Duct Smoke Detector Simplified

[@EP-xv2bj]

Hey Chris. Real quick. The supervisory contacts are closed because when they are powered down, they supv relay opens. Just like a door contact on an alarm. This is to monitor AC unit working. It’s also to monitor the tamper off of one alarm contact. Example: the 2 alarm wires tie into the alarm relay with the resistor across to keep it supervised. But pull one leg of the contact off of 1 alarm terminal. Replace it with a jumper that will connect from alarm terminal to common of supervisory relay. Then the other leg of the alarm contact will screw into the terminal of the normally open supervisory relay. So basically, the alarm is completing its circuit with the resistor strapped over the alarm relay, then to the “closed” supervisory relay. So that when the detector is tampered with, or loses power, the circuit will “open” and cause the fire panel to go into a trouble. Hope this helps!

[@hgbugalou]

24 volts can definitely hurt you... If you drop the transformer on your foot.

[@SodiumInduction-hv]

lol

[@cjkokay]

Easy about the relay. The no/nc refer to the de-energized state. The sup relay with normally be engergized to ensure the alarm if power to the unit fails.

[@44R0Ndin]

I was just about to comment this, that's why it indicates trouble when the power is cut. No power to pull in the relay, means you get an open circuit on the alarm wires.

[@Elysiann]

In Australia, the way duct detectors are done is different. They are powered from the fire panel itself, not an external/auxiliary power supply.They are wired on the detector loops, so any alarm or fault condition is seen directly by the panel. Usually , there is one duct probe on a supply unit, to check for "smoke" in the outside air and the unit is set to shut down on a "fire" condition. Then once the "smoke" is cleared, the fan will start back up. The idea is to stop smoke from outside being put into the building. For return units, the duct prob is set to generate an alarm, set off the warning systems, call the fire brigade, shut down supply units,etc ... what ever the fire/smoke matrix calls for. IE: there is smoke in the building somewhere. This is a latched alarm, so you need to reset it from the fire panel. The dectectors are usually addressable, so you know exactly which detector is in alarm or fault. The duct detectors you're using, we do use too. But we use them on "dumb" or non addressable fire panels. They are the only device on the circuit from the fire panel. Only used on return air ducts. That all being said, the fire codes for the US and Australia are vastly different. In some instances, I wish we had the set up you have ( as displayed), in some other cases, the system you have would causes a lot of problems here is Australia.

[@starlite528]

The installs that I've done, as a fire tech, had a 'less smart' unit, but the smoke head was addressable for the FACP and the detector unit still had the test/reset stations hooked up. The supervision and alarm all came through the addressable part, so a lot of smoke heads and duct detectors (dozens) are looped in on a single 2-wire circuit. There was a separate addressable relay (that the HVAC tech would tie to) that would activate upon alarm, or whatever other condition, from the FACP. A general fire alarm from the building would shut down the units, but a duct detector that has sensed smoke would usually only shut down the unit and send a supervisory alarm.

[@murkyturkey5238]

I like that bc if I’m working on that unit and accidentally trip the duct detector I don’t call the fire department over for a false alarm

[@CHOMAHOMA]

Thank you for taking the time to make this video. Extremely helpful.

[@trebrehenuf]

Deep sir, if one can recognize the complexities of fa systems. You skirted at the right places.

[@HVACRVIDEOS]

thanks!

[@seang.2046]

Perfect video, learned alot that I've seem to forget over the years. Refresh helped

[@rayregal6258]

great information, glad there's people like you with videos that make sense to watch.

[@publicmail2]

The resistor is an EOL end of line resistor to check integraty of wire loop, it has to be put at the end of the line loop.

[@thecurious6721]

Thank you for the great video. The only problem it took me 30 minutes to watch first 16 min trying to understand and figure out how you were getting 15kohms across SUP NO contacts 🤣 Thanks a lot for explaining that. If you skipped that I wouldnt be able to sleep today 😁

[@fredrosas2575]

I've wired these through the AUX contacts but never went in depth through all the other contacts and settings. Thank you so much for this video.

[@HVACRVIDEOS]

thanks for watching!

[@FJBANDHUNTER2024]

Great videos brother. Very in depth

[@joshhope9287]

So for people who are not in the fire or security industry(both are the same when it comes to EOl resistors I’m gonna break this down for you. On any wire that you have whether it be open circuit or closed circuit; the only way to ensure that the wire is good and hasn’t been cut down the line somewhere is to put a resistor with a certain resistance or ohm value at the end of the cable. 3.3 or 4.7k whatever it may be all it does is tell the control panel that the wire is intact. This is not voltage!!! It is a circuit. Ohms. Resistance. So you are correct we as fire people on a normal fire system are looking for a dead short, pretty much the wires touching together to indicate our alarm signal. In normal operation the panel is reading the value of the resistor. An open circuit or cut wire would indicate a trouble condition. This is different than a supervisory signal. Supervisory signals aren’t alarm signals!! Yes we want to know about it as it will report to the monitoring facility what the trouble but we don’t want it to create an alarm and activate horn,strobes and such. 99% of fire alarm circuits are open circuits because that’s the most efficient way of detecting the two states of the circuit open or closed. Closed for alarms and open for troubles. Anything else is just normal resistance value at the end of the cable or line.

[@HVACRVIDEOS]

Great information bud thanks for taking the time to leave some info!

[@Ufphen]

also the monitoring company should not be calling the fire department for a trouble signal when you turn off the unit.

[@abc-coleaks-info]

They put those damn things in the ducts at a prison facility. The damn dust triggered the detectors everywhere and people were kept on the run for months looking for fires that were never there. A big expensive pain in the butt. Their staff conducted fire watches continuously 24-7 anyway as a regular part of the job. When there was a fire, the staff caught it, the alarm came on later. They were ignored after that.

[@Akvan79]

Great video very informative. I also had problems with duct detectors until I decided to learn about them. I’m no expert but I do understand the concept

[@HVACRVIDEOS]

Thanks bud!

[@dudefixesstuff2153]

Way too many techs set these things off servicing the unit without calling to have service suspended. Great idea on putting the demo together!

[@HVACRVIDEOS]

thanks bud!

[@jeffreyarnold7042]

I have watched this video every time I have to install an duct detector

[@HVACRVIDEOS]

Right on man, hope it helps

[@jth1699]

I have run across controls that appear to be backwards - particularly in speed switches on generators that operate automatically- what is happening is that supervisory contact changes state when the power is applied. If installers dont realize this there will be start up issues. Why dont you measure the contact with no power applied and then turn on the power to the control unit and see if the switch changes state.. another advantage to that setup is if the n/c is closed with the power off and opens when it is energized the if the power went off the contacts would close to send an trouble signal - and for systems that depend on a normally closed circuit - which is generally the case - it would be the n/o supervisory contact that would be used to monitor for power and circuit trouble ... the resistor is generally referred to as an EOL resistor or End Of Line. Your explanation is correct except that the fire system senses the amperage or load on the detector circuit created by the resistor. No load equal open circuit and trouble alarm - shorted circuit equal alarm condition. These things are pretty simple once you know how they work. Course so is flying a 747 once your trained and have a few thousand hours of seat time... nice video

[@HVACRVIDEOS]

Thanks bud! I will be going live on KZbin this evening 12/16/19 @ 5:PM (Pacific Time) to discuss my most recent uploads and answer questions from emails, the chat and Facebook come on over and check it out if you can. kzbin.info/www/bejne/lWOTmXqkn89-apY

[@rookierefrigeration4357]

Excellent video Chris. I’ve learned a lot from you and your videos. Keep them coming bud.

[@HVACRVIDEOS]

thanks!

[@elijahgoodman3140]

Hey Chris, can you jump out the tamper switch to see if the amber light clears?

[@michaelsullivan479]

Excellent video STEELY EYED REFRIGERATION DUDE! I also set up electrical components on a board for our guys to learn on and become experts. We have to know how things work in order to know what is not working.

[@ryanprice5768]

I appreciate your videos so much. I'm in my first year of school for HVAC and your troubleshooting and thorough explanations of electrical problems etc. are more than helpful;they are incredibly interesting and well worded plus motivating. Thank you thank you thank you.

[@murkyturkey5238]

You’re welcome

[@jamiebaker3615]

Not sure if this is already been posted the reason why the supervisor is different is because when the powers on that actually energisers that relay so the normally open gets closed so when the power goes out at triggers a trouble conditions

[@DDRighteous]

Great video. I think the Supervisory relay is labeled backward because when the unit is in a Supervisory condition, the common to normally closed contacts are closed. If the relay was labeled "Normal Operation" then the labels would be reversed. Also, the Supervisory relay is normal when the Detector module is powered and there are no abnormal conditions. When power is shut off, the relay de-energizes, which alerts the fire alarm panel. Also, when the smoke heads get dirty (internally) the detector will go into a maintenance alert, and open the Supervisory relay. This will be indicated also by a blinking amber LED. You can clean the inside of the smoke detector with a clean horsehair brush, and reassemble the head, or replace the affected smoke head. I have not had very good results trying to clean with compressed air.

[@Ufphen]

I know its super annoying, you'd think it would work like the alarm contacts or any other set of dry contacts in existence, but no its got to be special.

[@DDRighteous]

@@Ufphen It has to operate like this so the panel shows a trouble when power is removed. Otherwise you would not know the detector has lost power.

[@Ufphen]

@@DDRighteous but why is Normally Open not normally open

[@DDRighteous]

@@Ufphen The supervisory relay is labeled correctly when there is no power applied to the duct-smoke. To make it supervised, they apply power to the relay when no trouble exists. That way it transfers when in a no power state, or when there is a trouble condition. If it were to operate the other way, you would never know when power has been removed. Or you would have to install an external power supervision relay to cause a trouble condition when power is removed.

[@Ufphen]

@@DDRighteous Its a set of dry contacts so regardless of power one side is going to be open or closed. Why would you have trouble condition be the normal state instead of no trouble condition as the normal state. These are dry contacts, they are passively designed, one side is always going to be shorted and one will always be open.

[@jacobmergens9135]

Danm, I've been making it so much harder on myself. THANK YOU!

[@jeffmoss2547]

great video!

[@joemartinez7619]

Thank dear sir. Putting food on many families tables. I prey u keep passing it forward.🇺🇸🎁🎄

[@brianmcdermott1718]

Great job. Good info.

[@pincheburro956]

Great video. Worked on a few lately.

[@HVACRVIDEOS]

right on thanks bud!

[@GabeDT567]

great video . adding to my learning folder . thanks

[@HVACRVIDEOS]

Thanks for watching bud

[@abazism]

Hi, what is that control board called ? The one that is connected to the smoke detectors

[@jaysingh-ho7eb]

Thank you for great video

[@lancerudy9934]

Very nice video. This is a great learning method for any body. Please keep up the great work!😁

[@aleksandrliudogovskii8491]

this video is understandable and helpful! thank you

[@HVACRVIDEOS]

Thanks for watching!

[@jackieg4277]

I need some help with wiring d4120 duct detector with rts2-aos multi signaling acc. On a Lennox 12.5 RTU

[@davetatro478]

Ever seen them wired to the power exhaust? I have...cant remember if it was code..

[@MrBdogg317]

Great video 👍🏼👍🏼

[@NOEISY1]

thank you, this was my first in RTU unit class and excellent

[@HVACRVIDEOS]

Thanks for watching bud!

[@SCOTTYD2031]

That was very interesting, thank you for that class teach!

[@anibalgutama9313]

Hi I’m Antonio I like your vireo help a lot thanks for thinking an other person

[@HumanRightsRevolutin]

Thank you very much VERY HELPFUL!!!

[@Randylazz]

Really enjoyed this video great job.......

[@HVACRVIDEOS]

Thanks Randy !

[@aircooledtx]

Great Info on SD wiring.

[@HVACRVIDEOS]

Thanks! I did this same presentation at my local RSES meeting once last year, it is probably time to do it again!

[@crazyk662able]

Thanks I been waiting on a video about smoke detector I get a lot of services call about smoke alarm an when I get there the Rtu is running but the alarm panel is showing fault and I’m lost from there cause I don’t know what to check so I just tell them to call the alarm company.

[@HVACRVIDEOS]

Thanks for watching bud if you look down in the show notes there is a link to an article I wrote for hvac school on the same topic

[@Colt-wr6wx]

Definitely not simple but thanks Chris!

[@TheMontanasv6]

It is residential house, I am trying to interconnect the duct smoke detector on the furnace to the ceiling smoke alarm. Would you please share some information how to interconnect these two? Thanks.

[@majindomttv3903]

Awesome video I don’t think I’ve seen one not come installed in a unit in a year or so now. Can you hook these up to an ansel system? Reason I ask is because the ansel system has dry contacts so it is breaking the signal from up above so is it possible to hook them to the smoke detector or is the ansel system basically taking the place of the smoke detector?

[@Ufphen]

ansel system is taking the place of fire detection, its actually covered under fire suppression and not fire alarm, we hook into it for an alarm condition when the ansel system as well as the electricians for electrical shutoff to the stove, griddle, oven, etc. Ive also seen damper controls hooked into it as well

[@jasonclements4607]

My AUX is causing a dead short. Causing transformer to pop the 5amp. Ill recheck wiring tomorrow. But I feel it has a bad relay in the smoke detector. Nothing pops if I pull the AUX wires. could not find a PDF when I was there. Any help would be appreciated.

[@tomtreece3224]

Great video these give me fits you cleared up some questions I’ve had. Love the board for training!

[@HVACRVIDEOS]

Thanks bud

[@franciscojesuspachecoballa2566]

Great video bro!!! Thank you for you help...

[@titolocho]

The reason that the sup contact are reverse is because you suppose to test it with the power off

[@bobcasseus7381]

I really appreciate your video very interesting and understood thank you again!!

[@apr9286]

Gonna need to look into a duct fire dector that have an alarm indicating it is damp. Any suggestions? They lowered the vav temperature from 68* to 64*. Not sure if it is in the same duct.

[@brennan2299]

So in hindsight i would call the fire panel monitors and let them know i was going to do something to the fire detection system that might set off a false alarm or trouble signal and or put that zone offline till works completed

[@HVACRVIDEOS]

Yep that's the best bet!

[@HVACRVIDEOS]

thanks for watching I'm gonna go live this evening 4/29/19 at 5PM (west coast time) to discuss my most recent uploads and answer questions from emails, the KZbin comments and the chat come on over and check it out . kzbin.infolive

[@andycheng4534]

thank you very much

[@Tactical-Black]

I know this is an old video I'm just looking around to see if anybody was able to get multiple key test stations to signal (independent horn and strobe on other keystation installed on other air handlers) I have three rts2aos and three d4120 duct detectors Everything works except signaling the other key stations. It probably cant be done but I'm checking

[@HVACRVIDEOS]

Im pretty sure I have seen multiple key stations lit up before when one was tripped, does the global shut down not do that? I will be going live on KZbin this evening 1/27/20 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from KZbin comments, emails and the live chat. Come on over and check it out if you can, kzbin.info/www/bejne/a3zXh5yflLmqa68

[@Tactical-Black]

@@HVACRVIDEOS no when you flip one key station only that one lights up and sound off, I called the supplier and they told me it cant work like that because their isn't a connection in there for that It's a d4120 and rts2-aos key station from system sensor

[@jareddory2155]

On the 7 minute delay for trouble, if you “solve” the trouble or close the detector cover before the 7 minutes would it still send the code to the alarm co?

[@HVACRVIDEOS]

No if you solve the trouble issue and or replace the cover before the timer ends it will not signal a trouble

[@wesjordan6972]

Right. Cause at the end of the day it isnt voltage that hurts you, its amperage.

[@HVACRVIDEOS]

I will be going live on KZbin this evening 10/14/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, KZbin comments, Emails, and Facebook comments come check it out if you can. kzbin.info/www/bejne/qnOUYo2KiK2bnqc

[@om6789gg]

What's the model of the smoke detector? Thank you

[@marisnchz]

We don’t have these but It’s cool to me 😎

[@leokim1873]

Hi @HVACR VIDEOS I realise by watching your videos and reading the manual that this particular unit has a separate unit to manually reset the alarm mode. Is there a way to make this automatically reset the whole unit? because it says there is a 0.6 seconds reset when powered down, please let me know your thoughts.

[@joshuaschaffner3973]

what would say is more common wiring from unit to the Aux? I’m guessing 24v from the RTU? Sorry to bother you still in school, we don’t cover this at all?

[@HVACRVIDEOS]

send me an email and give me more context to your question [e-mail] I will be going live on KZbin this evening 2/17/20 @ 5:PM (pacific time) to discuss past videos and answer questions from KZbin comments, Facebook comments, email’s and the Livechat, come on over and check it out. kzbin.info/www/bejne/mYWliZaVg5mCZ9k

[@gtmrefrigerationac]

Great videos

[@HVACRVIDEOS]

Thanks!

[@MrOhiousa]

how would you wire the (AUX) to a gas furnace to shot the fan off?

[@HVACRVIDEOS]

I am going live on KZbin tonight at 5:00pm pacific time come on over and check it out! kzbin.info/www/bejne/aoKrkn1mqMp1oa8

[@donaldmckee585]

Thank you it is VERY confusing I have some that just shut damper and others shut the whole unit down

[@HVACRVIDEOS]

no worries bud

[@joshhope9287]

Yes the Fire Marshall for the jurisdiction you’re in has the ultimate say so as to what he wants the detector to do. Shut the unit down, shut the fan down, close dampeners or just notify monitoring center. Main reason for shutting down the un8t if smoke is detected of course is to sto0 any airflow from feeding a fire but also to prevent pumping smoke to other areas of a location.

[@joshuaschaffner3973]

DECK-eM J what would say is more common wiring from unit to the Aux? I’m guessing 24v from the RTU? Sorry to bother you still in school, we don’t cover this at all?

[@AMTECHMECH]

clear as mud

[@hectornunez8262]

Can you please send me wire diagram for single smoke detector for Lennox package unit

[@ikennaogwogwo]

Thank you so much. I learnt a lot.

[@capitolrefrigerationheatin7501]

I have seen a hospital remodeling rooms and found the sensor in the detector not working proper, always was sensing smoke when none was present

[@HVACRVIDEOS]

Yeah sometimes the detectors can be faulty, usually hospitals do routine inspections on their detector heads as they are usually held to higher standards.

[@cristobalan]

What is the model duct smoke detector?

[@HVACRVIDEOS]

System Sensor 4120 I think

[@damarcojackson1005]

How do i do a manual global shut down...."chain multiple alarms together manually"...?

[@44R0Ndin]

You would need to put the contacts of each alarm in parallel, so that any one of them closing would close the circuit that you use to shut things down. If you only want the thing to happen when all the detectors are going off (for some reason), you need to put the contacts in series, so that you need to close all the contacts for the circuit to complete.

[@SamuelParedeslopez]

How much is the cost for install that ?

[@bharatbeerrama6455]

Thanks sir

[@HVACRVIDEOS]

Thanks for watching! Take a look in the show notes and there is a link to an article I wrote for the HVAC SCHOOL website on the same subject

[@airmechanical7163]

Excelllent!

[@HVACRVIDEOS]

Thanks man, I re shot the video 2 times because it just wasnt right!

[@HVACRVIDEOS]

Also look in the show notes and there is a link to an article I wrote on the same subject on hvac school

[@airmechanical7163]

HVACR VIDEOS - I will definitely read your article. Thanks .

[@JB-gx5vw]

Try saying where you wired the reset

[@MrDudezProductionz]

So, my fire alarm went off last night and when I turned off the AC, it turned off. I'm assuming that the duct detector detected smoke, the question is, from where?

[@HVACRVIDEOS]

It's really hard to say because the fire alarm can be initiated by several things

[@joshhope9287]

Duct detectors are notorious for having false alarms due to dust and debris being sucked into the return.

[@Game-ib3ql]

You ever had one making a whining sound?

[@dailylife4248]

Rts 151 2 wire smoke detector full detail

[@dailylife4248]

I have a smkoe detectors alarm generated by magnet / but not generate by rts key why any probelm pls tell me

[@harrydickson4575]

👍👍👍

[@TerryGannon-jj1xu]

How do I find a hvac dealer who can install this for me? I am zip 32164. Thanks Terry

[@rocker8692]

Just use a fire alarm

[@TheGpaul]

Too complicated I’ve seen sample

[@IFIXCASTLES]

I had an alarm company break a 24v wire at a terminal strip buried inside there alarm box. Drove me nuts ....couldn't find where I lost 24v..the wire was extremely hard to detect a break. The alarm company is a constant source of problems.. How many times the panel was not reset after they were done testing and I get a no heat or cool call. I then have to go to that location and punch in the reset code. Idiots..Smoke detectors mounted on the ceiling pop off there mounts because the tech didn't lock it in....Idiots...job security I guess...lol.

[@stevetreiber9162]

Great video , thanks