What is Zone-Doubling on a Honeywell VISTA System?

Zone-Doubling, available on the Vista-20P and Vista-21iP panels, is a method of using different resistor values to allow zones 2-8 to each be treated as two separate zones. When zone 2 is doubled, it becomes both zone 2 and 10. Zone 2 uses a 3K resistor, and zone 10 uses a 6.2K resistor.

The Vista-20P and Vista-21iP panels each have 8 hardwired zones built into the panel. Traditionally, additional hardwired zones were added to the panel using a Honeywell 4219 8-zone expansion board. But, in some cases, the user may only need to add one or two additional zones. In these situations, adding a 4219 is somewhat wasteful. Zone-Doubling is perfect for these circumstances.

Only zones 2 through 8 can be doubled, which adds up to seven additional hardwired zones. When zone 2 is doubled, it becomes both 2 and 10, when zone 3 is doubled, it becomes both 3 and 11, and so on. Zone 1 can not be doubled, as it is electrically isolated from all other zones on the panel, and it has a lower resistance tolerance than any other zone (100 ohms tolerance, vs. 300 ohms). This is because it serves as the panel's 2-wire smoke zone.

The following rules apply to doubled zones:

  1. Response Time. The response time programmed for the lower zone number will also apply to the higher zone number. If zone 3 is programmed with a 700 millisecond response time, zone 11 will also have a 700 millisecond response time.
  2. Normally Closed Only. Only Normally Closed devices can be doubled. A short across either resistor of a doubled zone will cause a tamper response (Day/Night) on both doubled zones. When the system is armed, this will report as an E135 and is treated as an alarm. When disarmed, it reports as an E383 and displays as a trouble.
  3. Double similar zone types together. Earlier panel versions had issues when unalike zones were doubled together, such as when an Entry/Exit zone was doubled with a motion zone. In that particular case, the motion zone will most likely be bypassed in Stay mode, while the Entry/Exit zone will be active. As a result, walking around and faulting the motion zone while in armed stay mode could sometimes cause a false alarm on the Entry/Exit zone. For this reason, it was recommended to only double similar zone types. This was corrected in later versions, but it's not a bad idea to adhere to this logic, even now.

    The video below will show you how to wire the 3K resistor to the lower number zone in a zone doubled pair:



    The videos below will show you how to wire the 6.2K resistor to the higher number zone in a zone doubled pair:




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That is correct EOL stand for end of line.
Why put resistors at the panel aren’t they called EOL resistors for a reason
DJ, You can get a check if there is an open on the zone. Zone doubling is for Normally Closed contacts only. Verify your contacts and your wiring.
It doesn't really show how to program the zones for zone doubling. I keep getting "check zone 2 -- check zone 10". Both are connected with the proper resistors.

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