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Old 12-13-2013, 06:57 AM   #1
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Water Pump

Why does my water pump pulse & how can I correct it? When you open a faucet it just constantly pulses as it pumps the water.

Thanks for any info
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Old 12-13-2013, 07:16 AM   #2
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What kind of pump--size, brand, etc? Does the water actually pulse or is it the pex pipes hammering? Some pumps are adjustable, while others require or prefer a small, inline expansion tank to smooth out the pumping cycle. Tell us more.....
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Old 12-13-2013, 07:27 AM   #3
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I had a problem like you are describing and I took "all" the faucet ends off and cleaned them, wow....there was a lot of junk in them restricting the water flow and when the pump wants to maintain a per-set pressure and is restricted the pump will cycle on and off as the pressure raises and lowers. I could not believe the good flow I had after cleaning the screens and flow restrictors in my faucet ends. Hope this helps.
You might also have a fine screen right in or inline in your pumps water line, look there also.
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Old 12-13-2013, 09:36 AM   #4
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Cleaning out the faucet screens may help but depending on the size/capacity of the pump, some large pumps [eg. 5.7 gpm] have recovery capacity that far exceeds the flow of a single faucet so without the benefit of an expansion tank, these pump tend to cycle rapidly. Use to think the bigger the pump the better but unless you routinely have multiple faucets open at the same time---they may not be a good fit for you....just saying....
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Old 12-13-2013, 09:57 AM   #5
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Quote:
Originally Posted by countrypair View Post
Why does my water pump pulse & how can I correct it? When you open a faucet it just constantly pulses as it pumps the water.
Thanks for any info
countrypair
Adding an accumulator tank can/will often eliminate "pulsing".
I used one of these: Shop Utilitech 2-Gallon Expansion Pressure Tank at Lowes.com

Mel
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Old 12-13-2013, 10:24 AM   #6
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Originally Posted by mel stuplich View Post
countrypair
Adding an accumulator tank can/will often eliminate "pulsing".
I used one of these: Shop Utilitech 2-Gallon Expansion Pressure Tank at Lowes.com

Mel
'96 Safari
I've installed one of these on my last three RVs, including my current Endeavor. It's a pretty easy retrofit and works great. Almost no temp change in the shower and the pump doesn't kick on every time you turn on a faucet.
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Old 12-13-2013, 04:52 PM   #7
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Camping World has a 1-pint/qtr model designed for RVs. Doesnt take up much space--probably all you will ever need.
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Old 12-14-2013, 09:42 AM   #8
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The water system pulses because it is controlled by a pressure switch. When you open a faucet, the pressure begins to drop until the switch senses its low threshold and turns the pump on, and the pump quickly drives the pressure back up until it reaches the high pressure threshold (usually about 45 psi). This cycle keeps repeating and is the way it is designed. You get more pulsing when a tap is only slightly open and less when it is fully open. That's because the pressure stays low and the pump runs longer.

There are two way to alleviate it, but it won't stop altogether.

1. Add a pressure tank (accumulator) to store a greater volume of water under pressure. This lengthens the cycle, especially when the faucet is only slightly open.

2.Install a variable speed pump like the Aquajet or Flojet Sensor. These pumps run at different speeds, depending on demand, and don't pulse as often or as loudly.

You can do both #1 & #2 if you like.
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Old 12-14-2013, 10:33 AM   #9
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When that happens it means that the pump is trying to force more water through the water pipe than the pipe can hold, so the "simple" answer is to close the tap till the demand is the same as the max supply!

Ed
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Old 12-14-2013, 10:54 AM   #10
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Old Scout is correct, an expansion tank will help. Water can't be compressed,, so the pressure fluctuations get 'telegraphed' right to the faucet. An expansion tank has an air chamber (often in a rubber bladder) that can be compressed and reduces the pulse. I'd opt for the smaller one, 2 gallon size is the type used in home plumbing and much too big for an RV and the 12 v pump it would modulate.
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Old 12-14-2013, 11:59 AM   #11
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Old Scout is correct, an expansion tank will help. Water can't be compressed,, so the pressure fluctuations get 'telegraphed' right to the faucet. An expansion tank has an air chamber (often in a rubber bladder) that can be compressed and reduces the pulse. I'd opt for the smaller one, 2 gallon size is the type used in home plumbing and much too big for an RV and the 12 v pump it would modulate.
BFlinn181
???
The 2 gal "home plumbing tank" I installed in my coach has worked fine for 10+ years.
(AND it was less expensive than the ones sold for RVs).
Mel
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Old 12-14-2013, 12:13 PM   #12
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Originally Posted by mel stuplich View Post
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The 2 gal "home plumbing tank" I installed in my coach has worked fine for 10+ years.
(AND it was less expensive than the ones sold for RVs).
Mel
'96 Safari
I didn't say it wouldn't work, just bigger than needed. Water Pump Accumulator Tank - PPL Motor Homes

Personally, I like the home made one here:
RV DIY Water Accumulator | ModMyRV
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