Domestic water accumulator purging

[Skipper]

The accumulator very slowly gets saturated and loses performance. Tone of the system gradually changes, and then soon it accepts no pressure. System then runs straight off the pump. Those with accumulators know what I mean.
So about every 6 months, I disconnect the line-in at the base and drain it. Good as new. Not a technically difficult job but a pain to get hose off, little bit of knuckle skin, keep the draining/splashing water directed away from things, make sure reconnected hose doesn't leak, etc.

Well, I just discovered that running the tanks dry does precisely the same thing.
Air in the lines purges the accumulator.

I've run them dry before, but I guess never at a time when the accumulator was nearing service requirement, so didn't notice the change.

 

[dlochner]

Shurflo makes a nice pressure pump that does not require an accumulator tank and it is much quieter than those old pumps. SHURflo Aqua King II Fresh Water Pumps

 

[Gunni]

Turn your pump off, run the water pressure out at the tap and air-up your accumulator via the schrader valve to the recommended pressure matching your pump. If you don’t have a schrader valve and a bladder accumulator you need to change out. A “saturated” accumulator is ancient tech.

 

[Manly]

One possible explanation for what's going on is there is a hole (perhaps a small one) in the rubber in your accumulator. Over time the water would be getting through that hole in the rubber membrane into the "air" side of the accumulator. This would cause the accumulator to quit working after the air dissolves into the water, which it eventually does.

I guess that's what you mean when you say it's getting "saturated." I would say that the accumulator is not working correctly because it shouldn't get saturated.

Recently I purchased this 2 gallon one off Amazon for $44 and am happy with it so far:

https://www.amazon.com/Accumulator-...799&sr=8-2&keywords=2+gallon+accumulator+tank

I can run a tap on high about 20 seconds (low about a minute) before the pump kicks on.

 

[pateco]

Recently I purchased this 2 gallon one off Amazon for $44 and am happy with it so far:

https://www.amazon.com/Accumulator-...799&sr=8-2&keywords=2+gallon+accumulator+tank

I can run a tap on high about 20 seconds (low about a minute) before the pump kicks on.

Manly,

Where did you mount it on your H31?

 

[Manly]

@pateco, the water system is still a work in progress (ie I threw out the old hot water heater and haven't replaced it yet), but the accumulator is mounted behind the kitchen cabinet. See top-right in attached picture. I like that it is higher than the faucets so it has gravity working too.

I moved the fresh water pump underneath the aft berth.

 

[Manly]

@dlochner I have the Aqua King II pump. You're right that I think they advertise it doesn't require an accumulator for the pump. However, I found the accumulator is nice for me (to not hear it cycling so much) even if the pump is ok without it

One thing about accumulators is they mask a leak in the system, whereas without one if you hear the pump cycle regularly you know there is a problem. That's why I waited until all the plumbing was replaced (with PEX) before putting the accumulator in. I'm very confident there are no leaks now with the new plumbing.

 

[Skipper]

There are no leaks.
It is ancient tech. 1984 original. But it works great for smooth flow. Like a home faucet. Also you can run multiple fixtures for a short period with no fluctuation in either.
I doubt there's a hole in the diaphragm; it takes months to saturate. It's just old tech. Or there might be seepage in it but it's so slight that I don't care. It's always done this since I got the boat 7 years ago.
This post was just an info piece for others with accumulators that do this, I've read of a few here and elsewhere, that you don't need to drain it; just let the supply run dry before you refill.

 

[Manly]

Hey Skipper, sorry for jumping to conclusions! It must be designed that way.

 

[Maine Sail]

Accumulator tanks do not need servicing or draining, unless something is wrong, such as water on the wrong side of the diaphragham. They are very simple devices, though though they do have a fairly high failure rate...

 

[Skipper]

I don't think mine has a diaphragm. Like mainsail's pic.
It's a simple approx 1 liter canister is all.
From another forum someone posted: "As a liveaboard I used to go through a water pressure pump every 4 months or so. I added an accumulator tank and got 6 months or more yet, the tank had no bladder and under pressure would absorb the air pocket into the water in about 2 or 3 months so I got a tank with a bladder...got a year out of the pump."

This matches my observations, although I'm not a liveaboard, so I get 6 months or so out of the air pocket.
Also my pump is 1984 original and unfailing.
A jabsco diaphragm pump.

 

[Skipper]

Therefore, yes. It is designed that way.

 

[Skipper]

So the original post stands:
Those with accumulators, especially bladderless accumulators, can simply let the tanks run dry to purge, instead of draining.

The reason I am certain that there is no diaphragm is because if there were a hole in it small enough to take 6 months to put pressurized water on the wrong side of it, then why does the tank drain immediately and fully in 8 seconds? Like emptying a Coke bottle. Remedying the issue and returning performance.
This couldn't happen through a pin hole.

 

[dlochner]

Those with accumulators, especially bladderless accumulators, can simply let the tanks run dry to purge, instead of draining.

The only accumulators that I have seen have bladders in them. If yours doesn't have a bladdercould you explain how it works?

 

[Skipper]

The only accumulators that I have seen have bladders in them. If yours doesn't have a bladdercould you explain how it works?

It just holds it.
Get it? No bladder?

Ok. First you explain the pinhole theory, given the observations above.

The accumulator has air in it. Then introduce water into it from the bottom with pressure. The air compresses. Water does not. Open a faucet, the water escapes under pressure from accumulator air and from the pump. The combination smooths the delivery and reduces pump cycling. -I believe the real culprit to the air pocket getting saturated is air leaking out the top of the acc tank from the bleed screw.-
Mainesail's pic shows the concept. He describes a diaphragm but I don't see one in his pic.

Even with no diaphragm, the air stays on top in the tank. Diaphragms are likely there in others to combat the air leakage I have.

 

[dlochner]

Mainesail's pic shows the concept. He describes a diaphragm but I don't see one in his pic.

OK, that's how I thought it worked. There is usually a something that separates the water from the air pocket. On MS's drawing the black line inside the tank is the diaphragm. There are probably several ways to construct the bladder, however, basically it is like a balloon. As I understand it the bladder is usually some kind of stretchy fabric like rubber.

Not sure what is causing your problem, and I'm not sure what you mean by "The accumulator very slowly gets saturated and loses performance." What gets saturated?

I had an accumulator and the same Jabsco pump. They were acting up and he pump would start up in the middle of the night, so I took them out and put in the Shurflo. Works fine, more room in the cabinet, fewer connections, no noisy pump in the middle of the night. If the pumping mechanism fails it is a (relatively) cheap and easy fix.

 

[Skipper]

Not sure what is causing your problem, and I'm not sure what you mean by "The accumulator very slowly gets saturated and loses performance." What gets saturated?

The tank. As in full of water and no air. Maybe there's a better term for it.

The pump never comes on unless I open a faucet.

By the way I dug up a picture of the accumulator. It's a lousy picture of it since it's too far away. But it shows the outline. That's it there on the left in front of (technically aft of) the Racor.
The tank is sealed. Only openings are input, out, and the bleed screw on top.
Edit: Actually the in and out use the same opening on a T.

 

[Maine Sail]

If you actually have an "accumulator" tank that does not have a diaphragham or bladder then simply replace it with one that does. They can be had for $30.00 to $50.00 and take but a few minutes to install...

Most every brand of accumulator I know of, suitable for use on a boat, uses a diaphragham or bladder to keep air and water separate. What was going on 30 years ago in the boat building industry is anyone's guess.

Brands with bladders or diaphragms:
Jabsco
SUREflo
FloJet
Groco
Johnson
Whale
SEAFLO - Even the cheap $29.99 Chinese knock-off accumulators use a bladder these days.

 

[Skipper]

If you actually have an "accumulator" tank that does not have a diaphragham or bladder then simply replace it with one that does. They can be had for $30.00 to $50.00 and take but a few minutes to install...

Most every brand of accumulator I know of, suitable for use on a boat, uses a diaphragham or bladder to keep air and water separate. What was going on 30 years ago in the boat building industry is anyone's guess.

Brands with bladders or diaphragms:
Jabsco
SUREflo
FloJet
Groco
Johnson
Whale
SEAFLO - Even the cheap $29.99 Chinese knock-off accumulators use a bladder these days.

Thank you sir.

 

[TomY]

Shurflo makes a nice pressure pump that does not require an accumulator tank and it is much quieter than those old pumps. SHURflo Aqua King II Fresh Water Pumps

That's what I'll be getting when my present pump gives out. I've never used an accumulator tank on my boats with several pumps, and never missed it. The pump comes on when you open the tap and stops a second or two after you close it. Am I the only one that doesn't use one?