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fire alarm sensor

Posted: Thu Apr 07, 2016 5:17 pm
by PleasureBay
Does anyone know where to find the small round sensor mounted under the bridge ladder that controls the fire alarm in the emergency panel? Mine started going off for no reason and I disconnected it but the alarm light is still on. I tried bypassing it but I can't make the light go out I have temporarily disconnected the alarm bell.

Posted: Fri Apr 08, 2016 4:40 am
by h2ojst
Jack, They're thermal switches and I think that Kidde still manufactures them, but something doesn't sound quite right. Are you sure that you bypassed the correct switch? There are several mounted throughout the engine room areas & mine had one aft in the geny hatch area also. The light & the bell should go off when the correct switch is bypassed.

Posted: Fri Apr 08, 2016 4:47 pm
by PleasureBay
I have to look for other sensors. The scematic only shows the one behind the port engine, if I'm reading it correctly. I'll check tomorrow. My boat does not have an automatic fire suspression system.

Posted: Sat Apr 09, 2016 7:09 am
by PleasureBay
Thanks Joe, I found all the sensors. Now I just have to find a replacement for the bad one.

Posted: Sun Apr 10, 2016 3:34 pm
by PleasureBay
Does anyone know where to get several of the fire sensors used on the Bertrams? They are about 1" - 1.25" in diamter.

Posted: Mon Apr 11, 2016 6:00 am
by Rick
Joe thinks Kidde still makes them, might want to start with them. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

Posted: Mon Apr 11, 2016 8:54 am
by h2ojst
Mine had a CO2 fire suppression system that I removed & replaced with a newer version. I also removed all the sensors but I think at the time that I did find them available from Kidde. Fireboy might also stock something similar, but someone has to still make them. It's just a heat sensing switch that opens at a set temperature.

Posted: Mon Apr 11, 2016 1:43 pm
by PleasureBay
Thanks to all for your help and info. Danny from High Tide called me back this afternoon and said he was able to locate the original type sensors. A company, I think he said in CA, makes them. I had already checked into a pencil type sensor from Edwards Security.

Posted: Mon Apr 11, 2016 4:02 pm
by Aquaman
PleasureBay The sensors and alarm bell is made by Aqualarm

Posted: Thu Apr 21, 2016 2:18 pm
by PleasureBay
I received the new alarm sensor and put it in the system but the alarm is still softly buzzing. Does anyone know how to trouble shoot the alarm system? Especially the fire alrm leg.

Posted: Fri Apr 22, 2016 4:08 am
by Rick
I think maybe the new sensor is set at the wrong resistance. Try measuring it with an Ohmmeter and then measure another that is still good in another location, but remove one of the wires first for accuracy. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

Posted: Fri Apr 22, 2016 7:58 am
by WetProcess
The original sensors are NOT thermistors (change resistance with temp) they ARE what is know as snap switches they are normally OPEN when cool and "snap" closed at 190F. They may or may not reset depending on any fire damage. A low buzzing is indicative of less than 12V reaching the bell. Al

Posted: Fri Apr 22, 2016 8:39 am
by PleasureBay
Thanks, I'll try to check the resistance with my meter.