FW Pump replacement question

[firstbase]

Time to replace my Shurflo Model 288, 3.3 gpm freshwater pump. I believe it is sold as 4gpm but the label shows 3.3. Never been real happy with the pressure from it. Don't turn the faucet on while the shower is going or you will both be pretty disappointed. Is it safe to upsize somewhat, nothing too major, say to a 5gpm pump? Would that make any real difference in my pressure? What could I move to without overpowering the system?

 

[tiltrider1]

Bigger pump pushes more volume but since your hose size isn’t changing what you will likely get is more pressure. This more pressure could cause a problem but not likely. However it won’t solve your shower issue. A bigger pump won’t need to work as hard which will mean a longer life but I think time and quality of the installation is the bigger threat to pump life.

 

[DDW]

The hose doesn't know volume, only pressure. So a 20 gpm pump, set to the same pressure, will be just as safe for the hose as a 2 gpm. All pumps have a pressure spec as well.

I've installed two Marco pumps of late and like, then provided they can be mounted at the same or lower altitude than the tanks. Available in many different flow rates.

 

[STB]

5gpm pumps usually run ~40-55psi vs ~25-45psi for a 4.0gpm pump, turn on to turn off. So the difference in turn on (low) pressure should make a difference to your shower, but the modest difference in turn off (max) pressure shouldn't be enough to hurt any plumbing that isn't already on its deathbed.

By comparison, that is still less than the ~65psi that most shore water inlet pressure regulators allow into the plumbing should one connect to shore water.

Often times higher capacity pumps are higher wattage, the impact of which is that they require more current -- and thicker wires and adjusted over current protection. Whether this matters to you depends upon the length of the run and how Mickey mouse it was wired before.

A 4.0 gpm pump is typically a nominal 10A device with a 15A fuse (or breaker) and a 5.0gpm pump is typically a nominal 15A device with a 20A fuse (or breaker). In each case the wire gauge chosen according to that fuse (or breaker) size for the round trip length of the wire.

You might want to check your wiring, circuit protection, and new pump specs and upgrade or adjust as needed.

 

[firstbase]

Thanks for the comments. The current 1999 Shureflo is 11amp max with 15amp fuse. 45 PSI pressure setting. I could replace it with a Shureflo Aqua King II 4gpm at 55 psi, 15 amp or the Aqua King II 5gpm. However, the 5gpm draws 13 amp and has a 20 amp fuse. I don't remember what my breaker is, 15amp or 20 amp but will check today. Maybe I should go with the first choice which has a little more pressure but still fits the old electrical specs?

 

[FF]

Many times the larger motor of the bait well pumps makes a drop in system that creates more pressure and volume

 

[firstbase]

Many times the larger motor of the bait well pumps makes a drop in system that creates more pressure and volume

Thanks. No baitwell pump, just two showers and sinks and a galley. Just want kitchen to flow while shower is going on. That would be fine. Not big water users and we never hook up to shore water.

 

[sunchaser]

FB
Have you considered an inline pressure tank? Very common and intended to smooth out water delivery. If set up right it could well solve your issues.

 

[firstbase]

FB
Have you considered an inline pressure tank? Very common and intended to smooth out water delivery. If set up right it could well solve your issues.

I have a small accumulator. Its possible that the 20 year old pump is the issue. It's leaking a little. Maybe the install of a new one will solve it.

 

[STB]

Well, I'd take a quick look at the wiring first. You could be good. Or breakers and fuses are easily swapped if that is the only miss.

Take a look at what gauge is stamped on the wire or cable sheath or insulation, e.g. 14AWG (American Wire Gauge) or whatever. Then estimate the length and double it to get the round trip length to and from the breaker (red plus black or yellow). Be sure to estimate turns, etc, into the length, not just straight lone. Once you've done that, look up the capacity here and you'll know and can make choices about how to proceed.

-- https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

I suspect it is the low number, i.e. cut in pressure, vs the high one that is causing you the most trouble.

 

[firstbase]

Well, I'd take a quick look at the wiring first. You could be good. Or breakers and fuses are easily swapped if that is the only miss.

Take a look at what gauge is stamped on the wire or cable sheath or insulation, e.g. 14AWG (American Wire Gauge) or whatever. Then estimate the length and double it to get the round trip length to and from the breaker (red plus black or yellow). Be sure to estimate turns, etc, into the length, not just straight lone. Once you've done that, look up the capacity here and you'll know and can make choices about how to proceed.

-- https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

I suspect it is the low number, i.e. cut in pressure, vs the high one that is causing you the most trouble.

Thanks. On the boat now. What brought this all about was an annual cleaning of our water tanks. I was just flushing the tanks and found that the pump is not emptying the tanks. The go down about a third to a half and then there is no flow. Getting a little bit of water leaking out of the pump. I’m thinking that the pump is just gone and can’t even pump without the status pressure of the water helping it. Probably don’t need to upsize anything. Just need a working pump.

 

[C lectric]

Some of those pumps are rebuildable. No matter how good a pump is they all need some help from time to time. Maybe that's all yours needs, a seal kit.
THe rubber parts harden and then can no longer seal. This hardening is often so slow you don't notice untill it gets the reseal and then the sudden change becomes very noticeable.

 

[DennisB1]

I had a problem with not pumping tanks empty. Replace pumps twice did not solve the problem. What I found was a very small hole/air leak when the tanks got to a critical level, it would allow air into the line and not allow the pump to empty the tank. Fixing the air leak allow the pump to pump the tank to empty. Look carefully for air leaks. I found a small hole and also found a crack hose near a hose fitting. Old hose and time caused the problem.(25 years old). So inaddition to checking pump check the hoses on the suction (vacuum) side. Also check the accumulator for pressure. The pressure charge should be slightly less than the pump cut in pressure when the water lines are depressurized. The suction/vacuum leaks are hard to find --- good luck.

 

[firstbase]

Spent the last day on the boat having it hauled for bottom paint and "stuff". Continue to drain tanks to clear out the water/bleach used to disinfect. What I find it that the pump works for 20 minutes or so, drains about 25% of the tank and then flow stops. Pump runs, no flow. Turn everything off for 1/2 hour or so and then boot them back up and.....flow again. Then it repeats. I can keep doing this until tanks are empty. My completely ignorant theory, knowing little more than my wife wants to brush her teeth, is that the underperforming pump can't keep up with the accumulator so I get flow until it is emptied and then it has to recoperate until full again? I haven't checked the air pressure in the tank but will today.

 

[High Wire]

System wise the reason for flow stoppage could be a blocked tank vent. Rule this problem out by opening the deck fill cap and try again.
Clean out the inlet strainer. You can remove the pump and remove the inlet housing to inspect for junk like algae.
If the pump used to be ok and now is not, just replace with like kind.
Upgrading the pump may need to upsize the wire, fuse, hoses, etc to get any benefits.
When the pump went or our current boat, I opened it up. 2 of the 4 little internal valves were broken. The other two crumbled in my hands. It might just be time for new.

 

[firstbase]

System wise the reason for flow stoppage could be a blocked tank vent. Rule this problem out by opening the deck fill cap and try again.
Clean out the inlet strainer. You can remove the pump and remove the inlet housing to inspect for junk like algae.
If the pump used to be ok and now is not, just replace with like kind.
Upgrading the pump may need to upsize the wire, fuse, hoses, etc to get any benefits.
When the pump went or our current boat, I opened it up. 2 of the 4 little internal valves were broken. The other two crumbled in my hands. It might just be time for new.

I tried with fill caps open and closed, no difference. Manufacturers date on the label is 1999. That's probably worthy of a new pump even if it isn't the problem. However, with some water leaking out I would think something is going on internally.

 

[High Wire]

I tried with fill caps open and closed, no difference. Manufacturers date on the label is 1999. That's probably worthy of a new pump even if it isn't the problem. However, with some water leaking out I would think something is going on internally.

Yep. Time to fling it.