accumulator tank size

[seattleboatguy]

I just got a new Jabsco 5 GPM fresh water pump, and I would like to add an accumulator tank, but I'm not sure which size I should get. They seem to vary from 0.7 quarts to 2 gallons. My boat is a 38' Marine Trader, and the pressure water system serves the galley and 2 heads (one of the heads has a shower). I have no direct hook-up to city water. Thanks.

 

[ranger58sb]

Our Jabsco pump PAR-MAX 4 4.3 GPM pump is meant to work with an accumulator (not all are). The accumulator is #30573-0000, capacity is 1L. Maybe that'll get you started...

Or the Jabsco tech, Paul Campagna, is very good about recommendations. Sorry I don't have his phone number on this computer... but you might find his name/contact info in posts by Peggie Hall (HeadMistress, PegHall).

-Chris

 

[Bacchus]

Accumulator tanks are like many other things... bigger is better. I doubt you will ever hear someone say they wish they installed a smaller one.
Their purpose is two fold...
1- prevent short cycling of pump. The larger the tank the longer the off cycle of the pump
2 - prevent hot/cold water temp variation when showering caused by pressure variation between hot & cold.
Best advice IMO is to put in the largest you can reasonably fit. I would say the benefit of the 0.7L one is minimal... 1 - 2 gal much better.
Above applicable to on/off pump controls but not applicable if pump is a variable speed one that is meant to eliminate the need for an accumulator.

 

[Larry M]

We have a 2 gallon tank. When the Jabsco tank failed we went to a plumbing supply store and bought an expansion/thermal expansion tank for less than $30 vs over $200 for the Jabsco. Other than the color and the pre-charged pressure there’s not much difference. You can adjust the pressure to match the pump. Most pumps cut on at about ~20psi.

https://www.supplyhouse.com/Amtrol-...FQiWJEtGxe9WtowS26MAf5pRZX_sNj_BoCY98QAvD_BwE

https://www.defender.com/product.jsp?id=121209

 

[jleonard]

We also have a 2 gallon.

 

[seattleboatguy]

We have a 2 gallon tank. When the Jabsco tank failed we went to a plumbing supply store and bought an expansion/thermal expansion tank for less than $30 vs over $200 for the Jabsco. Other than the color and the pre-charged pressure there’s not much difference. You can adjust the pressure to match the pump. Most pumps cut on at about ~20psi.

Do you ever need to use some sort of pump and pressure gauge to eventually get the accumulator tank back to the proper pressure, or is this an "install it and forget it" kind of device?

 

[Larry M]

Do you ever need to use some sort of pump and pressure gauge to eventually get the accumulator tank back to the proper pressure, or is this an "install it and forget it" kind of device?

Pretty much set and forget but maybe once a year I'll check the pressure with a tire gauge. They all come with a bicycle schrader valve. We use a tire gauge to check the air pressure after we first bleed off the water pressure. Turn the domestic water pump off then turn a faucet on. Once the water stops, check the pressure. To adjust the tank pressure, I use a hand held bicycle pump.

 

[Xsbank]

Irrigation shops have a large selection of reasonably-priced accumulators that will be just as good as a Jabsco or Groco. Another “marine” ripoff. I have had non-marine for 5 years with no issues.

 

[HopCar]

Which Jabsco 5 gpm pump didn’t you get? The 42755 series shouldn’t be used with an accumulator tank. It’s a variable speed pump and an accumulator tank seems to confuse them.

 

[C lectric]

To check which pump you bought turn on the system, open a tap and let the water run so the pump turns on. Then listen and if the pump slows but continues to run at a slower speed to adjust to the lower volume then the accumulator may not be a good idea as Hopcar said.

If the pump simply turn off fully and then on fully in cycles then an accumulator will work. The air pressure for a discharged, no system pressure, should be about 2PSI less than the restart pressure of the pump, likely 20psi, so charge the bladder to 18.

Or of course check the model number and ask the Jabsco vendor. Actually your manual, such as it is , should tell you to not use an accumulator if it is a problem but a tel. call would settle the question.

If the pump start setting is higher then adjust a bit but maintain the acc. pressure somewhat lower by 2 - 3 psi.

I check my 1 gal. unit yearly when I recommission from winter. It usually has not changed much if at all. I too use a bicycle pump as needed.

 

[kchace]

I bought a Watts 2 gallon potable water expansion tank for $38. Seems to be a good size for the boat.

Ken

 

[catalinajack]

Do you ever need to use some sort of pump and pressure gauge to eventually get the accumulator tank back to the proper pressure, or is this an "install it and forget it" kind of device?

It is most definitely not "install and forget". The tank must be pressurized to 2 PSI below the cut-in pressure of whatever pump you are using.

 

[sledge]

If i could revive this topic briefly, and yes a brief TF search shows the many threads on this and contributions from all of you that have experience with the pump/tank combinations.
If one has a basic pump and no tank yet, it looks like we have two choices: 1) Use a fixed speed pump and add an accumulator pressure tank... or
2) upgrade to a variable speed pump
It looks like most of you went with a pressure tank. Is this due to the cost of the variable speed pump or can anyone comment on the tradeoff between these two options?

 

[rslifkin]

I tried a variable speed pump at one point and found them to be rather unreliable (controllers failed frequently). I've read other similar accounts. So I think the preference for fixed speed + accumulator is based on reliability rather than cost.

 

[Larry M]

I went with reliability and cost. A spare pump was cheap and easy to replace if it failed while away from the dock. If the pump died, it took 15 minutes to swap out with the spare.

 

[Shifty]

We use two pumps in an active/active configuration with an accumulator tank. This allows us to run multiple faucets without loss of pressure and to have some redundancy if one pump fails.

Edit: Apparently I can embed photos with Amazon photos. So here's a link.

 

[STB]

When my pumps (or accumulators) have failed, I've just gone old school and replaced them with like kind. I don't claim to have made the correct decision or for the correct reasons.

I did what I did because of inertia, simplicity, and cost, in that order.

If the boats would have had variable pumps, I'd have just replaced them with vaiable pumps rather than add an accumulator. At least unless the variable pumps actual became a problem point. But, given that they didn't, I just stuck with what worked.
The accumulator provides the variable flow, so an electro-mechanical control system doesn't need to.

I'm also not a fan of turning things that play with or near water into computers unless needed. I'm sure it is perfectly fine and the controllers are sealed up well, etc. But, it just seems too east for a seal to vibrate lose, dry out, etc, and then become a problem when I spill water on it changing a filter or something.

Also, if something mechanical breaks, there's often a way to do something to make it go underway. I've sealed old gaskets, epoxied cracked things, etc. But, if an electronic component goes bad -- I just don't keep a ton of those aboard.

Lastly, given two levers, and no reason to spend more, I'll spend less.

But, again, I'd have thoguht more about it....but between inertia and price, performance would have had to be significantly better.

 

[caltexflanc]

We really liked having two water pumps, an AC shallow well pump and a DC GalleyMaid. Both very heavy duty and robust and great redundancy. They shared the same Well-X-Trol tank; each had its own pressure switch. Household grade water pressure consistency. You could have all three showers, the clothes and dishwashers, and a hose running all at once.
BTW, that canister downstream was empty, you want filters after the pumps, with a just a screen near the tank to catch any debris.

 

[sledge]

Thanks, good thoughts! one thought I had (like Gkesden) is to keep it simple and go back with something similar. maybe my only issue was that it seems to cycle quite a bit while a faucet is open but hey its a Johnson WPS 5.0 and has run for about 10 years so thats not too bad.
If i went with the newer comparable Johnson it is a 5-chamber diaphragm unit so it might run well on its own without a tank......

 

[Playin Hooky]

It is most definitely not "install and forget". The tank must be pressurized to 2 PSI below the cut-in pressure of whatever pump you are using.

I have an accumulator tank, but the pump started cycling under low volume load recently. Do you know the cut-in pressure of a Shurflo 3.5 gpm or a good place to start for pressure in the accumulator tank? I can't find cut-in pressure specs online for the pump.
Thanks

 

[AlaskaProf]

My fresh water system came with the boat, works well and I haven't paid much attention until recently.


In the lazarette, I have one of the two gal. blue tanks you can buy at Home Depot. I assumed that was the whole deal until recently I heard a gush of water and discovered that I also had a failed one liter crappy plastic Jabsco accumulator in a locker in my aft head (!) downstream from the pump and check valve.



Shut off the pump; sat and stared at the system for a while. Forty years ago, this would have been a "cigarette moment." Said to myself, "Self, why two accumulators in series?" "Beats me, Boss, let's just remove the broken one and join the hoses."


So, I did, and it works just fine, EXCEPT: Now, at irregular intervals from ten minutes to maybe three hours, the pump will "bump". Not even a short cycle, just, "bump" and off again. Short run solution is to turn it off at the breaker overnight and ignore it the rest of the time. (...and yes, the first morning, I did have a very short shower.)


I would suspect the check valve except for two things:


It is a brass item of obvious quality, though uncertain age.


The only change I've made is removal of the 1 liter Jabsco. Is it possible that the system needed that component?


Class, your responses...

 

[seattleboatguy]

I have an accumulator tank, but the pump started cycling under low volume load recently. Do you know the cut-in pressure of a Shurflo 3.5 gpm or a good place to start for pressure in the accumulator tank? I can't find cut-in pressure specs online for the pump.
Thanks

I had a similar question. The way I figured it out was to put an air gauge on the tank and then slowly bleed off the pressure until the pump came on.