How to Increase Pressure from Water Tank?

Question

Due to low water pressure and lots of water interruptions from our water supplier, we installed a water system. This is how our water system works:

water supplier > water/booster pump (0.5 hp) > pressure tank (21 gal, located in 1st floor) > water tank (located on 2nd floor) > water system in the entire house

This system solves our problem caused by our water supplier. We can now "pull" water even if the pressure is low and can store water in the tank.

After using this system for a few weeks, I noticed the following:

1. If the water/booster pump is off, the water pressure in our 2nd floor is low. We can't take shower properly since the water can't get out well from the shower head. I know the reason for this one is because the water tank is also located in the 2nd floor and there's not much difference between the water tank outlet and the pipe responsible for delivering water in the 2nd floor. For us to be able to take shower properly, we first need to keep the water/booster pump running. This is kind of expensive though in terms of electric bill because the pump is always running.

The question is, is it okay to place a small pressure tank after the water tank outlet to increase the water pressure in the 2nd floor? If so, what's the recommended size of the pressure tank? Is 6 gallons enough?

2. There are times when the water pressure from our supplier is high and the water can go up directly to our 2nd floor even without running the pump. However, I noticed that the water from our supplier can't fill the pressure tank.

I don't know the full functionality of water/booster pump but do water/booster pumps block the passage of water when not running? If not, what could be the reason why water from our supplier (even on high pressure) cannot get into the pressure tank when the pump is not running?

EDIT: We do have a pressure switch. I'm not sure what the settings are since this was installed by a 3rd party. Anyway, when the gauge reaches the upper limit (around 40 psi), the pump turns off automatically. I think this behavior is correct. However, a slight drop in pressure (say I just simply open a tap for a few seconds), the pump starts running again. I'm not sure if my term is correct, but it seems like it's "short cycling".

This system was installed 3 weeks ago so I'm assuming there's nothing that's been broken already since the day it's installed.

Answer 1

Two possibilities: tank higher or pump.

As tank higher is not possible, as you have just stated in a comment then that leaves the pump.

You mention the high electric bill, well a timer would be one way of reducing the pump run time.

Or you can use a "pressure drop" switch to fire the pump when a tap or shower is turned on. This was written prior to the edit with further information about the existing pressure switch and its settings.

Both timer and pressure drop can be used together if you wish.

Answer 2

On any of the booster systems that I worked on and serviced, the correct way to install them was with a storage tank mounted near the supply inlet piping which is usually in the basement or an equipment room. The piping leaving the storage tank would be equipped with a check valve, then a "TEE" fitting. One of the "TEE" outlets would be piped to the inlet of the booster pump. The outlet of the booster pump would flow into a pressure tank with a bladder, similar to a well tank and from the bladder tank to the house supply. The size of the bladder tank should be as large as feasible considering the cost and available floor area. A pressure switch controlled the operation of the booster pump with a maximum setting of your choice but usually at or slightly above 60 PSIG. The remaining fitting at the "TEE" at the storage tank discharge would be connected to the house supply piping just after the bladder tank discharge. Both of the supplies, the direct and the pump supplie would be isolated from each other with check valves strategically located in each section. The booster pump would only run when the supply pressure was too low. The actual booster pump settings would be at your discretion. Hope this helps.

Answer 3

The setup as described seems like an odd mish-mash.

A "no-pressure storage tank" as typically seen in UK systems needs to be located considerably higher than any point of use to be effective. In more global systems in non-freezing climates I'm used to seeing individual water towers per house for the purpose, often with a pump from a lower storage tank. They are more easily constructed from local materials where a bladder tank would be an expensive imported item.

A pressure tank (virtually all modern versions of which are bladder tanks, for good reasons) can be located at, above, or below the points of use. They require correct setting of the pressure in the bladder for proper operation, and the bladder needs to remain intact as well. You can use multiple pressure tanks in parallel for additional storage volume, but in the event of improper setting of the pressure in the bladder (with the water system depressurized) or a perforated bladder, storage volume will be very low.

Likewise, if the turn-on and turn-off points of the pressure switch are not properly adjusted a very small variation will not permit adequate storage. Typical pressure switches default to a 20PSI swing, so if turning off at 40 PSI turn-on would be expected around 20 PSI, and bladder pressure with no water pressure should be 17-18 PSI. If the observed turn-on was, instead (for example), 30 PSI, the bladder pressure would be set to 27-28 PSI. In general, the bladder pressure should be set 2-3 PSI below the turn-on point of the pressure switch/pump, so that water does not run out while the pump is starting up, but storage volume is maximised. Many pressure switches can be adjusted, not all can, there should be documentation for the particular model of switch you have.

A typical check on storage volume is to stop all water use, let the pump shut off, and measure the volume of water drawn before the pump turns on, as well as noting at what pressure the pump turns on. Your pressure tank will have paperwork or a website where you can check that the volume appears to be appropriate for the pressure swing, or not. Since you indicate that "a few seconds" of running a tap causes the pump to turn on, there is very likely something misadjusted or broken here, as you should typically be able to get a few gallons from a 20 gallon bladder tank before pump turn-on.