Boat HVAC and Dehumidifer Performance

Overall Installation

Besides the fact I seem to have let ‘Bubba’ do the HVAC install, for a pretty penny (sorry - how do you test an HVAC install if the sea pump doesn’t work, Bubba?), the Mabru unit works pretty well.

There’s a fair amount of discussion online regarding marine HVAC noise, and manufacturers claiming to be super-quiet and the like.
All I’m going to say on that is - fans move air, and there are few cases of truly quiet fans - the way to make fans quiet, besides obvious use of good quality bearings to not add any additional mechanical noises into the mix,  is to make them larger diameter so you can spin them slower RPM - to move the same amount of air (CFM).  The same applies to computer and electronic systems, power supplies and the like, although in their cases, some additional actions can be taken that would be counter-productive here, where the goal is to actually move that cooled air into the cabin, versus keeping specific components cool. 

So yes - you can certainly hear the fan spinning up and down, noticeably, but with no unusual mechanical noises, and when on full fan or putting it on auto mode - it can indeed move some air.  For cabin occupancy and sleeping - you get used to it, as the real noise involved is simply fan speeds stepping up or down (if in auto mode), or you can select a lower fan speed mode if you’d like, which is do-able in general as most nights are cooler.

The display is vertically taller than horizontal, so as mentioned before, it does not fit into the old SMX display cutout, which I have covered with a single gangbox cover - which I then mounted a CO monitor over.  

HVAC Cooling

I need to take some timings, but in general when gong to the boat, whether to just overnight at the slip, hang out, do some work, or taking her out, the routine is pretty much this - pull back or remove the cockpit cover, flip the water pressure switch on at the helm, then go into the cabin and flip on the HVAC/Air Conditioning Circuit, followed by powering on the HVAC from the display and letting it run in auto mode.   I’ll leave the cabin door itself open a few inches initially, just to help get some air circulating, as we otherwise leave the cabin buttoned up.

It cools down fairly quickly, often going from 90*F+ in the cabin down into the 70s seemingly within an hour.  I do plan to measure this exactly.

I have not tried to get the unit to put the temps into the high 60*, as my wife would think we’re in the Arctic then, but on the 100*F days, it hasn’t had any issues in getting the temps down to in the right range, which I generally set somewhere around 74*.  

I remain unconvinced of which of numerous thermostats is actually correct, as the HVAC display’s thermostat along with the thermostat/humidity gauge I have on the outside of the breaker panel are never reading the same, usually more like +/- 4* or so from each other - but it’s not easy to determine if it’s down to position of temperature sensors across the cabin, one or both of them being slightly off, etc.  In reality, it doesn’t matter all that much - set it to whatever is ‘comfortable’ and there’s your target temp - the absolute # is less relevant.  One of these days I will take my HVAC thermostat and see if I can sort which one’s correct, though.

Dehumidifier Performance

All in all, the Alfloia 2L unit works well.

The tank will fill up in the humid summers here in a bit over a week, so I’m glad I went with the largest tank I could find in a reasonably-priced and sized unit.  

At least on this unit, the ‘auto shut-off’ is really just a float that rises in the tank to hit a cutoff switch, so I’ve now tried running it without the tank installed but sitting in the galley sink - which will allow it to run without shutting off in the event it’s particularly humid or we don’t make it to the marina as planned.

It is quiet, but I wish it were a bit shorter, which would allow me when on the boat, to stow it under the V-berth table insert (we leave the bed made up).