LPG / CO Alarm malfunction

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   Our 7+ year old 345 was factory fitted with an LPG /CO alarm which decided to misbehave yesterday.  After a short motor sail to a visiting marina we were suddenly deafened by the alarm shrill with both LEDs shining brightly.  The test / hush button had no effect.  The apparently waterproof sensor below the gas cooker was totally dry and clean.  The Gas cooker had not been used for at least 6 months and the gas bottle in the cockpit was totally shut off.  A separate battery powered CO alarm was silent.  I checked the owner's manual and all circuit diagrams and could find no reference to the alarm system. I obviously fully ventilated the cabin and used a battery vacuum to draw air around the sensor and monitor to no benefit. 
After about 45 minutes of desperately searching for a connection, fuse or isolator, I removed the sensor to find a long encapsulated cable disappearing behind the plywood hull lining where presumably it connects to the wiring loom.  I was about to destroy the control panel when the alarm suddenly stopped.  Peace at last, though my tinnitus has been totally supercharged!
My questions from the forum:
Is there a fuse or isolator that will silence the alarm if it misbehaves again?
What is the life of such a system?
Are the sensors passive switches - normally open or closed?
I'll be contacting a specialist to check / replace the system and contact the UK manufacturer on Monday.  I am wondering if the hidden loom connection is the culprit with damp there playing a part.  Thanks in advance Paul

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pdc78 Members Profile Send Private Message Find Members Posts Add to Buddy List Commander Joined: 27 May 2016 Location: UK Status: Offline Points: 142	Post Options Post Reply Quote pdc78 Report Post Thanks(0) Quote Reply Topic: LPG / CO Alarm malfunction Posted: 11 May 2024 at 10:36
	Our 7+ year old 345 was factory fitted with an LPG /CO alarm which decided to misbehave yesterday. After a short motor sail to a visiting marina we were suddenly deafened by the alarm shrill with both LEDs shining brightly. The test / hush button had no effect. The apparently waterproof sensor below the gas cooker was totally dry and clean. The Gas cooker had not been used for at least 6 months and the gas bottle in the cockpit was totally shut off. A separate battery powered CO alarm was silent. I checked the owner's manual and all circuit diagrams and could find no reference to the alarm system. I obviously fully ventilated the cabin and used a battery vacuum to draw air around the sensor and monitor to no benefit. After about 45 minutes of desperately searching for a connection, fuse or isolator, I removed the sensor to find a long encapsulated cable disappearing behind the plywood hull lining where presumably it connects to the wiring loom. I was about to destroy the control panel when the alarm suddenly stopped. Peace at last, though my tinnitus has been totally supercharged! My questions from the forum: Is there a fuse or isolator that will silence the alarm if it misbehaves again? What is the life of such a system? Are the sensors passive switches - normally open or closed? I'll be contacting a specialist to check / replace the system and contact the UK manufacturer on Monday. I am wondering if the hidden loom connection is the culprit with damp there playing a part. Thanks in advance Paul
	H345 #269

Jojo Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 03 August 2022 Location: liljeholmen swe Status: Offline Points: 166	Post Options Post Reply Quote Jojo Report Post Thanks(0) Quote Reply Posted: 11 May 2024 at 20:27
	Hallo the sensor life expectancy is up to 15 years in non moisture environment It’s typically infrared diod in a small chamber that heat the air and a infrared sensor measuring the outcome They are sensitive to mould or dust that may enter the chamber You can try to use a camera dust safe air spray and blow gently in to that camber inside your sensor by opening it carefully If it’s dust it should come back but if it’s mould the sensor is gone The fire alarm works using the same parts I normally use a plastic bag and cover al sensors gas and fire alarm during winter to protect them from getting bad It’s like camera lenses that easily get mould inside when used in different temperatures Hope you can get the sensor working again Regards jonas Edited by Jojo - 11 May 2024 at 20:28
	3 Cabin, Hanse 342, Deep draft, Tiller version.



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