Residential Pump Problem

Mite want to check air bladder or air head pressure in tank. Both too little or too much will cause pump to short cycle. Old tanks did not have a bladder and would past air down the line would need to be correct frequently. Link below will help you.

www.inspect-ny.com/water/watertank.htm

Yes, that sounds like a faulty tank. It has a air bladder inside that maintains pressure when the pump is off. They can leak and the bladder no longer holds air.

Turn the pump off and let the water drain in your sink. Check the fitting on the tank (it looks like a normal valve stem) and use a tire pressure gauge to measure the tank pressure. It should be 2 to 3 lbs less than the pump's turn on pressure. That is, if your pump kicks in at 40 psi, then the bladder pressure should be 37 to 38 psi. If not, you can try adding air. However, chances are it is leaking (that's why it low on air, right?) and needs to be replaced.

I should add that it is not good to have the pump turning on and off rapidly. You could damage the pump. So get it fixed.

The problem could also be caused by the water heater or a combination of the heater and the pump.

These tankless water heaters have a throttle arrangement in them to control the temperature at the output.

This is not a problem in the sink as the water is only flowing for a relatively short time. The shower however if opened wide could be demanding more flow than the heater can heat which then chokes the water flow back.

I found this to be more of an issue during colder periods where the initial water temperature is lower and the heater chokes the supply more.

Compound this with a punp that is responding to pressure and you would get the results to describe.

Regards,
Sapper.

If you have a water saver shower head it may be restricting the water flow enough to cause the pump to reach cut off pressure point too soon.

And if the tankless water heater also has a valve restricting water flow that would also explain it. Evidently the hysterisis of your pressure switch is not wide enough. Switch should cut off when pressure reaches a set high level and not turn on until pressure drops down to a much lower set point. Water flow should be maintained by the air bubble in your header/pressure tank. Your tank should have a pressure gauge. If not, use a tire gauge on the schrader valve that is used to pressurize the hank. Water will absorb air when under pressure. You may have to add more air under pressure with a tire pump or similar. Pressure range is in the 40 - 70 PSI Consult the label on tank for specifics.

Increase the pump pressure is the answer. Somewhere you have a pressure switch that is operating. Probably because the bathroom is higher than the kitchen and/or the amount of water used is much less than in the kitchen when the tap is on....

You need a pressure set that can ONLY be reached by the pump, when no water is being drawn! That will fix the problem.

Turn on the shower and adjust the switch setting higher and higher till it stays on as long as the shower is on, but switches off a few seconds later after the shower is turned off!!

This is the old "Caravan water pump problems", many have tried to fix it but the above is the only real way.

If your pressure switch cannot be adjusted, then you are "Buggered", sorry!!! Buy one that can be adjusted asap!!!

Or add a remote switch that allows the pressure switch to be shorted out and not activate (turn off) just while showering!!!