Heat/AC Management Advice

[Sharron]

Heat/AC management question for C30 Luxury Edition. Boat is new to us and on previous sailboats we left system off, using damp rid and in winter, a space heater to prevent freezing. Boat is in Hilton Head, SC so we won't winterize because we will use it year round.

This summer we set the temp around 75, then engaged HU1. What's a suggestion for settings to prevent freezing of water lines, etc. over the winter? We don't care if it's in the mid 30s-40s when we are not there. Not sure how to set so that AC doesn't come on trying to drop the temp to 40. Is there a heat only setting that also dehumidifies or do we go "manual" again and leave systems off? I've seen the small dehumidifier set up to drain in the sink.

And what about heat in the engine room? Is that needed?

Thank you for your help.

 

[ALICE J]

I don’t think it is a good practice to leave the AC running when you are absent from the boat. The ac has a raw water pump that pumps water, it does not discriminate where the water goes. Into the AC or bilge. It will sink the unattended vessel. A dehumidifier draining into the sink will keep the humidity at a lower level

 

[iggy]

I don’t think it is a good practice to leave the AC running when you are absent from the boat. The ac has a raw water pump that pumps water, it does not discriminate where the water goes. Into the AC or bilge. It will sink the unattended vessel. A dehumidifier draining into the sink will keep the humidity at a lower level

Well, than that means the seacock is closed. Not just the AC is on. But I do agree, I would not leave it running when I am not there for long periods. As suggested, buy a small dehumidifier.

 

[rpmerrill]

You will find that the de-humidifier adds heat to the cabin as well.
It might be all you need.

With the boat in the water the engine compartment picks up a lot of warmth from the water under the boat. A full fresh water tank and full fuel tank add a lot of thermal inertia to the boat during cold snaps. Of course the consequences of an engine compartment freeze up are pretty serious. I'd most certainly keep the seacocks closed. The fresh water in the plumbing lines above the water line could be your highest risk. I'd use antifreeze to flush the head.

During one of those hard cold snaps, go down and check the fresh water temperature coming out of the faucet. That should give you an idea how it is going.

A few water jugs in the engine compartment could also help slow down a freeze and act as "canaries in the mineshaft". The engine compartment won't get below 32 degrees until the water jugs start to freeze up. Depending where you keep your boat the raw water needs to get below 32 in order to start the freezing. About 28-29 degrees.

I totally winterize here in MD so I have not tested all this, but I worked 30+ years in industrial refrigeration and have seen a lot of ice situations in my time.

 

[knotflying]

I would winterize running water lines and perhaps a ceramic heater with a thermostat at a low temperature in the engine compartment. The problem I see with a dehumidifier is that they normally require temperatures above 60 degrees. Below 60 degrees and there is a possibility of the coil freezing and the unit getting damaged.

 

[rpmerrill]

Ya, that is possible.

 

[Alpina]

I would winterize running water lines and perhaps a ceramic heater with a thermostat at a low temperature in the engine compartment. The problem I see with a dehumidifier is that they normally require temperatures above 60 degrees. Below 60 degrees and there is a possibility of the coil freezing and the unit getting damaged.

True. An alternative is a thermo-electric (Peltier) dehumidifier as it doesn’t use a compressor. They can’t handle the same load as a traditional dehumidifier but my unit has done well for me. Note that they size them in cubic feet as a marketing ploy so read the fine print.