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spencerin
Member
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# Posted: 30 Jun 2021 09:40pm
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I'm getting ready to have a pump hooked up to bring water into my cabin from a cistern. I believe it's an RV-style pump, but I didn't know these things can pulsate. Grrrrr. Any of you have this problem, and how did you fix it? I believe one way is to add a small pressure/accumulator tank on the pressurized side. Any of you go that route, and what were the results? How common is this issue? Or is this not really an issue any longer with newer RVs and their pumps?
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ICC
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# Posted: 30 Jun 2021 10:47pm - Edited by: ICC
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Question... if it is not installed yet just what is it that concerns you about the "pulsating"? Noise? Eveness of flow?
The motor spins and the mechanism drives a wobble plate (swash plate) with 3 diaphragm valves that push water. So there is some sound, maybe some vibration but the rubber mounts dampen that. I don't see any fluctuation in flow with my Shurflo pumps. The pump does cycle on and off when the faucet is only partly open. Depending where and how the pump is mounted you may hear it go on and off. I actually like that as if I hear it cycle on-off when I am not using water I know something is amiss.
You state it will be bringing water to the cabin from a cistern. What is the height difference and where will the pump be mounted?
Link to the pump to be used if possible?
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Brettny
Member
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# Posted: 1 Jul 2021 05:56am
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With this style pump you will get pulses if you dont use a pressure tank and the pump cant supply more water than your useing.
Basicly the water pressure drops, pump turns on until max pressure is seen then turns back of..and so on.
Home depot sell fairly cheap small (5-7gal) pressure tanks that will work well for a small pump. No need to buy the plastic one swallow or sure flow make. Or you could just use more water.
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spencerin
Member
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# Posted: 1 Jul 2021 07:20am - Edited by: spencerin
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The evenness of flow. The pump is outside in a pit below the frost line, so noise won't be an issue. Piping runs from tank to pump (maybe 6'), then from pump to cabin (maybe 20'), then around the inside. Max rise from bottom (bottom of tank) to top (shower head) I'm estimating to be at 12'. The contractor bought it from an RV dealer, so I'm giving him the benefit of the doubt that the 2 of them talled about the application and selected the right pump.
I don't have the make and model of the pump yet - actually going to see if I can find that today. I do have a pic, though, but how do I attach it? I believe the contractor said it has a 5GPM max flow rate and an adjustable pressure dial with a max PSI of 60. I'm not an expert on these things, but based on what I know, that seems good.
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WILL1E
Moderator
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# Posted: 1 Jul 2021 07:58am
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Quoting: Brettny With this style pump you will get pulses if you dont use a pressure tank
I don't think my 5th wheel has a pressure tank. Pretty sure it just pulls straight from the water tank and the output goes straight to the first faucet in the camper.
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Nobadays
Member
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# Posted: 1 Jul 2021 08:34am
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A pressure tank does help even out the flow, even the little ones Shurflo make. We use one of these.. We have thought about installing a 2-5 gallon tank but the fluctuation in the flow is slight and not annoying enough to bring that project up the list of projects.
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spencerin
Member
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# Posted: 1 Jul 2021 08:37am
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WILL1E, can you locate the pump and see if there's a small, similar-sized tank hooked up to it? These pressure/accumulator tanks in RVs are pretty small - maybe you have one and you didn't realize it.
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FishHog
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# Posted: 1 Jul 2021 08:48am
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I guess there is a slight pulse to my flow but I don’t see how that’s a problem. Sure isn’t for me and I wouldn’t be putting in something else that I need to winterize to deal with it.
I would try it before you worry about something that probably isn’t an issue.
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ICC
Member
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# Posted: 1 Jul 2021 09:26am
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I am with FishHog. I find it difficult to discern any pulsing in any of the systems I have used that use RV style water pumps. My cabin uses a Shurflo and my RV-bus uses a Shurflo. Both have no pressure tank. Shurflo calls it an accumulator.
They are simple to add later if forethought is given to providing a little space. They are usually plumbed into the line right after the water pump, but anywhere further along will do. I assume you will have a water heater. If the line from the pump is routed there first before branching off you could install an accumulator there later if you decided it was needed.
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WILL1E
Moderator
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# Posted: 1 Jul 2021 09:53am
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The only thing in my system besides the tanks, pump and hoses is the tiny filter right by the pump. The only time we experience pulsing is when the tank is almost empty.
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Brettny
Member
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# Posted: 1 Jul 2021 12:12pm
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If no pressure tank and no pulsing your useing more water than the pump can supply thus it never reaches its shut off pressure.
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spencerin
Member
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# Posted: 1 Jul 2021 12:41pm
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Thanks for the feedback. Just thinking ahead of time in case the pulsating happens. I have a 3'+ section of pipe before it feeds into the water heater to add a small or 2-gal tank if needed, but the pump pit may be maxed out on space if trying to add it right after the pump. I won't mind a barely noticeable pulsation provided volume and pressure are plenty.
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ICC
Member
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# Posted: 1 Jul 2021 01:35pm - Edited by: ICC
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Quoting: Brettny If no pressure tank and no pulsing your useing more water than the pump can supply thus it never reaches its shut off pressure.
I disagree, or I think we define pulsing differently or you are very sensitive to water flow.
I hear the pump cycle on and off frequently. The flow from the faucet does not pulse discernbly. I do not count the pump cycling on and off as a pulse.
Shurflo pumps are designed to turn off and back on as needed. The pump in my RV-bus is now 20 years old and never been replaced. Virtually every Shurflo pump that I know of being replaced was because of freeze damage or because someone didn't have a before pump filter and was maybe too lazy to take the diaphragm portion apart and clean it maybe replace the diaphragm. I have not heard of anyone who had the motor or switch burn out.
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Brettny
Member
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# Posted: 1 Jul 2021 01:54pm
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Quoting: ICC I do not count the pump cycling on and off as a pulse.
This is what I was thinking was a pulse. You are right in the fact that you could have a stuck check valve on one diaphragm. I was thinking a pulse was the pump turning on/off durring use.
I currently have a 12v diaphragm pump pumping from a 4in piece of PVC in the ground. The only filter is the foot valve. I havent got anything stuck in any of the valves. How ever I have seen junk in the diaphragm before.
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Nobadays
Member
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# Posted: 1 Jul 2021 01:58pm
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I’ve actually had the pressure switch burn out on a pump last spring. Put in a new switch and it’s worked flawlessly since. Maybe a defective switch?
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ICC
Member
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# Posted: 1 Jul 2021 02:13pm - Edited by: ICC
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Maybe, or maybe just dumb luck. Having a mean time between failures (MTBF) of thousands of hours is just an average. There have to be lower and higher numbers. You were given the "short straw". Maybe I got the long one. 
I have had to clean out tiny specks of dirt that prevented a valve from sealing. That's when the pump goes brrrrp hours after any water was drawn anywhere. That is not normal.
But at least you repaired the pump unit and didn't do the more common thing of tossing it in the trash bin and buying a new one.
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paulz
Member
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# Posted: 1 Jul 2021 03:08pm
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We have a bidet in our luxury cabin, connected to the Shurflo, helps my disabled wife stay clean and sanitary. She was complaining though that it was squirting out too much water. So I figured plugging a couple of the jets would be a good test, and toothpicks fit perfectly. Almost. The reduced flow and extra pressure caused one to shoot out, to a resounding YEOW, What The..!! coming from the bathroom. Fortunately it narrowly missed the target and was easily extracted.
May have been a pulsating issue, not really sure, just thought I'd mention it.
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ICC
Member
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# Posted: 1 Jul 2021 05:56pm
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Try a valve in the supply line, before the bidet to reduce the volume of water that reached the bidet.
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spencerin
Member
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# Posted: 1 Jul 2021 08:51pm
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Ah, here's the pump. Any ideas on brand and model? Neither the contractor nor the supplier remember (long story).
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Brettny
Member
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# Posted: 2 Jul 2021 05:27am
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The tag is on the side of the motor. Has it been in a mud pit long?
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spencerin
Member
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# Posted: 7 Jul 2021 08:20am - Edited by: spencerin
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I was able to test the pump this weekend, and it was woefully underpowered. Not sure what the contractor was thinking when he selected it. So, I want your thoughts on what to replace the pump with. Here's the setup -
500-gal in-ground cistern, the pipe runs underground 5' from the tank to the pump pit, then 25' underground into the cabin, then the longest run inside the cabin is 15'.....so, 45' total. The pipe I believe is 5/8" nominal (pex) the entire run. Total head - from the bottom of the cistern to the shower head - is 15'. I have 5 points of use - 2 faucets, a shower, a toilet, and an outdoor spigot - and assume standard GPM capacities on all 5 and that only 2 would be used simultaneously at any given time.
I'm thinking a self-priming shallow well/jet pump, with either an integrated pressure tank or a separate pressure tank downstream - would work best. Most I see are advertised as good up to 25' of head and are 10+ GPM at their best. But they typically have 1" or 1 1/4" inlets and outlets, so I'm not sure how that would impact performance, if at all. The contractor said he could do a submersible pump, but that would require a riser and limit the capacity of the tank plus add seams where dirt could get into the system. So, I think the shallow well/jet pump idea makes the most sense.
What are your thoughts?
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paulz
Member
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# Posted: 7 Jul 2021 08:50am
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My pump has gone from weak to good along with electrical upgrades. When I had LA batteries and a long run to the pump it was much weaker than the now shorter run with 10awg wire and LFP batteries averaging 13-13.5v. Very noticeable difference, the shower head has gone from trinkling down my back to actually blasting some of the crud off.
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Brettny
Member
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# Posted: 7 Jul 2021 09:50am
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What voltage do you want to run the pump at?
I think 10gal/min is way to much pump. Generaly a shower is going to use 2gal/min. They do make diaphram pumps that will do 5.5gal/min and in 120v or 12v.
If you want water in freezing weather or even get freezing temps at all I would use a submersible well pump. The outlet size being 1-1 1/4in really makes no difference.
I use a shallow well/jet pump and it's a total pain in the ass to prime. I have since put it down hill of my spring water supply making it self priming but you dont have this option.
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spencerin
Member
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# Posted: 7 Jul 2021 10:10am - Edited by: spencerin
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Brettny, from what I've read, a lot of these shallow well/jet pumps are primed at installation and then stay self-primed. Am I missing something? Or are you implying the pump is going to be emptied to be winterized and so you have to prime it to use it again?
To answer your question - 120V.
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ICC
Member
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# Posted: 7 Jul 2021 10:26am
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I have a cabin water setup that may be similar, in that I have a buried cistern. It is frost protected by depth and foam insulation panels sort of like a shallow frost protected foundation can be done.
I use a Rule IL (inline submersible pump) dropped into he tank. 24 VDC. It feeds into a 15 gallon water tank inside the cabin. It's sold as an RV tank. From there I use a Shurflo RV pump to distribute water through the cabin; shower & sink in bathroom and kitchen sink.
The interior tank has a controller that turns on the Rule pump when the level inside gets low. Shuts off when full. The Shurflo supllies all the water we need.
The Shurflo is easy to winterize. The Rule pump does not need winterizing. The line from the Rule into the cabin is self draining as there is no foot valve at the Rule pump. So even in winter when I go there I can pump water up into the heated cabin, use as needed. Then I drain the interior tank back into the cistern through a dedicated drain line. The interior pipes are blown out with the aircompressor that is under the counter with the Shurflo.
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Brettny
Member
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# Posted: 7 Jul 2021 11:59am
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Quoting: spencerin Brettny, from what I've read, a lot of these shallow well/jet pumps are primed at installation and then stay self-primed. Am I missing something? Or are you implying the pump is going to be emptied to be winterized and so you have to prime it to use it again? To answer your question - 120V
Yes once the non frost protected (jet pump/shallow well pump) is winterized it will need to be primed again..and they dont come pre primed.
For 120v get a standard submersible well pump. Like this one. https://www.amazon.com/iMeshbean-Submersible-25GPM-Electric-Stainless/dp/B08L32D8YS/r ef=sr_1_22?crid=1WH44LW3Q3PG8&dchild=1&keywords=120v+well+pump&qid=1625673497&sprefix =120v+well+%2Caps%2C222&sr=8-22
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spencerin
Member
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# Posted: 10 Jul 2021 07:55pm
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After talking with the contractor, we're going to go the jet-pump-with-tank option. My question now has to do with the inlet and outlet pipes on these pumps - they're usually 1" in diameter, but the existing piping I have is 5/8" nomimal pex. I know I will need reducers, so will using reducers in and of itself have any impact on pump performance? The manuals are clear about using piping at least as big as the inlet/outlet, but I don't see in practice how reducers themselves will impact anything.
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FishHog
Member
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# Posted: 11 Jul 2021 08:40am
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I would do some more research on a jet pump. I bought one years ago and standing in line an older gentleman said “good luck with thatâ€. Having run 12v diaphragm pump for the past 7 years I’ll never buy another jet pump
I guess some people must like them and that might be you but it sure isn’t me
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spencerin
Member
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# Posted: 11 Jul 2021 06:12pm
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I don't believe there are any 12V pumps strong enough for what I need.
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Brettny
Member
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# Posted: 12 Jul 2021 07:23am
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Quoting: spencerin I don't believe there are any 12V pumps strong enough for what I need.
They make them 12v 5.5gal/min...but there about $120. The same price as a 1/2hp jet pump. Typical shower head is 2gpm, same for a standard sink.
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