FAQ - pressure vessels GWS

Here we have prepared answers to the most common questions regarding the selection or operation of pressure vessels.

The questions are mainly focused on GWS pressure vessels, which is at the forefront of innovation and new technologies for pressure vessels and is the most comprehensive supplier of pressure vessels in the world.


What is the maximum working pressure of GWS tanks?

 Maximum Working Pressure  BAR  PSI

 Pressure Wave



 10  150
 Max 16   230
 UltraMax  25  360
 HeatWave  10  150
 ROWave  7  100
 Challenger  10  150
 C2 Life  8,6  125
 SuperFlow  10/16/25  150/230/360

What is the maximum working temperature of GWS tanks?

 Maximum Working Temperature  °C °F 
 Pressure Wave  90  200
 HeatWave  100  210
 ROWave  40  100
 Challenger  90  200
 C2 Lite  50  120
 SuperFlow  90  200

Can I use glycol (anti-freeze) in a GWS tank?

We recommend not using over a 50/50 mix. of propylene glycol. Ethylene glycol shall not be used. Under no circumstances can the product contain a petroleum base.

Can I use petroleum base products in my GWS tanks?

No. The material in our diaphragm will not tolerate petroleum-based products.

Can I install my GWS tank on its side?

Tanks larger than 100 liters are not recommended for installation on their side since it may cause diaphragm damage and failure.

What is the warranty on GWS tanks?

GWS warranty varies by market- please contact your local distributor for warranty applicable in your area.

Does the warranty cover labor?

No, unfortunately there are number of factors that can contribute to a failed tank and the only factor that GWS can insure is the tank.

My tank was just installed and the water has a funny taste – what should I do?

Flush the new tank by allowing water to flow through three or four pump cycles. If the taste continues, you should probably have the source water tested. 

Can I use chlorinated water with my GWS tank?

Of course. GWS tanks are designed in the knowledge that chlorine is often used to periodically treat a well.

What is a cycle?

A cycle refers to the pump run time. A cycle starts when the pump starts and a cycle is completed when the pump stops. Pump starts and stops are determined by the pressure settings of the system. Below, we demonstrate a tank’s drawdown feature that assumes a water system with a 30/50-psi pressure setting. This means that the pump will start (“cut-in”) whenever the pressure inside a tank is reduced to 30 psi and will stop (“cut-out”) when the pressure reaches 50 psi. Common pressure settings are 20/40, 30/50 and 40/60.

How does a pressure switch control the pump and tank?

The pressure switch communicates with the tank and the pump. The pressure switch monitors the pressure inside the tank and activates and de-activates the pump when cut-in and cut-out pressures are reached inside the tank.

What is drawdown?

Drawdown refers to the amount of water that evacuates the tank before the pressure switch will activate the pump. Drawdown is a affected by the pump, the size of the tank and the pressure settings that govern your water system. 

What is pre-charge pressure?

Pre-charge pressure refers to the amount of gas (air is used in GWS  tanks) in bar/psi that is pumped into a tank prior to installation – usually at the factory. The pre-charge is the “spring” that helps to create water pressure. As the diaphragm fills with water, it compresses the pre-charge. In a 30/50 system, the pump will continue to propel water into the tank until the pressure in the tank reaches 50 psi.

What is the standard pre-charge GWS tanks provided with?

 Standard Pre-Charge  BAR  PSI
 Pressure Wave  1,9  28
 M-Inox  1,9  28
 Max  4  58
 UltraMax 4  58


HWB-2LX and HWB-24LX

HWB-60LV and HWB-80LV





 ThermoWave  1,9  28
 SolarWave  1,9  28


 Inline and Plasteel






 Challenger  1,4  20
 C2 Lite  1,4  20
 SuperFlow  4  58

How much pressure (pre-charge) should be in my tank?

Your tanks should be pressurized to 2 psi less than the cut-in pressure setting (for example, if your pressure settings are 30/50, then you cut-in pressure setting is 30 psi and your tank should have a 28 psi pre-charge).

How do I check or change my pre-charge?

You must completely drain the tank to check pre-charge. To do this, shut the power off to the pump and open (turn-on) a faucet in the house. This will drain the tank and not allow it to refill. On the top of the tank you will find an air valve (similar to the air valve on your tires) – use a tire pressure gauge to check the air pressure.

What is the maximum chlorine tolerance of the diaphragms?

We recommend 5 – 50 ppm for flowing treatment and a maximum of 250 ppm for system disinfection.

How to connect a FlowThru tank to a bigger or smaller diameter pipe?

The pipe diameter should be changed to the connection diameter 50cm before and after the tank.

How do I install a carbon filter?

Insert the carbon filter into the housing and tighten the cap. Run water through the housing for 3 minutes, then close the tap. After 5 minuts open the tap and allow the water to run for 5 minutes. This will completely flush the cartridge. During the flushing you will note black / grey water containing carbon fines.