Accumulator tank or not

[Constellation1]

Greetings,

As I work through my boat to understand every system, upgrade, and do maintenance to set my baseline before any long distance cruising - I have a question I’m looking for some input on.

I have a Marco freshwater pump that works very well. Doesn’t cycle, keeps up with all demands, no issues. The boat also has an accumulator tank (not connected) that the previous owner tells me he disconnected after installing the Marco. I really don’t like things on the boat with no purpose - old wiring, an accumulator tank taking up space etc.

My question is: should I reconnect the accumulator, or get rid of it? Second part to the question is - is reconnecting it an easy task?

Thanks

 

[DavidM]

An accumulator tank is useful for a water pump that only has one speed: on and off. The accumulator dampens out the pressure so the water flow at the faucet doesn't change much as the pump starts and stops.

But some modern water pumps are variable speed and match the speed of the pump to the water flow requirements to keep the pressure steady. You can hear the pump speed up and slow down as you vary the flow at the faucet.

So it all depends on what type of pump you have and even with a fixed speed pump you may be happy with how it works.

David

 

[Constellation1]

An accumulator tank is useful for a water pump that only has one speed: on and off. The accumulator dampens out the pressure so the water flow at the faucet doesn't change much as the pump starts and stops.

But some modern water pumps are variable speed and match the speed of the pump to the water flow requirements to keep the pressure steady. You can hear the pump speed up and slow down as you vary the flow at the faucet.

So it all depends on what type of pump you have and even with a fixed speed pump you may be happy with how it works.

David

Thank you David, that helps. The Marco is a variable speed pump and it does a good job. I think I will remove the accumulator tank, but hang onto it.

Cheers!

 

[Lou_tribal]

What I like about the accumulator tank since I installed one is that the pump does not start each time you open a faucet for few drops.


L

 

[rwidman]

I installed an accumulator tank on my boat even though the pump instructions said I didn't need one. Water delivery is much smoother and the pump doesn't have to run every time I crack open a faucet.

I used to live in a home with a private well. There was a pump and a large accumulator tank. It's pretty standard for private well systems and your boat is very similar to that.

 

[High Wire]

If the pump doesn't cycle, then ditch it. But leave the connection point plugged in case future owners need it. Make a notation in the log WHY you removed it. It may be needed with a standard pump.

 

[Frosty]

I'm with Lou_tribal and rwidman. Even with a variable speed pump, I like to have an accumulator tank. Not a tiny one, but 2 or more gallons (the more the merrier).

Reason? Water pump does not even come on for a midnight flush, or small galley sink tasks. Also, if running water at a trickle, no unhappy pump sounds (in fact no sound at all).

The pump does of course have to run, but it does so all at once and more infrequently -- to refill the accumulator.

Then again, I suppose it depends on where your pump is, and whether or not the noise is a nuisance. And whether you tend to run the water at a trickle.

 

[tiltrider1]

If you read the Marco installation manual you will see that it says an accumulator tank is not needed. It also says use of an accumulator tank will extend the life of the pump. Since you have the accumulator tank you should use it.

 

[FF]

Some of the modern pumps simply by pass the pump internally when little water flow is used.

That means your battery is discharging at a higher rate for nothing.

A big accumulator with a dumb pump and house shallow water pump relay works the best for living aboard.

 

[Constellation1]

Thanks for all the input; I'm going to try it. One more question though - this pump has no cut in pressure published. Nothing on the pump or the manual. I sent an email to Marco support several days ago and have heard nothing back. The only pressure on the pump is 36 PSI - which I assume is operating pressure. What pressure should I set my accumulator to with a variable speed pump?

 

[MurrayM]

Had an interesting chat with a dock neighbour.

He has a semi-planing boat with 2 big diesels in aft deck engine compartments. He was cruising happily along one day, until his feet started getting wet. Turns out there was a break/leak somewhere in his water line, and the pump was more than happy to keep running.

Hearing this, I now make it a habit to flip the accumulator tank/pump breaker switch on whenever water pressure gets low, then flip the breaker switch off when the accumulator tank pressure shuts the pump off.

I'll keep the accumulator tank.

 

[sunchaser]

Like Murray, we use the pump off switch a lot. Heads flushing at night and drawing coffee in the morning means no noise to bother others.

 

[Constellation1]

I set the pressure at ~20 PSI and everything is working as it should. I do like washing my hands or flushing the head with no pump noise.

 

[DDW]

Thanks for all the input; I'm going to try it. One more question though - this pump has no cut in pressure published. Nothing on the pump or the manual. I sent an email to Marco support several days ago and have heard nothing back. The only pressure on the pump is 36 PSI - which I assume is operating pressure. What pressure should I set my accumulator to with a variable speed pump?

I have a Marco pump on the boat, put it in with the accumulator tank still in the system. It works well. I put a Marco pump in the camper, small camper so not much piping and no accumulator, and it did not work well. There was a hesitation in pressure when a faucet was suddenly turned on (such as the push button shower head). There was just not enough resilience in the water system and the Marco could not respond quick enough. I put in an accumulator and it fixed that problem.

If the accumulator pressure is set too high, it is effectively disabled. I started at 35 psi and it helped a little but wasn't doing much, I bled some off and now it works great. Haven't measured it yet but a guess would be about 25 psi. In a house well system, you set the accumulator pressure to just a couple of psi below the cut in of the pump, but on a variable speed pump there really isn't a defined cut in pressure. As I bled off pressure what I was looking for was I could open a faucet and run for a couple of seconds before the pump started to run.

 

[Boatcrazy]

What brand of accumulator do you find that gives enough capacity for flushes+hand washing...+a coffee? I'm assuming you're talking only about those accumulators with a bladder, and the biggest I've found is about a quart, give-or-take???

 

[Lou_tribal]

What brand of accumulator do you find that gives enough capacity for flushes+hand washing...+a coffee? I'm assuming you're talking only about those accumulators with a bladder, and the biggest I've found is about a quart, give-or-take???

I have a 5 gallon one aboard, I think it is a sale or something like that. Just need to be sure that it is for potable water as some are for heaters and not intended for potable water.

L

 

[Frosty]

I have a 2-gallon, due to space constraints (not a trawler). I started with a smaller one that came bundled with a Whale pump - I forget the size but it was probably 1/2 gallon or so. That wasn't useful for avoiding the pump coming on, for me.

With the 2-gallon, I can get a flush or two, and the corresponding hand washes. Or a reasonable amount of sink usage. That said, I'm not living like "at home" in water usage. More like ye old days sailboat-style conserving.

For more robust usage I'd think something like the 5-gallon mentioned above would be better.

 

[Lou_tribal]

This is the one I have
https://www.amazon.ca/gp/product/B002JEQGYO/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&psc=1

Cost me about 60 Canadian bucks at the time.

L

 

[RickyD]

I have the programable X-Caliber water pump. It is set for 60 lbs pressure. I have yet to set the cut in pressure as my accumulator died and I just kept running without it, although its a little annoying when you quickly turn the water on and off and then the pump runs for 15 seconds. After a couple years like this the pump started to make more and more noise while running. I just bought a new one with the accumulator from the same company so I can get back to normal. I'll rebuild the old pump and sell it as these things last a long time. When talking to the factory, they recommended the accumulator.

 

[Boatcrazy]

They all look like standard home accumulators, not marine.?? Makes good sense to go with a larger capacity and with a bladder, but I've been concerned about not using one rated/graded for marine use. Those of you that have the non-marine type....how long do they last? And corrosion concerns? Any other issues?

 

[Lou_tribal]

They all look like standard home accumulators, not marine.?? Makes good sense to go with a larger capacity and with a bladder, but I've been concerned about not using one rated/graded for marine use. Those of you that have the non-marine type....how long do they last? And corrosion concerns? Any other issues?

It is a tank with a bladder to pressurize water, not a safety device.
What would be the difference with a so called marine one? Corrosion resistance?
I am on fresh water so not sure in salt water but a tank should last some years before being rusty to the point to fail, and at 60$ when too old replace it and recycle the old one.

L

 

[captnhunt]

expansion tank

I would keep the tank and use it next time you replace the pump. I do not like variable speed pumps. The problem with them is you cannot hear them. If someone is taking a really long shower, you do not hear the pump cycle or if there is a small leak. It is hard to know if someone is using lots of water when you can not hear it. If you have huge tanks and a water maker this may be less important. I hate running out of water on a cruise.