Tireman9

Pressure Accumulator?

22 posts in this topic

While I have a small Class-C, I find the water pump noisy. I installed a 2' x 3" closed end pipe on cold line is a space under kitchen sink as a pressure accumulator and it slightly decreased the cycling of the water pump. The volume it too small and I am wondering about having just air over water pressure accumulator.

I have found some commercial units with about about 1.3 Gal capacity and have figured out a location for mounting.

Thoughts?

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The first Class C coach we owned used a 25 gal. water tank and a small air compressor to force water to the shower and sink. Think one could install a similar system to supplement to water supply and limit the pump running time.

The size of the tank ? , but one built for holding water under pressure.

Air pressure would need to be set lower then the water pump pressure using a pressure switch (PPV) on the air pump circuit or an air tank. Add solenoid that opens to vent the secondary water tank when the water pump is running. Also think one would need to install a fluid sensor / float switch in the tank to close the vent valve and allow the water pumps internal pressure switch to turn off the water pump at its preset pressure level.

Some fine tuning would be required, but I think it would be doable.

Thing is you would still hear a air pump running if an air tank of limited size was used. One might be able to mount an air pump in a location that would not be as noisy inside the coach.

Rich.

PPV=Preset pressure valve.

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Tireman9,

I have had similar thoughts and questions. I have been thinking about putting in some type of accumulator. Not just because of the noise but also to keep the pump from short cycling when I use a small amount of water or use water at a slow rate.

I hope your post generates some thoughts/ideas/replies as I would like to see them also.

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I think Rich is talking about a very different pressure system found on some old coaches where they used an air compressor to pressurize the potable water system.

With your water pump- based system there are two things you can do-- with different results:

Add an accumulator with bladder. Set PSI at 2 PSI less than cut-in pressure for the pump. For many, that means setting it at 23 PSI with city water off, pump off and pressure bled off by opening a faucet. This will do little to change the noise level, but help a lot in smoothing out water pressure at the faucets. The accumulator is generally plumbed into the system with a "T" after the outlet of the pump.

To quiet the pump, one needs to have the pump attached to the plumbing with a length of flexible hose, NOT hard pipe. This is both on the inlet and outlet. If plumbed with rigid pipe, the pump noise is transmitted through the pipes. This can normally be done for around $10 worth of hose, clamp and barb fittings. In fact some pump manufacturers suggest this flexible hose installation in their installation instructions. As an alternative, sometimes using foam rubber around the hard lines will help absorb some of the vibration-- it will not be as successful as isolating the pump with flexible hose, however.

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Thanks for replies.

Already have the flex hoses on the pump but after re-building the pump & water inlet system due to rust of poorly painted metal parts and adding insulation around the locations where hard PEX lines touched the floor and some drain piping the noise is better.

I plan on adding more foam insulation to hard line that is laying of sub-floor under bathroom as the vibration is making the wood floor into a large sounding board.

Looking at THIS tank

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Roger,

That one will work just fine-- a little large in terms of storage space it will take, but will certainly do the job.

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Hi Tireman,

I had the same tank in an earlier installation. It worked fine and kept the pump from cycling each time we filled a glass of water.

To reduce pump noise further, we installed rubber pads under the pump's "feet" so any pump vibration would not transfer to the floor. That has also helped considerably.

Good luck,

Tim

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Wolfe10, thanks for the info. on how to set the pressure. Tireman9, thanks for the link. Shields, thanks for the verification that the tank works and gets the job done.

The fact that it "smooths" out the water flow so the pump doesn't cycle so often is exactly what I was trying to accomplish.

A follow on question. Since the tank in the posted link has a membrane between the water and the air, so the two can never mix, does it matter if the tank is mounted sideways instead of up and down? This would give more options for the mounting location.

Thanks again.

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The bladder-type accumulator tanks can be installed vertically or horizontally. Should be in their instruction sheet, both with the product and on-line.

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Blueflame,

Position doesn't matter. When the tank is empty the bladder will expand to take up the space where the water will be. When you turn on the pump or connect to city water it will compressed is the space is filled with water. When the water pressure reaches the preset shut off point then the pump will shut off. In our coach, we can get at least one and some times two flushes before the pump will start. I hope I explained this well enough.

One thing I have discovered is that sometimes when the city water pressure is not too high and we have left the pump on, it will take water from the tank and we will have an empty tank when we start to leave the site. I, fortunately, am able to look at our tank to see the level.

Herman

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I believe that there is a pump that is being made that has a pressure bypass within itself so that the pump always runs when water is needed. This would eliminate the need for an external tank, saving space, etc. I have been using a variable speed pump that when the volume of usage is low the pump runs slow.

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Wolfe10, thanks for the info. on how to set the pressure. Tireman9, thanks for the link. Shields, thanks for the verification that the tank works and gets the job done.

The fact that it "smooths" out the water flow so the pump doesn't cycle so often is exactly what I was trying to accomplish.

A follow on question. Since the tank in the posted link has a membrane between the water and the air, so the two can never mix, does it matter if the tank is mounted sideways instead of up and down? This would give more options for the mounting location.

Thanks again.

Might work but the in/out fitting is in the bottom or the curved bottom so mounting on side may not be best. I saw a video on how these tanks are made and the bladder is shaped to fit the bottom of the empty tank.

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All

While my coach is small at 21' My basement is larger than any other I have seen at 6'x4'x5' (approx). If I go this route I will maout in upper corner so I will not really lose any space.

Will post pictures if I do the job. Have a few other more important items to take of first so may be July before this gets to top of list of stuff "To-Do"

Thanks for comments.

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Brett

Thanks. I had not found the instructions yet. That answers the mounting question. Guess I wasn't correct in my assumption.

Horizontal mount may provide more options.

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Wolfe10, thanks for the link. Like Tireman9 I hadn't found the instructions yet. The project is at least several weeks away so I didn't have time yet to do much research, I was just following this thread.

Unlike Tireman9 I don't have a lot of space for mounting. I'll probably be putting it under the bed where the fresh water tanks and the water pump are located. That's why the horizontal mounting will help, I don't have much height but I have room from side to side.

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I see there numerous different sizes (gals) of areaccumulator tanks. Can a person buy a tank that is to big (gal)?

I'm looking at the 6 gal tank but does a motorhome pump create enough pressure to fill it? What is the best size tank to buy??

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The vertical mount with the water connection on the bottom is what I intend to go with. This will make emptying for winterizing easier.

This project is taking a back seat to my repair & redesign of the holding tank dump valves. Coachmen didn't properly orient the slide valves so two have been damaged from road debris.

Have the new parts and was about 85% done with removal of old connections when Winter set in here in Ohio so it will be March before I can finish that wonderful job. :unsure:

After that I will re-visit the water surge tank.

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I had installed the 1.3 gallon tank in our Santara C. It was the best thing I did. Showers using the pump were comfortable steady flow. We also get about 3 toilet flushes without the pump running. I also isolated the pump with rubber mounts and put the foam pipe insulation on all of the hoses. Made a huge difference. Our water tank and pump were under the bed in that rig.

Here is a photo:

post-43469-0-39702700-1423406050_thumb.j

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The directions for using an accumulator tank are for reducing water hammering in a stick house with a closed system, the mounting position doesn't really matter.

In a camper it is used for two things; extra capacity and to keep the water pump from cycling every time you turn a faucet on. If you mount the tank with the inlet/outlet on top, the bladder has to lift the water out. If it is mounted on its side or preferably with the inlet/outlet on the bottom the water falls out under pressure with better results, IMHO.

Some water pump instructions discourage the use of an accumulator, I don't know why, especially with a check valve installed at the pump.

I did have one of the HD/Lowes accumulator 5 gallon tanks get interior rust causing a problem, my current tank is an Reverse Osmosis drinking water tank. There may be no interior difference but since I had the availability I went that direction.

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