The open cover causes the detector to go into supervisory alarm. This doesn't cause a shutdown unless it is tied to an alarm system that shuts the HVAC units down. There will be a separate relay connected to the fire alarm system when this happens. If the detectors are tied to a alarm system this usually generates phone call from the alarm company. Every once and a while it will get a code 3 response form the fire department. Always best to put the system in standby and notify the alarm company, before even cutting power to units monitored by an alarm company. Any decent sized magnet will work, but the magnet is will only put the detector into alarm. The alarm can only be cleared with the test/reset button or remote accessory. The magnet tripps the sensor, the sensor can't clear the alaem. Inspectors in my area will not accept a magnet test, so have a can of smoke ready. Take a Gatorade bottle and cut it just below the shoulder. While it is cupped over the detector spray the smoke in and seal with your hand to hold the smoke in. It may take a couple of trys to get it to trip. The indoor sensors have a plug in them designed to spray the smoke in the little hole with a straw connected to the can of smoke. Unfortunately I've never seen a can of smoke come this way. Most residential systems with an ECM blower will require separate relay to cut high voltage to the ECM blower. You will fail inspection in many areas if the blower doesn't shut down instantly. You need to cut power on the provided terminals on the board or cut power to the board. Cutting 24 to the t-stat will allow the fan to continue for a few minutes. That will cause you to fail inspection in many areas. I see where technicians cut 24 to the blower contactor without cutting power to the board. This can cause damage if the system keeps running without the fan. What if the high limit switch doesn't shut the gas off? A nothing situation can turn into a real problem.
Wow, this is really great info! Thank you! You know a lot when it comes to this. I’m assuming you’ve worked on smoke detectors for some time. And you’re right on the ECM. I was working on two systems where on one, it cuts the ECM immediately when the thermostat loses power but on the another one, the ECM stays on even after the thermostat loses power.
When you cut the high voltage of the ECM motor, do you cut either L1 or L2 when you’ve done it? Normally with ECM motors, when you unplug and the plug the high voltage on the ECM motor, it messes the motor up. I know because it’s happened to me and you see a small arc and there goes the motor.
Inspectors in my area reqire you to sample air after the blower motor. I will sometimes mount the detector in ahead of the blower with a tube going through the wall past the blower.
EXCELENT CLASS THANK YOU
Wow amazing job thank you for taking the time and explaining this. I am new to HVAC and i was able to understand everything nicely. Thank you.
Excellent explanation thank you
Please keep posting videos
Thanks for your help Good job
Thank you 😎 🤟
The open cover causes the detector to go into supervisory alarm. This doesn't cause a shutdown unless it is tied to an alarm system that shuts the HVAC units down. There will be a separate relay connected to the fire alarm system when this happens. If the detectors are tied to a alarm system this usually generates phone call from the alarm company. Every once and a while it will get a code 3 response form the fire department. Always best to put the system in standby and notify the alarm company, before even cutting power to units monitored by an alarm company.
Any decent sized magnet will work, but the magnet is will only put the detector into alarm. The alarm can only be cleared with the test/reset button or remote accessory. The magnet tripps the sensor, the sensor can't clear the alaem. Inspectors in my area will not accept a magnet test, so have a can of smoke ready.
Take a Gatorade bottle and cut it just below the shoulder. While it is cupped over the detector spray the smoke in and seal with your hand to hold the smoke in. It may take a couple of trys to get it to trip. The indoor sensors have a plug in them designed to spray the smoke in the little hole with a straw connected to the can of smoke. Unfortunately I've never seen a can of smoke come this way.
Most residential systems with an ECM blower will require separate relay to cut high voltage to the ECM blower. You will fail inspection in many areas if the blower doesn't shut down instantly. You need to cut power on the provided terminals on the board or cut power to the board. Cutting 24 to the t-stat will allow the fan to continue for a few minutes. That will cause you to fail inspection in many areas.
I see where technicians cut 24 to the blower contactor without cutting power to the board. This can cause damage if the system keeps running without the fan. What if the high limit switch doesn't shut the gas off? A nothing situation can turn into a real problem.
Wow, this is really great info! Thank you! You know a lot when it comes to this. I’m assuming you’ve worked on smoke detectors for some time. And you’re right on the ECM. I was working on two systems where on one, it cuts the ECM immediately when the thermostat loses power but on the another one, the ECM stays on even after the thermostat loses power.
When you cut the high voltage of the ECM motor, do you cut either L1 or L2
when you’ve done it? Normally with ECM motors, when you unplug and the plug the high voltage on the ECM motor, it messes the motor up. I know because it’s happened to me and you see a small arc and there goes the motor.
Putting it on exhaust will pickup HVAC smoke from motor or heat strips quicker.
Inspectors in my area reqire you to sample air after the blower motor. I will sometimes mount the detector in ahead of the blower with a tube going through the wall past the blower.
Try it with 1 magnet I believe stuck together you are cancelling poles, try it on steel.