Will a metal door interfere with wireless sensor operation?

Many types of metal doors, windows, and patio door frames can interfere with the operation of a wireless door sensor, severely undermining the RF signal. The sensor may operate flawlessly prior to installing the unit. But once mounted to the door or frame, there may be little, if any, detected signal at the controller / receiver.

Does the problem affect all wireless door sensors?

While most any wireless door sensor may be subject to this kind of impediment, our GEN2 "classic" sensor is designed with a copper coil antenna that makes it less susceptible, though not completely immune.

Is there a viable solution?

Fortunately, there is a relatively simple approach for combating the problem. Click here for details.

Which wireless system should I choose? (GEN2 vs GEN3)

Our HSRS wireless systems are available in two generations: GEN2 & GEN3. While both are functionally equivalent, there are some key differences to consider when making your purchase. (Bear in mind that the two generations are not cross-compatible. Therefore, you may not use a GEN2 sensor with a GEN3 controller, or vice-versa.) The two product generations are discussed below.

For a comparison summary, scroll to the bottom of the page.


Manufactured by Honeywell, these sensors are the same type found in compatible security systems. They feature sleek, modern design and long battery life (batteries included). We offer two GEN3 sensor models: mini and basic. Both operate at 345 MHz, and are advertised with a transmission range up to 200 ft. (open air). However, we have found the usable range is typically lower and can vary widely from one installation to the next. (The RF signal can be diminished by some types of metal door framing.) Therefore, you should presume a max range of 75 ft. GEN3 sensors store a factory-assigned ID (address) and need only be registered (i.e., paired) once at the controller/receiver.


Tried and true, our GEN2 classic (X10) sensor has withstood the test of time. Operating at 310 MHz and featuring internal copper-coil antenna, this device packs a wallop. Less susceptible to signal degradation issues, it yields a usable transmit range up to 100 ft. The sensor stores a random, self-assigned ID (address). Therefore, re-registration at the controller is required whenever batteries are replaced. Two (2) AAA batteries are required, delivering up to 2 years of reliable operation. Lithium batteries will last 5 years or longer!

Comparison Chart:

The chart below compares critical features of the two wireless product generations:

    GEN3   GEN2
  • Modern design
  • Permanent ID (address)
  • Battery included
  • Copper coil antenna
  • Excellent range (100 ft.)
  • Diminished range
  • Temporary ID (address)

What is the current-switching capacity?

The Kadtronix family of smart relay systems are rated as follows:

  •   5A @ 125vac

Any tips for completing a proper install?

Installation is straightforward and requires no special skills other than your existing expertise with HVAC systems and basic wiring. Consider the following tips for a smooth, trouble-free installation:

Tip #1: When installing the HSRS wireless system, be careful to avoid contacting the antenna to any grounded surface such as the HVAC equipment chassis.

Tip #2: For best RF reception, locate the antenna as high as possible (i.e., just below the ceiling). Also, ensure a minimum separation of 3 feet from any of the following:

  •   - Wireless devices (wi-fi routers, cordless phones, etc.)
  •   - Metal equipment (HVAC, laundry appliances, water heater, metal shelving, etc.)

Tip #3: Before permanently mounting wireless door/window sensors, first complete the registration (i.e., pairing) procedure, keeping the sensors close-at-hand for convenience. Following registration, test to ensure the controller unit recognizes door sensor activity. Once you are satisfied the system is behaving properly, apply the sensors as desired.

Tip #4: When installing a wireless door/window sensor, consider the following:

  • - The mini sensor requires no setup other than inserting a CR2032 battery (included)
  • - The basic sensor contains two wiring screw terminals which must be wired together with a short jumper. Apply the jumper prior to inserting the battery. (The jumper can be omitted if you plan to apply a wired door switch at these wiring terminals.)
  • - The classic sensor must be properly initialized after inserting batteries. To do this, press & hold the white push-button for 5 seconds.

Is it safe for my A/C compressor?

Absolutely! First, consider that modern HVAC systems are equipped with built-in delay mechanisms to ensure that refrigerant pressures have equalized before allowing the compressor to start. Second, our HSRS controller features its own configurable delays, described below:

Delay #1 minimizes the possibility of short-cycling by preventing shut-off unless the monitored door or window remains open for a preset time period. Configurable from 0 to 600 minutes (10 hours), the typical setting for most installations is 2 minutes. Therefore, a door must remain open continuously for 2 minutes before shut-off is invoked.

Delay #2 is a configurable re-activation timer that prevents the HVAC system from restarting until the desired time elapse. As mentioned earlier, most HVAC systems provide their own built-in delay for this purpose, so a secondary delay is typically not required. Still, we find that some customers prefer to deploy it for added peace of mind.