Monday, January 24, 2011

Water Pumps

Water pumps seem to be a major topic for LD'ers because of all the problems they cause. You'd think by now that someone would have invented a good dependable water pump that worked as advertised.

For many years Lazy Daze installed the Shurflo Whisper King pump in its coaches. The Whisper King was a fairly dependable pump, although a bit noisy and subject to the pulsing that comes with most pumps.

In 1994 Lazy Daze switched to the new Shurflo Extreme 5.7 Smart Sensor pump. Designed with a circuit board, microprocessor and pressure sensor, these pumps used the latest cutting edge technology to maximize flow and pressure while delivering "Just Like Home" flow. Although very quiet and good at providing a steady flow at most any rate, they turned out to be very unreliable with many failures. Some owners went through several swap-outs of their pump.

After experiencing many failures with the original design of the Extreme pump, Shurflo re-engineered the pump, replacing the original pressure-sensing membrane with a pressure switch. This pump was supposed to be more reliable, but it also had a little quirk of a slight pause shortly after a faucet was opened.

In 2009 Shurflo introduced the Revolution 4008 pump, a replacement for the old Whisper King, and a much simpler, and thus hopefully more reliable pump. In 2010 LD began installing the Revolution in its motorhomes. The Revolution uses a by-pass function to smooth out the flow of water. The by-pass is a spring loaded diaphragm that opens up allowing water from the discharge side back to the inlet side. The by-pass is set to begin opening at about 40 PSI and creating full by-pass at about 62 PSI. The pressure switch on the pump is set to shut off at 55 PSI. The pump operates normally up to 40 PSI, where a spring loaded by-pass valve opens, allowing flow back from the output side to the input side, providing smooth, steady flow with virtually no cycling, all the way down to a trickle. As a faucet is opened back up, the pressure will drop, the by-pass will close and full flow is obtained.

To their credit, Shurflo has been good about honoring its warranty on the Extreme pump, and if an owner was ready to give up on that model, Shurflo would replace it with two Revolution pumps, since the price was about half that of the Extreme. That gives owners the bonus of having a spare pump in case its needed, although the Revolution seems to be much more reliable than the Extreme.

Replacement Pumps

- One LD'er replaced the original Whisper King with a Flojet Sensor VSD. It worked fine but was a bit noisy when either starting up or when using a lot of water. The VSD pump lasted less than a year before it developed a leak in the pump diaphragm. It was replaced under warranty and the new one has been working since. I cannot say that I'm happy with it. The Pressure sensor is insensitive. When opening a faucet, the pressure noticeably drops and then the pump starts and revs up to full speed for a moment and then slows down, making a big racket for a couple of seconds. I have tried to quiet it by adding flexible hoses, packing it in foam rubber it and have even tried using an accumulator. Nothing has made it quiet.
- Another says: When the Revolution fails I will replace it with a Flojet Quad. Model 04325143A. This is a fixed speed pump with a flow rate of 4.5 gallons per minute and draws 6 amps.

Trouble-Shooting

Pump continues to run when faucet shut off

- In our 95 23 1/2 FL when we turned off the faucets the pump continued to run, though more quietly than normal. It seemed to me that the pressure didn't build up enough to cause the pump to turn off. I checked the pump closely and found a slight leak between the motor housing and the diaphragms. The Shurflo people said one of the diaphragms had developed a leak. Ours was the Whisper King model. I ordered a replacement part, and that corrected the problem.

Noisy Pump

- The pump started making a heck of a racket. A call to the Mother Ship made me understand that it was most likely air in the lines. I was told by Vince to turn on the pump, open two faucets at a time and let it run for a minute or two. Then open two other faucets and again let it run a while. The idea is to purge all of the air from the system so all of the outlets (faucets) must be bled free of air, including the toilet and outside shower if you have one. Once that is complete, go around and open the pressure relief valve on the water heater until all water stops flowing, then snap the valve shut again. This procedure worked so well that I hardly know my pump is running now.
- As to the noise, I'd read that it is important to have 2-3 feet of flexible tubing into and out of the pump and, ideally, no right angle bends in those sections. Shurflo also suggests that the flexible output line have a 360 degree loop in it. So I bought Shurflo's Silencing Kit (about $16 at CW) and installed it yesterday.
- The standard LD installation of my original Whisper King had short straight sections of flexible tubing running from and to the rigid PEX plumbing that runs throughout the motorhome, both terminating in 90 degree fittings at the pump. I didn't change those when I installed my first 5.7 Extreme pump. So when installing the Silencing Kit, I removed those and the 90 degree fittings and installed the two flexible tubes from the Silencing Kit in their place, the output tube with a 360 degree loop as suggested by Shurflo, and placed new 1/2 inch pipe insulation around the tubing at critical points to protect against vibration. This seems to have greatly improved the noise situation. Now, when the pump runs it is easy to see the pulsing and vibration in the output line cause by the pump's operation. But the loop of flexible tubing absorbs most of that without transmitting it to the rigid PEX plumbing.

Extreme model cycles too often

- The newer Extreme pumps with the pressure switch have an adjustment screw which is used to adjust the sensitivity of the pressure switch. I was told to proceed as follows.
First, access the pump and locate the adjustment screw. The new version has five screws in the plate covering the pressure switch. The old pressure sensor version had just four screws. Otherwise the pumps look the same. The adjustment screw on the new versions is in the center, surrounded by the other four.
Then turn on a single faucet to a moderate flow. If the flow and the pump speed are steady no adjustment is needed. But if the pump cycles or speeds up and slows down significantly you should turn the screw clockwise until the pump runs at a steady speed with a moderate flow from one faucet.
If the pump is not activating or has an excessive delay in activating then turn the screw counter-clockwise. What you're seeking is a steady pump speed with little or no cycling when the demand is just a moderate flow from one faucet.

Extreme model leaks
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Shurflo says that the 5.7 creates about 65 psi in the system, but this can build to over 100psi when the water in the water heater is heated without any pressure relief. That can damage the pump and is why they recommend a check valve. Oddly, their instructions supplied with the pump say nothing about this. So, I installed a brass check valve just downstream of the pump. The check valve allows water to flow downstream unimpeded from the pump into the coach plumbing system to all the fixtures. But it prevents water downstream that may be under higher pressure from either the city water supply or water expanding when it is heated from returning to the pump. Since installing the check valve my pump has worked well.

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- I had a pump that leaked in the morning when I turned on the water heater. I installed a water pressure meter to allow me to monitor what was happening in the system. When I turned on the heater, system pressure would start at 80 psi, and climb to 150, when leaking would start.
- I obtained and installed a small accumulator tank in my system. I charged it to 80 psi, the resting pressure of my system. Thus, unless the pressure climbed above 80 psi, the tank would be invisible to the pump. This morning, after sitting overnight with no leaks, the system looked ready for the next step. I turned on the heater, with system pressure at 80 psi. So far, I have no leaks and my system pressure maxed out at 105 psi. Remember, this is with the pump that was leaking. Here is what I have provisionally determined and/or concluded:
-- First, Shurflo recommends against the use of an accumulator tank OR AIR IN THE SYSTEM!
-- Second, Atwood requires an air pocket in the heater, thus introducing air into the system, in contravention of Shurflo instructions.
-- Third, when water is heated, it expands. In a closed system such as our units, there is no place for the expansion to occur except in the air space in the heater. I do not see how the Shurflo requirements can work without pressure surges.
-- Fourth, I believe my tests show that the air space in the heater is inadequate to accommodate water expansion. More air space is needed.
-- Fifth, the only option for the expanding water in our systems as designed and installed is to force itself out through the weakest link in the system. This SHOULD be the pressure relief valve. In my case, it was first, the under-sink faucet connections and after that was tightened, it was the pump.
-- Finally, the accumulator tank I installed provides some expansion space when pressure climbs above 80 psi. The result seems to be a stable, non-leaking system.
- For more on accumulator tanks, see the Accumulator Tanks FAQ.

Revolution cycles too much

There is a center adjustment screw on the pump. Shurflo suggests turning the center allen screw clockwise in 1/8 increments until the problem resolves. The limit to making that adjustment, again according to them, is when you have gone too far the pump won't shut off. They say the ideal operation would be that when you shut off the water the pump stops in 1/4 second.
On the plus side, you may also see water pressure increased noticeably pretty much from the first adjustment.

Pump won't pump - only hums

- It might just be that the pump has gotten air into it and has lost "prime". I've had a case once or twice when the pump would just hum and not pump water. Try turning the pump off and opening a faucet and let it sit for awhile and then turning the pump back on. You could also try hooking up to a city water connection and make sure you have water in your lines. This might help to get water into the pump and re-prime it.

Tips

- There is no way to remove your water pump without draining your fresh water tank first. Installing a valve between the tank and the pump will solve that problem. And while you're at it, adding a valve on the output side of the pump as well gives you the ability to use city water with a faulty, leaking pump. I bought two plastic valves that would work on the type of tubing present. They had 3/4" threaded connections to which I attached 1/2" barb to 3/4" threaded nylon adapters. I connected the valves in line on the inflow and outflow hoses, shut both off, and re-pressurized the system. With this set-up I can completely remove the pump while my shore water supply is under pressure. Here's how to do it:
1) Purchase two plastic shut-off valves with 3/4" threaded female fittings.
2) Purchase 4 nylon adapters, 1/2" hose barb male to 3/4" threaded male.
3) Purchase 4 hose clamps big enough to go over the hoses.
4) If you don't have teflon tape, get some.
5) Using teflon tape on the threads, connect two of the adapters to the ends of each of the valves.
6) Turn off your pump, open a faucet and drain your fresh water tank.
7) The hoses attach to the Extreme pump with snap-on and snap-off plastic clips. Put a towel under the pump and remove the plastic clips. You should need no tools for this.
8) Use a magic marker to note where you want the valves to be.
9) Pull off the nearest hose.
10) Cut the hose at the magic marker mark, put the hose clamps onto the hose ends, push the barbs fully into the hoses, and place and tighten the hose clamps.
11) Replace the hose fitting on the pump and re-attach the plastic clip. Note that the narrower opening on the clip should face toward the hose and the wider opening toward the pump. If necessary to rotate the valve position, loosen the hose clamps by the valve, turn the valve to the desired position and re-tighten the clamps.
12) Repeat steps 9-11 with the farther hose.
13) Open both valves.
14) Refill your fresh water tank, purge air from the system and turn the pump on to check for leaks.

While at it, you might consider replacing the LD supplied water supply line from the fresh water tank to the water pump with stainless steel braided hose that can be purchased at most hardware or home improvement stores. Get a long braided hose that you can form in a loop between the tank and the pump so that there none of the 90 degree bends that were in the LD supplied line. It's also easier to use teflon paste instead of teflon tape on the threaded fitting on the water tank; it is much easier to get the paste on the threads than the tape.

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- Make replacing your Extreme easier: Install four studs into the coach floor where the pump mounts, in place of the screws normally used to mount the pump. The pump now anchors to the studs with four wing nuts and washers. You can also install male/female plug/receptacles (like you'd use when making an extension cord) where the pump connects to the power supply. This makes swapping pumps quick and easy.

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- The quick connect fittings on the Shurflo 5.7 pump are nice but can be tricky.
-- First, you need to be absolutely sure that the fitting on the end of the line is all the way into the socket on the pump. You can still press the C-shaped lock ring into place even if the line is not fully seated, but you will not get a secure result.
-- Second, those C-shaped lock rings are "sided." One side is labeled "Fitting." You need to be sure that side is facing away from the pump.
-- Then once the lock rings are on you need to try to pull them off to be sure they are locked.

Contributors: Les Bowers, Steve S., Terry, Larry Wade, Ken Fears, Art, Don Malpas, WxToad, Steve

Revised 19 Aug 11

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