Help with fresh water pumps not priming

[Busted Knuckle]

Sometimes things don't work out on buses the way we thought they would.  My freshwater plumbing doesn't work the way I designed it so I have to redo all of it except the tank itself.  My plumbing had many leaks and I was only able to fix 50% of them before my trip.  We just turned the pumps on and off as necessary and minimized water use.

I am not at all surprised! Brian from most of what I've seen you do an excellant job of doing research & you even ask all the right questions! But then 90% or of the time you go and do exactly the opposite of what the majority that has BTDT reccommend! I for the life of me can not understand why you even ask if your gonna try and make what others have found to fail work! Beats all I ever saw got 2 good eyes and still can't see! Sorry not try'n to bust your chops, just tell'n it the way I see it!
  BK 

[gumpy]

BK,

That's not necessarily a detriment. It's the way it should be. A smart busnut will solicit all available information, and then
make an informed decision based on that information AND his needs and applications. Sometimes it works. Sometimes it
doesn't. I've been on the doesn't side of the thing several times in this project.

Brian,

If I recall, you decided to use worm clamps on PEX tubing. Correct? 

I agree with the concensus here that you have a suction leak somewhere or you have debris in your pump valves.

On our AK trip, I developed a leak-back problem on our pump, as did my Father-In-Law, on his identical pump which I had installed for him. The pressure wouldn't hold and the pump would kick on periodically with no use of water. There were no leaks, so it had to be leaking back through the pump. I contacted the mfg, and then opened up the pump head. Turned out I had a piece of teflon tape in my pump head, which was preventing the valves from sealing properly, allowing some of the pressurized water to leak back through. I pulled my Father-In-Law's pump head, too. Didn't find anything obvious in his, but it fixed the problem, so whatever it was got washed out in the dismantle. I've since installed screen filters on the inlet of each pump. They're available for a few bucks at Camping World. Worth the money.

Also, I might suggest you install a 2 gallon pressure tank. Available from Menard's for about $30. Then you always will have pressure at the faucet. leave the pump on all the time you're parked. If you get the leaks fixed, the system will work as it's
intended.

[belfert]

BK,

That's not necessarily a detriment. It's the way it should be. A smart busnut will solicit all available information, and then
make an informed decision based on that information AND his needs and applications. Sometimes it works. Sometimes it
doesn't. I've been on the doesn't side of the thing several times in this project.

Brian,

If I recall, you decided to use worm clamps on PEX tubing. Correct? 

I agree with the concensus here that you have a suction leak somewhere or you have debris in your pump valves.

Any suggestions on how to check for leaks in the suction tubing?  There is a loop of about three feet of tubing from the tank outlet to the pump inlets.  The big loop was used to avoid more fittings.  The fittings at the pump are Qest compression fittings and the fittings at the tank are push lock fittings bought at Menards.

I used Oetiker stainless steel stepless clamps along with copper and brass fittings from Menards.  No hose clamps anywhere.  I got the idea to do this from my travel trailer that used Oetiker clamps.  A number of the joints leaked when the system was first pressurized.  There was also a leak in the copper manifold my father and a friend built for the bus.  The travel trailer had used a softer more flexible PEX tubing plus plastic fittings instead of copper so I think that is why it worked there.

I do have a pressure tank, but we let all the air out of it as the it was causing water to leak out of the manifold until the pressure tank was empty. 

I'm going to take the pumps apart soon to see if there is anything in there.  I used teflon paste instead of tape specifically so I wouldn't end up with tape in the pumps.

[maria-n-skip]

Belfert,

Off the wall thought.

Since the paste was on the suction side. Do yo think it
is possible to have some Teflon gunk sucked into the pump?

If you can get to both ends or have a valve at one end.....I'd use an air tank with about
20 lbs of air and plumb the hose to the pump hose. Turn the air on look listen and have a beverage.

Skip

[HB of CJ]

Sorry it sounds like you need to overhaul the water pressure system, but after you described the performance of your pump(s) it's easier now to understand why.  Either you get 27 psi, which is NOT a whole lot, or you get 2.3 gpm, which is also NOT a whole lot, but hardly BOTH at the same time.  You trade one for the other.  Again, look closely for suction air leaks.

Usually pumps of this nature and installation trade off psi for gpm or the other way around.  Other than going to the very $spendy$ (and good) positive displacement pumps, your only other answer is to buy a good, high volume diaphragm type RV pump at the highest pressure rating you can find.  Go ahead and spend the money here.

If given a choice, again trade higher pressure for higher volume-or, ideally, go for both.   You will be more happy in the long run.  Higher pressure gives you the feeling of more volume, but not the other way around.  Especially in the shower/sink.  You will need/want at least 35 psi, hopefully 50 psi, at a volume that's reasonable-say 3.5 to 5.0 gpm.  Also a good installation is vital.   

[TomCat]

Brian,

I know you have your own way of doing things, as do we all, but in the interest of doing this one more time, and ONLY once more, with zero leaks or pressure problems, here's a proven plan you can choose to follow, or not...

You'll need...
1. A new roll of PEX, and proper PEX cutting device. (Do not re-use any of your existing tubing)
2. The required amount of SharkBite fittings. (cashacme.com) Read the installation directions before use.
3. A ShurFlo 5.7 Extreme Series pump or equivalent (Not close, Equivalent!) with inlet screen/filter.
4. To connect the above parts in your desired plumbing plan.
5. To then cross fresh water plumbing off your list of projects, and move on to whatever's next.

In the event your plumbing plan changes in the future, the SharkBites can be disconnected in one second with a small tool, then reused with no leaking.

Good luck, regardless of your action.

Jay
87 SaftLiner

[belfert]

Brian,

I know you have your own way of doing things, as do we all, but in the interest of doing this one more time, and ONLY once more, with zero leaks or pressure problems, here's a proven plan you can choose to follow, or not...

You'll need...
1. A new roll of PEX, and proper PEX cutting device. (Do not re-use any of your existing tubing)
2. The required amount of SharkBite fittings. (cashacme.com) Read the installation directions before use.
3. A ShurFlo 5.7 Extreme Series pump or equivalent (Not close, Equivalent!) with inlet screen/filter.
4. To connect the above parts in your desired plumbing plan.
5. To then cross fresh water plumbing off your list of projects, and move on to whatever's next.

In the event your plumbing plan changes in the future, the SharkBites can be disconnected in one second with a small tool, then reused with no leaking.

This is almost exactly what I plan to do.  I already bought a Flojet Sensor VSD 4.5 pump on sale at Camping World.  I bought the Flojet over the Shurflo due to better reviews and because it will 12 and 24 volt.

I did some research here and on BNO and had already planned to use Sharkbite fittings after seeing a number of recommendations.  I bought some push-lock fittings to do emergency repairs of leaking crimp connections, but I think they might work loose over time in a vehicle.

I was planning to maybe reuse some of the PEX after cutting off the ends.  I will have to buy another 100 foot roll anyhow so I might as well just go all new.

I've got other projects to do before I get back to plumbing.  My next trip will hopefully be in April.

[gumpy]

Any suggestions on how to check for leaks in the suction tubing?  There is a loop of about three feet of tubing from the tank outlet to the pump inlets.  The big loop was used to avoid more fittings.  The fittings at the pump are Qest compression fittings and the fittings at the tank are push lock fittings bought at Menards.

How do you get the antifreeze suction line into the pump?  Is it Tee'd into the loop from the fresh water tank?

Best way to find leaks is to pressurize it with air. if you have a loop directly from the tank to the pumps, there's only two fittings.
You can undo the tank fitting, and pressurize the line and sustem and spray it with soapy water.

I used Oetiker stainless steel stepless clamps along with copper and brass fittings from Menards.  No hose clamps anywhere.  I got the idea to do this from my travel trailer that used Oetiker clamps.  A number of the joints leaked when the system was first pressurized.  There was also a leak in the copper manifold my father and a friend built for the bus.  The travel trailer had used a softer more flexible PEX tubing plus plastic fittings instead of copper so I think that is why it worked there.

Yeah, if these are like the oetiker clamps I used on my sprinkler system, this could very well be part of your problems. They are not designed for PEX. If you're going to clamp, you should be using barbed PEX fittings and solid crimp rings designed for PEX.  Oetiker's have an inherent weak spot where they are crimped.

The manifold system I use works great for dealing with all these problems. You can isolate any part of the system and pressureize it from the
inlet. I can suck antifreeze into the pumps and blow it into any part of the system.  If you're planning to redo your system, you might
want to come out and take a look at my manifolds and build similar. Sure make it easy to handle all water system issues.

craig

[gus]

John Ed,

I don't really agree with you about not having water leaks on the suction side. If the suction line is below the water tank level as he says and the line has a hole it will leak water. My fuel supply line has sucked air too, but it was quite a bit higher than the fuel tank so it never leaked fuel.

I do agree that it will suck air while pumping but unless it is a big hole it will still pump water. Essentially what he will have is air bubbles in the water.

BK,

As Gumpy is saying, what we post here is informational only, not requirements. Any busnut can do as he pleases on his own bus and is not obligated in any way to follow our recommendations. I hope you're aware that the internet is crammed full of bum dope and these conversion forums are no exception. Don't get me wrong, these forums are great and I'm grateful for them, but all postings are not the final word.

TomC,

Why can't he reuse the pex tubing if it is cut short of the original fitting? I'm completely dumb about pex having never used it or done any plumbing so far. That is due to change very soon on both fresh and waste plumbing

[belfert]

Any suggestions on how to check for leaks in the suction tubing?  There is a loop of about three feet of tubing from the tank outlet to the pump inlets.  The big loop was used to avoid more fittings.  The fittings at the pump are Qest compression fittings and the fittings at the tank are push lock fittings bought at Menards.

How do you get the antifreeze suction line into the pump?  Is it Tee'd into the loop from the fresh water tank?

Best way to find leaks is to pressurize it with air. if you have a loop directly from the tank to the pumps, there's only two fittings.
You can undo the tank fitting, and pressurize the line and sustem and spray it with soapy water.

I forgot to allow for antifreeze so I just disconnected the pushlock fitting at the tank outlet and stuck the PEX stub into my bottle of antifreeze.

I don't have a compressor right now so I will have to borrow one to test with.  I need to get the winterization done soon as it might actually freeze by Saturday.

Yeah, if these are like the oetiker clamps I used on my sprinkler system, this could very well be part of your problems. They are not designed for PEX. If you're going to clamp, you should be using barbed PEX fittings and solid crimp rings designed for PEX.  Oetiker's have an inherent weak spot where they are crimped.

The manifold system I use works great for dealing with all these problems. You can isolate any part of the system and pressureize it from the
inlet. I can suck antifreeze into the pumps and blow it into any part of the system.  If you're planning to redo your system, you might
want to come out and take a look at my manifolds and build similar. Sure make it easy to handle all water system issues.

I'm not sure why the Oetiker clamps didn't work.  Jayco uses them with success in the RVs they build.  I had to make repairs to my Jayco TT because the water heater bypass valves split one winter and the Oetiker clamps used for repair held fine.  I also noticed on Flair-it's website that they sell Oetiker clamps for PEX.  Nonetheless, I will be using the Sharkbite fittings and forgetting about the Oetiker clamps.

I just looked at your website and the manifolds I built are almost idnetical to what you have, at least for the output side of the pumps.

[gumpy]

... actually freeze by Saturday.

Yeah, it's close out there now!

I just looked at your website and the manifolds I built are almost idnetical to what you have, at least for the output side of the pumps.

I don't have the current manifold set in the website write up yet. If you looked at the ones on the website (laid out on the chest freezer),
they were not used. I made a whole new set.

With the setup I have, I install an air fitting in the side of the coach, and just blow out all the air lines. Then I suck in a gallon of
antifreeze and blow it throughout all the lines with shop air. Takes me about an hour to do a good job and make sure all the water is out.