Connecting multiple valves to an alarm panel.

When considering how to connect more than one valve to a water leak detection alarm panel, there are a number of factors that need to be considered.
The first thing to understand is the current each valve will draw when energized. There is usually a resting current and an in-rush current/start-up current, which are different.

Current is measured in Amps, the more valves the more Amps will be drawn.  For example a single 15mm actuated ball valve is specified to draw 5 watts.  To calculate Amps from Watts the following formula can be used:

Watts / Volts = Amps  

Example:  15mm actuated ball valve:     5 Watts / 230VAC = 0.02 Amps

In this example the actuated ball valve does not have an in-rush current, so we do not need to factor this in when considering multiple valves connected to an alarm panel.

Alarm Panel to No. Actuated Ball Valves Chart:

Alarm Panel	Max Number of Valves	Current Drawn
LeakStop	100	2 Amp
LeakStopper 1	25	0.5 Amp
LeakStopper Multizone	25 per zone	0.5 Amp

What influences the maximum number of valves connected to a water leak detector is the current rating of the alarm relay fitted in the alarm panel.  In the example above the LeakStop alarm panel has an 8 Amp relay and the LeakStopper alarm panels have a 2 Amp relay.

Now let’s consider all of this when using a solenoid valve.  These work differently to motorized ball valves using a electromagnetic coil to either lift or lower a plunger.  Unlike the motorized ball valve, solenoid valves do have an in-rush current.  The best way to think about an in-rush current is to imagine it as a spike of electrical power required initially to make the valve open or close.  This spike is usually only a fraction of a second long, after which it will settle to a resting current.  The in-rush current affects the number of valves that can be connected to an alarm panel, let’s look at how:

As seen before, current is measured in Amps and the more valves fitted the more Amps will be drawn.  Now we need to consider the maximum Amps required to open or close the solenoid valve against the rating of the relay.

Example :  15mm solenoid valve:     In-rush current 23VA / 230VAC = 0.1 Amps

Alarm Panel to No. Solenoid Valves Chart:

Alarm Panel	Max Number of Valves	In-rush Current Drawn	Resting Current Drawn with 80 valves
LeakStop	40	4 Amps	3.2 Amp
LeakStopper 1	20	2 Amps	1.6 Amp
LeakStopper Multizone	20 per zone	2 Amps	1.6 Amp

The chart above shows how the in-rush current is used to calculate the maximum number of valves.  For example a LeakStopper alarm panel with an 2 Amp relay can have up to 20 valves attached.  This is because each valve has an In-rush current of 0.1 Amps.

2 Amps / 0.1 Amps (in-rush current) = 20 valves

If there was no in-rush current to consider, the LeakStopper alarm panel with an 2 Amp relay could actually have 25 valves connected to it.

2 Amps / 0.08 Amps (resting current) = 25 valves

To conclude, the number of valves that can be connected to an alarm panel will depend on:

The rating of the relay in the alarm panel.

The current required to open or close the valve.

If there is an In-rush current or not.

Note:  The figures given are for guidance only and based on the specification supplied by the manufacturers of the valves.  It is important to remember that the figures quoted are a result of a best case scenario.  It is good practice to factor in some slack when specifying multiple valves for use with an alarm panel.  It would be our recommendation to keep the number to no more than:

Alarm Panel to No. Actuated Ball Valves Chart:

Alarm Panel	Max Number of Valves
LeakStop	40
LeakStopper 1	10
LeakStoper Multizone	10 per zone

Alarm Panel to No. Solenoid Valves Chart:

Alarm Panel	Max Number of Valves
LeakStop	20
LeakStopper 1	10
LeakStopper Multizone	10 per zone

In doing this, you greatly reduce the load on the alarm panel, this will give a much longer and reliable product life.

Finally, it’s worth mentioning best practice for connecting the valves to the alarm panel.  It is recommended that multiple valves are connected in parallel.  The primary reason for this is to prevent the combined conductor size getting too big and not fitting in the connector block inside the alarm panel.

The LeakStop alarm panel has a dedicated valve connection for exclusive use with normally open valves.  The LeakStopper alarm panels require the valves to be wired through the common alarm or individual alarm relays.  This means that a live wire must be linked from the mains incoming connection to the common of the relay.  A switch wire must then be added from either the normally open or normally closed connection, depending on the type of valve being fitted.   Full connection instruction are given in the product manuals.