Fresh Water Accumalator

[Jaybeaux]

In my view, yes. The purpose of the accumulator tank is to reduce the pressure "slams" when you open the faucet and the pump comes on or in reverse when you close the faucet. Ever been to someone's house where you shut off the water, the pipes go "clunk"? That's what the bladder in the accumulator prevents. On the hot side, it also gives some volume for the hot water to expand into without raising the pressure on your hot supply too much.

Jaybeaux

 

[bbwhitejr]

So i installed the accumulator tank this weekend, similar as described above and set the psi to 42. Can't say i'm very impressed as it only gave me a little bit of time when opening a faucet before the pump kicks in. I want to say it kicks in about 7 seconds of opening a faucet and every time we flush one of the toilets. Is this expected?

2 gallon tank?

I have not measured the time, but I know I get more than a toilet flush and more like 3-4.

I will time mine this weekend.

What size pump do you have(gpm)?

Bennett

 

[Blueone]

Accumulator Tanks
An accumulator tank is an important part of any pressure-controlled water system. Fitted close to the pump discharge, it acts as a pressure buffer, absorbing flow from the pump when demand is low, and smoothing the outlet pressure. By removing the need for the pump to run immediately an outlet is opened, it extends pump life and reduces battery drain. The larger the accumulator tank, the less often the pump has to start.

The larger tanks have an appreciable water storage capacity - approximately half the nominal tank volume. The larger your pressurised system, or the higher the demand for water, the larger the accumulator tank should be. For minimum wear and tear on your pump, fit the largest accumulator tank you can.

Accumulator tanks are also used as expansion vessels in conjunction with water storage heaters.

https://www.jabscoshop.com/advice-and-support/jabscoshop-about-pressurised-fresh-water-pumps.htm

 

[Irie308]

I'll have to check the pump as it seems it was replaced. No issues with flow our pressure however I never liked that the pump kicked in as soon as your cracked a faucet or flushed the head. I do appreciate that you can wash your hands without the pump cycling but wanted to get rid of it cycling with every flush.

 

[Woody]

So i installed the accumulator tank this weekend, similar as described above and set the psi to 42. Can't say i'm very impressed as it only gave me a little bit of time when opening a faucet before the pump kicks in. I want to say it kicks in about 7 seconds of opening a faucet and every time we flush one of the toilets. Is this expected?

At what pressure does your water pump kick in? The accumulator air pressure shouldn't be higher than that. The water system must be de-pressurized before you can set air pressure in accumulator.

 

[Jaybeaux]

I was going to dazzle all of you with a bunch of Ideal Gas Law calculations (pV=nRT) and the fact that water is an incompressable fluid,and the amount of water that will flow before the pump kicks on is in fact quite small.....From Woody's comment above it doesn't take a lot of water flow out of the spigot for the pressure on the air side to reduce to equilibrium ($3 word) and then drop below the Fresh Water Pump "turn on" pressure. I'm amazing.

Jaybeaux

 

[bbwhitejr]

When we bought our boat, the FW pump was a Rebel 5.5gpm. It came on and off and ran whenever any kind of water was called for. Never any hammering or cutting off/on, it just ran.

Fast forward 18 months and after replacing the pressure switch, the pump would not always come on and pump water. I replaced it with a Jabsco 6gpm. It would cut off/on very rapidly anytime water was called for from one outlet. Turn on 2-outlets and it would just run with terrific pressure. The “off/on hammering stuff” would self destruct the pump. Research told me to install the tank. I did just that as close to the pump as I could get it. The pressure is better than the dock water. No more hammering, etc. I will time it this weekend. The only con was I have had some more leaking fittings that I have replaced as I find them.

Bennett

 

[Woody]

I was going to dazzle all of you with a bunch of Ideal Gas Law calculations (pV=nRT) and the fact that water is an incompressable fluid,and the amount of water that will flow before the pump kicks on is in fact quite small.....From Woody's comment above it doesn't take a lot of water flow out of the spigot for the pressure on the air side to reduce to equilibrium ($3 word) and then drop below the Fresh Water Pump "turn on" pressure. I'm amazing.

Jaybeaux

If the accumulator bladder is properly charged, lets say 30lb, and the pump kicks in when water pressure drops to 30lb, the accumulator would be empty of water. The pump would pump water until it pressurized the water side, including the accumulator, to whatever the high limit water pressure setting would be. If the setting was 50lb the pump would pump until the water side and accumulator air side would be 50lb. The amount of water that could be drawn out before the water pressure reaches 30lb and the pump kicks in would be determined by the accumulator size.

 

[techmitch]

I was going to dazzle all of you with a bunch of Ideal Gas Law calculations (pV=nRT) and the fact that water is an incompressable fluid,and the amount of water that will flow before the pump kicks on is in fact quite small.....From Woody's comment above it doesn't take a lot of water flow out of the spigot for the pressure on the air side to reduce to equilibrium ($3 word) and then drop below the Fresh Water Pump "turn on" pressure. I'm amazing.

Jaybeaux

Old hat man!

 

[techmitch]

Old hat man!

Oh, and size matters.

 

[Irie308]

Checked the specs on the pump and its as follows: 5 GPM at 55 psi. I don't recall if i pressurized the accumulator tank before I turned the pump back on to the water system so will check that. Since my pump is 55 psi based on what Woody stated above I did some research and there is a formula based on the cut out psi of the pump which determines what the pressure should be set to on the tank. I'm going to see what my cut out psi is.

 

[Irie308]

So read up on my pump and found I needed to set the tank pressure to 2-3 psi below the cut out pressure of the pump. From what I have read that’s about 30 psi so I set the tank to 27 psi. Now I can run the faucets for about 48 secs before the pump kicks in and multiple flushes of the head with no cycling. Pressure is also very good.

 

[bbwhitejr]

So read up on my pump and found I needed to set the tank pressure to 2-3 psi below the cut out pressure of the pump. From what I have read that’s about 30 psi so I set the tank to 27 psi. Now I can run the faucets for about 48 secs before the pump kicks in and multiple flushes of the head with no cycling. Pressure is also very good.

Great! That’s more like it!

Bennett

 

[wyrman]

I installed the two gallon tank on my RV today, I know it's not a boat, but it all works the same.
I have a Shurflo 2088-403-144 pump, it has a 45 psi shut off, but I can't find the psi that it kicks on at.
Any ideas on how to go forward?
I don't know if it matters or not, but I 90'd out of the tank and put the T in right after the pump output.
Right now the tank isn't helping at all.

 

[wyrman]

I found the info on my pump. I kicks on at 25 psi, +- 5 psi. Going on that, I'm thinking I should have 23lbs in the accumulator tank. Does that sound right?

 

[wyrman]

So I answered my own question. I set the tank at 23lbs and it works great.
I can now run the faucets for quite a while without the pump kicking on.
I had to take the mounting bracket off because of the space I had to mount it, so i screwed a couple of clamps to the floor.
I straightened up the clamp after I got things working.

 

[douglee25]

I installed this accumulator over the weekend. Not a bad unit for the price. Definitely supplies much more even water pressure now. No more cycling!