Best (functional) location for accumulator tank?

[14apex]

I'm about to install an accumulator tank in my '14 Apex QBS. In previous RVs I've seen the little tanks installed inline just after the water pump. While I'd like to install it there, there just isn't room to "comfortably" get it in there (pump/plumbing all practically "hidden" in a small closed compartment, behind the potty & almost inaccessible!!). What if I install in the cold line, under the bath sink? Will it function similarly as if it were "upstream" & nearer to the pump outlet? It seems to me that this should be a no-brainer...but, I can't seem to get my no-brain to decide if it'll work and may well not matter where it is, as long as it's inline? Thanks for any experience/expertise-sharing!

[DougW]

It will work if it is not right next to the pump, it may not work quite as good but it will still serve it’s purpose as long as it is on cold water line.

[joshuajim]

Water is not compressible. Only the air in the tank is compressible. Put it where ever you want and it will work exactly the same.

[14apex]

Thanks for replies! We've had an inline accumulator in last RV and we do boon dock occasionally, using shower, etc.. In comparison to one we had without, an accumulator sure seems to make the pump do less "work", not pulsate, sound better and keeps pressure good and constant. It made sense to me that it should function anywhere in the (cold) line...but I just wasn't certain. As soon as Amazon gets it here, in it goes as we "ready for spring"!

[BehindBars]

I had a little mini football sized accumulator next to the water pump in my previously owned class C. It worked fine.

In my new Sunseeker, I just installed a 2 gallon well pump tank in the kitchen cabinet next to the water heater, connected to a cold water line that was passing right by. There was not enough room for the accumulator tank near the pump. I haven’t full tested it yet but I’m hoping it will work well. It is probably 10 feet from the water pump.

The way I see it, at slower water flow rates, the pump and the accumulator will alternate in supplying water to a faucet. When the source switches from pump to accumulator or vise versa, then depending on the faucet location, there may be a reversal in the water flow direction in some piping. I expect this flow direction change will go unnoticed and have no impact on the water flow at the faucet.

Wherever the accumulator might be located, you’ll want to be sure it doesn’t leave a dead end water line that can’t be easily drained or winterized (if you store or camp in freezing weather). In my case I added a dedicated valve and drain line coming off the pressure tank and draining below the floor. If your accumulator is small and tees in closely with an existing water line, that shouldn’t be a problem.

[Alloutdrs1]

Originally Posted by 14apex

Thanks for replies! We've had an inline accumulator in last RV and we do boon dock occasionally, using shower, etc.. In comparison to one we had without, an accumulator sure seems to make the pump do less "work", not pulsate, sound better and keeps pressure good and constant. It made sense to me that it should function anywhere in the (cold) line...but I just wasn't certain. As soon as Amazon gets it here, in it goes as we "ready for spring"!

Sure does make a huge difference when having to use the pump and fresh water tank. Well worth it modification, I was lucky enough to have room where the pump is located for install.

[Wolf26]

I installed mine in the under the bed storage area. The water heater is in the basement storage area which connects to the bed storage. Tee'd into the cold water line & works great. Pump doesn't run every time you turn on a spigot.

[markb422]

I have installed an accumulator tank in every rv we have owned as a first mod. In our current rv I installed two, two gallon well tanks. Thought if one is good two is twice as good. The main reason I installed them is so we can turn the pump off at night. If someone gets up to go, they can flush without needing the pump. I get up early and she likes to sleep in so I can make coffee and rinse dishes in morning also. The pump is located under the bed.

[14apex]

Originally Posted by markb422

I have installed an accumulator tank in every rv we have owned as a first mod. In our current rv I installed two, two gallon well tanks. Thought if one is good two is twice as good. The main reason I installed them is so we can turn the pump off at night. If someone gets up to go, they can flush without needing the pump. I get up early and she likes to sleep in so I can make coffee and rinse dishes in morning also. The pump is located under the bed.

...so, these are the regular "well" type accumulators (some are blue in color, as I recall?). I'm a "more is better" sort, too, and may just go this route...IF I can spare the room for install.

[BehindBars]

If you want ideas (good ones and bad ones), here is a picture of my 2 gallon tank installation in a kitchen cabinet next to the water heater.

I teed into a cold line at the top rear in the picture. A valve follows from there so I can isolate the tank from the system. The pressure gauge was added for fun. The valve at lower right drains the tank and pipes though a tube going through the floor for winterizing. I have an extension hose for the hidden tank Shrader valve that’s routed around and is accessible by removing the drawer on the right.

A question for others that have installed the 2 gallon tank(s): What precharge pressure are you running?

[14apex]

Originally Posted by BehindBars

If you want ideas (good ones and bad ones), here is a picture of my 2 gallon tank installation in a kitchen cabinet next to the water heater.

I teed into a cold line at the top rear in the picture. A valve follows from there so I can isolate the tank from the system. The pressure gauge was added for fun. The valve at lower right drains the tank and pipes though a tube going through the floor for winterizing. I have an extension hose for the hidden tank Shrader valve that’s routed around and is accessible by removing the drawer on the right.

A question for others that have installed the 2 gallon tank(s): What precharge pressure are you running?

Wow -- super neat installation! The gauge is a nice feature, too! I can't quite see the drain valve exit -- will it drain completely for winterizing, or will you leave some antifreeze in it? I like it...gonna remove a "baffle" in that area to see if I may have room for it. Thanks for the pic.

[markb422]

The tanks I have look just like the one in the photo I bought from a home improvement store. They come pre-charged with pressure behind the diaphragm at about 15 psi. I had to experiment with the pressure to find the best pressure to set. If you leave it at 15 psi the pump will switch off when there is less than a gallon or so in the tank. With one tank I think I set the pressure around 7 or 8 psi for the most volume and still have good pressure. I ran the pump until it shut off, then turned it off. I used the kitchen faucet and a gallon jug to measure water volume. With the two tanks I had to decrease the air pressure down to around 5 psi to get the most volume and still have good water pressure for the shower.
You can install the tank/tanks anywhere on the pressure side of pump in the cold water system. So if you wanted to, and have the room, you do not have install both in the same location.

[BehindBars]

Originally Posted by 14apex

Wow -- super neat installation! The gauge is a nice feature, too! I can't quite see the drain valve exit -- will it drain completely for winterizing, or will you leave some antifreeze in it? I like it...gonna remove a "baffle" in that area to see if I may have room for it. Thanks for the pic.

Thanks for the kind remarks!

When I looked at the pre-pressurized tank before installation, the internal diaphragm or bladder appeared to be right against the exit hole, as if it would have zero water in it if allowed to empty against atmospheric pressure. So I’m hoping the tank will completely drain in the horizontal position when I want it to, for winterizing. Worst case, I could cycle some antifreeze through it once or twice and be assured it would not freeze up. I would have liked to have installed the tank vertically, but there wasn’t enough space.

The riskiest part of the installation was drilling through the floor for the drain pipe. I tried and tried, but couldn’t get an exact pinpoint as to where the hole would end up underneath. There was some underbelly steel framing right nearby but I lucked out and the drain pipe just cleared the steel.

[BehindBars]

Originally Posted by markb422

The tanks I have look just like the one in the photo I bought from a home improvement store. They come pre-charged with pressure behind the diaphragm at about 15 psi. I had to experiment with the pressure to find the best pressure to set. If you leave it at 15 psi the pump will switch off when there is less than a gallon or so in the tank. With one tank I think I set the pressure around 7 or 8 psi for the most volume and still have good pressure. I ran the pump until it shut off, then turned it off. I used the kitchen faucet and a gallon jug to measure water volume. With the two tanks I had to decrease the air pressure down to around 5 psi to get the most volume and still have good water pressure for the shower.
You can install the tank/tanks anywhere on the pressure side of pump in the cold water system. So if you wanted to, and have the room, you do not have install both in the same location.

That’s very helpful information. Thank you.

I wish I knew what the set points are for the pump’s pressure switch. I guess with the pressure gauge I installed, I figure it out. I’ll be using this tank for the first time in a couple weeks.

[DRiveWell]

You don't need to drain ALL the accumulator's water for winterizing. The bladder will absorb the expansion of the remaining freezing/thawing water. Don't leave the ball valves "closed" however, as these will break from the water trapped in the ball.

[14apex]

Originally Posted by DRiveWell

You don't need to drain ALL the accumulator's water for winterizing. The bladder will absorb the expansion of the remaining freezing/thawing water. Don't leave the ball valves "closed" however, as these will break from the water trapped in the ball.

Good info. & makes sense. As simple (relatively) as these accumulator tanks are, it's taken a bit for me to wrap my simple brain around them. All of the experience, pics and info. already shared here has really helped. What a wealth of very useable(!) information we all have "here"!!

[BehindBars]

Originally Posted by markb422

The tanks I have look just like the one in the photo I bought from a home improvement store. They come pre-charged with pressure behind the diaphragm at about 15 psi. I had to experiment with the pressure to find the best pressure to set. If you leave it at 15 psi the pump will switch off when there is less than a gallon or so in the tank. With one tank I think I set the pressure around 7 or 8 psi for the most volume and still have good pressure. I ran the pump until it shut off, then turned it off. I used the kitchen faucet and a gallon jug to measure water volume. With the two tanks I had to decrease the air pressure down to around 5 psi to get the most volume and still have good water pressure for the shower.
You can install the tank/tanks anywhere on the pressure side of pump in the cold water system. So if you wanted to, and have the room, you do not have install both in the same location.

I looks like with your routine, what with shutting the pump off over night, your goal is to get maximum water volume into the tank first. I can see how the low tank charge pressure would do this.

For me, using the tank as an accumulator with the pump switch always on, I expect some point of higher tank pressure would maximize the time between pump cycles, which is my goal. I won't be shutting the pump off overnight.

I guess I'll start with the charge pressure at 2 PSI below the pump turn on point, as is apparently suggested for most well tanks, but I'll keep your experience/findings in mind. Thanks for posting!

[SailorSam20500]

My understanding is that RV water pumps generally have open flow operating pressures of about 55 PSI and have a start limit switch setting of about 40 PSI. From a Shurflo Revolution pumps have shut offs of 50-55 PSI.


My 2 gallon Water Worker tank came pre-charged at 38 PSI. I have not changed that setting.

[SeaDog]

Something I did when I installed my accumulator was to place a stop valve at the outlet of the accumulator so that when I winterize I don't put antifreeze into the tank just something to consider when you install. Mine is a 2 gal tank

[markb422]

Originally Posted by SeaDog

Something I did when I installed my accumulator was to place a stop valve at the outlet of the accumulator so that when I winterize I don't put antifreeze into the tank just something to consider when you install. Mine is a 2 gal tank

I did the same thing so I can isolate the tanks from the system if I want to shut the water off to work on the plumbing or something. Without the ball valve I would shut off the pump and have to wait for the accumulator tanks to empty. That was losing water and putting extra water in the gray or black tank.