Air Conditioner Portable

[The Islander]

Hey Guys,

Just bought my first Mac 26M. 2008 model. Day and night temps with humidity are not good for being inside the cabin. Following are my findings to date and would appreciate some feedback in a few areas.

Bought a Midea 5000 watt portable ac unit from Walmart for $226. Weighs 47 lbs and is 11.5" wide, 11.5" deep and 28" tall. Requires 10.5 amps and uses 1200 watts. Starts and runs in the eco mode on my Honda EU2200 generator. Yes the generator powers up to full throttle while the heat pump is blowing cold air. I got 6 hours of use with one gallon used in the Honda gas tank.

I have placed the unit in two different locations to vent the exhaust. This is a 6inch diameter flexible hose that expands to 48 inches long if needed. I placed the unit in the walkway in front of the head and vented the exhaust out of the front open hatch. I also placed the unit on the port side just behind the galley when the galley is in the forward position and vented the exhaust out of the companionway hatch with a couple of cushions to close off the remainder of the doorway opening. I started the unit on two different days when the outside temperature here in SW Florida was at 82 degrees, the inside cabin temperature was at 84 degrees. After 5 hours of running I got the cabin temperature down to 72 degrees on both days with partly cloudy skies. I am happy with the results and you can barely hear it run.

Here are my questions relating to possible permanent venting locations.

How much water spray does the starboard side roof skylight over the head get under normal sailing and or power and planing conditions? I am thinking about mounting the unit either on the forward dinette seat or inside the head area and venting the exhaust out of that skylight plexiglass with a snorkel style vent that will prevent rain water coming in. I will have to cut a hole in the mirror to either run the vent tube thru or exit the cold air into the middle portion of the cabin. Since I have yet to put the boat on the water it would be helpful to now how much splash this area receives under normal conditions.

If I were to mount the unit behind the galley, I think mounting the exhaust tube out into the port side fuel locker might be the easiest place. I am a little concerned about lingering gas fumes from the fuel locker mixing in with the exhaust fumes and a spark from the AC unit. Maybe mount the exhaust tube either on the port side pillar in the cockpit or out of the transom to avoid venting the exhaust into the fuel locker? This exhaust tube is 6 inches in diameter.

Thanks for your insight,

Ed

[1st Sail]

I would vent out of one of the upper port or starboard port lights. The window is near vertical and you could most likely build a shade/rain gutter above the opening to divert rain. If and when you ever bury the bow in to a wave the water will wash over the fore deck and climb right up to the windows. It is a rare occurrence and predicated by a sea state you definitely would not want to be in. However, I have seen pictures and post from other M and X sailors that unfortunately encounter those conditions. That said you definitely need a vent system you can close off to the elements.

There have been post and much written about single vent portable AC's. Macs have next to zero R-value in the hull. Single vent AC's pull the vary air you have cooled in the cabin pass it over the evaporator coils and then vent the air you just cooled back out side. That said you are actually creating a vacuum in the cabin air which then replaces the just cooled cabin air with the hot outside air. Dual hose AC's on the other hand pull outside air thru the externally vented intake hose across the evaporator coils the exhaust the warm air from the coils via the externally vented exhaust hose. The closed loop air systems leaves the cooled cabin air within the cabin and recirculates just like your house AC. The overall efficiency is significantly better than a single hose AC.

Most report a 5k btu portable will cool an M cabin approx. 10°F at 90°F outside air. IIRC they were using a window unit mounted in the cabin way with a modified hatch door. Window units by design are vent evaporator heat externally and again are more efficient. To be fair single hose units are less $. Since M's have hulls have no insulating value getting a much efficiency out an AC is important. Fair winds.

[Gordo]

I have an 8K portable single hose unit. It works, but poorly. Your temp changes for running 5 hours are abysmal IMO. Mine aren't much better. I REALLY wish I hadn't cut a hole for that vent I'd switch to a window unit in a heart beat!

One the genset, I rigged a 3 gallon boat tank to a nipple in the gas cap, works great 12+ hrs run time.

[NiceAft]

I took a different route. I purchased a window air conditioner; An LG, 5000 BTU unit ($169) that fits quite well into the companionway. I cut two pieces of thin plywood to fit into the gap on either side, and connected them with a piece of smoky plexiglass so we would have a window. This slides nicely into place and seals the unit efficiently enough that any opening were meaningless. I did have a small piece of foam that I shoved into a gap, but it did not matter. The cool air entering was more than enough to compensate for any such gaps. That gap was just a sliver.


It works amazingly well. It is used when we are in the cabin for the evening. In the morning, I simply lift it out of the way, and place it on a seat on the port side next to the companion way steps.

If someone has a generator, then they could use it wherever they anchor. I can only use it when we are at a marina with shore power.

[rsvpasap]

In conjunction with the post from NiceAft above, suggest folks consider the Frigidaire FFRA051WAE 5000 btu unit or similar item specifically with mechanical (not digital) controls. https://www.google.com/search?q=Frigidaire+FFRA051WAE

1. It draws only 450 watts and will thus run on the Honda EU2000i or EU2200i generator in "eco" quiet mode. Expect probably 6 or a little more hours of runtime on a single tank of gas. Also, you can set up a siphon system to draw gas into the generator directly from your boat fuel tanks, allowing to run indefinitely. Siphon systems for the Honda generators are readily available very inexpensively.

2. It can be powered by batteries from your inverter. For example, this air conditioner will run for at least 2 hours of air conditioner compressor continuously running powered by a 100ah lifepo4 battery (with a 20% charge remaining on the battery as per manufacturer's recommendations).

3. Because it has mechanical controls, it can be left on continuously while boating and a timer can be added in line between the unit and the electrical outlet, allowing it to come on and off periodically overnight, or at a set time or predetermined intervals for a specific amount of time. This is also useful for controlling humidity in the cabin as well as temperature. I use these mechanical timers year-round to control my 2.1 cf 110v freezer and a dehumidifier in the winter.

[NiceAft]

In conjunction with the post from NiceAft above, suggest folks consider the Frigidaire FFRA051WAE 5000 btu unit or similar item specifically with mechanical (not digital) controls. https://www.google.com/search?q=Frigidaire+FFRA051WAE

1. It draws only 450 watts and will thus run on the Honda EU2000i or EU2200i generator in "eco" quiet mode. Expect probably 6 or a little more hours of runtime on a single tank of gas. Also, you can set up a siphon system to draw gas into the generator directly from your boat fuel tanks, allowing to run indefinitely. Siphon systems for the Honda generators are readily available very inexpensively.

2. It can be powered by batteries from your inverter. For example, this air conditioner will run for at least 2 hours of air conditioner compressor continuously running powered by a 100ah lifepo4 battery (with a 20% charge remaining on the battery as per manufacturer's recommendations).

3. Because it has mechanical controls, it can be left on continuously while boating and a timer can be added in line between the unit and the electrical outlet, allowing it to come on and off periodically overnight, or at a set time or predetermined intervals for a specific amount of time. This is also useful for controlling humidity in the cabin as well as temperature. I use these mechanical timers year-round to control my 2.1 cf 110v freezer and a dehumidifier in the winter.

Good points made by rsvpasap.

I decided to check out my LG. I know it’s mechanical, but the rest I didn’t know, so here it is. 440 W





I never thought about a generator until it was posted earlier. We were out for 17 days with hotter than normal temperatures. At night we slept under blankets. In the morning , there was condensation on the outside of our opening ports.

[OverEasy]

Hi!

We mounted our on board A/C unit in the aft berth next to the little seat aft of the galley of our Mac26X.
It too is of the single exhaust air hose variety which we ducted to the interior wall of the cockpit foot well under the bench seat.
We installed a protective hatch cover to close things up when not in use.

This works great for us on multiple levels.
First the A/C is wonderful! Cools the cabin down to below 70 F when the outside air is nearly 90 F.
Takes the humidity right out of the cabin air which is also fantastic.
( Note: We added a micro bilge & pump to drain the condensate overboard.)

Second it has a dehumidifier function that is also fantastic all by itself.
We run this function when we are tied up at the slip and when the boat is stored to virtually eliminate any mold or mildew.
Really dies the boat out and helps keep it that way. Spring cleaning is so much easier!
Also use the dehumidifier function when cold weather overnight boating as it dries out the personnel respiration humidity and as a result no condensation on the hull interior!

We have only used the A/C when in a slip with shore power so far for the past 3 seasons.
We have a small portable Honda generator that is more than sufficient for the A/C power needs.
We will hopefully be utilizing that on our future extended trips along the ICW.

Great investment.

We documented installation in the Mods section and eslwhere on the forum.

Best Regards,
Over Easy

[The Islander]

Hey Over Easy,

Sounds like your are happy with your portable AC performance.

Can you be a little more specific on where you are ducting the exhaust to? Is it an enclosed compartment under the bench seat on the port side of the boat? What happens to the heat in that enclosed compartment? How much effect do you think it has on the cabin temperature since the hot air is not really escaping the cabin area?

Thanks, Ed

[OverEasy]

Hi The Islander!

Sorry for the delay getting back to you….been busy with our dry land projects this past month up here in NH trying to get them done while my younger daughter is here before she heads west for the winter ski instructor season.

The venting is directly through the cockpit bench side wall to the cockpit foot path.
This exhaust the hot air directly outside, not into any interspace area.
Mind you this is on our 2001 Mac26X.

We posted the basic details and photos of it in the Mods section of the forum.
I’ll look for the link and post it when I get a chance.

Best regards,
Over Easy

Our A/C Mod Link:
https://macgregorsailors.com/mods/index ... em&id=2166