Well pump cycles too much

PatrickS2222 · Dec 30, 2016

nikdfish said:
If your tank is bad & you need to replace, go with the largest you can fit in the space if you can afford it. The larger the tank, the longer between pump cycles & the more steady your output pressure (also, the more water you are likely to have available during a power outage).

Nick

Almost certainly a tank problem - been there done that as well. First, switch off pump power, then release all water pressure. Leave one tap turned on is a good idea. Correct the air pressure in the storage tank as Turnkey described. Turn off tap, switch on pump and allow it to build up full pressure and then it will stop. Turn on a tap and check if an increased amount of water under pressure is delivered before pump restarts. Allow it to run for a minute or two whilst checking if any air is released. This may prove a split diaphram in the tank as Valveman described. Turnkey's mention of a plugged pressure switch or pipe is a possible but very unlikely fault for these symptoms.
Nikdfish's advice of a large tank being advantageous is spot-on as well. Starting up is what kills electric motors - especially under load, or against the inertia of heavy shafts or pulleys. They'll happily run 24/7 for ever ... or until their bearings wear out, but frequent starts will result in a very short working life.
A good friend gave me a huge pressure tank which was spotlessly clean, and cost him almost nothing (was in an auction lot of scrap metal) for our house water supply pump. Pump cycles between 45 & 65psi, but I can almost have a shower before it starts up! :laughing:

Valveman · Dec 30, 2016

You can get diaphragm or bladder (bag) tanks in either steel or fiberglass. Either fiberglass or steel a diaphragm is better than a bag tank. The diaphragm doesn't touch the sides of the tank as it moves up and down like a bag tank does.

But diaphragms and bladders are both susceptable to failure from flexing back and forth as the pump cycles on and off.

Even a large 80 gallon size pressure tank only holds about 22 gallons of water between 45 and 65 PSI. This is why the pump still has to come on when you take a shower. But with a large tank the pressure is decreasing from 65 to 45 for almost the entire shower. Only in the last couple of minuites after the pressure drops to 45 and the pump is started does the shower pressure increase back up to 65 PSI. With a smaller pressure tank this fluctuation in pressure from 65 to 45 may happen several times during a shower.

As was stated eariler, pumps like to run 24/7, starting is hard on a pump/motor, and starting against a load is even harder. So the fewer starts the better. The way to decrease the number of starts is to increase the run time of the pump. It is better for the pump to run for as long as you are in the shower, than it is for the pump to cycle on off even twice, much less multiple times. The longer the shower and the smaller the tank the more times the pump will cycle.

As for starting a pump against a load, it is just the opposite of what you may think. Starting at the low pressure of 45 PSI without any restriction is the bigest load and the hardest way for a pump to start.

Starting a pump against a closed or almost closed valve, as with a CSV, gives a mechanical soft start to the pump and decreases the starting load or amperage.

25+ years ago I would have also said the bigger the pressure tank the better. But those days are gone as there are much better ways of controlling a pump. There are several ways to get constant pressure to the house, and eliminate cycling while using a very small tank.

There are variable speed pumps and countless types of tankless controls, but I believe (and of course I am a little biased) the simple nature of a constant pressure valve is best.

turnkey4099 · Dec 30, 2016

Something not mentioned (or I didnt' see it). If you have to correct the pre-charge in a tank, you will have to do it repeatedly. The air in thebubble is slowly absorbed by the water and eventually the pump will be short cycling again. Best to replace the tank...or the bladder if it is replaceable - some are. There are still a lot of old non-bag/bladder tanks out there. They have 'snifter valves' or other means of adding a bit of air every so often when the pump starts. Those valves also fail.