Washing Machine triggers endless cycling of Pumptrol Pressure Switch

[Zachrey]

Greetings!

My wife, Nicole, and I live at the Greater World Earthship subdivision near Taos, New Mexico. All the homes in this 630 acre subdivision are completely off the grid. The homes heat and cool themselves and provide water, hot water, electricity and on-site, contained, sewage treatment systems using nothing but the sunshine and rainfall that strikes the home (www.greaterworld.org).

We have 3,600 gallons of cistern storage for the rain that lands on our metal roof that is pressurized with a Shurflo 24Vdc pump. Since the pressure switch on the Shurflo failed (open circuit, thank God), I added a Square D Pumptrol 30/50 switch which works very nicely (very quick and clean cutoff when the pressure hits 50psi). The only problem is the washing machine now triggers an oscillation.

When the solenoid valve in the washing machine opens or closes (I'm not sure which or both) AND the standing pressure of the system is somewhat close to the cut-in pressure of about 30 PSI, the Pumptrol will cut-in, cut-off, cut-in, cut-off ad nauseum with a period of about 1 second until I open a valve or unplug the Shurflo 24V pump.

I installed a Sioux Chief 600H Mini-Rester water hammer arrestor on both the hot and cold water feeds to the washing machine. This did not solve the problem!?!



While troubleshooting previous problems, I had drained the pressure tank and the pre-charge was about 25psi (using a tire pressure gauge that is not the most accurate in the world). Pumptrol cut-in is about 30psi according to the water pressure gauge on the system.

The Pumptrol switch is about 1 foot away from the Shurflo pump. The pressure tank is about 8 feet away from the Pumptrol switch with the water line running just underneath the brick floor. I'm not sure how long the line is from the washing machine to the pressure switch since I wasn't the one to install it, but I believe they went up into the ceiling and then back down for some of the pipe runs (they used Wirsbo Pex).

Where is the best place for the pressure switch? Should it be by the pressure tank?

I have a third Mini-Restor 600H. Should I install this next to the Pumptrol?

Now we also have a Solahart 302 Black Chrome 80 gallon solar hot water heater on the roof (the 80 gallon tank is on the roof). The cold water feed to the Solahart is about 15 feet long from the floor to the tank on roof. Could that be a problem somehow?

I also tried increasing the pressure difference between cut-in and cut-off but it didn't seem to help. I'm pretty much baffled at this point! I know it has to do with the momentum of water and sudden changes in water flow but what is the simplest solution?

Thanks so much in advance for any suggestions!

[Bob NH]

I can't quite figure out the relationship between the pressure switch, tank, pump, filters, and washing machine tap. Can you post a schematic?

I suspect that the problem might be related to pressure drop in the filters. If the washing machine solenoid causes a flow through a filter in a way that will affect the pressure at the switch, then it could cause the switch to actuate.

I like to see the pressure switch at the tank. The switch then "sees" the pressure in the tank which can't change quickly because of the air cushion.

The problem will be made worse if your filters are near end-of-life and the pump is pumping to the pressure tank through the filters.

When you put the pressure switch at the tank, you will have to take great care with the filter changes. I believe that your pump is a positive displacement pump.

One very nice solution with filters is to put a pressure tank at the pump, controlled by the pressure switch, and another tank after the filters. That way your pump gets an adequate cycle and the filters can work while the pump is off. Also, the filters have smaller effect on the delivered pressure than they would if they are after the tank. You will be able to get more life out of the filters. The tank at the pump should be sized for cycle time and the second is sized fou your pressurized storage needs.

Roof water should be disinfected in some manner. Bird sits on roof. Bird droppings get washed off by the rain. Bird droppings may contain fecal coliforms and viruses, both of which are easily killed by a little chlorine or by an ultraviolet system. You could put in enough Chlorox or equivalent to just get detectable color with a DPD test kit in a sample taken before any carbon filter. I would start with 1/2 cup per 1000 gallons of water each day until the color shows up in a test sample.

[vaplumber]

Hello. I see 2 things that may be causing your problems. First with a standard pressure switch you want it as close to the pressure tank as possible, not at the pump. Your 24 volt surflo pump, if I am not mistaking, used a pressure switch mounted directly to the body of the pump. Since you are now using a "household" type switch, you need it at the inlet of the tank. The second thing I see is your bladder air charge pressure. You need to adjust this so it is 2 psi below the pressure switch cut in. Use an accurate tire guage for this. For example, if you have a 30/50 switch, then the air pressure needs to be 28 psi. It doesnt matter what type of pump it is, or what voltage the pump is, the basic function is still the same. You are very fortunate to be living in this type of environment! I want to check out the web site later on, but as of now I have to sign off and go run a shop! Best of luck and I hope this helps.

[speedbump]

I would get rid of those (so called whole house) filters and use something that is going to do some good.

If all else fails that the guys mentioned above, I have a pulsation plug made specifically for your problem. It is not the recommended fix. The above advice is the correct way to go. But if all else fails, let me know and I'll get one to you.

bob...

[Zachrey]

Hi Guys,

Sorry I was so late in replying! I thought I was supposed to get an email when someone responded to my question. Good thing I logged in today!

Here is a schematic of the water system:

<pre>
                                                 pressure          (press)   to rooftop hot
                                                 gauge             (tank )   water tank
   ----------                        Shurflo     [ ]               (     )   |
  |          |               60 mesh Positive     |        500 mesh   |      |
  | cistern  |   cutoff      filter  Disp. Pump   |        filter     |      |
  |          |======X==========/=====(0)===================/===================cont'd
  |          |                 \     | |          |        \
  |          |                 /     | |          |        /
   ----------                  \      |          { }       \
                               /      |__________{ }       /
                                                 pressure
                                                 switch



              Little
              Sioux
              mini-restor
              ()
resuming      ()        ---------
   =======[[==()==]]===| washing |
         cw            | machine |
         tap           |         |
              ()       |         |
              ()       |         |
   =======[[==()==]]===|         |
         hw             ---------
         tap

</pre>

I don't have any kind of drawing tool so I used ascii art. Hope it comes through legibly!

To Bob:
I suspected that the pressure switch should be over by the pressure tank, but I really like the idea of two pressure tanks. How big should the tank next to the pump be? 1 gallon, 10 gallon, 100 gallons?

I understand your concern about the filters now. Having the pressure switch by the tank could blow out the pump if the resistance is high enough in the filters!

Our drinking water goes through a Seagull water filter that takes out the cooties. Each sink has a little drinking water tap on it for easy access.

When we wash the dishes, we use straight hot water from the rooftop solar tank (water gets up to about 170 F so it's sterile).

To vaplumber:
Do you have any recommendations for make and model of a tire pressure gauge? I would really like to get a good one for the pressure tank precharge AND to keep my tires at max rated pressure for better fuel economy. I have a 1995 Susuki Swift (think Geo Metro) that gets 55 MPG!

We love to give people tours of our home and they even have seminars at the Earthship Biotecture office on how to build your own. So do look us up if you are in the area.

To Speedbump:
I'm thinking the pulsation plug is the way to go for the moment. They seem to come with pressure switches, but can I get one separately for my Square D 20/40 switch (model 9013FSG 2)?

Also, what would you recommend in place of the whole house filters?

BTW, I put a bunch of dimes in the pvc fitting just before the pressure switch in a failed attempt to do the same thing as a pulsation plug; introduce enough resistance to water flow to dampen the pressure spikes. I better take them out though. They could cause corrosion in the diaphragm of the pressure switch even though the dimes are not in galavanic contact with the pumptrol. Rainwater eats metal like crazy.

Thanks again so much everyone! I really appreciate the support.

Cheers,
Zac Helmberger

[speedbump]

HI Zac,

I'm not an expert on the type of pump you are using. I use one to spray weeds on the back of my golfcart at my tree farm. It has it's own built in switch and doesn't mind being cycled a bit. If you were using the kind of pump I am familiar with (jet pump with pressure switch ((Fsg-2) I would recommend getting rid of all filters. I don't like to see anything in the suction line of a pump. I don't like sediment filters period. There are many better filters than those in line varieties and you won't have to be buying filters all the time. I am not sure how big the cooties are that these filters are removing, but I can't imagine them being that plentiful. There are a few guys that can recommend ways of treating this water after you get a water test done.

The pulsation plug is really not the answer. Moving the tank is the best solution.

bob...

[vaplumber]

Hi Guys,


To vaplumber:
Do you have any recommendations for make and model of a tire pressure gauge? I would really like to get a good one for the pressure tank precharge AND to keep my tires at max rated pressure for better fuel economy. I have a 1995 Susuki Swift (think Geo Metro) that gets 55 MPG!

Zac Helmberger

Just pick something that feels and is priced quality. I do not know the pricing in your area, but around here you can walk in an auto parts store and pick up a cheap guage for $1.99, and a top of the line for about $7. I would recomend a truck stop because I have found commercial guages to be most accurate. If you can find a digital (about $20) I have found most of them to be very accurate. I agree with these guys about the whole house filters. I would recomend a treatment system, but if you do decide to stay with the filters, place them after your pressure tank. With the design and function of the tank, nothing will ever accumulate in the tank, and you should never have any filter or screening between the pump and the water source.

[Zachrey]

I think I figured out the problem! The 500 mesh spindown filter was clogged.


It looks like the negative water hammer pressure transient turns on the pump and then the combination of the water hammer positive pressure transient and the positive back pressure from the 500 mesh filter was enough to turn the pump off.

Then, the sudden on/off cycling of the water pump sends positive pressure pulse and the subsequent pressure drop via water hammer effect switches it back on again ad infinitum.

But, if the 500 mesh filter is clean, then the only the hammer positive hits the pressure switch which, evidently, is not enough to shut off the pump and the transient dissipates.

Also, the clogged filter tricks the pressure switch into turning off too early so the pressure tank never gets up to the desired 50 psi which makes it all the more susceptible to turning on due to a negative transient. If the tank is at 50 psi and a negative transient causes a 15psi drop, it is not enough to trip the pressure switch with a 30 psi kick on.

[Raucina]

I would take your dimes out too. Or be sure they are pre 1968 - silver - they might help with the disinfection.

Seems if you move all your filters after the pump, tank and switch, you would only experience reduced flow: a good indicator for maintenance.

[speedbump]

Silver doesn't kill bacteria, it simply stops reproduction.

bob...

[Rancher]

I would take your dimes out too. Or be sure they are pre 1968 - silver - they might help with the disinfection..

I believe that's 1964 or older, the half dollars (Kennedy) went till ... maybe 1968 at 40% silver.


Rancher

[Rancher]

Silver doesn't kill bacteria, it simply stops reproduction.

Ok how do I slip a pre 1964 dime in my wife's beer...

Rancher

[speedbump]

You have to use Dark beer.

[Raucina]

If your wife is pre-1964, never mind, I would replace it. Wives, like checkvalves, rarely are good for more than 10 years. This is one case where Lowes is a good start, they have some young cashiers.

[Rancher]

This one is a '55 model, and I've checked out the cashiers at Lowes, and trust me, I can't afford to replace her.

Plus I want to live till retirement.

Rancher