Gas detector wiring

[Kukri]

The new to me boat has a very fancy gas detector which, like Cerberus, has three heads and a very healthy appetite, for amp hours in this case. It’s hard wired in circuit, which is certainly idiot proof. Is this customary? Some people have theirs wired on the solenoid circuit. Any other ways of doing it?

 

[ottow]

I found myself with the same problem after installing a 3Gas detector, my solar panel could no longer keep the batteries full.
Initially I had it hard wired to the batteries with no off switch, just a fuse. On all the time.
Changed that to be hard wired to just after the main battery switch, so when I switch on power it starts automatically.
I wouldn't do this however unless you have a gas-proof battery switch though, as a spark could potentially set of any gas in the bilge when you switch on.
I use a Blue Sea 9003e switch

 

[Kukri]

Thanks. That is extremely helpful. That’s just the problem I’ve got: it’s no issue on shore power... but...

 

[Robin]

Thanks. That is extremely helpful. That’s just the problem I’ve got: it’s no issue on shore power... but...

We inherited that problem on one boat and finally traced a 0.5A constant drain from the engine battery to the gas sniffer.shifted it to power from main battery switch so not running 24/7 unless on we were board.

 

[Yngmar]

Just be aware that the gas sensor chip has a warmup time of several minutes before it can realiably sense anything. This is why they're often kept running. The other reason is that the gas alarms can be wired to control the solenoid, i.e. shut off the supply if gas is detected in the cabin. And the solenoids are power hungry too.

 

[thinwater]

Just be aware that the gas sensor chip has a warmup time of several minutes before it can realiably sense anything. This is why they're often kept running. The other reason is that the gas alarms can be wired to control the solenoid, i.e. shut off the supply if gas is detected in the cabin. And the solenoids are power hungry too.

^^ This. If you turn it on only when the solenoid is energized, it may detect the propane just after the boat explodes.

I think you will find a modern detector draws virtually nothing. Workers wear these on their belts. It is the solenoid that draws power, if it is left on long hours running things like heat, hot water, or gas refrigeration.

Some systems (Xintex) can be turned off, BUT they have a time delay in their programming that prevents the solenoid from opening until the detectors are warmed up. Very safe.

 

[Kinsale373]

I supply and service Gas Detection equipemnt for a living , most of it in Boiler Houses, Refridgeration plants and General Process. Im still not convinced that I need fuel gas detection on my Boat! The issue is indeed power consumption the Flammable Fuel Gas Heads are the issue. All makes that I have seen draw around 60mA continuously to run a Fuel Gas (Propane/Butane head). The recommended installation is to have a normally closed Gas shut off Valve connected, controlled by the detecton panel so that if the unit is turned off when you leave the boat or if Gas is detected then the Gas supply is shut off automatically. The solenoid does require power to keep it open as pointed out earlier. This in theory allows you to turn off the detection safely when you leave the boat for a period. It presumes that once the gas valve is turned off that the boat cannot fill with gas. I believe that this is reasonable enough if your Gas Locker is correctly vented and that if there was a leak in the line before the shutoff valve that the gas could not enter the hull. It means that typical consumption of a 2 detector head system and valve is 200 mA or 1Amp/ Hour every 5 Hours.

My conclusion is that for commercial craft, Trawlers / Work Boats/ Boats used daily with lots of Power generation , then Gas Detection is a no brainer.
For smaller leasure craft , especially sail boats with limited power generation and limited use then being careful with the Manual Gas Shut off valves and maybe the addition of an elecrtical solenoid valve that only opens when main power is switched on, is more practical.

Id highly recommend the battery powered Domestic Carbon Monoxide detectors, despite the recent discussions over marine certification. They work!

Kinsale 373

 

[Kukri]

Thanks - that’s a very clear and complete explanation.

 

[Frank Holden]

^^ This. If you turn it on only when the solenoid is energized, it may detect the propane just after the boat explodes.
...............

Mine is very similar to this one.... http://www.bepmarine.com/en/600-gdl turn on unit .... it makes happy little beeping noises while having a sniff and only when it is happy does it operate the solenoid.

In NZ at least you can buy a BEP solenoid/ regulator combo that puts the solenoid between tank and regulator... doesnt get much better than that. http://www.bepmarine.com/en/vr2-2

 

[Frank Holden]

And also... wiring diagram and other instructions here..
http://www.bepmarine.com/en/~/media/inriver/333784-30444.pdf

Power consumption isn't an issue as in my case everything is switched of at the main switchboard unless cooking is in progress.

As mentioned above a gas tight self draining locker is a must.

 

[Kukri]

Thanks!

 

[PaulRainbow]

For smaller leasure craft , especially sail boats with limited power generation and limited use then being careful with the Manual Gas Shut off valves and maybe the addition of an elecrtical solenoid valve that only opens when main power is switched on, is more practical.

I'm not a gas engineer, but that all makes sense to me. If the OPs current system closes the solenoid when power is turned off, there is no way for gas to get into the boat (that assumes a proper gas locker that drains overboard), so no need for the detectors to be on whilst away from the boat.

If it opens the solenoid when power is restored, before actually testing for gas, so what ? We already know that no gas can be present. If one was to be somewhat paranoid, then turn the gas off at the bottle, shut the system down and leave the boat. Upon return, turn the power on but don't open the gas valve until the detector system has had a sniff. IMO, that's pretty paranoid.

Id highly recommend the battery powered Domestic Carbon Monoxide detectors, despite the recent discussions over marine certification. They work!

Couldn't agree more :encouragement: There are plenty of marine certified detectors out there for sub £20 that work perfectly well. Everyone should have one.

 

[prv]

maybe the addition of an elecrtical solenoid valve that only opens when main power is switched on

Why run a solenoid all the time you're on board instead of just when you're cooking? Assuming a typical yacht where the gas is only used for the cooker, not space heating or water heating, anyway.

To me the best combination seems like a gas detector run from the normal service supply (so on when the boat is occupied, off when it isn't) plus a solenoid in the gas locker controlled by a switch (with an indicator light) near the cooker. Then the gas (and power consumption) is on only when needed, and automatically off when the boat's unoccupied because the batteries are isolated so the solenoid closes even if the switch was accidentally left on. If the detector has a relay for controlling a solenoid then you could run the feed through that so it automatically shuts off if there's an alarm, but since it should only be on when there's someone actively using the cooker anyway, that doesn't seem like a critical bit of automation.

Unless the solenoid has a manual operation lever on the side of it (fuel valves often do, I don't know about gas ones) I would always rig a manual bypass valve around it so that your cooker isn't hostage to your batteries in the event of electrical problems.

Pete

 

[Kukri]

If one was to be somewhat paranoid, then turn the gas off at the bottle, shut the system down and leave the boat. Upon return, turn the power on but don't open the gas valve until the detector system has had a sniff. IMO, that's pretty paranoid.
.

The OP is paranoid, and intends to stay that way. I like Frank’s set up.

 

[PaulRainbow]

The OP is paranoid, and intends to stay that way. I like Frank’s set up.

You've been watching that Lord Trenchard video again

Franks setup was what i was describing, if it's anything less, shut the manual valve off.

 

[Kukri]

You've been watching that Lord Trenchard video again

Franks setup was what i was describing, if it's anything less, shut the manual valve off.

Yes. I have. :encouragement: