CruisAir plumbing-solenoid valve mystery

[Angela]

Now, it’s my turn for a CruisAir question!

I’ve got one of those funky “made for Hatteras only” systems on one of my three systems. It’s a modulating condensing unit (new) that runs four individually controlled evaporator units in each of the four staterooms. The gas supply to each evaporator unit is controlled by a set of solenoid valves that open and close as each individual evaporator unit would come on and call for cooling.

I had a valve go bad and lost all of my refrigerant. Some how, the enclosure tube (the “stems” sticking out in the photo) got punctured from the outside. That stem gets fully enclosed in the coil when it’s in place, so I have no idea how a puncture in there occurred.

Anyway, I took the solenoid valve assembly off so I could work on the one punctured valve. I bought a new enclosure tube to replace the punctured one. It was not necessary to replace the entire valve. I unsweated the bad valve from the entire assembly so I could put it in a vice in order to unscrew the enclosure tube without bending the copper.

Upon getting the old enclosure tube off, I found that there was no plunger inside this old valve. My first thought, “I’ve been robbed!” LOL Have any of you had a peek inside any of these valves? Is there some reason why the valve would NOT have a plunger? It seems to me that without a plunger, the valve is meaningless and just open all the time. I have not had a problem with getting gas to that evaporator unit, at least not until the puncture let all the gas out and there was none to deliver.

Also, I am looking at the assembly wondering what good the valve is if the attached dryer creates a bypass around the valve. Can someone educate me on that design? One thing I do know is that the system does work, regardless of the strange “plumbing”.

Before I evacuate and recharge the system, I’d like to be enlightened as to why there was no plunger in that valve and whether it was, for some reason, intentional. When I put the new enclosure tube on, I did replace the plunger which came with the rebuild kit I used to fix this.

Thanks.

[Pascal]

just thinking out loud here, but is it possible that one of the valves need to remain open at all time to allow gas to circulate in at least one system and prevent a massive pressure spike when the valve closes and the compressor still has pressure?

[SKYCHENEY]

just thinking out loud here, but is it possible that one of the valves need to remain open at all time to allow gas to circulate in at least one system and prevent a massive pressure spike when the valve closes and the compressor still has pressure?

Just thinking out loud here, but if the one system needed to be open all of the time, why would they bother with a valve at all including the solenoid and the wiring?

[krush]

you sure them ain't check valves? They could also be limited flow bypass valves to ensure that some circulation occurs in all 4 evaps. This would be required to ensure all the oil doesn't pull up in one evap and starve the compressor.

Still a stupid design /normal shakes my head wondering WTF they were thinking...too complex and PITA for a boat.

[SKYCHENEY]

Each of the those stacks has an electomagnetic coil that slides onto it, right? And that coil is energized by the thermostat in each room to open that valve? Is that what we're looking at or is it more like what Krush is talking about?

[krush]

Each of the those stacks has an electomagnetic coil that slides onto it, right? And that coil is energized by the thermostat in each room to open that valve? Is that what we're looking at or is it more like what Krush is talking about?

My comments assumed that the coils slide over those "stacks".--just like you mentioned. I was referring to the bypass looking things, not the "stacks".

Edit: Oh yeah, you may have an open valve because one evap is supposed to remain in service at all times.

While you have it all apart, why not rebuild all the valves? Also, add in a drier why you have the system open if you can. You may want to do mulitple pull down and nitrogen purges since you have such a mess of long pipping and it's so humid down there.

[Angela]

While you have it all apart, why not rebuild all the valves?

Because they're not broke and I want my AC back ASAP. And I'm using up all my "Gil" tokens with the relocation of the davit and washer/dryer removal/installation.

I've heard from some of the older, wiser folks that this commercial refrigeration system Hatteras used in these 58MYs was a bit "before their time." I like the concept - each stateroom can control its own temperature to the occupant's likings without infringing upon anyone else's comfort. The only other way I know to achieve that is to add three more condensing units and I'd never be able to run 6 condensing units on 50 amps.

Meanwhile, I've been doing to research...these valve require a converstion kit to be bi-flow. Since these are reversing units, supplying heating and cooling, wouldn't these valves ned to be "bi-flow"? The conversion takes place by swapping out some internal parts. I wonder if the plunger found in the new rebuilt kit is not supposed to go in there. This is a Alco 200RA valve which you can't find anymore. I suspect the 200RA model has been replaced with the 200RB series. Anyone have any knowledge on these Alco solnoid valves in this regard?

[Angela]

Each of the those stacks has an electomagnetic coil that slides onto it, right? And that coil is energized by the thermostat in each room to open that valve?

Yes.

[Angela]

While you have it all apart, why not rebuild all the valves? Also, add in a drier why you have the system open if you can. You may want to do mulitple pull down and nitrogen purges since you have such a mess of long pipping and it's so humid down there.

Ok, that's a project for another day after I blossom some more brain cells for that. Although I've been around the block with this system perhaps a few more times than my last AC tech, I'm no expert here. I have enough knowledge in this area to know when I'm being BS'ed by an AC tech who doesn't know this system, but I'm not smart enough yet to do all those nice things you mentioned. I hope that one day I will be, though.

I've often wondered that if I were to tear out the entire AC system and start from scratch, how would one re-do this in this boat and still have individual control over each guest's SR.

[Pascal]

short of adding one condensing unit for each SR, that's the only way... it's pretty simple actually. if i get this right, when a Tstat calls for cooling it opens its valve via the solenoid to send gas to the air handler, correct ?