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Old 04-16-2017, 11:25 AM   #1
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Paragon SR Fresh Water Pumps

Just thought I'd share my recent experience with Groco Paragon SR fresh-water-system pumps:

There was such a pump in place on my 2003 Selene 53 when I bought her in 2013. The pump—age unknown, but with all bronze fittings—served well until 2016. The failure lay in pump itself: the internal rotor ceased to seat snugly against the interior of the case, presumably from long wear. The sign: the pump operated continuously without building pressure.

I installed a new pump, of a later design with PVC fittings instead of bronze. This 2nd pump failed within a year. The sign: the pump cycled once when powered up, but didn’t restart when the water system pressure dropped. If the pump was reset (power was switched off and then on), the pump would run once. We replaced the pressure switch, but that didn't help, so we concluded that the pump's control electronics had failed and replaced the entire pump with a spare I had on hand. That 3rd pump was of the same design as the second. BTW, as I now have learned the hard way, one can test for a pressure-switch failure by putting a jumper wire across the pressure switch leads; if the pump then runs, the problem is the switch. On the newer-design pump, the connections for the pressure switch are easily accessible on top of the motor case.

Anyway, after a couple of months, the 3rd pump failed in the same way as the 2nd: it would run once after reset but wouldn't restart upon a pressure drop.

It helps to understand that, at one end, the motor is mechanically linked to the pump and that attached to the other end of the motor is a housing that protects a small circuit board that controls the motor; a solenoid is attached to the end of this housing. The housing is held on to the motor by two cap nuts.

It also helps to understand that these pumps have a "no-flow" sensor to shut off the pump if there is no water in the inlet. The sensor’s electrical connections are studs threaded through, and protruding perpendicularly on, each side of the inlet. Leads from the control circuit to these studs are held in place by hex nuts.

Groco gave me excellent telephone support. With their step by step advice (me on phone at pump with tools in hand), I got the pump to operate. The fix(es): I disabled an apparently-failed over-voltage-protection diode, by removing the orange wire inside the housing where circuit board is located. I also disabled no-flow sensor, by placing a jumper wire across the two studs of the no-flow sensor.)

Groco advised that the pump commonly installed with the no-flow sensor disabled; in fact, pump comes with brown jumper wire in place, which must be removed in order for the no-flow feature to work. The pump has a 10-minute timeout shut-off for protection if there is no water supply.

With 20/20 hindsight, I noted water leakage and corrosion of the no-flow connection studs where they emerge from the PVC inlet. I am now a bit doubtful that I needed to disable the diode, and I may try restoring its function, while no-flow sensor remains disabled, to see if the no-flow was really the only problem.

IMHO: Groco C+ for design, A for telephone support.
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Old 04-16-2017, 12:16 PM   #2
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The basic pump used on the Groco Paragon Sr and Jr is very reliable.
I had a Paragon Jr for more than 25 years on Possum. I changed the pressure switch just once in all that time.

Why didn't you replace the rotors on your original pump?
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Old 04-16-2017, 02:09 PM   #3
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We have a Paragon Jr. on Traveler. Age unknown. It has been intermittently been having difficulty. Sometimes it kicks on and immediately builds pressure, and other times it might take 10 seconds or more before "catching" and building pressure. If it goes on too long (20 seconds or so) we fully open a cold water faucet and it soon pressurizes. But then we get spitting water for 5-10 seconds before running smoothly.

I've checked the two accumulator tanks and they are holding pressure fine. At this point my options appear to be rebuild the pump, or install a Paragon Sr. a friend gave us 5 years ago. I am fairly certain he said it was even rebuilt, but not entirely sure. As the Sr. has different mounting points I think I'll try rebuilding the Jr. first. The basic service kit is $27 at Fisheries and includes 2 seals and 4 o-rings.

But is there an appreciable difference between the two?
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Old 04-16-2017, 02:41 PM   #4
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Darren, before you start rebuilding pumps, take a look at the intake side of the pump between the tank pickup and pump. It kind of sounds like the pump is sucking air from somewhere. It may be the pump, but check the cheap repair first.
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Old 04-16-2017, 05:02 PM   #5
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I Was Badly Advised, It Seems

Quote:
Originally Posted by HopCar View Post
The basic pump used on the Groco Paragon Sr and Jr is very reliable.
I had a Paragon Jr for more than 25 years on Possum. I changed the pressure switch just once in all that time.

Why didn't you replace the rotors on your original pump?
I was advised by Boat Owners Warehouse that repair company had said a rebuild would not be economic. I assumed this was the word from Groco. Apparently not. Alas, I already disposed of the old pump!
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Old 04-16-2017, 05:05 PM   #6
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Quote:
Originally Posted by Moonfish View Post
We have a Paragon Jr. on Traveler. Age unknown. It has been intermittently been having difficulty. Sometimes it kicks on and immediately builds pressure, and other times it might take 10 seconds or more before "catching" and building pressure. If it goes on too long (20 seconds or so) we fully open a cold water faucet and it soon pressurizes. But then we get spitting water for 5-10 seconds before running smoothly.

I've checked the two accumulator tanks and they are holding pressure fine. At this point my options appear to be rebuild the pump, or install a Paragon Sr. a friend gave us 5 years ago. I am fairly certain he said it was even rebuilt, but not entirely sure. As the Sr. has different mounting points I think I'll try rebuilding the Jr. first. The basic service kit is $27 at Fisheries and includes 2 seals and 4 o-rings.

But is there an appreciable difference between the two?
I've never looked at a Paragon JR up close. It looks different (motor above, belt drive). My understanding is that the Paragon SR is a more powerful (and more power hungry) pump, designed for larger water fresh water systems. I would stick with the Paragon JR if it works for you.
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Old 04-16-2017, 05:52 PM   #7
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Quote:
Originally Posted by zshipley View Post
I was advised by Boat Owners Warehouse that repair company had said a rebuild would not be economic. I assumed this was the word from Groco. Apparently not. Alas, I already disposed of the old pump!
I don't know about the electronics of the Paragon Sr but the pump itself is pretty simple to service.

It uses a hockey puck like rotor that is caused to wobble by an eccentric on the shaft that goes through the puck. It is capable of high pressures and is pretty chemical resistant depending on what the puck is made of.
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Old 04-16-2017, 06:46 PM   #8
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A reason to disable that no flow sensor is that if you are primarily using water made with a water maker, the sensor will think there is no water flowing and shut down. Something about the water being to pure.

Also, these pumps will not build pressure if the check valve in the outlet of the pump is failing. It starts out with the pump cycling for no apparent reason and gradually gets worse. The water will bleed back thru the pump to the tanks. I bought a new check valve from Fisheries Supply in Seattle. ( Part number P9021A)
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