to a 3/4 hp pump? I'm off grid solar powered, so energy consumption is something I need to watch.
What about the 1" pipe? Did I screw up by not going with 1 1/4"? Any thoughts and advice are greatly appreciated!
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Steve_S
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# Posted: 29 May 2023 08:50am
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The 1" pipe is big enough for your needs but you nailed it, it's the pump size for the distance & pressure that is the gotcha.
Now, given that you smartly stated this is powered by Solar/Battery then whatever pump you look for should be a SOFT-START model so you do not hit your inverter with a large surge draw (which also hits battery performance). There are several out there, so it is a matter of shopping around a bit. If memory serves, Red-Lion makes a softstart models of Jet Pumps.
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spencerin
Member
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# Posted: 29 May 2023 11:07am
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1" pipe is fine. It seems to me like it's the pump, yes, especially since it's a garage sale find. The rise and run both before and after the pump shouldn't be taxing for a 1/2 HP jet pump.
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mleman
Member
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# Posted: 30 May 2023 07:31am
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Thanks - I didn't know that "soft-start" pumps were a thing. My current pump definitely maxes out the battery at startup. Just to clarify, is it your opinion that a new 1/2 hp pump should suffice, or do you think that the 20' rise/175' run is ok for a 1/2 hp?
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spencerin
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# Posted: 30 May 2023 10:29pm - Edited by: spencerin
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A new 1/2 HP jet pump should suffice. They can pull up from up to 25' deep, and push 100'+ up - well within your requirements. And pressure loss from 1" pipe over 175' is minimal.
Have you checked your existing pump for any obstructions, or leaks anywhere from the point of intake to the cabin/pressure tank? Also, does the pump not have its own pressure switch? Most have their own, and I'm wondering if a switch at the pump and a switch at the tank could be messing things up for you.
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mleman
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# Posted: 31 May 2023 07:22am - Edited by: mleman
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I haven't checked for obstructions, but it's a brand new water pipe that I ran myself, so that's unlikely unless a mouse snuck in while I had my back turned. No leaks anywhere.
There was a pressure switch on the pump - I removed it and put that on the pressure tank, since I figured that's where the pressure actually mattered. Of course, it won't turn off, now, because the pressure won't go above 27 psi at the cabin. I could put it back on the pump, but I don't think it wouldn't do anything to help with the pressure. I suspect it would make it worse.
I know very little about this pump, but one thing I noticed as i was browsing new ones yesterday is that some come with a special ejector nozzle/venturi for using min a deep well setup, like this one: https://www.homedepot.com/p/Everbilt-3-4-HP-Convertible-Jet-Pump-DP370C/206280707
Maybe the impeller it has isn't right for this setup? The pump I have doesn't look quite like the ones I see at the store, and I think it might be ancient. Maybe its time to open it up and take a look - I suspect I'll find a worn impeller, bearing, seal, or something.
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rpe
Member
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# Posted: 31 May 2023 08:32am
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The pump moves water and pressurizes the tank up to the 29 psi properly? If that's the case, then I don't think line restriction is an issue. If you have no leaks anywhere, then the pump impeller may be worn, or partially plugged preventing proper operation? That pump should put out more than 60 psi (at the pump) based on the data sheet here:
https://www.pentair.com/content/dam/extranet/nam/product-related/product-manuals/flot ech/37832.pdf
Note that pressure at the pump would be about 9 psi higher than the pressure tank given the 20ft elevation difference you mentioned. It doesn't sound like your gauges are off by much.
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Brettny
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# Posted: 31 May 2023 11:30am
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40psi at the pump..turn it up to 50 and see if that helps.
I have a 1/2hp jet pump I use to fill a tank up on a hill. I believe it's about 60' vertical. Idk the pressure as I'm going for volume. I fill a 275gal tank in about 35min.
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mleman
Member
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# Posted: 8 Jun 2023 08:29am
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Update: I took the pump apart and found one of the o-rings was hard and gnarly, so the blow-by was preventing the pressure from building. I scared up another used, but newer 1/2 hp pump and it works perfectly. I plan to find a replacement o-ring for the older one and will probably keep it handy as a backup or irrigation pump. Thanks everyone for the input and advice. I'm glad I didn't end up buying a bigger pump!
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spencerin
Member
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# Posted: 8 Jun 2023 08:50pm
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