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Small Cabin Forum / Cabin Construction / Pulsating RV-Style Pump
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spencerin
Member
# Posted: 12 Jul 2021 08:27
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With total distance, head, and friction loss in a narrower pipe, I'm afraid 5.5 gpm will turn into, at best, half of that at any single point of use. But, I'm not an expert, so I don't know.....

FishHog
Member
# Posted: 12 Jul 2021 08:36
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Even at half that it still seems like more than enough volume but I don’t know what your needs are and if you need more volume than normal

spencerin
Member
# Posted: 12 Jul 2021 18:04
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I do need more volume and pressure.

My next question - I'm going to bury it, so do any of you have ideas for in-ground, waterproof storage containers for this? The pump is 1' 8" L x 11" W x 1' 10" H. Not huge, but there has to be room for pipe gymnastics, electrical wiring, and foam board insulation. The contractor suggested a concrete vault, but he said that's also overkill for its size and usage. Or, what materials could it be built out of?

spencerin
Member
# Posted: 26 Jul 2021 21:09
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Fish, what make and gpm is your pump?

FishHog
Member
# Posted: 27 Jul 2021 18:22
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Quoting: spencerin
Fish, what make and gpm is your pump?


Sorry just saw this. Flojet 2.9gpm but sureflow pumps are well liked as well

spencerin
Member
# Posted: 4 Aug 2021 19:34 - Edited by: spencerin
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This is really frustrating me. It seems like the contractor undersized the system with 1/2" pex as the main and pairing it with a 3.0 GPM pump (Hydromax). But based on a lot of what I've read so far, this should still work. But it doesn't.

I want him to replace the main, and everything up until it becomes supply lines, with 3/4", and replace the pump with a variable-speed 5.3 GPM Remco Aquajet. Remco said this would work fine, but they're trying to sell a pump, too.

Does what I want to do seem like the right idea in anyone's humble opinion? The final option is a jet pump, but then we're talking about 1 1/4" into the pump and a 1" main. That definitely seems like overkill. For comparison, my dad's has a 7.0 GPM submersible deep-well pump with a 1" main that supplies what's really a full-blown house.

Remco also said their 7.0 GPM pump wasn't meant for residential applications because some of the materials used inside it weren't food-grade, which they said could breed bacteria as a result. But, I also don't want to forgo a high-volume pump on account of something that could be avoided by either not consuming it or making sure the water in the cistern is treated regularly.

FishHog
Member
# Posted: 5 Aug 2021 08:37
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I’m surprised your system isn’t working but how far is you 1/2” run. And when you say it’s not working what is the actual issue?

ICC
Member
# Posted: 5 Aug 2021 09:00
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I don't understand what the issue is exactly either. Maybe a re-hash of the system details, lengths, elevation changes etc would help. I used 3/8" pex in my 35 ft. bus/rv with a basic Shurflo pump. No big elevation changes of course . It works superbly.

spencerin
Member
# Posted: 5 Aug 2021 09:28
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So total elevation change - from bottom of cistern to showerhead - is no more than 15'. Longest run of pipe is max 70'. Everything is 1/2" pex. The main runs into the water heater but branches off beforehand and tees to supply a sink on one end and another sink, shower, and toilet on the other end. The hot water branch does the same thing, minus the toilet obviously.

I ran the pump 45+ mins and a 30-gal water heater filled maybe 25%, and I got some weak flow out of a faucet, but that was it. I tried the points of use 1 at a time as well - both the shower and the other faucet spit out some water but were essentially dry. The plumbing itself seems good - no leaks that I could see.

I used several friction loss calculators online and they all gave me quite a bit of friction loss, which could explain part of this. After doing (way too much) research on pumps, the 3.0 gpm pump is probably half that at 55 psi, which could explain the rest. However, real-world experience tells me this should still work better.

jsahara24
Member
# Posted: 5 Aug 2021 10:07
Reply 


When you are trying to fill up the water heater are you opening up a faucet on the hot side to keep the system from creating a vacuum?

I have a standard well setup at my cabin with 3/4 Pex trunks, and 1/2 pex lines to the bathroom and kitchen.... but when I'm filling up the water heater it will stop filling if I don't allow a place for air to escape....and until the whole system is pressurized I only get low flows everywhere....

I could be off as I haven't dealt with a system like yours, but worth looking into...

FishHog
Member
# Posted: 6 Aug 2021 18:02
Reply 


70’ is much longer than mine but still doesn’t sound right to me. Are you sure you don’t have a partial blockage somewhere

spencerin
Member
# Posted: 14 Aug 2021 00:05
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A plumber I talked to suggested a partial blockage also. But, the water I saw was crystal clear, which to me rules out dirt blockage, although it could've been the way something was installed. I really think it's a weak pump to begin with, and it DID get submerged several times due to a draining issue in the pit it's in. But, when I ran it, no water leaked out anywhere, which likely means no dirty water got in anywhere. But, it's all conjecture at this point.

I bought a much better pump and will install it this upcoming weekend. I'll let you know how it goes. My gut is telling me it'll work a lot better.

FishHog
Member
# Posted: 15 Aug 2021 07:32
Reply 


Fingers crossed

spencerin
Member
# Posted: 15 Aug 2021 22:25
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Good news and bad news -

The good news is the pump worked great (except for one thing, which is the bad news). It was a Remco Aquajet 5.3, and it was able to push water to 2 faucets and a shower without much drop in volume or pressure.

The bad news is it had a loud vibration when it was pumping. It's a variable speed pump, so although it still cycled, it was able to maintain consistent volume and pressure no matter the demand. When it cycled on, it sounded like a wave machine, you could feel the vibration in the main line and the cold water trunk, and it actually vibrated the surrounding floor and wall some. Definitely not something I could live with.

Would an accumulator tank absorb this vibration and not pass it along the entire system? I can't use one with the Aquajet, but Seaflo makes a pump-and-accumulator-tank combo that might suffice for me. If the Seaflo happens to vibrate also, I'm wondering if the tank would absorb it.

FishHog
Member
# Posted: 16 Aug 2021 07:26
Reply 


Flexible lines attached to the pump can reduce that. Rubber mounts on the pump also help but I’ve never had one that doesn’t make noise a vibrate. I don’t mind it and it’s a great leak detector

spencerin
Member
# Posted: 16 Aug 2021 13:08
Reply 


It was pretty loud. The pump is outside, 50'+ away and in the ground, and itself ran quietly. The sound was coming through the water/pipes and vibrating the floor, water heater, and pipes affixed to the wall. I thought about dampening mounts, but think they would have minimal impact. The previous pump, although weak, I couldn't hear.

FishHog
Member
# Posted: 17 Aug 2021 08:43
Reply 


That is exactly what happens they cause vibration through the pipes. Most are recommended to have a flexible connection to each side of the pump and twisting that flex line into a loop helps quite a bit.

RKaji
Member
# Posted: 17 Aug 2021 09:35
Reply 


Good to know, I could have done a big mistake.

spencerin
Member
# Posted: 18 Aug 2021 14:00
Reply 


I had flex lines on each end. I think it was just way overpowered for my system.

Now I can't decide between a less powerful variable-speed pump (Shurflo 4084 high-flow) or a constant-speed pump with an accumulator tank. I like the dampening provided by an accumulator tank, but it's more parts to have malfunction, and I can't find a constant-speed pump similar to the Shurflo (4 GPM 55 PSI) in performance. It's generally either 3 GPM or 5GPM at 55 PSI, or something in the middle with a much lower PSI. (The Aquajet was 5.3 GPM 65 PSI).

Decisions, decisions.

gcrank1
Member
# Posted: 18 Aug 2021 18:15 - Edited by: gcrank1
Reply 


How about using what others are using with satisfaction that have comparable plumbing and usage as you.

ICC
Member
# Posted: 18 Aug 2021 20:16
Reply 


I get along fine with 35 PSI.

spencerin
Member
# Posted: 18 Aug 2021 21:15
Reply 


gcrank1, I'd definitely be interested in knowing what others use. So far, I think FishHog said he uses a 3.0 GPM pump, assuming 55 PSI (?). ICC, what's your GPM?

ICC
Member
# Posted: 18 Aug 2021 22:23 - Edited by: ICC
Reply 


The cabin uses a Shurflo 4088, 3 GPM. The bus uses a Shurflo 4048, 4 GPM pump. Both are fitted with a pressure reducer valve to 35 PSI.

My home system uses a Rainflo MHP75; capable of 26 GPM depending on what the total head distance is. It lifts and pushes water up about a total of 100 feet from the rainwater storage to the home. At that TDH it can deliver something like 15 GPM. IIRC it cost over $400 in 2010. I have a pressure reducer set at 35 PSI for within the home but it supplies 45 PSI in the shop.

If that seems like a lot of capacity it is because it can also be used to supply water to a fire suppression system.

spencerin
Member
# Posted: 24 Aug 2021 00:41 - Edited by: spencerin
Reply 


I bought the Shurflo 4048 high-flow and installed it today. Much quieter (just a low hum) and runs 2 points of use simultaneously just fine, 3 with some drop in pressure and volume but still acceptable. Happy that's solved, now it's on to the next project!

gcrank1
Member
# Posted: 24 Aug 2021 10:19
Reply 


Wha-Hoo, This forum works again!

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