Hydro pneumatic water system pump does not cut out
#1
08-07-17, 05:11 AM
Hydro pneumatic water system pump does not cut out
Member's location is UK.
Hi,
Our house system is pressurised by a hydro pneumatic cylinder. Till recently, all working fine. Now, pump runs and water pressure is fine, but pump just keeps going so I have to turn it on and off manually as water pressure is required. It gets up to pressure from 2 to 5.2 bar in about 10 seconds. Turn off pump and pressure stays around 5 bar for a long time. Run the cold tap with pump turned off and pressure slowly goes down from 5 to 2 bar in circa 30 seconds. There is air in the cylinder. The cylinder is 24 litres capacity.
From this, I am deducing that the cylinder/bladder is all OK?
Thus problem is either the pump or the pressure switch... Any ideas please on likelihood of problem and further diagnostics I can try?
Thanks
Casa am
Hi,
Our house system is pressurised by a hydro pneumatic cylinder. Till recently, all working fine. Now, pump runs and water pressure is fine, but pump just keeps going so I have to turn it on and off manually as water pressure is required. It gets up to pressure from 2 to 5.2 bar in about 10 seconds. Turn off pump and pressure stays around 5 bar for a long time. Run the cold tap with pump turned off and pressure slowly goes down from 5 to 2 bar in circa 30 seconds. There is air in the cylinder. The cylinder is 24 litres capacity.
From this, I am deducing that the cylinder/bladder is all OK?
Thus problem is either the pump or the pressure switch... Any ideas please on likelihood of problem and further diagnostics I can try?
Thanks
Casa am
Last edited by ray2047; 08-08-17 at 09:24 AM.
#2
08-07-17, 08:52 AM
If the pump will not turn off by itself when it gets to 5 bars (or whatever cut out pressure you wanted) then you should replace the pressure switches being sure that the connections to the water system are not rusted or clogged. Not worth it to just clean and adjust old switches, they will fail again and again and require constant attention.
Twenty four liters is small for a well water pump system. Your pump will still run frequent short cycles which is not the best working conditions. A second cylinder, preferably more than 100 liters, can be added and connected to the main water line near the first cylinder, each cylinder prepressurized to 2-1/4 bars after letting all the water out of the system, and the pump will run less often while delivering the same amount of water.
(Do not connect the second cylinder to the top of the first cylinder.)
Twenty four liters is small for a well water pump system. Your pump will still run frequent short cycles which is not the best working conditions. A second cylinder, preferably more than 100 liters, can be added and connected to the main water line near the first cylinder, each cylinder prepressurized to 2-1/4 bars after letting all the water out of the system, and the pump will run less often while delivering the same amount of water.
(Do not connect the second cylinder to the top of the first cylinder.)
Last edited by AllanJ; 08-07-17 at 09:16 AM.
#3
08-07-17, 09:25 AM
Thanks Allan.
It is not a well system. We pump water to a tank above the house. This then gravity feeds the house. Because the tank is not very high, we only get 2 bar, the pump and hydro pneumatic tank is used to increase this to run appliances and water heater. I guess that's why only 24 litre tank.
I cut off water, ran faucet then pumped air in as you suggested. pressure wouldn't rise above 1.2 bar. I guess a new switch is required? Do you agree with my assessment that the tank is OK?
Thanks CA
It is not a well system. We pump water to a tank above the house. This then gravity feeds the house. Because the tank is not very high, we only get 2 bar, the pump and hydro pneumatic tank is used to increase this to run appliances and water heater. I guess that's why only 24 litre tank.
I cut off water, ran faucet then pumped air in as you suggested. pressure wouldn't rise above 1.2 bar. I guess a new switch is required? Do you agree with my assessment that the tank is OK?
Thanks CA
#4
08-07-17, 06:15 PM
Do you have two pumps, one to get the water up to the tank on the roof and the other to add pressure to the water coming back down?
Is the tank on the roof sealed and pressurized? Or is it vented to the outside or have a loose fitting lid?
Where in the path of the water from city water main to your faucets is the hydro-pneumatic cylinder located?
Is the tank on the roof sealed and pressurized? Or is it vented to the outside or have a loose fitting lid?
Where in the path of the water from city water main to your faucets is the hydro-pneumatic cylinder located?
#5
08-08-17, 05:41 AM
Hi Allan,
Yes, have a borehole pump that gets water up to tank. This tank is not pressurised, loose fitting lid. This then gravity feeds to the house. Where it comes into the house is the pressurising pump/cylinder. There is no mains supply, I am off grid.
I've just stripped down the installation. The switch, joining pipe and cylinder are all very badly clogged up and corroded. I've bought new replacements and will try to install them now. Tricky job as accessibility is very tight!
Any tips on how to prime it once plumbed in??
Thanks
CA
Yes, have a borehole pump that gets water up to tank. This tank is not pressurised, loose fitting lid. This then gravity feeds to the house. Where it comes into the house is the pressurising pump/cylinder. There is no mains supply, I am off grid.
I've just stripped down the installation. The switch, joining pipe and cylinder are all very badly clogged up and corroded. I've bought new replacements and will try to install them now. Tricky job as accessibility is very tight!
Any tips on how to prime it once plumbed in??
Thanks
CA
#6
08-08-17, 07:10 AM
I once had a gravity feed tank above my ceiling supplying water to my living quarters at a off-the-grid hunting camp back in the woods.
But my water holding tank was 100 gallons (378 liters) laying horizontally, and I used a gasoline water pump to fill it once every day or two.
A larger tank would give your pump a rest, if you can find a little more space.
But my water holding tank was 100 gallons (378 liters) laying horizontally, and I used a gasoline water pump to fill it once every day or two.
A larger tank would give your pump a rest, if you can find a little more space.
#7
08-08-17, 02:41 PM
Does your hydro-pneumatic cylinder have a bladder or diaphragm or air bag inside?
If so you would prime it with air while the the pump is off and a cold faucet is open. Or if it is new or was discaonnected from the plumibing it can be primed in advance or connecting it up. Set the air pressure inside to be a trifle less than the pump cut in pressure. For example if the pump is supposed to turn on at 2.0 bars you might prime the cylinder at 1.8 bars.
If a cylinder with a bladder will not hold prime it should be removed, discarded, and replaced. A torn or ruptured bladder inside will give erratic and unprdictable performance.
Any kind of hydro-pneumatic cylinder can be primed with air after installation. A cylinder with no bladder is primed after water has stopped draining ffrom the cold faucet and the faucet is turned off.
If so you would prime it with air while the the pump is off and a cold faucet is open. Or if it is new or was discaonnected from the plumibing it can be primed in advance or connecting it up. Set the air pressure inside to be a trifle less than the pump cut in pressure. For example if the pump is supposed to turn on at 2.0 bars you might prime the cylinder at 1.8 bars.
If a cylinder with a bladder will not hold prime it should be removed, discarded, and replaced. A torn or ruptured bladder inside will give erratic and unprdictable performance.
Any kind of hydro-pneumatic cylinder can be primed with air after installation. A cylinder with no bladder is primed after water has stopped draining ffrom the cold faucet and the faucet is turned off.
