Fresh Water Pump Question

[Scott T-Bird]

RTFM.... A novel concept and a good rainy day activity.

Actually there are 2 pressure adjustment screws, the downstream valve prevents pressurized water from back flowing into the tank and the other starts the pump when a tap is open.

Good idea and I'm glad this topic came up! A few weeks ago, I finally activated my new system. I have the Shurflo Aqua King with the accumulator tank installed. When I filled my water tank and switched the pump on, it had a noisy, grating sound that I thought surely couldn't be right. I also had no flow with an open faucet. I realized that it needed to fill the water heater (5 gallons) so I let it run until the WH was filled, which took about 15 minutes (possibly). Once the water heater was filled, I got flow thru the faucets, but the flow is weak.
When I turn on a faucet, I get momentary full pressure, then the pressure goes weak and the pump runs continuously while the faucet is open. As soon as I shut the faucet off, the pump stops. The pump seems to build pressure in the system but the pressure gets weak and the pump runs as long as a faucet is open. Doesn't matter if I run hot, cold or both at the same time, the pressure is the same weakness. And the pump is disturbingly noisy.
I called Shurflo and they suggested that my intake line is constricting flow. They said nothing about a pressure adjustment on the pump. I have about 6 or 7 feet of 1/2" PEX between the tank and the pump. There are 3 - 90 degree bends with sharkbite fittings. The tank has a 3/4" female opening for the water line so I have a 3/4" male to 1/2" PEX conversion right at the tank (which feeds right into the first 90 d bend).
I'm living with weak pressure and a noisy pump right now until I figured that I would convert to a 3/4" flexible line to increase diameter and eliminate bends. I have since realized that the inside diameter of 1/2" PEX is significantly less than 1/2". I figured that there is not a problem with the 1/2" PEX on the discharge side of the pump because pressure does build up, if only momentarily. I had the feeling that the problem with a noisy pump is that the pump is starved for water.

 

[dlochner]

The pump seems to build pressure in the system but the pressure gets weak and the pump runs as long as a faucet is open. Doesn't matter if I run hot, cold or both at the same time, the pressure is the same weakness.

The issue may be the accumulator tank. Regardless of what the pump is putting out, if the accumulator tank pressure is low, the flow will be low. There may be a Schrader valve (like on a auto or bike tire) check the pressure with a pressure gauge. Also make sure there are no leaks however small. One culprit is the pressure relief valve on the HW tank. With the pump running and the HW tank pressurized work the valve handle a little to clear out any crud.

I'm living with weak pressure and a noisy pump right now until I figured that I would convert to a 3/4" flexible line to increase diameter and eliminate bends. I have since realized that the inside diameter of 1/2" PEX is significantly less than 1/2".

The ½" OD lines on my boat are more like ⅜" ID lines. I suspect that the PEX ID is also about ⅜". The sharp 90* bends don't help, but they shouldn't reduce the flow that much.

I had the feeling that the problem with a noisy pump is that the pump is starved for water.

Could be. Make sure the pump is not touching anything that can resonant. Try backing the mounting screws out a ½ to a full turn. That should decompress the rubber feet and help insulate the pump and the noise resonating from the boat structures. The Shuffle I just installed is barely noticeable. The pump ran intermittently because I had a very small leak (hose clamp not quite tight enough) didn't notice the pump running from time to time until the bilge was full of water.

 

[Scott T-Bird]

The issue may be the accumulator tank. Regardless of what the pump is putting out, if the accumulator tank pressure is low, the flow will be low. There may be a Schrader valve (like on a auto or bike tire) check the pressure with a pressure gauge. Also make sure there are no leaks however small. One culprit is the pressure relief valve on the HW tank. With the pump running and the HW tank pressurized work the valve handle a little to clear out any crud.

The entire system is brand new from stainless steel supply tank to HW heater, lines, fittings, faucets, pump, acc. tank. I checked the pressure in the acc tank (Schrader valve) and it was 35 psi to start with (recommended 30 psi). I played with that for a while, reducing it down to 0 and back up to over 30 psi. That didn't make any difference. Noise does not seem to come from the rubber feet. I don't recall seeing anything about an adjustment for the pump pressure on the Aqua King but I have to admit that I installed the pump in February and didn't get around to actually using it until a few weeks ago (not finished with all system improvements). The manual has been buried since February, so I will have to re-read it. It will be a pleasant surprise if all it takes is a simple adjustment.

Shurflo suggested that I should do a bucket test for both the supply side and the discharge side to determine if there is a problem with the pump. I haven't taken that step yet.

 

[dlochner]

Scott,

I don't the pressure adjustment instructions are in the manual. They are in the instructions for the various replacement parts. A scan of that section is attached. You might wonder why I have the replacement part manual for a brand new pump. I'll let you continue to wonder.

If the rubber feet are too tight the noise from the pump is transmitted through the feet and onto the mounting surface which then acts like a sounding board and amplifies the sound. Thus the suggestion to back off the screws a little to let the rubber absorb more of the vibration. The pump is a diaphragm pump which are inherently noisier than other types of pumps.

 

[Scott T-Bird]

Scott,

I don't the pressure adjustment instructions are in the manual. They are in the instructions for the various replacement parts. A scan of that section is attached. You might wonder why I have the replacement part manual for a brand new pump. I'll let you continue to wonder.

I'm skeptical that these switch settings are the issue. The factory settings are likely to be correct. Besides, I don't have the problem that the pump won't shut off. It shuts off almost as soon as I shut off a faucet so the bypass setting for full bypass is surely greater than the pressure shut off. My problem is low pressure when the faucet is running. It certainly isn't friction loss between the pump to the galley faucet and the accumulator tank has the correct setting.
Perhaps if the bypass opening is set very low, too much water is recycling and not enough is flowing to the faucet? But I really doubt that to be the case. If the pump shut off pressure is too low, the pump simply wouldn't run even when the faucet is open. The Shurflow rep seems to think it is a supply side issue and he says the pump will be noisier when it is starved for water.

 

[Capt jgw]

A Shurflo pump shouldnt make ugly noises. Id expect that from Harbor Freight crap but not a Shurflo. That and low pressure has me thinking its defective.

 

[dlochner]

The Shurflow rep seems to think it is a supply side issue and he says the pump will be noisier when it is starved for water.

Go with what the factory rep tells you before you believe some guy on the internet. Shuflo does say that the maximum draw from the water tank is 6 feet.

 

[jibes138]

Scott do you have a filter on the inlet side of the pump? There should be one, just a course screen but if it is clogged or air locked it might starve the pump. On mine there is a screw on top to pull off the bowl and clean it but you also loosen the screw to get air out then tighten when it fills with water. Like bleeding a fuel filter.

 

[Scott T-Bird]

Scott do you have a filter on the inlet side of the pump? There should be one, just a course screen but if it is clogged or air locked it might starve the pump. On mine there is a screw on top to pull off the bowl and clean it but you also loosen the screw to get air out then tighten when it fills with water. Like bleeding a fuel filter.

Yes, the small filter came with the pump and is brand new, so a clog is not likely. I don't see an air bubble, but it's worth taking a closer look. Installation manual says to use a flexible line leading into and out from the pump. I am using a 12" braided steel plumbing line (1/2") on both ends and the inlet side has a pretty tight 180 degree sweep to feed into the filter, just ahead of the pump. There is no kink, but it could be adding to the difficulty. If the inlet side of the pump is the problem, I intend to convert everything to a 3/4" flexible line to eliminate hard bends. The model I have is Aqua King 4 gpm to serve hot and cold to galley and cockpit shower and cold water to the vanity, so there are 3 fixtures. I don't have the shower connected yet, but if I open all faucets (2 cold & 1 hot) pressure is same as if I open just one.

 

[jibes138]

Try sticking a hose on the inlet side in a bucket of water and see if it matters? I had bad flow one year and the aerator screens at the faucets were clogged, take those out for an easy check.

 

[Davidasailor26]

This spring our pump started acting as Scott describes - good pressure after the pump could build it up, but dropping quickly to a low flow after the faucet was on. In our case it turned out that the housing of our 3 year old Jabsco pump was losing its seal, preventing the pump from getting good suction and reducing its efficiency. We disassembled it and added some form-a-gasket to the sealing surfaces and it works like new again. I'd imagine any leaks on the supply lines from the tank to the pump could cause the same symptoms as well.

 

[jibes138]

Scott 1/2 inch should be ok for a hose size for indoor plumbing. A 1/2 pipe at 58 psi will flow over 8 gpm.

 

[shemandr]

I found the pump! So, I don't think it's wired correctly. So far I haven't found any wiring diagrams but since I didn't get a picture of the pump label I don't know the exact model. But there are two red wires coming out of what I think is the pressure switch and they aren't attached to anything. The positive for the pump motor are wiring directly to the 12 v system, through the panel. I think the positive from the panel should go to the pressure switch red and the red coming out of the switch should go to the pump motor. The black can stay as is. I think if I rewire it so the positive goes thru the switch it should work. Any comments?

 

[Gunni]

It does seem like some jackleg decided to bypass your pressure control switch rather than remedy a problem with the pressure control switch. Wire it up and expect the pump to not work, or work badly. Then the question: Is the pressure switch available as a part?

 

[shemandr]

It was that PO guy, again.

 

[Gunni]

You never know, perhaps the PO retained the services of a jackleg! "Got your water running, send me $50."

 

[kloudie1]

Yup, Hot to pressure switch, press switch to pump motor (red). Black as is.. If it does not work, you can take the pressure switch apart and take the trash out or clean up the port.

 

[NotCook]

Try sticking a hose on the inlet side in a bucket of water and see if it matters? I had bad flow one year and the aerator screens at the faucets were clogged, take those out for an easy check.

Good point. Also, if you have multiple water tanks with a manifold to select tanks, try switching tanks. This could help reveal if you have a tank inlet clog reducing the flow from that tank. We have one tank from which we simply cannot extract water. Unfortunately, there is no way to get to/reach the hose connection at the tank to check/replace it (poor, custom design). If we select that tank, the pump can kill itself trying to pump water to no avail. One way to confirm this is to simply remove the suspect intake line from going into the manifold and suck or blow on it. If nothing, you may have found your problem.

Just one of the possible issues...

 

[shemandr]

Thanks for the responses everyone. I'm going to rewire it Wed. and see what happens. I'll file a report. I hope it will be positive.
The story of finding the pump is worth telling. I've been looking for it since I got the boat in June. I could hear it but couldn't tell where it is. I stuck my head under the sink in the galley, and the sink in the head, and the engine "Lack of" room," but no pump. When I told the PO that the pump didn't shut off, he said "I guess that's what those other two wires are for." We talked about a number of issues and I knew I had to come back to that. While anchored Sunday morning a guy on a jet ski came by and told me he has the same boat and has for 31 years. I think I had the question out before he finished "31 years." I asked "Where is the fresh water system pump?" He told me it was under a bunk and you have to remove a plywood panel to access it. Thank you and that's how I found it. Not all jet skiers are bad people.