Dual AC issues


twarble

twarble

Member
Guys,
When i went to sea trial my new 45, they discovered issues with both AC units down below. As a result both were supposed to be replaced by new units so that the issues would go away. However, almost immediately issues popped up with both yet again. The master AC unit continues to go to HPF alarm while the salon unit will actually pop the circuit breaker. After having someone take a look at it, the first thing that he told me about was that it's not installed according to MarineAir specs. He said that the single large sea strainer going to two water pumps is not a supported installation. According to him, each unit should have a dedicated sea strainer.

I'm wondering if any of you guys have any issues with the dual AC units running simultaneously? Do you tend to do this? Or do you only run one at a time to avoid issues? Have any of you had a tech point out this design flaw? I'll probably call TAG later today to see what they say as well. I've used this guy before, and he's always been really good...I'm just wondering if he's being overly anal about this, or if the installation works if all the other issues are taken care of. I'm leaning towards doing my own descaling to see if it solves the issue.

thanks,
twarble
 
MANY BOAT MANUFACTURERS USE ONE STRAINER, ONE PUMP TO FEED MULTIPLE UNITS. FRIEND HAS AN OLDER CHRIS CRAFT WITH THREE AIRS, ONE PUMP, AND ONE STRAINER. THERE IS NOTHING WRONG WITH THE INSTALLATION, AS LONG AS ALL PARTS ARE SIZED ACCORDINGLY.
 
it's actually one strainer, and two pumps running off of it. and i think this is the cause for his concern. i'm not sure i buy it though...
 
Well... like GSENT said as long as the intake and strainer are sized appropriately this shouldn't be an issue.

You are correct, this is a little different since most setups use a single pump - notice the water shooting out of most boats in two different locations at the same time. This usually means single pump for which both units kick in at same time and is the more common setup.

I wonder though... if it's not sized correctly could the two pumps be combining and trying to pull too much water to each unit but not getting enough for each as a result??? If this is the case then this should be happening on each 45 Yacht setup like this so not sure about that one.

hmm...
 
exactly...that's why i was hoping someone else with a 45 could confirm or deny this type of behavior. my other thought is that one pump may shutoff, and in the process inject some cavitation or air causing the HPF scenario. according to the manuals low water flow can cause both the HPF and the circuit tripping behavior...
 
Try and find the model numbers of the units and download the install manuals online.

I would think in a 45 yacht, you would have a 5-10 gallon sea water chest for the units.

Youre saving the units have a single strainer and two pumps.

In my opinion that seems like a cheap way of doing it. Theres alot of gpm moving from those two pumps and also wonder if one pump might be a higher rated pump and stealing water from the other.
 
i'll pull the part numbers for you guys this afternoon, but i think that all 3 pumps are the same, and it's probably a 2.5" Groco sea strainer. i'm also planning to double check the manual to make certain that the circuit breaker installed for the salon AC is properly sized.

my tech said the same thing...that there should be a sea chest used in this application. i'm not sure if that will even fit where they've installed everything. i noticed another cheap move...the salon AC doesn't have any place to drain local moisture, or leaks. it sits in a 3-4" deep metal pan that's slightly larger than the unit itself. i can tell that this one has filled about 2/3 with water at some point in time due to the corrosion that is evident. i'm going to see if i can figure a way to get this drained to the grey water box.

plugging one of the connections for the duration of a test is a good idea. i may try that if i get some time today.

thanks again all,
twarble
 
Congratulations on your 45, mine also had issues with the a/c's... all three pumps were replaced with better ones cant remember which ones but I'll check tomorrow, setup is like yours one sea strainer for all three units and I think I remember seeing a condensate drain for the salon a/c, I'll check and report back.
Last weekend we ran with all three units on, with only one hiccup, the cockpit unit going to HPF but that was after going thru some weed line and coming of plane so not sure if this was a coincidence, but after reseting it was fine for the rest of the weekend....and btw it was very hot down here.
 
I just cant believe Formula would use a single strainer for 3 units.

Formula does so many things great, but things like this leave me scratching my head for a "yacht"
 
one correction...it's two strainers between the three AC units on my 45. there is a larger strainer which supplies both AC units down below, and a smaller strainer which supplies the cockpit AC. and i would agree there are a few things which have me scratching my head...

i'll try to post some pics here, but it's hard to make out what's going on as the pumps and strainers are in two separate compartments. mar-ttini, i'll look forward to your follow up. did formula initiate the larger pump switch out? or did you do that on your own? and if you do have a condensate drain, was it there from factory?

first pic shows the 3 pumps, they are all Little Giant 3-MD-SC.
second pic shows how the 3 supply lines run to the pumps.
third pic shows the two strainers. the one on top runs the salon/master AC, while the lower one runs the cockpit AC.
fourth pic shows how the two lines split off of the large strainer towards the pumps.

thanks for the feedback guys!
twarble
 

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hey Todd a quick thought here. the last pic shows a "t" type fitting coming off the strainer. that is usually a check valve. any chance you could have some kind of issue with that? just a thought.
 
On the last picture, i could see where if one of the pumps could steal flow from the other.

If you only run one of the pumps at a time, does the problem happen?
 
Okay, wasn't able to spend to much time at the boat but It appears I do not have a condensate drain for the salon a/c, I looked with a flash light and mirror...the a/c pan is open to another larger aluminium pan that had some water in it, we need to look in to this a little further..to understand the design...
as far as strainers looks like I only have one but I need to look a little more, and hopefully the pic with water pumps will upload...

water pumps were replaced right before I got her, as far as I know Formula was not involved.
 

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Tenn, good point about the check valve. i'll see if i can figure it out...it's really hidden from view based on where it's installed, but I'll see if i can get access.

FanMN, the problems persist even if I run only one unit at a time. I have to add that the problems may have nothing to do with the sea strainer and pump config. the units were newly installed, and have never worked properly. my purpose in starting this thread was to see if anyone else was having a similar set of issues with this setup. sounds so far like mar-ttini had to at least upgrade the pumps, so that's interesting.
 
Mar-ttini, thanks for the reply. i do find it interesting that you had the pumps upgraded...thing is that i get a good water flow when the units are running, so i'm not convinced that the pumps are the issue. i'll have to keep looking...i want to do a descaling on both units to try and clean out the lines in hopes that this will take care of some issues, but if i have good water flow, i'm not sure this will do much. i'll keep you guys updated on what the tech finds...

twarble
 
slight update...i found a condensate drain in the aluminum pan under the salon unit. it was buried under a bunch of sand! i thought it was all rust, but it looks like the previous owner had an inbound line leak, and he liked to anchor a bit too close to the beach. :-\ i'm gonna take a shop vac down there tomorrow and try to unclog it...and rinse it out real well. no other updates because the tech hasn't gotten back in there yet...but he's adamant that the dual pump setup isn't condoned by MarineAir.

Mar-ttini, the condensate drain is in the aft most portion of the pan, on the port side. it drains into the grey water box.

twarble
 
Thanks twarble thats good info, I'll look for the drain mine must be clogged to. I had a similar problem as you a few yrs ago on an older pc and it was just dirty coil... I looked in to it and cleaned it myself with muriatic acid, you could see green stuff like alge come out...
 
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