Leave A/C running when away?

Quick question, finally got all my new A/C units installed and going, one in berth, one in salon, one in galley. Should I leave one or more units running during the weekdays when no one is on the boat? We use it every weekend only. I have a frig that I'm concerned about get to hot with the units off. Advice please.

Well, yes, maybe. I would leave just one unit on, set at about 80 (during summer) to keep the temps and humidity down. But make sure that all sea water connections are good, particularly the one from the raw water pump and the one to the thru hull discharge. You don't want to fill your boat with water.


David

Hot as it is down here in summer, I would leave them set on 78*. Winter I set it just on dehumidify.

Maybe it goes without saying, but be sure you keep bromine tabs in the condensate pans. A plugged condensate drain will soak your carpets...ask me how I know.

wpc691 said:

Maybe it goes without saying, but be sure you keep bromine tabs in the condensate pans. A plugged condensate drain will soak your carpets...ask me how I know.

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What does the Bromine tabs do?

I live aboard so I leave them running when it is hot or humid. Typically just the salon at around 78 to keep the humidity down.

Djoub said:

What does the Bromine tabs do?

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Prevent slime/sludge from building up and blocking the condensate drain line. Work better than the pan tabs sold at HD/Lowe’s. Still need to put the wet vac on the condensate line thru hull every 3 months or so.

I run a dehumidifier that drains into the galley sink. Run one air conditioner set at 80 degrees. The dehumidifier keeps the boat dry at around 50 % relative humidity.

Ted

O C Diver said:

I run a dehumidifier that drains into the galley sink. Run one air conditioner set at 80 degrees. The dehumidifier keeps the boat dry at around 50 % relative humidity.

Ted

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what dehumidifier do you use? would you buy the same one again ? I don't feel comfortable leaving my air on . it's an old boat and you never know when a bad connection could pop up .also really strong winds can blow the water out and set her in the mud. we only use the boat every other weekend or once a month. but I would like to control the moisture inside.

I would love to here anyone's recommendation .

Curious about your dehumidifier as well? When it is cold and clammy I have to turn my AC down to the low 60's and I'd rather not

I use a cheap Home Depot dehumidifier. Cost about .12 boat units and has lasted 3 summers in Florida.

Mike

We put the salon and forward cabin units on Humidifier mode and it works well for us.

We just had a blocked hose this past week that I blew out with a small inflator from HD.
I like the idea of a bromide tab though!

I don’t know y’all. I have certainly contemplated the idea before, and down here in NC, it certainly gets hot enough to want to... but dang... I would never be able to sleep at night knowing there was a high-flow pump just waiting to fill up my boat with water. Sure, chances are very low. And while lots of people do it and I have never heard of a boat sinking from this, to me, it’s not worth the risk.

I worry too......have thought about a 110v relay to ac and pump (or just pump) controlled by a float switch or water sensor.

If it was just to the pump, my ACs throw a code and shut down.... but I think I would prefer just cutting the power.

I leave mine running, have no concerns about it as the system is keel cooled so water intake is not required...

timb said:

what dehumidifier do you use? would you buy the same one again ? I don't feel comfortable leaving my air on . it's an old boat and you never know when a bad connection could pop up .also really strong winds can blow the water out and set her in the mud. we only use the boat every other weekend or once a month. but I would like to control the moisture inside.

I would love to here anyone's recommendation .

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https://www.amazon.com/gp/aw/d/B00UWP07NI?psc=1&ref=yo_pop_mb_pd_title

This is the unit I purchased. Very happy with the unit and would purchase it again. Noteworthy points are:

30 pint dehumidification per day
Programmable humidistat
Fan shuts off when not dehumidifying
External hose connection
Cleanable air filter

Ted

psneeld said:

I worry too......have thought about a 110v relay to ac and pump (or just pump) controlled by a float switch or water sensor.

If it was just to the pump, my ACs throw a code and shut down.... but I think I would prefer just cutting the power.

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I too have considered the same kind of rig, but my pump is below the waterline, so I would still worry about water intrusion. Not sure if the worry is valid, but I would still not be comfortable with it. YMMV ;-)

I leave one A/C on.
I am gone for 2 month and when I get back, all is well.

Tom.B said:

I don’t know y’all. I have certainly contemplated the idea before, and down here in NC, it certainly gets hot enough to want to... but dang... I would never be able to sleep at night knowing there was a high-flow pump just waiting to fill up my boat with water. Sure, chances are very low. And while lots of people do it and I have never heard of a boat sinking from this, to me, it’s not worth the risk.

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You don't feel your boat is seaworthy? Lack of plumbing integrity and bilge pump capacity? Do you now turn all your seacocks off when you leave your boat (some people with sketchy plumbing do this as a preventive measure for same). Do you shut shore power off at the pedestal too to prevent electrical fires?

The plumbing should be as solid as that of a house.

It won't be the pump action itself filling your boat with water, unless it is a poorly secured hose from the AC to the overboard through hull, as it will be shut down by the AC when water flow stops.

I’m too worried to leave the AC units on. Even though the boat is in hot and humid Florida, I just turn on my two little humidifiers and shut off the ACs. I’ve done that for about a year and no mold or mildew problems so far— even during the hurricane.

I’m not comfortable with a cooling hose breaking or condensate drain clogging.

These are the little humidifiers I have. I drilled a hole in the tank and just put them in the sink. https://www.amazon.com/hOme-Small-Dehumidifier-Bathroom-Closet/dp/B072C3NMK1

I chose to use the dehumidifier for several reasons.

It keeps the boat's humidity to a set level regardless of temperature (controlled by a humidistat).
Cheaper to run than the air conditioner
Cheaper and easier to replace (when it wears out) than an air conditioner
No need to worry about a clogged strainer or failed water pump

I have turned the one AC unit on now that we are having days in the 90s, but found that the dehumidifier was all that was required most of the rest of the year when I wasn't on board.

Ted

I run my portable on dehumidify.

My boat is poorly insulated and the AC would run and run. I turn it on when I get down there and it cools down pretty quick.

I should also note that I have a 15k btu rooftop and a 8k btu portable so not much temp control either.. On the flip side i'd worry about the lines getting clogged while I wasn't there on a traditional marine system.

O C Diver said:

https://www.amazon.com/gp/aw/d/B00UWP07NI?psc=1&ref=yo_pop_mb_pd_title

This is the unit I purchased. Very happy with the unit and would purchase it again. Noteworthy points are:

30 pint dehumidification per day
Programmable humidistat
Fan shuts off when not dehumidifying
External hose connection
Cleanable air filter

Ted

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*1
Same one we have. We run ours even when at anchor and genset on. BTW, our insurer mentions the importance of closed through hulls when not on boat, another discussion I’d guess but certainly negates the use of AC when boat untended.

Get a dehumidifier a drain to a drain overboard. The mold /mildew is going to be your biggest problem,not the temps in the boat while gone. Only runs when humidity gets to set point and dries boat out. The hotter the temps ,the more moisture into the air , and the unit gets it out. By cooling the boat with a/c you remove some moisture BUT it stops at temp setting not humidty,so a cool place will hold more moisture, and cool and wet means mildew /mold over time. Your new a/c might have a humidity setting and this will work the same and only run to humidity setting not cool setting so boat will be hot when you walk in. Set to cool and it will cool down in no time. If cooling system is in great working order and all water fittings are tight, then run it, Condensation overflow still might be a problem either way and you are removing water thru it, and could get blocked. But with new units ,you wont have the buildup of slime,but check it when you clean filters. I always close all seacocks when away for a long time, just don't want it to happen to me..

Instead of a wet vac for the condensate drain line you can simply use a wash hose to force water backwards from the hull outlet. It doesn't seem to matter if the pump is running or not.. In fact if it is running sometimes lot of junk will flush out when you stop the hose.

I use bromine to stop barnacles and green stuff from growing in the water lines.

A small 120V AC fan helps stop mold. A dehumidifier works well in FL for extended periods.

Florida and other southern states must be overwhelming without A/C on a boat. Easy to understand why folks would run there A/C 24/7. So how do marinas charge for electricity in areas where A/C usage is common especially during warmer months?

If you do decide to run you air 24/7 you will get growth in the water intake stainer, hose and thru the discharge waterline. This growth will slow down water flow and cause the unit to run hotter and finally cutout on high pressure. The aminals that need flow to survive will grow. Shelltype, alge, and more,anything that need water movement. When you clean your strainer basket, drop a broken 3 inch chorine table into basket. This will kill the growth and since water will flush the line as the a/c works no harm.

foggysail said:

Florida and other southern states must be overwhelming without A/C on a boat. Easy to understand why folks would run there A/C 24/7. So how do marinas charge for electricity in areas where A/C usage is common especially during warmer months?

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Some charge per cord or amp size, others are metered.

cardude01 said:

I’m too worried to leave the AC units on. Even though the boat is in hot and humid Florida, I just turn on my two little humidifiers and shut off the ACs. I’ve done that for about a year and no mold or mildew problems so far— even during the hurricane.

I’m not comfortable with a cooling hose breaking or condensate drain clogging.

These are the little humidifiers I have. I drilled a hole in the tank and just put them in the sink. https://www.amazon.com/hOme-Small-Dehumidifier-Bathroom-Closet/dp/B072C3NMK1

Click to expand...

I have several similar units that I leave running on the boat all the time. One I drilled a hole in the tank and run a 1/4" hose to the galley sink, the other two I just empty when on the boat. They work OK but their biggest advantage is that they are quiet enough that I leave them on in the cooler months even when we are on the boat.


However, they don't work as well as the portable compressor type dehumidifier. I've own three of them and they all work great. I set them on the galley counter top and run the drain hose to the galley sink. They keep the boat very dry, better than the peltier type dehumidifiers. The disadvantage is that they are noisy (no worse than an AC unit) and are heavier to move and store.

dhays said:

I have several similar units that I leave running on the boat all the time. One I drilled a hole in the tank and run a 1/4" hose to the galley sink, the other two I just empty when on the boat. They work OK but their biggest advantage is that they are quiet enough that I leave them on in the cooler months even when we are on the boat.


However, they don't work as well as the portable compressor type dehumidifier. I've own three of them and they all work great. I set them on the galley counter top and run the drain hose to the galley sink. They keep the boat very dry, better than the peltier type dehumidifiers. The disadvantage is that they are noisy (no worse than an AC unit) and are heavier to move and store.

Click to expand...

The installer back in 1970, ran both my condensate hoses to the sump shower pump box. It is interesting to see it fill up. But I wonder about simply drilling a small hole and sending it directly over the side. Our marina gives us free power, twin 30 amp plugs, but I was specifically told they don't want the AC left on when no one is at the boat. Well I don't pay for electricity, so I am ok with this.
I find the AC works real cold at night, too cold even.But if the sun is blazing hot, we have lots of windows and the upper salon gets warm, if it is breezy it is not a problem to have no AC even with 90 outside and humidity 50% or less. It helped the boat a lot to make the large center window swing up full open. And all the side windows already can be opened. But the center big window really brings in the air. The lower cabins tends to collect a lot of cold air since of course cold air falls. So it can be very pleasantly chilly in the forward half of the boat, if you wish.

Another big improvement was I made white window curtains for the upper salon, and also the bimini takes away direct sunshine off the roof.

Here is that window partially swung open on a rainy day. The curtains roll up like shades. And all 3 forward windows have them.