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Old 03-02-2011, 01:31 PM   #1
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Leaving the air conditioner on

I've finally got my boat in a regular marina and am able to get full power, 2 30 amp connections. My air cond unit has a humidity mode whose purpose is to reduce the humidity by cycling the compressor on and off at reduced levels while the boat is unattended. I left the boat today with the ac system in the humidity mode, but on the drive home I began wondering if this is a good idea.

The air cond water pump probably pumps several gallons a minute, far more than my 3 dc powered bilge pumps can pump combined. My system is setup with one water pump servicing 2 ac units. If a pump tube were to leak or a connection were to come apart, the pump would continue pumping sea water into the boat. If a connection were to break near one of the units, that unit would overheat and shutdown, but since the pump services two units, the other unit would still command the pump to operate.

A couple of thoughts:

A high water bilge alarm connected to a cell phone notification system might work to alert one to the problem. But unless you get to the boat and stop the pump within an hour or two, it may be too late.

Circuitery that would shut down the pump if one ac unit overheats. The problem I have with this is all the ac plumbing on my boat is below the water line, so I would still have water intrusion at the break or broken connection.

I'm headed back down to the boat this weekend and will problably leave the air cond off with the thru hull valve closed unless you guys have better advice.
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Old 03-02-2011, 01:38 PM   #2
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RE: Leaving the air conditioner on

Tim

Have you considered a de-humidifier parked over a sink drain? This is a common answer to the humidity question.
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Old 03-02-2011, 01:46 PM   #3
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RE: Leaving the air conditioner on

Here in GA and TN boaters seem to leave their HVAC on 24/7. Right or wrong- that is mostly the reality. Yes there is a risk that a hose could break and sink the boat. How often does it happen....like I said, probably 95% of boaters at the marinas around here leave their HVAC on and I've yet to see a boat sink due to it- but definitely it could happen.

This does beg the question though- if it is not safe to leave the HVAC on, is it safe to even leave the boat with any sea cocks open?
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Old 03-02-2011, 01:47 PM   #4
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RE: Leaving the air conditioner on

Might install*a boat nanny*which can call three people.* http://www.theboatnanny.com/index.html
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Old 03-02-2011, 02:01 PM   #5
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Leaving the air conditioner on

Quote:
Woodsong wrote:
...

This does beg the question though- if it is not safe to leave the HVAC on, is it safe to even leave the boat with any sea cocks open?
We know quite a lot of people who close all the sea cocks when they leave the boat.* We don't.

Edit: I might add, the only boat I know of that sank in our marina sank due to rainwater coming in and*the bilge pump not working.* It sank VERY VERY gradually over months or years (obviously this was a neglected vessel).* Nobody noticed it was gradually going lower and lower in the water as the growth at the waterline rose as the waterline sank.* Then one big rainstorm, glug glug glug, down she went.* There was a broken out hatch covered with the tarp and the tarp had long since disintegrated.

Only story I know of involving a through hull, the owners were actually aboard. No idea why their high water alarm did not go off.* Husband got up at O dark early and stepped in water.* Quickly called the fire department and got the water pumped out and the problem isolated before the boat went down.* This was a million dollar custom "motor yacht".


-- Edited by Pineapple Girl on Wednesday 2nd of March 2011 03:06:55 PM
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Old 03-02-2011, 02:23 PM   #6
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Leaving the air conditioner on

Thanks folks for all the timely replies.

I also see a lot of boats with the AC on all the time. Here in SW FL is almost a no brainer. The dock I was at before did not have the electrical capacity to run my AC last year and it did OK. No mildew.

Like Dave and others have said, I have no confidence is alarms or electronic gizmos that are suppose to save your a$$.

Dave, I've thought of the bigger bilge pump route, but you are relying on that pump working for a couple of weeks while the boat stays unattended. What if someone or something accidentally unplugs your electrical. Yes the ac pump will stop but not the water intrusion if the system is below the water line.

Perhaps a de-humidifer like sunchaser suggests is an alternative.

I personally close all the sea cocks when leaving the boat, except today when I left the ac open. I had to come up with some creative ideas though to get to some of the sea cocks to avoid cramming myself down into my dog house sized ER to open and close them.


-- Edited by timjet on Wednesday 2nd of March 2011 03:26:11 PM
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Old 03-02-2011, 02:48 PM   #7
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RE: Leaving the air conditioner on

Tim,* If you always close all the thru hulls when you leave the boat, you would probably not be comfortable leaving the AC on unattended.

Anything floating can sink, but you have to learn to live with and minimise the risks.

Inspect every below waterline plumbing system carefully.

Replace old hoses, double clamp, grease seacocks(if applicable)* check everything out.

I have an extra 2000gph pump and switch also mounted about*6 inches higher than the main pump.

It never runs unless I purposely add water or lift the float.

I think if I were in Florida I would leave*my system on in the dehumidifer mode.

You just have to be sure it is installed right and in good condition.

To me it would be an exceptable risk.

The only boats I have seen sink at the dock* were the result of freezing and thawing of seacocks, strainers, or fittings.

No long term hard freeze in Florida, so for me it would be okay.

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Old 03-02-2011, 03:23 PM   #8
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RE: Leaving the air conditioner on

This is only the second year we have had AC on the boat so I'm new at this.* So far I haven't worried about a hose coming off associated with the AC and*flooding the boat any more than from one of the other vessel's system.* What I have seen happen twice*is that the AC*pump has sucked something into the intake that has caused the AC units to thermally shut down do to lack of water, as they were designed for.* In both cases I was around so I didn't burn out the pump.*
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Old 03-02-2011, 03:28 PM   #9
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RE: Leaving the air conditioner on

Quote:
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* What I have seen happen twice*is that the AC*pump has sucked something into the intake that has caused the AC units to thermally shut down do to lack of water, as they were designed for.* In both cases I was around so I didn't burn out the pump.*
********* The intake was blocked on the outside of the boat?

********* Or was the internal strainer totally clogged?

********* Is there a lot of eel grass in your waters?

********* Good point about being there to monitor the operation.

JohnP

*
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Old 03-02-2011, 06:40 PM   #10
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RE: Leaving the air conditioner on

I've always left mine on. Make sure all the hoses, clamps, seacocks etc. are in good shape.

I have a high water bilge pump / alarm setup. If water ever activates it, a siren/strobe combo outside goes off. I also have two engraved plates on the sides of the boat that say "In case of emergency, call xxx-xxx-xxxx". In any emergency, anyone can contact me at my cell phone immediately. Cheap insurance. I've been called because of those, but it was when I was in the shower!
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Old 03-02-2011, 07:53 PM   #11
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RE: Leaving the air conditioner on

Tim,
We leave our A/C on (two out of three) when we leave although we turn up the thermostats so they don't run constantly and have done so for years. That said, our hoses are in new condition and I check them regularly these hoses are not under very much pressure and are more likely to fail due to age then anything else. Since the hoses tend to get a build up inside from marine growth I like to replace them every other year, they are not expensive and this eliminates the age issue
Our high water pumps (two 3700 gph Rule pumps) are also wired to an audible alarm in the salon and one on the bridge. Our dock office has a set of keys and would certainly react to an alarm, not to mention our neighbors who live on board their boat. We never leave the dockside water on though.
As far as the pump burning out, it has never happened to us and if the A/C shuts off due to the high temp sensor, this would turn off the pump.
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Old 03-02-2011, 08:27 PM   #12
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RE: Leaving the air conditioner on

Timjet, I don't know whether it would be worth the cost for you, but a keel cooler and closed system would eliminate the concern, as well as extend the longevity of your equipment.* I used the old half pipe keel coolers on Delfin for the a/c and like having a closed system.
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Old 03-03-2011, 04:48 AM   #13
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RE: Leaving the air conditioner on

A house de humidifier is cheap, and can be set over a sink to drain for months.

If you can install it, the rotary vents that are use in attics will keep the boat dry , free wind power.

The better units are aluminum (not galvanized) and have sealed lubricated bearings.

Not Yachtty to look at , but they work.
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Old 03-03-2011, 06:54 AM   #14
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RE: Leaving the air conditioner on

Quote:
JohnP wrote:

The intake was blocked on the outside of the boat?

Or was the internal strainer totally clogged?

Is there a lot of eel grass in your waters?

Good point about being there to monitor the operation.

JohnP
In both cases the intake was clogged, once at the tru-hull and once at the strainer.* There's a lot of plastic in the water and bits of sea weed/debris.* The thru-hull is a 1" mushroom with no screen or scoop.

*
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Old 03-03-2011, 07:40 AM   #15
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Leaving the air conditioner on

My suggestion is to stay home and build a bomb shelter and climb in and never come out!!!

Seriously though, any thru hull can sink your boat. *Mainship does put a "Jesus" pump on all of their newer boats and attached to that same floatswitch is a wicked piercing alarm. *The people at the marina WILL NOT ignore it....they can't. *It is too obnoxious.


Now....airconditioners and paper bags and expensive repairs. *My pump only runs when the compressor is running. *If water flow is stopped(ie the theoretical paper bag scenario), it shuts down the compressor(temp sensor I would imagine) thus shutting down the pump.....NOTHING is damaged. *ANY digital controller can be set up this way. *The manual controllers will not shut down the pump but the compressor still shuts down. *So in that scenario, the pump would burn up. *While not cheap, I would not call that "expensive". *Obviously you don't want to be replacing these all the time but...you won't be.


With all of that said reference humidity control.....my HVAC set in the humidity mode does NOT do a good job of controlling humidity. *Actually, it sucks!!!! *So I run my HVAC in the heat mode or AC mode depending on season and my boat stays dry and smelling nicely. *These newer digital HVAC controllers are infinitely adjustable so I would imagine there may be a way for me to modify the humidity cycle on it....I just haven't dug that deeply. *Keeping your interior in tip top shape is worth the added expense.


Is there risk involved in leaving thru hulls open?....sure there is. *But it is very small. *How do you mitigate that very small risk????......Insurance! *Now, sleep tight!!!


-- Edited by Baker on Thursday 3rd of March 2011 10:11:28 AM
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Old 03-03-2011, 08:43 AM   #16
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RE: Leaving the air conditioner on

I close the seacock that feeds the raw water head, but leave the AC and engine seacocks open. I run the AC in thye dehumidify mode in summer, and the recerse heat set at 60 degrees in winter.

Yes, there is some risk involved.
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Old 03-03-2011, 08:46 AM   #17
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RE: Leaving the air conditioner on

Quote:
Baker wrote:

My suggestion is to stay home and build a bomb shelter and climb in and never come out!!!


Seriously though, any thru hull can sink your boat. *Mainship does put a "Jesus" pump on all of their newer boats and attached to that same floatswitch is a wicked piercing alarm. *The people at the marina WILL NOT ignore it....they can't. *It is too obnoxious.


Now....airconditioners and paper bags and expensive repairs. *My pump only runs when the compressor is running. *If water flow is stopped(ie the theoretical paper bag scenario), it shuts down the compressor(temp sensor I would imagine) thus shutting down the pump.....NOTHING is damaged. *ANY digital controller can be set up this way. *The manual controllers will not shut down the pump but the compressor still shuts down. *So in that scenario, the pump would burn up. *While not cheap, I would not call that "expensive". *Obviously you don't want to be replacing these all the time but...you won't be.


With all of that said reference humidity control.....my HVAC set in the humidity mode does NOT do a good job of controlling humidity. *Actually, it sucks!!!! *So I run my HVAC in the heat mode or AC mode depending on season and my boat stays dry and smelling nicely. *These newer digital HVAC controllers are infinitely adjustable so I would imagine there may be a way for me to modify the humidity cycle on it....I just haven't dug that deeply. *Keeping your interior in tip top shape is worth the added expense.
What he said!*

Also Tim, I have a nice de-humidifier I will sell cheap.* It has a pump built in so you can stand it on the floor and just run the drain hose to a sink.* I bought it when we were re-varnishing the interior.


*
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Old 03-03-2011, 09:56 AM   #18
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Leaving the air conditioner on

When the Eagle is at the dock, which is 99.5% of the time, all the sea cocks below the water line are closed.* When away from the dock, 00.5% of the time, only the engine and gen set are open. If a long cruise the DD 671 has a cruise gen so I can shut down the main gen and close the through hull also.* *I took out all the other*through hulls below the water line, 7 of them.*

I installed regular old dirt window air conditionings, that I made enclosure that match the teak and are butted up against a port hole, and or a salon window.* Three 600 btu in the stateroom and a 800 for the salon which cost about 500 bucks. We leave the AC on most of the time and even use in the winter on fan to circulate and purify the air.

Also doubled the size of the bilge pumps and installed two bilge pumps so if one fails the other is back up and double the capacity with alarms.* I heard double bilge pumps where a requiement in Canda?***Also have a portable bilge pump that has came in handy several times on neighboring boats.*

Over the last 14 years of living aboard the failures are, 1) when hook up to the dock water a hose/fitting failed, because of the high water pressure, 2) engine raw water and/or exhaust hose failed, and 3) of course AC and head.


-- Edited by Phil Fill on Thursday 3rd of March 2011 10:57:31 AM
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