Water pressure/volume problem

[Sefuller]

Our new-to-us Oday 39 suffers from very poor water flow both in the galley and the head. Initially I replaced both faucets - a basic household Kohler faucet in the galley, and a Dura marine/rv faucet in the head. The pressure pump is an ITT-Jabsco Par belt drive pump (3.7 gpm) which I really like because it is much quieter than the diaphragm pumps we used (and replaced every two-three years) on our last boat. There is a small Shur-flo accumulator tank which I have properly pressurized to 20psi. The flow at the faucets is dismal when the system is fully pressurized, and almost non-existent when the pump cycles on. Today I replaced all of the 1/2" John Guest piping and fittings through the entire system with 1/2" Pex piping and fittings. The John Guest is 1/2" OD, the Pex is 1/2" ID. The only improvement, and it is marginal, is at the galley sink. The head faucet if possible got worse. I am wondering if I should rebuild the pump, although it seems to be functioning fine? I don't have a good way to test the actual pressure - it should be cycling on at 20psi, off at 40psi. When I checked the pressure in the accumulator for the first time it was low, after increasing it to 20psi, there is pretty pronounced pulsing in the water flow as the pump reaches full pressure. There are two 50 gallon tanks feeding the pump, from the pump the water goes through a check valve to the accumulator, then to a manifold which supplies water heater, galley cold, and head cold. Coming from the water heater is a line to the head with a T in the middle to serve the galley faucet. The pump is under the galley sink, midway between the heater and head. Distance from heater to head is about 21 feet. The previous water heater was an additional 7 - 8 feet aft of the current heater. Not sure what else to try??

 

[Stu Jackson]

1. Have you checked the pump flow with just a short piece of pipe or hose attached to it?

2. Are you using both tanks at the same time? Many report that one at a time cures some ills (me, too).

Good luck.

 

[dlochner]

Have you verified the pump's output? 3.7 gallons per minute is not that much. Use a gallon jug and a stop watch, how long does it take to fill the jug?

 

[Ralph Johnstone]

I don't have a good way to test the actual pressure - it should be cycling on at 20psi, off at 40psi.

Unless you know the pump discharge pressure, you're lost.

Before disassembling the entire system, can you increase the pump pressure set point to see if the flow increases ?

 

[Sefuller]

Have you verified the pump's output? 3.7 gallons per minute is not that much. Use a gallon jug and a stop watch, how long does it take to fill the jug?

I have not, I am really only comparing to our previous boat. That being said it would be hard to imagine this flow being acceptable under almost any circumstances. That is probably the easiest place to start however. I would guess I'm getting something around 1 - 1 1/2 gpm currently at the galley sink.

 

[Sefuller]

Unless you know the pump discharge pressure, you're lost.

Before disassembling the entire system, can you increase the pump pressure set point to see if the flow increases ?

I don't believe the pressure switch is adjustable like they are on the diaphragm pumps. I should probably see if I can figure a way to put a pressure gauge inline somewhere.

 

[DayDreamer41]

Have you taken the aeration screens off the faucet(s) and tested without them, many time those screens plug with tiny particles

 

[Sefuller]

Have you taken the aeration screens off the faucet(s) and tested without them, many time those screens plug with tiny particles

Done that, no difference with them on or off.

 

[NYSail]

As Stu said, test the pump output right after the pump and work from there......

Greg

 

[Sefuller]

I swapped out the complete pump for another similar one I had and the flow is much better.

 

[odaydokay]

Is there no filter anywhere in the system, like between the water tank and that pump? There should be and if so, they clog. I keep a spare, cleaned screen handy as at least once a season my flow rate falls apart.

 

[jssailem]

My water pump has a screen before the pump. That can get clogged. This would limit water flow. There are sometimes check valves in the system.

On an old boat or a new boat to me, I just start at one place like the water tank and go along the system till I find and correct the problem. It is almost always at a pipe junction or a filter/screen along the way. Sometimes it can take an hour or so but finding the solution is like finding a $20 bill in a jeans pocket you did not know you had.

 

[Scott T-Bird]

Definitely check to see if the filter ahead of the pump is clogged. Now that you have changed the feed line to 1/2" PEX, my thought is that you didn't go big enough. I had that problem with my previous boat after I installed all new plumbing (starting from scratch since I didn't have a pressurized system to start with). I used 1/2" PEX with at least three 90 degree bend fittings to make a relatively short run to the pump. Pressure from the brand new pump was awful - it wasn't getting any water. I changed the input side to 3/4" reinforced PVC tubing so that I could eliminate the bends and make sweeps, instead. Pressure was great - problem solved. I should have known to begin with … the tank manufacturer put a 3/4" connection on the tank and I reduced the pipe size coming out of the tank!

My new boat has 15 mm (basically 1/2") rigid tubing (looks like PEX) and I get lousy pressure when using either the bow tank or the aft tank. I think the pipe diameter is too small and there are too many fittings. Skin friction in the pipe and tight bends is a pressure killer! When the filter was clogged, I had no pressure. I've closed the shut-off valves , respectively, to draw from only one tank at a time. It doesn't really make a difference to me. I have a Shurflo pump but I'm not confident with it, either. The pump I chose for my old boat was Shurflo AquaKing. This one is different and it almost seems like the low water pressure is by design, as a means to water conservation. I'm planning on making all the conversions necessary to get the pressure that I would be satisfied with. That is going to start by increasing the input pipe size and eliminating fittings as possible. Then, I'll see about the pump.

 

[odaydokay]

The screen before the pump is a key line of defense. Once I season mine goos up and I see water flow drop. I keep a clean spare sitting right on the tank which has a nice indentation to fit it. Unscrew dirty one, screw in clean one. Done in 10 seconds. I never have problems down stream from there (since 1995 on this boat)