Pump cycling no pressure tank

I added a 1/2 HP pump, foot valve, and presssure switch to my 400 gallon rain barrel. This is connected to a hose to water the garden and such. To stay cheap I decided to not use a pressure tank. With the hose nozzle full open the pump runs continuously. However, if I go to a spray pattern using the hose nozzle, the pump starts cycling as it reaches 60 psi shuts down and then starts up again when the presssure drops. Any way around this without having to add a pressure tank?

Here is a picture of the setup: http://thehemps.com/gallery/main.php?g2_itemId=16793

Thanks, Tom

I wonder if a "cycle stop valve" would work?

You can add an "unloader".... An adjustable relief valve that can send the water back to the tank when the pressure reaches a few pounds under the shutoff point. These are about 12 bucks - check graingers or the plumbing shop locally. You can also raise the shut off setting on the pump to 80 or 90 pounds, but don't take a long phone call while the pump idles.

A Cycle Stop Valve with a little 2 gallon size tank would solve that problem. In this way you can just open a faucet when you want water, and close it when you are finished.

You could also just turn the pump on and off manually, and not use a pressure switch. Ether way you should have a pressure relief valve in case you forget to manually turn it off, or the pressure switch sticks closed.

A small pressure relief valve cannot be used to dump excess water back to the tank. It would pop open and closed to do so and would cause major water hammer. I have done this before with larger, modulating type pressure relief valves but, never one of the small dump type pressure relief valves.

themp said:

Any way around this without having to add a pressure tank?

Click to expand...

The key to answering this question without saying you need a pressure tank and a Cycle Stop Valve is, remove the pressure switch, install a regular toggle switch, when you want to water the garden, open the nozzle, turn on the pump, wa la, no more cycling of the pump.

This sure does eliminate the cost of the pressure tank and CSV.

BTW you should never have a pressure switch without a pressure tank.

Rancher

Kids turn off the faucet and forget to turn off the manual switch, pump burns up and you have to start all over again. Even if you don't put on any faucets, and just have the pipes open ended, somebody will put one of those spray handles on a hose and when it shuts off, the pump burns up. I have had this happen many times. Automatic systems using a pressure switch are much safer. Manual systems need a sprinkler timer, and have NO place for a garden hose.

A pressure tank and a CSV would be serious overkill for that setup. You aren't going to run it long because you will run out of water.

I wouuld install a small line that returns water from the pump to the rain barrel. As long as there is water in the rain barrel it will not overheat. You can put a 1/4" valve on the pressure switch line (remove the switch) and use that to adjust the bypass flow.

Alternatively, just run a 1/4" or 3/8" plastic tube back to the tank without a valve. There may be a 1/4" fitting on the pump where you can connect a 1/4" adapter for a 1/4" tube that just drops into the barrel.

Connect the cord directly to the motor. If you use a separate line for the bypass (see above) you can connect the motor to the input side of the switch and just use it as a junction box.

You start the pump by plugging in the cord. With the nozzle closed, a small stream (adjust to maybe 1 or 2 GPM with the valve) runs back to the barrel.

When you open the nozzle the pressure drops and there will be less bypass flow.

Unplug the pump when you run out of water.

As long as nobody closes that 1/4" ball valve. As long as that small 1/4" line doesn't stop up. As long as you remember to shut the pump off, before it heats up the water in the storage tank. As long as you are there to unplug the pump when the storage tank is empty. As long as you don't mind manually turning the pump on or off when needed. As long as you don't need the 1 or 2 GPM that is returning to the storage tank. Otherwise a CSV, small pressure tank, and a low pressure cut-off switch makes everything automatic and safe.

Thanks for all the posts. On valveman's post it says:a CSV, small pressure tank, and a low pressure cut-off switch makes everything automatic and safe.

small pressure tank, is this like an expansion water heater pressure tank you see at Home Depot?

low pressure cut-off, not sure what this is or does in protecting the system.

And I guess I am confused on how to add this to my system in terms where to add the CSV, small tank, and low pressure cut off.

Thanks again, Tom

That looks like a square D pressure switch on your setup, just take off the cover and tighten the center spring loaded nut clockwise until the switch doesn't turn off when your nozzle is in the spray pattern.

Cost = $0.00

Rancher

"I'm not sure what Valveman low pressure cutoff switch does for you, just one more part to fail... along with the pressure tank and CSV." Rancher

The low pressure cut off switch is a simple pressure switch that is commonly used on low producing wells. It will shut the pump off if your tank runs out of water, or if you have a major line break.

This switch will not fail any sooner than any other type of pressure switch.

The CSV is also dependable and is what keeps the pressure tank, pressure switch, pump, motor, capacitor, and everything else in a pump system from failing.



"Raucina's adjustable relief valve is the cheapest way to do what you want to do, Bob NH's system will also work cheaply." Rancher

Again.....A small pressure relief valve cannot be used to dump excess water back to the tank. It would pop open and closed to do so and would cause major water hammer. These small pressure relief valves are not modulating type valves. They dump and shut, not modulate evenly.



"My system will also work just fine, you didn't mention if you had kids that could mess with the system, just that you wanted to water the garden with the 400 gallons of rain water." Rancher

There is always something that can mess with a pump system. You should plan for the worst, and expect the best, instead of the other way around.



"The pump will work fine running continuously even with brief periods of a completely closed nozzle." Rancher

The operative word here is BRIEF. Just walk away for a few minutes and you pump is toast.


"Or... you could just raise the pressure cutoff of your existing switch so the pump will not cycle when you are in the spray mode of watering." Rancher

Ranchers first quote...."BTW you should never have a pressure switch without a pressure tank."
And he was right the first time!!!!!

themp... Yes the same size as an expansion tank, just make sure it doesn't have a tiny opening. I will attach a picture of one similar to this.

And the cost of the pressure tank, CSV, pressure gauge, and fittings is....


Oh by the way Valveman, I do like all the brass pipe fittings, very clean.

Rancher

I am sure Speedbump can give us a price. Should be much less than not having these things and forgetting to turn the pump off just one time.

If the guy wants to burn some money to save rainwater then so be it - but he might just as well use the city or well water...

Other "green" options - raise the tank a few feet off the ground and gravity feed drippers.

Find [really easy in a real city] a old water heater. They are exactly plain tanks when devoid of water or at least with a bit of air in them. Crank up the shut off to just below pump maximum pressure and hose away. The air cushion will keep the pressure switch from endless cycling, and the high pressure will imitate the csv.

Must be getting boring here for all the ado about this little matter.

There is nothing less expensive, and probably nothing as reliable, as a little plastic tube bypass together with bypassing the pressure switch.

You can add up the cost yourself, and try it for a month. If it doesn't satisfy your needs you can spend $250 or so on a small tank, CSV, and low pressure cutoff pressure switch.

Cost for the three items mentioned above. $159.00 plus shipping of around $10.00 and your good to go. It would also be nukeproofed which the other mentioned solutions are not.

bob...

speedbump said:

It would also be nukeproofed which the other mentioned solutions are not.

Click to expand...

Sorry nothing is nukeproofed, what happens when that small bladder tank you're going to sell him gets waterlogged? Rapid pump cycling.

Bob NH's bleeder plan is probably the most reliable.

My plan of raising the cut off point on the pressure switch uses no additional parts, and that centrifugal pump can't make TOO much pressure so that won't be a problem.

Rancher

Don't forget the CSV that is in front of it.

bob...

*grins* get a 3 phase pump and a VFD (variable frequency drive)
that way the pump can slow down as needed.

Just trading 2 problems for 10. Here is what I think about VFD pumps.

http://cyclestopvalves.com/comparisons_14.html