Brisson Vapor Alarming

[MCADRG]

Vapor alarm started alarming almost daily on and off around noon to evening. Started when battery charger was on. Immediately turned off over a week ago. No Fuel detection. Possible Hydrogen. Have solar. Inverter off and charger in standby. Issue continues. Blower does seem to temporarily relieve alarm.
Checked battery water levels all good.
Is sensor being finicky or do we have a problem?
Mike

[bud37]

If the sensor itself is lower than the batteries it is likely not hydrogen , as hydrogen is less dense than air and rises readily. It is interesting you say this starts up around noon, perhaps some daytime heating here.
At this point you should assume you have a problem until you can make darn sure there is no fuel leak. So with all sensors they have a life span and do go bad, especially if the power is bad.
You say no fuel detection, how did you realize this? The human nose surprisingly can smell gasoline vapour/fumes at extremely low PPM, less than 1 PPM......remember gas fumes are more dense than air so will migrate downwards .

Be very careful here until the cause is found.

[Midnightsun]

I had a similar unit made by Xintex and yes the sensors will go bad after many years. I always tested mine with a butane lighter every spring just to make sure it was operational. Simply put the lighter up against the sensor inlet and press the gas without lighting the lighter, should fire up the alarm rather quickly. If there was a gas leak problem you would definitely get a whiff of it so highly unlikely, if your battery levels are fine and not hot or bubbling then this also can be eliminated as they do smell quite a bit when they get to boiling. my vote is the sensor is bad and regardless it would not be a bad idea to swap it out after all these years.

[MCADRG]

That’s kinda where we were at. Thank you for concurring.

[MCADRG]

Update
Had mechanic onboard conducting battery load test (all good) and alarmed again. Found the sensor box itself was very hot, may have got increased voltage during a loss of shore neutral/reverse polarity alarm. Issue started at the same time. Ordering new sensor. Fingers crossed. Want a reliable alarm system.

[km1125]

The sensors do heat up. That's why they will alarm when you first put power to them.. they are heating the sensor up to its operational temperature.

I have found that some of the degrading sound insulation foam will also set off these detectors.

[MCADRG]

Has anyone replaced the actual sensor on the Brisson fume / vapour detector? I have been told there are 5 pin and 6 pin sensors depending on when your boat was manufactured by Carver (ours is a 1991 3608 aft cabin). I was told to check the number of pins before ordering a new sensor by pulling straight down on it to pop it out of unit. Thanks.

Mike.

[km1125]

I have, but it's been a long, long time. However, I know mine are the six pin type because they are the same as my portable detector.

Yes, you do just pull out the sensor. It's a small grey round plastic 'plug' about 3/4" tall. The pins below look like an old vacuum tube.