2 PUMPS FED FROM SAME CITY WATER PIPE !!!

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Bob1000

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Dear All

My house consists of 4 apartments , ground floor has 0.5 H.P pump feeding it with an electronic pump controller on it
other 3 apartments are fed by another 0.75 H.P pump with another pump controller on it

Both pumps are fed from the same point which is the city pipe which has very weak pressure of 15 psi max

The problem now is in the second pump , the controller would stop the pump when pressure reaches 80 psi , when you open any tap it kicks in and stay on till you close the tap then the pressure would reach 80 psi then pump stops

But since few days now I noticed the the manometer in the second floor shows that AFTER THE PUMP STOPS AT 80PSI , the pressure KEEPS INCREASING VERY VERY SLOWLY TILL IT REACHES 100PSI AND MORE WHILE THE PUMP IS STOPPING AND NO WATER USE IN ALL THE 3 TOP FLOORS AT ALL !!!

This resulted in flixible connections burst , water filter burst and leaks everywhere , a lot of damage caused by that unjustified increase in pressure of UNKNOWN SOURCE !!!

I immediately checked the city pressure and found it the same 10psi

EACH PUMP HAS A NON RETURNING VALVE AT SUCTION SIDE

PLEASE ADVISE WHAT IS THE CAUSE OF THAT SILENT SLOW INCREASE OF THE PRESSURE WHILE THE PUMP IS STOPPING AFTER REACHING ITS MAX CLOSING PRESSURE OF 80PSI

Thank you all in advance
 
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Greenmonster123

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It is probably your water heater. If you don’t have an expansion tank or if it is waterlogged as the heater heats the water it raises the pressure and with check valves on your pumps the pressure can’t push back out to the city main and becomes trapped within your house. Check your pressure relief valves and expansion tanks
 

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Your booster pumps should have a little pressure tank with each. Those VFD or electronic controlled pumps sometimes do not have a pressure tank, or the one built into the unit is just not large enough to handle hot water expansion. Or it could be that you just think the electronic controlled pumps are off, when they are really still running and increasing the pressure to 100. That is a regular problem with those VFD or electronic controlled pumps and you can see one going to 100+ PSI in the following video.

A regular jet pump with a PK1A control kit would have a large enough tank to stop hot water expansion. Plus it would also be much more reliable and long lasting than the electronic controlled pumps.

 

Bob1000

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It is probably your water heater. If you don’t have an expansion tank or if it is waterlogged as the heater heats the water it raises the pressure and with check valves on your pumps the pressure can’t push back out to the city main and becomes trapped within your house. Check your pressure relief valves and expansion tanks

I had this system since long time and it was working perfect but this silent mysterious increase in pressure is a new problem!
The system does not have expansion tank and never had it in the past should i connect one?!
But if i connect one , the pump would work more to fill it till 80psi achieved so it would not have a room to hot water expansion which i dont think is the reason of the problem

I suspect the other pump might increase the pressure by one way or another as it suck water from same point ... deos that make any sense?

I switched off the other pump and the phenomena seem to have disappeared ! does that make any sense ?

Edit

It seems it is the electric water heater .. as when i switched it off the pressure did NOT increase

If i want to fix an expansion tank to allow for the excess hot water expansion , will it stop increasing the pump cut out pressure value of 80psi ? or it will increase anyway ? . where is the best place to connect it?
 
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Bob1000

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Your booster pumps should have a little pressure tank with each. Those VFD or electronic controlled pumps sometimes do not have a pressure tank, or the one built into the unit is just not large enough to handle hot water expansion. Or it could be that you just think the electronic controlled pumps are off, when they are really still running and increasing the pressure to 100. That is a regular problem with those VFD or electronic controlled pumps and you can see one going to 100+ PSI in the following video.

A regular jet pump with a PK1A control kit would have a large enough tank to stop hot water expansion. Plus it would also be much more reliable and long lasting than the electronic controlled pumps.


Thank you for your reply but
I am 100% sure the controller has stopped the pump , I have pilot lamp in kitchen shows pump is on or off , plus i can hear it when it kickes in or stopped .. so it is NOT that probability
 

Fitter30

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Pumps off has to be expansion. Water heater would raise total system pressure both hot and cold. What type of flex hose burst and how old was it? They do have a life spand.
 

Bob1000

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Pumps off has to be expansion. Water heater would raise total system pressure both hot and cold. What type of flex hose burst and how old was it? They do have a life spand.

The flix hose of the water boiler and it was old , but also the check valve of the boiler that has spring released some water jet when pressure increased due to boiler heating water
 

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Because your plumbing system is pressurized to 80 psi, an expansion tank pre-charge should be calibrated to 80 psi. At 80 psi, the tank will contain 0 water so any additional pressure rise due to expansion will be absorbed by the tank. When any faucet is opened or toilet flushed, the water pressure will reduce to below 80 psi so any absorbed water will be pushed out from the tank.

The expansion tank should be installed on the cold water line prior to the water heater.

Is it possible to adjust the cut-out setting on the pump? A 60 psi setting should be sufficient and will reduce stress on your plumbing system.
 

Bob1000

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Because your plumbing system is pressurized to 80 psi, an expansion tank pre-charge should be calibrated to 80 psi. At 80 psi, the tank will contain 0 water so any additional pressure rise due to expansion will be absorbed by the tank. When any faucet is opened or toilet flushed, the water pressure will reduce to below 80 psi so any absorbed water will be pushed out from the tank.

The expansion tank should be installed on the cold water line prior to the water heater.

Is it possible to adjust the cut-out setting on the pump? A 60 psi setting should be sufficient and will reduce stress on your plumbing system.

Unfortunately the type of controller i use stops the pump when it achieves its max pressure and no flow so I have no control on pressure and it is in my case 80psi

How i can calibrate pressure tank to be 80psi? you mean i fill its air content till 80psi ?
 

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you mean i fill its air content till 80psi ?
Yes. This maybe performed prior to installation or after, while there is no water within the tank and with the pump and water supply shut off and a faucet remaining open so there will be 0 pressure in the plumbing system.

https://images.app.goo.gl/qWWK6cAnka1x9Cea8
16114235735211549998674.png

1611423531594254798762.png

thermal-expansion-tanks
 
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Valveman

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Unfortunately the type of controller i use stops the pump when it achieves its max pressure and no flow so I have no control on pressure and it is in my case 80psi

How i can calibrate pressure tank to be 80psi? you mean i fill its air content till 80psi ?

That type pump is the problem. They have a teaspoon size tank built in, which isn't enough. When it goes out soon, which is what those kind of pumps are made to do, go back with a regular jet pump and a PK1A control kit. That will solve your problem and should last 30-40 years.
 

Bob1000

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That type pump is the problem. They have a teaspoon size tank built in, which isn't enough. When it goes out soon, which is what those kind of pumps are made to do, go back with a regular jet pump and a PK1A control kit. That will solve your problem and should last 30-40 years.
That type pump is the problem. They have a teaspoon size tank built in, which isn't enough. When it goes out soon, which is what those kind of pumps are made to do, go back with a regular jet pump and a PK1A control kit. That will solve your problem and should last 30-40 years.
Unfortunately the CSV is not available in Egypt or I would have used it long time ago so we have to use the electronic pump controller which is very common here and have replaced the pressure tank and pressure switch
 

Reach4

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I would consider treating this with a pressure tank after the pump by the pump maintainers, if possible, rather than a thermal expansion tank problem. That would call for a larger pressure tank with precharge set lower. If you choose to treat this as needing a thermal expansion tank, you need one big enough for for all of the units on your side of the pump, I would think, because you are going to be potentially receiving expansion water from all of the pressurized water heaters.

Another alternative, that consumes water, is to have a 100 psi pressure relief valve dump the excess water pressure. Maybe have that dump water onto some plants that could use the water.
 

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Unfortunately the CSV is not available in Egypt

We ship to several other countries when asked. But yeah, most other countries do not make it easy for Americans to compete. My little $63 valve ends up costing people 300-400$ or more, to pay the broker, tariffs, and other fees. Several countries will not let the customer have the valve until they come in a grease some palms. Americans are supposed to purchase from all other countries and help them prosper, but we are not allowed to sell our products to these other countries. Causes a huge trade deficit that someone was trying to fix. But that would be racist for Americans to try and protect their economy. Other countries trade policies with the US have never been fair to the US.
 

Bob1000

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In addition to the existing pump electronic controller , Is it possible to fix a pressure switch that would switch off the pump when pressure reach 60psi ? but connect the circuit at any value less than 60psi when a water tap is open?

I am afraid of cycling when i use such switch and that was the only reason i use electronic controller in stead
 

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Yeah they make those electronic controllers sound good. But they are really designed to predictably shorten the life of the pump/motor. They allow the pump to run too close to dead head conditions. The pump will usually stay on down to about 1/5th of a GPM, which may not be enough to keep the pump cool.

Usually you can just take them off and add a regular pressure switch and pressure tank. But the pump you have may not build enough pressure to work with a pressure switch, as with the electronic controller, a pump that builds good pressure will cause too much pressure in the house. So, they use a low head pump and let it work at max head all the time. Check the max pressure of your pump? The pressure switch can be set to shut the pump off about 10 PSI lower than the max pressure of the pump.
 

Bob1000

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Yeah they make those electronic controllers sound good. But they are really designed to predictably shorten the life of the pump/motor. They allow the pump to run too close to dead head conditions. The pump will usually stay on down to about 1/5th of a GPM, which may not be enough to keep the pump cool.

Usually you can just take them off and add a regular pressure switch and pressure tank. But the pump you have may not build enough pressure to work with a pressure switch, as with the electronic controller, a pump that builds good pressure will cause too much pressure in the house. So, they use a low head pump and let it work at max head all the time. Check the max pressure of your pump? The pressure switch can be set to shut the pump off about 10 PSI lower than the max pressure of the pump.


As I said before , my problem with a pressure switch and a pressure tank is cycling during shower which results in hot and cold shots , as long as the CSV is not available this system is not good for me.

any way , today I connected a pressure tank to the cold line as advised here and it seems it solved the problem so far , it made the pump less nervous and does not start immediately when i open any tap and the water pressure going smooth from tap , no water hammering like before , does that make sense ?
 

Reach4

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As I said before , my problem with a pressure switch and a pressure tank is cycling during shower which results in hot and cold shots , as long as the CSV is not available this system is not good for me.

any way , today I connected a pressure tank to the cold line as advised here and it seems it solved the problem so far , it made the pump less nervous and does not start immediately when i open any tap and the water pressure going smooth from tap , no water hammering like before , does that make sense ?
Makes sense.

The air precharge should be set below the lowest pressure that the pump ever delivers. Air precharge is set with the water pressure zero.

This will help not only you, but everybody who uses the same pump. It is possible that you will detect an oscillation effect at some time. If that does not occur, then good deal.
 

Bob1000

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Yeah they make those electronic controllers sound good. But they are really designed to predictably shorten the life of the pump/motor. They allow the pump to run too close to dead head conditions. The pump will usually stay on down to about 1/5th of a GPM, which may not be enough to keep the pump cool.

Usually you can just take them off and add a regular pressure switch and pressure tank. But the pump you have may not build enough pressure to work with a pressure switch, as with the electronic controller, a pump that builds good pressure will cause too much pressure in the house. So, they use a low head pump and let it work at max head all the time. Check the max pressure of your pump? The pressure switch can be set to shut the pump off about 10 PSI lower than the max pressure of the pump.

Actually the pump I have produce 5 bar on its own add to that the city pressure at night which can reach more than 1.5 bar so the total pressure can reach 7 bar which is too much for the piping system

I know that the CSV is the best solution but I can not find it in Egypt , any suggestions to avoid cycling during shower?
 
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