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Old 08-09-2015, 11:11 PM   #1
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Default No pulsing water pumps

An interesting question came up on the Yahoo board concerning water pumps. It was in combine with several others that had pump issues.

The poster had replaced his Shurflo stock pump, with a Shurflo model that promised less cycling, pulsing, and noise. His issue was getting the pump to prime, which is probably not related to the other issues or probably not the pump, but when I looked up the pump, it was a very unusual setup from what I am used to seeing in pumps.

I am used to seeing mostly 3 kinds of pumps. Pressure controlled shut off/on like the basic Shurflo is, variable speed to control flow to match use controlled by pressure like the Flojet new model is, and bypass pumps that run full speed at pressure with any excess flow going through a bypass back to the inlet of the pump.

The Shurflo in question is a pressure shutoff and bypass pump, with both active at the same time, which I have not seen before. It appears they are balancing the bypass flow to reduce pulsing, against the shutoff pressure from the pressure switch. There were notes all over the manual for the pump about how critical the settings are, so I do wonder how they will do as parts in them age. A full pressure (almost full pressure in this case) pump also uses full power whenever running, as it is pumping full pressure and volume when running, so it would probably be using more power than an on/off or especially a variable speed.

It will be interesting to see how they work and hold up once there are more of them in the field.
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Old 08-09-2015, 11:51 PM   #2
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I think that a far simpler and more cost-effective solution to these problems is to add a pressure accumulator downstream of the pump:



Amazon.com: SHURflo 182-200 Pre-Pressurized Accumulator Tank: Automotive

We specified one in our Legend, and it makes even a "dumb" off/on pump smooth as silk and very quiet.
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Old 08-10-2015, 12:01 AM   #3
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Quote:
Originally Posted by avanti View Post
I think that a far simpler and more cost-effective solution to these problems is to add a pressure accumulator downstream of the pump:



Amazon.com: SHURflo 182-200 Pre-Pressurized Accumulator Tank: Automotive

We specified one in our Legend, and it makes even a "dumb" off/on pump smooth as silk and very quiet.
The certainly do help a lot, every home well setup has one. Our home one has a hysteresis of nearly 20 psi, however, and I assume you might have similar, so flow still varies quite a bit. We have had the Flojet variable speed in the Roadtrek for about 2-3 years and it has been very good for us so far. Very even flow and very quite. Nice that it spools up to full speed when priming (no back pressure to speak of) so it tends to prime much more quickly.

I think most anything is better that the super noisy, pulsing stock Shurflo so many manufacturers use. You can hear then 3 campsites away.
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Old 08-10-2015, 12:03 AM   #4
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Sounds like the ShurFlo Revolution pump the Wynns installed in their new Bounder. "self-priming" and "Internal Bypass-Low Cycling". They were raving about theirs.
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Old 08-16-2015, 06:20 PM   #5
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The above accumulator tank is one of those "must have" upgrades. It doesn't take much space, and because it has a balloon that fills the container when empty, it doesn't affect blowing out the lines when winterizing.
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Old 08-16-2015, 07:34 PM   #6
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Yes. Also, note that although it is designed so that you can run the water through the tank, this isn't necessary. it is equally effective to cap off one end and run a single pipe to a "T" anywhere downstream of the pump. This allows for great flexibility in installation, so finding a place for it is rarely an issue.
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