Anybody know about Accumulator Tanks?

Medskipper

Medskipper

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I have a crack in mine and I need to replace it. It is a 1ltr plastic type accumulator.

Just looking at a few web sites and the funny thing is the 2ltr metal accumulator tanks are far cheaper than the plastic 1ltr tanks. Also it is stated that the 1lt tank is ok up to 2 outlets. My boat has four outlets although it would be very rare that more than two were being used at any one time.

I know they help to smooth the flow, but do they do anything else, like help to raise the pressure in the system? I have felt for a while now that my pressure was not great from the taps, but it may be the crack has been there a while and I have been losing pressure without really knowing.

I have room enough for the 2ltr tank, so is it best to have a larger accumulator tank rather than the small one? metal vs plastis? etc.

Any experts out there on domestic water supply on boats?

All helps gratefully received

Barry
 
The bigger the accumulator tank the better, obviously subject to the space you have. The reason is that water pumps are 'lifed' on the number of cycles. The fewer the cycles the longer the pump will last.

Pressure is determined by the pump/pressure switch - it's typically 20lbs for yachts. Keep in mind to check the pressure in the bladder inside the tank, needs a car tyre pressure gaugue. Check the pressure setting in the manual and try to keep the bladder at that pressure. Do not overinflate.
 
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Medskipper said:
I have a crack in mine and I need to replace it. It is a 1ltr plastic type accumulator.

Just looking at a few web sites and the funny thing is the 2ltr metal accumulator tanks are far cheaper than the plastic 1ltr tanks. Also it is stated that the 1lt tank is ok up to 2 outlets. My boat has four outlets although it would be very rare that more than two were being used at any one time.

I know they help to smooth the flow, but do they do anything else, like help to raise the pressure in the system? I have felt for a while now that my pressure was not great from the taps, but it may be the crack has been there a while and I have been losing pressure without really knowing.

I have room enough for the 2ltr tank, so is it best to have a larger accumulator tank rather than the small one? metal vs plastis? etc.

Any experts out there on domestic water supply on boats?

All helps gratefully received

Barry
Click to expand...

I have a two litre metal one on the boat and a 1 litre plastic one in the camper. Each has hot and cold at the galley and hot and cold in the heads, plus the camper has hot and cold shower supply. No problems with either of them, although the pump may run more in the camper. So long as the accumulator is big enough that the pump isn't running all the time through small leaks I don't see how it makes much difference to have a small one (accumulator, that is!)
 
I can't see any real differences in metal vs plastic tanks- you just have to watch the steel ones to ensure the paint's intact against rust. I would rather go with the 2l one, but why not "solder" the crack with a clean soldering-iron? The pressure's not very high, and then you could put a second hydrophore [jargonese!] in as well- giving you some sort of redundancy- arrange to chuck the repaired one when it finally gives out. If it's a pressurised tank, you may need to re-pressurise it with a mountain-bike pump- the schrader valve is like a MTB valve.
FWIW, one of my customers uses two 8-litre units on each boat, and he says they supply enough volume to brush your teeth without the pump cycling!
 
I had exactly the same problem as you a few years back. We were in Tunisia at the time and a replacement was difficult to source or very expensive to import. I just happened to be fibreglassing some lockers into the bilge so decided to key up the old accumulator and give it a few wraps of glass and resin. Turned out to be far stronger than the original so I still have that temporary bodge aboard three years later. Total cost zero which is my kind of price.

The problem with metal ones is that they have a rubber bladder inside which can deteriorate and require occasional replacement, plus they rust. The benefit of them is that they can be mounted in any orientation. You do have to get the pressure right with any pressurized vessel though, best to consult with the manufacturer. When I worked with (rather large versions) the rule was never more than 90% of pump maximum pressure.

The problem with the small plastic ones is that the plastic degrades and cracks (but you know all about that). They do not have a bladder but simply rely on the cushion of air trapped within them, this however means that they must always be mounted inlet at the lowest point. Plus generally plastic ones are quite small for a lot of applications.
 
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Be there several times and in the end got rid of them.
I went from the basic 1 litre plastic to the more expensive 1 litre plastic with the built in bladder, Complete waste of money.
As far as tap pressure goes I was getting less and less over time. I changed the taps and a humungous difference. Couldn't believe it. You now have to be careful when you turn on a tap. The shower on board is now terrific.
 
Get the biggest accumalator you can fit, get an industrial type pressure switch for the pump and bypass the one on the pump, set the pressure to the max on the pressure switch, as written on the pump, normally 2.8 bar, set the low limit to 2 bar, set the pressure on the diaphragm in the accumalator to 2 bar (the lower limit of the pressure switch). Bob's, yer mothers brother! This will smooth the flow and you will be amazed, believe me, I know a thing or three about boat domestic water supply.
 
>I have a two litre metal one on the boat and a 1 litre plastic one in the camper. Each has hot and cold at the galley and hot and cold in the heads, plus the camper has hot and cold shower supply.

I think you are talking about calorifiers not accumulators. Both are pressurised but a calorifier has a heating element and usually can be heated by engine water.

In both cases the less the pump cycles the longer it will last. As a general rule a calorifier can take a higher pressure than an accumlator but will work on the accumulator's pressure, assuming you are are feeding water from the accumulator to the calorifier (which makes sense) .

ccscott49 said use an industrial presssure switch, it is a good idea they last longer than boat pressure switches (as anything industrial does). Be careful though - check what pressure your pump can produce (which should be less than the tanks) and that the industrial pressure switch operates at that pressure.
 
I think you will find that pumping up the air pressure in the accumulator tank to the lower setting on the pressure switch will the reduce the function of the accumulator. Most domestic ones are set to 1.5 bar max on systems running at 2.5 to 3.5 bar.
A
 
DownWest said:
I think you will find that pumping up the air pressure in the accumulator tank to the lower setting on the pressure switch will the reduce the function of the accumulator. Most domestic ones are set to 1.5 bar max on systems running at 2.5 to 3.5 bar.
A
Click to expand...

Absolutely correct, which led me to re-read my own post in which I spotted a mistake. When I said 'the rule was never more than 90% of pump maximum pressure' what I meant to say was 'the rule was never more than 90% of pump cut-in pressure'.
 
>yes I really did mean accumulator tank and not a calorifier!

I'm intrigued. How do you get hot water from an accumulator tank which is designed to store cold water? You said you have hot water so you must have another way, on demand heater perhaps?
 
Pressure accumulator

Yes, we had a split in the plastic Jabsco one, too this year. And roughing it up and sticking a fibre tape/epoxy patch over it works just fine. We discovered it after mysterious water in the bilge and some unexplained pump cycling.

Re the aforesaid posting, the accumulator 'stores' pressurised water by means of the air cushion. This is normally in the feed to the cold water and to the hot water tank (calorifier), hence affects both hot and cold equally.

One of the posters must be very extravagant when he brushes his teeth!
 
accumalators

Mine is plastic but has a ball inside,so you dont need to pump up.my previous boat had one similiar for 10yrs and no probs.this one 8yrs and no probs.Cant remember make but if anyone interested can check.
 
KellysEye said:
>yes I really did mean accumulator tank and not a calorifier!

I'm intrigued. How do you get hot water from an accumulator tank which is designed to store cold water? You said you have hot water so you must have another way, on demand heater perhaps?
Click to expand...

I have a calorifier, I didnt say it stored hot water! the accumulator tank smooths out the flow on the domestic water supply and is in line before the calorifier, unfortunately it is split and needs replacing.
 
According to the paperwork which came with my accumalator, the diaphragm should be pumped up to the lower limit of the cut in (Downwest) on the ADJUSTABLE pressure switch (Vonasi). Mine is and the system works wonderfully, its an 11 liter accumalator.
You of course need a pressure gauge to adjust the switch. The max pressure of the pump, should be mentioned on the pump, however if its not, it's easy to find out, on google for your pump.
Sorry if I did not make it clear. ASAP supplies do an excellent industrial pressure switch.
The small spring is the high pressure cut out and the large spring is the low pressure cut in, that statement will become obvious when you open a presure switch.
 
CC, interesting, I did say that most of my experience was on domestic systems. The 24lt accumulators used on nearly all the smaller systems were labeled 1.5 bar max for prechargeing the air, and were supplied at that. And the working range was normally 2.5 to 3.5. The pressure switches were usually italian and the big spring set the upper limit while the smaller one set the differental between the upper and lower pressures. The odd boat one I've dealt with was much the same (but big boats)
A
 
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