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Adding a Water Flood Sensor to my Vista-20p alarm system

My Honeywell Vista 20p alarm system is fairly comprehensive, but I want one more feature: an alarm that lets me know when my sump pump isn't working properly. Here is how I added one for about $8 in special parts.

 

Float Sensor on custom bracket for my Vista 20p Alarm

I'm afraid of a flood in my finished basement. I'm fortunate - my basement sump pump system is already redundant, with two independent pumps and two outflow pipes. The primary pump kicks in when the water level reaches 6 inches, and if that doesn't work, then the backup pump kicks in when the water level reaches 7 inches.  The backup pump should never kick in unless the primary pump is having a problem pumping.  

But there is a problem with this setup: I might never know if my primary pump has failed, leaving me with no redundancy.  I want to be informed when I have one (or god forbid, two) pump failures.

My goal is to have my Vista 20p alert me when the sump's water level is ever beyond the point where my primary pump should have kicked in, alerting me of a problem.

My Sump Level Alarm Concept

As noted earlier, my primary pump kicks in at a 6 inch water level, and my backup kicks in at 7 inches.   I'd like to add a float sensor to one of the sumps which will be triggered if the water level gets higher than the normal high level, maybe at 6.5 inches,  as shown in Figure 1:

Drawing of Float Sensor in Sump
Fig 1: Drawing of Float Sensor in Sump
 

Effort Required

I have a Vista 20p alarm system, which I have configured mostly as a wired building protection system.  It is great because it requires no batteries or radios and is extraordinarily reliable, comprehensive, and expandable. In order to pull off this sensor I'll have to do the following:
  • Bring a 2 conductor wire from the panel to the sump. 
  • Mount a float sensor inside the pump
  • Program the alarm panel so that when the float is raised, the panel sets off an alarm

The Parts I need

To create a sump level sensor I'll need some parts.  The only special part I'll need is a float sensor, but I need a bunch of other generic supplies too.  I went to Amazon and bought a few things:

The Water Sensor: $8 for two.

The float sensor I bought ($8 for a 2-pack) is of the "normally closed" (NC) variety, meaning that when the float is NOT floating, its circuit is complete.  When the float rises, the circuit is broken.  My Vista 20P can detect this change.

This sensor is much less expensive than the purpose built "alarm water sensor units".  Since the package came with two floats, I have a spare in case the first one fails. 


Fig 2: Float sensor with EOL resistor


Alarm Panel Resistors: $5.50 for a pack of 20.

Most wired alarm panels offer a feature to detect wiring failures in case the line is shorted or cut.  That way, the alarm system can constantly monitor the health of the sensor wiring.

For the Vista series of panels, usually a  2k Ω "end-of-line" (EOL) resistor is put on the line. But I'm using a very old 4219 zone expansion module that requires a 1000 Ω  EOL resistor.  Therefore, I bought a pack of 1k Ω resistors for about $5.50.  Note that the modern 4219 zone expansion module, uses the standard 2kΩ resistors.

Security System Wire: $35 for a 500 foot spool

I only needed about 20 feet of two-conductor alarm wire, but since I like projects I decided to buy a 500 foot spool of four-conductor wire for $35 - which is in essence a lifetime supply of wire for me.  So I spent a lot more on wire than I had to, but I will likely never need to buy wire again.

Other items I used to make a neat installation

I didn't need to buy any of the following items, but to make it neat and secure I used the following stuff from my "junk inventory":
  • A piece of scrap plastic, to form a bracket to mount the sensor. 
  • An "old work" electrical box, to make the wiring neat.
  • An old analog telephone jack, again to make the wiring neat
  • An RJ-12 pigtail, so I can easily remove the sensor.
  • Some heat shrink tubing, solder, zip ties, screws, and other minor parts.

Tools I used

  • Soldering Iron
  • Multimeter
  • Fish tape
  • Other common tools (screwdriver, scissors, etc.

Installation of my Sensor

This is where the rubber meets the road.  Once I had the float sensor, the resistor and the wire, I was able to bring it all together. 

 

fig 2: the float installation plan

Here is the construction process:

Wiring

  1. Pull my 4-conductor wire from my alarm panel to my sump pump.  Since the wire went through a partially finished basement ceiling, I used a fish tape to draw the wire through. Note that I really only needed 2 conductors, so I have some future-proofing built in.
  2. Install an old work box in the drywall
  3. Wire up the box to my telephone-style wall jack.
  4. Label the jack so future users will know that it's only for a flood alarm sensor, and not an analog telephone or anything else.

 

Photo: pretty in-wall wiring for my float sensor

Float Sensor

  1. Solder a 1k Ω resistor to one of the float sensor's leads
  2. Attach my RJ12-style pigtail wire to each lead of the float sensor.  Something like this adapter looks like a nice choice, but I used a scrap telephone cord.
  3. Use heat shrink and electrical tape to make the connection robust and secure
  4. Use scrap plastic to fashion a sensor bracket.  Note that plastic doesn't rust in the sump.
  5. Mount sensor bracket in sump pit.
  6. Manage cable with zip ties as necessary.

Connections

  1. Plug in the float sensor into the wall box.
  2. Test the leads at the alarm panel with a multimeter.  It should read about 1kΩ in my case.  It does.
  3. Prop up the float and test.  It should read infinite Ω.  It does.  UN-prop the float.
  4. Power down the alarm panel and disconnect battery.
  5. Attach the wiring to the alarm panel.  I attached it to the last zone in my 4219 module.
  6. Power everything back up. 

Alarm Configuration

  1. Go into programming mode
  2. Configure the alarm panel.  
  3. Exit configuration mode

Test

  1. Lift the float
  2. Alarm should sound within 1 second
  3. Drop the float
  4. Reset alarm condition.

Conclusion

My home built sump water level sensor is working great.  If and when the float moves out of its "dry" position, my alarm panel sends an alert to my phone and announces the fault on my home's keypads, and I get an alert from the alarm monitoring company.  Now I can react quickly if there is a pump failure.

In all, I spent about $50, but I spent so much because I wanted an additional supply of wire and resistors for my home improvement / hobby inventory.  In practical terms, the entire project used about $8 worth of supplies:

  • One Float: $4
  • "Old work" electrical box: $1.50
  • Wire (about 20 ft):  $1.50
  • Resistor: $0.30
  • Misc: $0.50 
  • "Useless" stuff in my junk bin: $0.

In terms of time, it took me about 8 hours of effort: 5 hours for planning, 2 hours for construction & installation, and 1 hour for panel programming/testing.

That's all there is to it.  I highly recommend pursuing this fairly easy and inexpensive project. 



 

 

 




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