Pressure Switch advices

[danny.h]

I have a pressure switch on my 20l watertank, I set the range to 30-50 even 30-60
the problem is when it reach 60psi motor stops and its good, but it only takes 12 sec before it
reach 30 psi and motor starts. last time I had this problem I put air into the water tank, and so it reach 25sec before motor starts, but my plummer is saying I cant do that. In my motor manual its saying max 20 start/stop per hour. something I do wrong? because I dont want to ruin my motor.

 

[WorthFlorida]

Is your pressure tank with a bladder? It is possible you have a bladder with a leak. Have you looked at the check valve that it is functioning correctly?

 

[Sponsor]

 

[danny.h]

yeah it has bladder, this is the one I have https://www.jula.se/catalog/bygg-oc...umpar/vattentankar/hydrofortank-710607/#tab02 I dont think I have a check valve, I should be able to see it right?

 

[danny.h]

I guess I am confused, because if I didnt had a check valve, my motor would run constantly, I will ask my plummer to check if the check valve works correctly. how fast should it drop from 60 to 30 psi in sec would you say?

 

[WorthFlorida]

The check valve would be between the pump and the tee to the tank. The time between high and low pressure is variable because of many factors, the size of the tank, the amount of water drawn, etc. This picture shows what may be wrong with your system by your statement that when you added air, it performed better. The tank manufacture should have instructions on how to properly set the air pressure.

 

[danny.h]

okay I see the plummer needs to check that. I dont have any manual of my pressure tank I just know its 8 bar and if I google other pressure tanks and read manuals it seems it doesnt show how to properly set the air pressure. what I have done is when the gauge shows 30 psi I measure the psi in the pressure tank and it was 30 psi also.

 

[LLigetfa]

what I have done is when the gauge shows 30 psi I measure the psi in the pressure tank and it was 30 psi also.

That test is futile. You need to check the air precharge when the water pressure is zero and the drain valve open. It should be 2 PSI less than the pump start pressure.
How quickly the water pressure drops depends on how many GPM you are drawing.

 

[Fitter30]

If your not using any water and the pressure in the systems drops the check valve is bad water is flowing back down the well. If water comes out of the air valve the tank is bad needs to be replace.

 

[Reach4]

okay I see the plummer needs to check that. I dont have any manual of my pressure tank I just know its 8 bar

That is just going to be a maximum working pressure ( 8 bar=116 psi). If you replace that tank, and there is a good chance that it needs replacing, you will want one big enough. Rule of thumb is that if the pump pumps X gpm or lpm, you want a tank of at least X*4 nominal gallons or liters volume respectively. That comes from the tank delivering about 1/4 of the nominal volume between cut-on and cut off of the pump, and you wanting a minimum of 1 minute run time. A 20l tank would be good for up to about 4 lpm from your pump. If you want a small tank, there is a thing called a CSV that can let you use a smaller tank with a centrifugal pump if the pump has the capacity.

It is possible (conceivable) that bad air precharge could cause your symptom, but it is unlikely that that tank has not failed. Extra air can work around the problem while you get a new tank installed, as you did. Just avoid adding so much air that air blows out of the tank and out of a faucet, where it could startle or knock something out of a hand.

Better tanks have a diaphragm rather than an actual bladder today, but some people are used to the bladder terminology and use that word for all precharged tanks.

 

[danny.h]

If your not using any water and the pressure in the systems drops the check valve is bad water is flowing back down the well. If water comes out of the air valve the tank is bad needs to be replace.

If I am not using any water, the pressure doesnt drop at all.

 

[Valveman]

Pressure tank bladders or diaphragms wear out because the pump is cycling on and off too much. Your check valve is fine, the tank is bad.

 

[danny.h]

Pressure tank bladders or diaphragms wear out because the pump is cycling on and off too much. Your check valve is fine, the tank is bad.

thanks for the video, as they talked about start and stop tear out the tank with time, even mine is only 3 years old, they also talk about to maintain a constant pressure of 50 psi "cycle stops valve" meaning the motor will not off as long you are using water.
I have a grundfos motorpump and in the manual its saying max 20 start/stop per hour, but can it be on lets say 10mins without stopping? dont you put too much tear and wear on the motor that cost much more money than a pressure tank??

 

[Valveman]

Nope. Pumps are made to run 24/7/365. I have one on a stock well that hasn't turned off in over 18 years. Too many on/off cycles will destroy a pump, running continuously makes them last.

 

[danny.h]

Nope. Pumps are made to run 24/7/365. I have one on a stock well that hasn't turned off in over 18 years. Too many on/off cycles will destroy a pump, running continuously makes them last.

okay good to know because right now with a on/off every 10sec, not good at all, I will adjust it to run steady as they mention in the video also.

 

[danny.h]

I have a weird problem again, you told me in he beginning that I might change my pressure tank, because my grundfos pump on and goes to 50 psi and doesnt off before I off the water faucet. but as you said motor are build to run 24/7/365 so i didnt do anything and it works. but now suddenly the motor only reach 30 psi so we change pressure switch, pressure tank and check valve. but still same problem, doesnt reach more than 30 psi, is it really the newly grundfos pump that is defect already or?

 

[Valveman]

Pumps are made to run pumping water 24/7/365. BUT, if they are running and not pumping any water and not building to 60 to shut off, the pump will get very hot and melt down. I don't know if the pump is worn, have a hole in the pipe, or the well water is not adequate. But if it is not pumping enough water to build to 60 and shut off that is a problem.

 

[danny.h]

but should a grundfos pump not shut down automatic if no water is pumping throgh it?

 

[Valveman]

The SQ series is supposed to do that. The S or SP series does not unless fitted with something like the Cycle Sensor.

 

[LLigetfa]

I don't know if the pump is worn, have a hole in the pipe, or the well water is not adequate.

My guess is a hole in the pipe. OP mentioned replacing check valve (I assume topside) which would mask a hole in the pipe. There should not be a topside check valve.

 

[Valveman]

My guess is a hole in the pipe. OP mentioned replacing check valve (I assume topside) which would mask a hole in the pipe. There should not be a topside check valve.

Probably right. Either Grundfos pump have good built in check valves so probably a hole in the pipe.