Fresh water pump lifespan

What is everyone seeing for freshwater pump life?

My pump is a Pentair Shurflo Aqua King II. It was manufactured Jan 2020, installed in the boat in April 2020. The boat sat unused for a season and I purchased the boat in May of 2021. We have used the boat for 4 seasons now, (generally May to October up here)

The pump died today, have not diagnosed if it is the pressure switch or something else. Thanks to the previous owner Bob, I have his spare pump from 2006 installed and working.

Should I expect longer life? We are not liveaboards, we are seasonal boaters up here. 4 seasons of use seems pretty short.

What’s your experience? Is this a cheap pump? Should I upgrade to something else? I would like a quieter pump.

In my limited experience, I think it may depend on your luck. Here is the pump that is in my boat. I just happened to have a photo of it from when I was doing something else in the same area. It is a Shurflo Smart Sensor 4.0, part number 4901-0211. This pump was manufactured in 2012 and was installed by the PO in my 2010 boat. The PO had to repair/replace a bunch of items that year after a little incident with a large rock.

Anyway, my boat gets primarily seasonal use, but not so much the last few years. Still, the pump still works. I believe my pump has a 3 year limited warrantee. My guess is that yours is the same, so just recently out of warrantee.

Shurflo/Pentair has excellent technical support. Give them a call (800)854-3218. They were incredibly helpful to me when I replaced my entire freshwater system.

I have never had to replace one in about 65 years of boating, maybe just lucky…

I have not had good luck with Shurflo pumps. The motors have never been the problem. The problem has always been with the pump head.

I switched to Marco pumps.

A great deal of life expectancy revolves around how long and often the pump is run dry. Many diaphragm pumps are water cooled and distort from heat when run without flow.

Ted

I am wondering if my pump was oversized. It is a 4GPM model, now thinking about it the pump did cycle on and off a lot....maybe this contributed to failure? It was almost like the pump was too much for the system, which are really 2 faucets and a toilet. It was almost like the water demand was too little for the pump, leading to a continious cycling. I'm looking at replacing it with a 3GPM unit with a small accumulator tank.

I kind of came to this conclusion after shopping for replacement pumps and seeing that the majority of them were around 2-3 GPM which I thought was low until I started doing some sizing.

mncruiser said:

I am wondering if my pump was oversized. It is a 4GPM model, now thinking about it the pump did cycle on and off a lot....maybe this contributed to failure? It was almost like the pump was too much for the system, which are really 2 faucets and a toilet. It was almost like the water demand was too little for the pump, leading to a continious cycling. I'm looking at replacing it with a 3GPM unit with a small accumulator tank.

I kind of came to this conclusion after shopping for replacement pumps and seeing that the majority of them were around 2-3 GPM which I thought was low until I started doing some sizing.

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Continuous cycling can be related to the pressure adjustment or even the slightest and tiny leak.

Pump life is a crap shoot these days. 25 years ago, any pump you bought would almost last a lifetime. I’ve had modern pumps fail a few times. My next pump will be a Marco. I’m using a sea flow right now, and it was a poor choice. It’s a bypass style, and doesn’t work well with voltage fluctuations. If I set it to work well with float voltage, it won’t shut off when I’m on the anchor. So I set it to work properly at 12.5 volts and when Im at the dock it cycles instead of bypassing.
I think if I were using a lithium house bank it would perform better as the voltage is flatter.

Not as lucky as Dave, I replaced one pump in 50+ years. I actually still have that pump because it was the built in pressure switch that failed. Fuzzy memory, it may have started to cycle. Keep it as a spare, can always power on/off until the next new one.

PhilPB said:

Continuous cycling can be related to the pressure adjustment or even the slightest and tiny leak.

Click to expand...

What I meant, not cycling when not in use, but when we use water through a faucet, it almost seemed like the pump was too fast, it would not run constantly, it would cycle on and off several times while using water, like there was not enough usage for it to stay on.

mncruiser said:

What I meant, not cycling when not in use, but when we use water through a faucet, it almost seemed like the pump was too fast, it would not run constantly, it would cycle on and off several times while using water, like there was not enough usage for it to stay on.

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My Shurflo pump is 4gpm, 50psi but is a variable speed pump. So it doesn't cycle on and off while water is being used but simple slows down or speed up as needed. Maybe that makes a difference?

An accumulator tank would make a big difference. I've had the sensing pumps before, and they do get irritating as they are constantly cycling up and down.

Mac2 said:

An accumulator tank would make a big difference. I've had the sensing pumps before, and they do get irritating as they are constantly cycling up and down.

Click to expand...

Is an accumulator then a pressure vessel? I've never had one on a boat.

dhays said:

Is an accumulator then a pressure vessel? I've never had one on a boat.

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Yes, with a variable speed pump it stops the pump from doing the very slow speeds which are the hardest on the pump. While they all advertise no accumulator necessary with the variable speed pumps they all recommend using an accumulator for best life and performance.

tiltrider1 said:

Yes, with a variable speed pump it stops the pump from doing the very slow speeds which are the hardest on the pump. While they all advertise no accumulator necessary with the variable speed pumps they all recommend using an accumulator for best life and performance.

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Thanks. I learn new stuff all time.

I have found that the most common failures for diaphragm pumps like that are the pressure switch, and valves that leak a little pressure back toward the tank which causes cycling as though there's a slow leak somewhere. Expensive and cheap pumps of that style seem to have the same issues. The motors seem to last forever if they don't get wet.

My solution

1. Install a one way valve between the pump inlet and the water tank to address the leak back issue
2. Install a pressure tank to slow the cycling in general
3. Bypass the factory pressure switch and use a switch meant for a house water pump (if you have gasoline engines, these switches cannot be installed anywhere that fumes can accumulate.) to address the weak OEM pressure switch.
4. Install a quick-connect electrical connector on the boat wiring and the pump wiring.
5. Use pumps that have quick-connect plumbing fittings.
6. Use silicone hose for the plumbing. It stays flexible forever and makes pump swaps really easy.
7. Always carry an identical spare that's pre-wired to plug right in.

The steps above will make a cheap pump last a long time and when it does fail the spare can be swapped in, in minutes. The only tool I need to swap a pump is a Phillips screwdriver for the mounting screws.

Mischief Managed said:

I have found that the most common failures for diaphragm pumps like that are the pressure switch, and valves that leak a little pressure back toward the tank which causes cycling as though there's a slow leak somewhere. Expensive and cheap pumps of that style seem to have the same issues. The motors seem to last forever if they don't get wet.

My solution

1. Install a one way valve between the pump inlet and the water tank to address the leak back issue
2. Install a pressure tank to slow the cycling in general
3. Bypass the factory pressure switch and use a switch meant for a house water pump (if you have gasoline engines, these switches cannot be installed anywhere that fumes can accumulate.) to address the weak OEM pressure switch.
4. Install a quick-connect electrical connector on the boat wiring and the pump wiring.
5. Use pumps that have quick-connect plumbing fittings.
6. Use silicone hose for the plumbing. It stays flexible forever and makes pump swaps really easy.
7. Always carry an identical spare that's pre-wired to plug right in.

The steps above will make a cheap pump last a long time and when it does fail the spare can be swapped in, in minutes. The only tool I need to swap a pump is a Phillips screwdriver for the mounting screws.

Click to expand...

Great ideas. I ended up ordering a pump/accumulator kit from Whale. I also figured out it was just the pressure switch on the old pump, ordered a replacement switch for it. I'll be using it as a spare, love the idea of quick disconnect for the water and power to facilitate swapping in a spare.

I'll be rigging up the old pump...now new spare with some flexible hoses to allow it to go in easily, and also be used on friend's boats if needed as a spare, and my new setup won't be a bolt in for the old pump. I went with this for a new setup:
It is from Whale, I had good luck replacing a shower box drain with one of their pump systems. Not a fan of their 15mm connections as I have to use an adapter to go to 1/2" fittings with pex on my boat, but hoping it will be a smoother more reliable setup.

A spare pump is a must, no pump really can pretty much end a trip for us. No water, no flushing is a big deal!

I think the Shurflo pump was oversized for my boat, and the constant cycling of the switch caused early failure. The pump would only ever fully run with 2 faucets on. I think the Whale model I bought is a 3GPM vs a 4 GPM, and the tank will help with the cycling and even pressure delivery.

Shurflo tech support was great, helped me figure out how to fix the pump. Whale pre sales support was great as well.

Thanks for all the replies everyone!