Replacing the gas panel

Today’s saga starts with a line from the survey we had done: “no gas fume detectors”. That seemed like a pretty important bit of safety equipment, so I started looking into how to add one. The starting clue was a picture of the panel we took during the survey:

There’s a light for an alarm there, so the natural first thought is: can I just install a sensor on this? After some fruitless searching for a part number or a wiring diagram, I emailed this picture to Trident to ask for help. They got back to me, but sent this rather unhelpful email:

That panel was part of a gas detection system (consisting of control panel, solenoid & gas detector) which we stopped selling nearly 12 years ago.  The manufacturers of the panel & detector closed down, and we have long since sold all components of the system.  We have designed a new system, which unfortunately is not compatible with the system you have now.

Observing your panel, I see the reset button is broken off, not there, and most likely the sensor/detector had long since been disconnected from the panel because it wasn’t functioning properly.  And all you really have is an On/Off panel which will operate the solenoid.  There is nothing available at Trident for you to revamp the control panel you have to make it into a full gas detection system.

You may have to replace your existing system for another.

Well, that sounds pretty definitive. But at this point I know I have a working solenoid, so I went ahead and bought the new gas detection panel from Trident, minus the solenoid. The kit comes with instructions, but not really any explanation – wire positive here, negative here, and these two wires go to the two wires on the solenoid, in any order. The wires in the back of the old panel, meanwhile, are all color coded, and the pair going to the solenoid are red and black, which made me wonder if that “not compatible” above was broader than it had sounded at first. Maybe the old panel has something useful on the back that can identify the wires?

Nope. This looks like essentially a circuit breaker with some minimal logic board attached. Maybe we can learn something interesting from the solenoid?

Well, there’s a part number there, so that’s something. Parker Hannifin NM22-0501-G952. An internet search for this turns up a hot mess of nothing, so I tried calling the company, and got routed to somebody’s voicemail box. Perhaps I’ll hear back some day.

Maybe I can track down a better wiring diagram for the system I have? The product page has a link called “specifications”, which… ISN’T THAT AT ALL. Seriously, fuck this company.

Anyway. In the meantime, I read a bit more about solenoid valves, and it turns out that they’re just electromagnets with a spring on them, and set up so that it doesn’t really matter which side you put the positive on. And in fact, you can see from the picture above that both wires coming out of the solenoid are black, and the fact that they go into a color-differentiated pair is pure whimsy on the part of the builder. So with that, and some tracing through the bulkheads to figure out which pair went forward, we’re off to the races.

Except, wait, hold on: there’s one more set of wires that goes off in a totally different direction. Since I’d already found the set that goes to the electrical panel, by process of elimination, that has to be the old sensor. Where does it go? Is there even still a sensor attached? The wires disappear into an inaccessible space… but with the help of a toner, we can trace them even where I can’t see the wire:

(Actually that picture shows the toner connected to the “ground” cable, which since it’s the sensor’s connection to ground and not actually grounded, is very much wrong and makes it not work at all. Facepalm.) And if we follow that wire under the seat cushions into the port side of the bridge deck, back through the battery compartment to starboard, into the closest thing this boat has to a bilge, and finally up through the floorboard into the space under the oven… we dig up this beauty:

Which is to all appearances a gas sensor. Ah well. Who knows whether that thing still works – at this point, I’ve disconnected the old panel, so I can’t use the “spray it with a lighter” test. So that will have to just sit there for a while, because it’s time to wire up the new panel:

Fuck yeah, I’m using that electrical engineering degree. Labels and everything, because my future self deserves better than I found in there. The completed panel:

Not super pretty, because Trident changed the form factor on me. Jazz says she’ll put a frame around it, so it’ll eventually be prettier than this. I’m just excited that the solenoid still works – I wasn’t excited about replacing that one.

And the new gas sensor, tucked into a corner but visible so that the next surveyor can find it:




  1. I don’t always follow the details, but I admire both yours and Jazz’s tenacity on these engineering projects. You are lucky she is tiny! She is right that the next owner is going to love that you have all this documented. xo

  2. Wow, Andrew, you can write, too. Really well. The solenoid wiring and gas sensor piece is great! Smiled many times. And reading this is way more fun than going downstairs to sand and prime two metal Kohler motor mounts from my friend’s 1987 Ingersoll garden tractor. The bit about whimsy, the color coded wires when the DC circuit doesn’t care about polarity (if I understand correctly).

    1. Thanks Doug. 🙂 And yeah, you read it right – apparently the direction of the magnetic field doesn’t matter for these things.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.