Having issues with pumping water from my tank to my shack with a 12v 35psi water pump. I've only recently put one them in (previously gravity fed) so I can run a hot water unit.
Problem is I seem to have gone through 2 in 3 months. The first one died and I assumed it was just a faulty unit and threw it away and bought another (Ebay item, Shurflow knockoff i think). However the next one did the same within a few weeks,so I started to think it was my set up. Checked all the electrics etc for voltage drop and that wasnt the problem. Checked inlet and strainer for blockages, all ok. Increased inlet pipe to 3/4 inch for the 20 foot length between the tankand pump. Eventually decided to pull the pump apart and see what was going on. Removed pressure switch etc and eventually tracked down a faulty micro switch (The motor still worked fine). I pulled it apart and noticed that the constant cycling of the pump on and off had worn away part of a plastic stop keeping the switch permanantly open. Now my questions.
(1) Have I just got two faulty pumps with faulty micro switches? (They are Ebay Chineese copies but I would still expect more than a month each).
(2) Do the more costly Shurflo or other Brand pumps use the same system ie: pressure swith with spring and micro switch?
(3) I noted that both thses pumps constantly drew their startup Amps of 8amps instead of dropping back to their rated power draw of 3.9amps when I used my mixer taps(They have a reduced flow), but dropped back to the normal power draw when I opened a normal tap(Higher flow). I assume then that using the mixer taps causes the pump to constantly cycle, reaching off pressure temporarily, then opening again when the pressure drops. Whilst using the normal tap the pump just contunually runs. Is this causing the wear on the microswitch?
(4) The hot water unit has a capacity of 8L (Sorry not sure what that is in gallons) per minute and the pump 12.5L per minute. Could this reduced flow through the Hot water unit be causing the same issue, ie: The constant cycling of the pump on and off causing wear?
(5) Should I buy a pump with the same capacity Ie: 8L per minute to match the Hot water unit or even lower?
(6) Can I use an impeller pump which will operate only when I open a tap?
Any hints would be useful. I am happy to buy a Shurflow pump but don't want to destroy it to with the same problem.