Pump Silencing & Accumulator

[Vintage465]

So I got all my stuff together to quiet the pump down and smooth out the flow. The little ShurFlo accumulator tank is pumped with 40 psig of air. It is hooked up to the pump with 1/2"X36" flexible hose with 1/2 Female Pipe Threads(FPT), and from the accumulator tank to the Pex with another 1/2"X36". The accumulator accepts 1/2" FPT, the pump accepts 1/2" FPT and the Pex water line accepts 1/2 FPT. That made it easy to hook up. I could have used a shorter flex line for the hook up but I figured the total 6' of soft pipe would dull the pump.


To further help take the harshness out the pump running I glued(PL-400 subfloor glue) a piece of 1/2 wood to a 1" thick piece of ergo-mat the screwed the pump to the wood, then glued it to the floor with a dob, 'bout the size of a quarter of the PL400 on each corner of the ergo-mat. That way if I had to, I could get it back off.

This little mod really made a difference. The pump is not silent, but is very quiet. The water flow is real steady even on low flow. the water that comes out of my filter faucet(dual stage under-sink)is much more steady too. When I ordered my accumulator tanks, my intention was to install one just like you see and the other one downstream of the under-sink filter to help out the flow with that little dude. Not really sure I need it now. I have a pretty good amount of room under the sink, behind the drawers and around the water heater. So I may just put the other one on the "shelf of things to do" and install it later on. I would be real easy to install it if I get around to it. It would be equally easy to yank it if it doesn't work out.

[Dusty_R]

I've done that also. Now the pump does not run every time the toilet is flushed.

[Vintage465]

Wow! As I was scrolling thru the topics I see this post.......thinking, that's just like the post I did years ago! Still working perfectly at nearly six years, never check or adjusted pressure. Still a nice even, non pulsing flow at low volume settings on the faucet.

[deltabravo]

HOLY THREAD RESURRECTION BATMAN!
Someone revived this 5 year old thread.

It has good info though, so I might as well add to it.

I've been using accumulator tanks in all my RVs since 2004 or so.
It evens out the flow of water on low flow situations and prevent the pump from constantly cycling on/off/on during low flow.

I also added some pipe insulation to quiet my water system.

Quieting my RV Water System with foam pipe insulation

[EMD360]

I replaced an old accumulator with a one gallon in our old RV. The pump was already nicely isolated. I’ve been thinking about installing it in our new RV. The pump is really loud when it runs. This 25b is closer to total weight though and the tank would be on the rear axle. So using the little one again seems to make sense. I have a lot of projects one winter is over!

[profdant139]

Very nice job on the installation, and a good write-up, too!

I've found that after taking my trailer to high elevations (above 9000 feet), the accumulator sometimes loses pressure and does not function properly. So I bring a small bicycle pump with us. It is easy to restore the pressure to 30 psi (which is the recommended psi for our very small accumulator).

[Bobbo]

At, or possibly 1 PSI higher than, the pump cut on pressure. If you go less than the cut on pressure, the accumulator will not completely empty so you are reducing its effective volume.

[Boon_Docker]

Sunbrook279 wrote:
I have ordered an accumulator. Should its pressure be higher or lower than pump pressure? Im guessing higher? thanks for inputs!

The accumulator pressure should be set at the same PSI as the pump start up pressure.

Example: If pump starts at 30 PSI then set the accumulator pressure at 30 PSI.

[Sunbrook279]

I have ordered an accumulator. Should its pressure be higher or lower than pump pressure? Im guessing higher? thanks for inputs!

[Vintage465]

time2roll wrote:
Looks great. I mounted mine on some closed cell foam used for shipping.

If those flex lines rub on anything consider some foam pipe insulation to wrap them. Provides a cushion to prevent vibrating against a sounding board.

I fastened the flex with the "mountable zip-ties". Just went out and listened to it again..........real quiet and smooth. Can't imagine why I would need it any quieter.

[time2roll]

Looks great. I mounted mine on some closed cell foam used for shipping.

If those flex lines rub on anything consider some foam pipe insulation to wrap them. Provides a cushion to prevent vibrating against a sounding board.

[Dutch_12078]

The water in the tank is under pressure from the compressed air in the tank's bladder. As water is drawn by the system, the water in the tank is pushed out by the pressurized bladder until the line pressure drops below the pump cut-in setting. At that point, the tank should very nearly empty of water. When draining the system for winterizing, repairs, etc, the tank will completely empty of water.

[Vintage465]

DrewE wrote:

Vintage465 wrote:

Vintage465 wrote:

mbopp wrote:
Nice job! That pump should be real quiet. I had the room so I installed a 2-gallon residential expansion tank.

I have actually thought about using the larger accumulation tank, but in reality for our use I think the larger tank would be overkill. However, if we actually started using our shower for something other than storage and a coat rack...........this could be logical.

Furthering that thought...........A two gallon tank would add two gallons of fresh water capacity...............

It adds to the total capacity, yes, but not as much to the (easily) usable capacity. I don't know offhand if accumulator tanks are usually specified based on their total volume or on the nominal water volume--I would suspect the former, in which case some portion of the whole must be reserved for the air to pressurize the tank. The usable increase in water capacity would be the difference between the "full" water capacity and the "empty" water capacity at whatever pressure you deem to be the lowest practical pressure for the water system.

It's somewhat akin to how a six gallon water heater tank increases the fresh water storage capacity of an RV by six gallons, but it doesn't really mean you have six more gallons of water you can use before refilling (unless you pull the water heater drain plug to collect water for the last several toilet flushes).

Yes I see your point............Unless you mounted it upside down like my little one is. Seems to me it would drain or be pushed right out into the water system.........right?

[Sam_Spade]

Vintage465 wrote:

Furthering that thought...........A two gallon tank would add two gallons of fresh water capacity...............

Yes but once you get your pump quiet, it would add virtually nothing else really useful. Who cares if the water flow varies a bit when you are washing your hands ? Or doing anything else for that matter.

And as Drew pointed out, it would not be USABLE capacity. It would be 16 pounds of extra weight that you would be carrying around all the time though.

[DrewE]

Vintage465 wrote:

Vintage465 wrote:

mbopp wrote:
Nice job! That pump should be real quiet. I had the room so I installed a 2-gallon residential expansion tank.

I have actually thought about using the larger accumulation tank, but in reality for our use I think the larger tank would be overkill. However, if we actually started using our shower for something other than storage and a coat rack...........this could be logical.

Furthering that thought...........A two gallon tank would add two gallons of fresh water capacity...............

It adds to the total capacity, yes, but not as much to the (easily) usable capacity. I don't know offhand if accumulator tanks are usually specified based on their total volume or on the nominal water volume--I would suspect the former, in which case some portion of the whole must be reserved for the air to pressurize the tank. The usable increase in water capacity would be the difference between the "full" water capacity and the "empty" water capacity at whatever pressure you deem to be the lowest practical pressure for the water system.

It's somewhat akin to how a six gallon water heater tank increases the fresh water storage capacity of an RV by six gallons, but it doesn't really mean you have six more gallons of water you can use before refilling (unless you pull the water heater drain plug to collect water for the last several toilet flushes).