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abrasv · 04-24-2015, 04:35 PM

Just installed a new Shur-Flo water-pump to gain increased volume. That part works as it should however, when the pump is running it seems like it is pulsating and the interior lights flicker. I hooked it up to the same wires as the older Shur-Flo was hooked to. I'm currently in a campground and plugged into 50 amp service which has been checked out and works ok.

Am I drawing to much current for the somewhat larger pump? Went from 2.8 gpm to 4.4 gpm.

thanks,
Jim

Bigd9 · 04-24-2015, 05:07 PM

My first gut feeling is it may be an adjustment on the pump itself. I don't see how it can be a 12 volt supply problem. Is your pump as hard to get to as my coach is? I can't even see it unless I use a mirror to look behind the metal panel.

I think a call to the Surflo people is in order.
Good luck and keep us informed as this pump is on my "to do" list.

abrasv · 04-24-2015, 05:42 PM

Pete, My pump is located in the compartment next to the one with all the pipes and dump valves. Still have to stand on my head to work on it but at least it is not behind the metal panel.
Think I'll call Shure-Flo on Monday to see if they have an answer.

Gary RVRoamer · 04-24-2015, 05:48 PM

That pump does indeed draw more amps and the wiring may be a bit on the skimpy side. Also the pump relay (controller as well). A skinny wire under a high load will cause a reaction like that.

What model Shur-flo? Is a variable speed type? My Aquajet variable speed pump can draw up to 10 amps.

The pulsing is a result of the higher pump capacity. It can deliver a lot more water than the old 2.8, so it reaches the cut-off pressure (40-45 psi) more quickly and cycles off, then quickly comes back on as the water continues to flow out of the faucet. The old 2.8 gpm pump just ran flat out all the time trying to keep up with demand.

Mentor · 04-24-2015, 06:01 PM

Hook up an accumulator to the system. The larger the better.
Sometimes called an extrol tank.

Ray,IN · 04-24-2015, 06:03 PM

Quote:

Originally Posted by Gary RVRoamer

That pump does indeed draw more amps and the wiring may be a bit on the skimpy side. Also the pump relay (controller as well). A skinny wire under a high load will cause a reaction like that.

What model Shur-flo? Is a variable speed type? My Aquajet variable speed pump can draw up to 10 amps.

The pulsing is a result of the higher pump capacity. It can deliver a lot more water than the old 2.8, so it reaches the cut-off pressure (40-45 psi) more quickly and cycles off, then quickly comes back on as the water continues to flow out of the faucet. The old 2.8 gpm pump just ran flat out all the time trying to keep up with demand.

That was my initial thought too. The pump volume is too much for the plumbing size.
A work-around might be to install a 2G expansion tank just after the pump.

Old Scout · 04-24-2015, 06:09 PM

Some pumps have/had adjustment screws at the bottom not sure what they adjusted [smile]. As mentioned, wiring can be an issue--epecially if your coach has two or more switches [three-ways] and no pump controller is used [long wiring run + small wire = drop voltage]--adding a relay and wiring a clean/direct 12v supply line may help this issue. Large capacity pumps can/will out run single faucets, causing the pump to cycle--adding an expansion tank will help.

Gary RVRoamer · 04-25-2015, 09:32 AM

You have faucets that can release water at a rate of maybe 1-2 gpm, and usually much less if not turned full on. Your pump is pushing out 4+ gpm, so of course it shuts off, then turns on again after a few seconds. Yu can experiment with this simply by opening the faucet more or less and observing the pulse change. Open a second faucet and the pulse may go away altogether. The only value of a higher capacity pump is to allow more than one faucet to get full flow simultaneously. Otherwise its just wasted capacity. It's nice though, to be able to turn on a faucet without causing the person in the shower to yelp!

An accumulator changes the duration of the pulse, i.e. you can run a bit of water before the pump starts cycling. Once you have depleted the accumulator reserve, the pump cycles again to refill the accumulator, so you get wider spaced pulses. And you can run water briefly with no pump cycle at all.