To run the A/C or not..

[rofish59]

My "new to me" '84 46 convertible just got two new Cruiseair compressors. We live on the Gulf Coast and obviously have a long and hot summer. Should I leave the A/C on while at dock or switch them off and run a dehumidifier. Should I be concerned about pumping water thru the boat (to run the A/C) while I'm away? Am I wasting "compresssor life" when I dont need it?

Surely you good and helpful people have some advice for me.

 

[Liquid Asset]

We never shut our A/C's off. I turn up the temperature to about 79 when we leave the boat and maintain that temperature. Good luck!

 

[bobk]

I leave the salon AC set to low 80's, others are off. It keeps mold from forming. It has to shorten life.

Bob

 

[SKYCHENEY]

I would never leave them on if I were away, but that's just me. I don't like having water pumping through the boat if I'm not there. There are just too many problems that can happen. I'll admit that it would be a rare occurrence to have a boat sink from a broken A/C hose, but it sure could be a mess. You also have the potential for some sort of electrical failure that could cause a fire. Again, that would be rare, but it could happen. If you have the older style controls and limit switches, you could burn up a compressor by cycling it on and off if you lose water flow. And so on....

If you want some air circulation, open up the ports in the showers. It can rain in there some and it won't hurt a thing. You'll save on the electric bill and your compressors and controls will last much longer. But that's just my 2 cents. Many other people leave them on all of the time without incident.

 

[captddis]

Ditto Sky's thoughts. Leaving units running constantly causes major growth in the water lines and I don't want the risk of a leak. If you do not have the digital controls [ properly installed ] and plug the thru hull with a bag or growth, the unit will shutdown on high press and then try to restart. The process will repeat until the comp dies.
If you pay for the power it can get very costly to run the units as well.
I use a dehumidifier and have never had any smell or mold inside. I place the de humidifier on top of the stove and run the drain hose into the galley sink.
I have the same boat and live on the Gulf Coast.

 

[stormchaser]

Gotta agree with the others...if we are leaving for long periods of time, the ACs go off. Not if we're like going out to dinner..but leaving for the whole day or overnight, they are off...unless the dogs are on board, then the salon unit stays on. We also only run the units for the areas we are in. So during the day, it's the salon and galley/bow...at night in the aft. The guess cabin one hardly ever gets used.

 

[Pascal]

about the plastic bag, it depends on the unit but some also have a manual switch on the compressor, once that trips it will not try to restart.

I've never seen controls that will not shut down the compressor on HP. Some will try a couple of restart but that's not going to damage anything.

In most large boats, the water flow stays in the ER... the typical Air Con pump on our hatts pump between 1200 and 1800gph, that's a fraction of the bilge pump capacity you have...

with everything double clamped and inspected, the odds of a leak are near zilch. Even if a hose fail, flow to the compressors will stop and so will the pump. The only risk will be if the leak is in the short section below water line.Then again, if your bilge pumps cant handle that you got more things to worry about. open the strainer with the sea cock open, even a small 2000gph rule will only cycle 50/50

It takes a while to cool the boat on a hot day, electronic incl. TVs, and... dont like heat.

The extra wear and tear on the compressors are minimal since they cycle on and off. on the other end when you come back they will run for an hour or two non stop to get the temp. back down.

Set them slightly higher (high 70s) and enjoy. that's why they're there.

as to growth in the water hoses, I'm not sure flowing water leads to more growth than sitting water.

now if you're going to be going to a long time (weeks...) then you can consider shutting them down, but not for hours.

 

[stormchaser]

Slight thread hijack there...but speaking of growth in the lines...how do you combat this? Can it be flushed somehow? I've never had a problem with ti...but suspect its something that should be maintained?

 

[REBrueckner]

Why not try running a de humidifier instead of a/c units...if the boat begins to get a bit musty inside, rather than just hot, you'll have your answer and can then run an a/c unit as others do set at a higher temperature. A dehumidifier is nothing but a reduced size a/c which will use a lot less power and is triggered by humidity levels rather than temperature levels.

Typically mold growth is inhibited at around 60% relative humidity and below. So set a humidifier at about this level to start or follow humidifier directions and check inside boat conditions...if not to your liking, lower the relative humidity setting a bit.

I used to set mine at 60% in NY when I was away and that controlled humidity quite well....in warmer climates perhaps a lower setting will be reuired. In rainy conditions outside, a 55% setting seemed to cause the unit to run a lot more but it felt more comfortable when I was aboard.

 

[MikeP]

Agree that they are off if we are not around. I won't even leave them on when we leave for a few hours though I can't argue that's overkill.
When I leave the boat for extended periods I open the ports in all three head showers for boat ventilation; works fine.

The units heat/cool the boat very rapidly so we've never found it an issue to walk into a warm (or cold) boat. Then again, if I lived on a boat in FL, I might feel differently. I've never lived on a boat in FL but we have spent time in the Miami and Palm Beach area and it's just too hot/humid for us between May-Sep. It's great in the winter!

 

[SKYCHENEY]

I don't know about the early 70's boats, but on mine, the compressor will continuously cycle on and off for high pressure if water flow is lost. It will get very hot as it keeps doing this. Don't ask me how I know.

 

[Angela]

If you lived in South Florida during the summer, you might re-think the notion of not running the AC at times while you were not on the boat. Think about how much your refrigerator is going to run when you create an oven in side the boat by turning off the AC; that is, assuming you leave your refrigerator running while you’re not there.

I don’t know about your system, but if water ceases to flow and my condensing units are running, they trip an overheat breaker over in the wall and shut down themselves down. Until I manually reset that, it won’t try to restart. As for water sitting in my condensing unit pipes...well, when the pump stops running all of that water drains out and those tubes and hoses become empty.

I’ve thought about what would happen if the flow of water got diverted to the bilge since I have a 3000 gph pump for my AC system. I guess I’ve just gotten used to idea and I don’t worry about it much anymore. I do inspect it often to make sure all is well. Like Pascal said, if a hose fails and water stops flowing to the condensing units, the units will shut down and shut off the pump. Then, all I have to worry about is my bilge pump keeping up with whatever amount can get through the seacock, or through the pump...whenever the failure was, but I won’t continue to pump 3000 gph into my bilge.

If I lived up north, I may have a different opinion as to how I would run things, but living in South Florida in the summer...you just gotta run it. Plus...I just couldn’t do that to my kitty cat - that would be like leaving a baby in a hot car in a parking lot. Those portlights in the showers just don’t circulate enough air in these big boats during the summer here.

 

[stormchaser]

Interesting...mine cuts it off and it doesn't come back until I turn off then back on at the controls. What kind of controls do you have?

 

[SKYCHENEY]

Interesting...mine cuts it off and it doesn't come back until I turn off then back on at the controls. What kind of controls do you have?

The big Honeywell thermostats and the PWX boxes, vintage 1985.

 

[stormchaser]

Ah, ok...I have SMXht controls. One of the great features on them is the wide variety of settings. There's even a dehumidify setting. I'm loving them over the old controls that she had when we first got her.

 

[captddis]

about the plastic bag, it depends on the unit but some also have a manual switch on the compressor, once that trips it will not try to restart.

I've never seen controls that will not shut down the compressor on HP. Some will try a couple of restart but that's not going to damage anything.

In most large boats, the water flow stays in the ER... the typical Air Con pump on our hatts pump between 1200 and 1800gph, that's a fraction of the bilge pump capacity you have...

with everything double clamped and inspected, the odds of a leak are near zilch. Even if a hose fail, flow to the compressors will stop and so will the pump. The only risk will be if the leak is in the short section below water line.Then again, if your bilge pumps cant handle that you got more things to worry about. open the strainer with the sea cock open, even a small 2000gph rule will only cycle 50/50

It takes a while to cool the boat on a hot day, electronic incl. TVs, and... dont like heat.

The extra wear and tear on the compressors are minimal since they cycle on and off. on the other end when you come back they will run for an hour or two non stop to get the temp. back down.

Set them slightly higher (high 70s) and enjoy. that's why they're there.


as to growth in the water hoses, I'm not sure flowing water leads to more growth than sitting water.

now if you're going to be going to a long time (weeks...) then you can consider shutting them down, but not for hours.

Reread my post, I said that IF YOU DO NOT HAVE DIGITAL CONTROLS that are properly installed, the unit will keep trying to restart. It will destroy itself. Your Rule pump is not going to keep up with the amount of water a 3000 Gph pump will pump. No to mention salt water sprayed all over the ER and engines and gen.
It is a fact that nothing grows inside the hoses that have stagnent water, but barnacles love clean water. Do as you wish. I make a lot of money on AC work from hardheads that do not listen.

 

[krush]

Running compressors doesn't really wear them out if they are properly charged with refrigerant and oil. How many years has your fridge lasted? Ironically, cycling is harder on them then running.

 

[Pascal]

angela brought up a good point of fridges and freezers, they will strugle if the inside of the boat is at 100degrees, which is what you'll get here in so fl in summer without air in a closed boat... better start thinking about how you will get that fridge up the stairs

Dave, check out Genesis post on cleaning heat exchangers in the FAQ section, it works with air cons. up north, it needs to be done every 2 or 3 years.

My condensing units are Ocean Breeze, they have a resetable high pres. switch. Once that trips, compressor stays off, no matter what control i woudl have (I have some aftermarket digitals, forgot the brand)

 

[67hat34c]

Pascal that is one of the benefits of the Ocean Breeze, you have to re set it by hand, Great safety feature. The Thremal Overload breaker shuts down the whole panel on the unit and will prevent the pump, condensor and the evaporator from running.

We always left ours on , day setting 85 and stepped down to 80 then 78 at night. Had it that way for about 6yrs. Of course in the winter it most likely did not run very much if at all.

Not sure about growth though. We never had any in the lines and the PU for the AC was the only one that would remain clean. Never had to worry about it as our hoses and fittings were always in #1 shape. and if anything was to happen the themal overload swithch would have tripped and not re set. Also many watchdogs at our marina so if anything was to happen then I would have a call very quickly.

 

[captddis]

Most Hatts have Cruisair and they will keep trying to restart. Mermaid and I guess Ocean breeze trip a resettable switch. The adid flush is OK if needed, But I see many problems with cooling systems plugging up in a few months or less. Barnacles LOVE white PVC. Boats that use a PVC tube that everyting dumps in to are especially prone to problems.
Two cases in point.
First is a 45 Viking that the owner likes to keep at 75 degrees while he is away. He summers in the NE and I am on the boat every other week. The two Ac units empty into a pvc tube that the sinks also empty into.
I come to the boat in late August and water is overflowing out of the cockpit sink like a waterfall. The tackle drawers are full of salt water and the overflow is running over the fuel tank. Even though I put tablets in the sea strainer every other week, the barnacles grew enough to plug the tube and the only outlet was the sink.

I tried to convince him to let me put seperate thru hulls in for the AC units but he would not hear of it. The next August when the waterfall reappeared. he gave in and let me add the dedicated thru hulls.


Example 2 a 40 Tollycraft

This boat has the common tubes and in addition to the ac units and sinks, the bilge pumps discharge into the tube. When his tube plugged up the ac water found an outlet going back through the bilge pump discharges into the bilge. Caught that one just in time.


My personal experience is that using the dehumidify function where the unit only runs a little each day, there is not a problem. On a large boat with many units the pump is almost always running. And those crap up.

Above all try to keep pipe nipples out of AC plumbing, they are the weak link and sink many boats. Schedule 80 grey PVC holds up the best. YMMV