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Old 29-03-2020, 17:12   #16
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Re: Air con for heat in winter?

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Originally Posted by sailorrob View Post
We lived In Annapolis for 5 years...experienced winter temps as low as 5 degrees. What worked best for us and the other live a boards was applying clear shrink wrap. Creates a green house effect. Wasn’t uncommon, when the temps were in the 30’s, to open the hatches. We used only two electric, oil filled heaters, on a 44’ monohull. Key is to use at least a 12 gauge exterior, professional grade extension cord run direct to the dock pedestal.
Hi SailorRob,
Out of curiosity, did you diy your shrink wrap it have it done? How much did it cost you? Do you feel that it added to condensation issues?
My husband isn't sold on the whole shrink wrap idea. He grew up sailing in southern California, so his mentality is that the boat should be ready to sail year round. I think January sailing sounds a bit nippy! Help me convince him, please! Lol
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Old 29-03-2020, 17:17   #17
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Re: Air con for heat in winter?

Shrink wrap should not make condensation worse. But you will need to ventilate the boat both for fresh breathing air and to release humidity. Living in a boat creates a lot of moisture that has to go somewhere.

Items that creates considerable condensation are port lights and hatches. Putting clear plastic wrap over the outside of port lights will help prevent condensation inside the boat. By creating an air barrier between the port light and the outside air the glass and frame stay closer to the inside cabin temp. Thus they dont drip water all the time.
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Old 29-03-2020, 17:23   #18
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Re: Air con for heat in winter?

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Originally Posted by transmitterdan View Post
Shrink wrap should not make condensation worse. But you will need to ventilate the boat both for fresh breathing air and to release humidity. Living in a boat creates a lot of moisture that has to go somewhere.

Items that creates considerable condensation are port lights and hatches. Putting clear plastic wrap over the outside of port lights will help prevent condensation inside the boat. By creating an air barrier between the port light and the outside air the glass and frame stay closer to the inside cabin temp. Thus they dont drip water all the time.
Thanks transmitterdan, that's a cool trick. Anyone have ideas on how much it would cost to shrink wrap a 30 foot boat? Thanks!
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Old 29-03-2020, 17:36   #19
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Re: Air con for heat in winter?

One issue on the Chesapeake is the water freezing inside the "cold" part of the heat pump if it isn't salty enough. We live on a side bay near Annapolis and most winters the water is too fresh so once the water hits about 35 degrees F the system literally freezes the circulating water and shuts down. It works like a champ to keep our Mahe 36 toasty warm though with no shrink wrap of any kind, right up to the point it just stops working altogether.
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Old 29-03-2020, 17:41   #20
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Re: Air con for heat in winter?

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Originally Posted by redneckrob View Post
One issue on the Chesapeake is the water freezing inside the "cold" part of the heat pump if it isn't salty enough. We live on a side bay near Annapolis and most winters the water is too fresh so once the water hits about 35 degrees F the system literally freezes the circulating water and shuts down. It works like a champ to keep our Mahe 36 toasty warm though with no shrink wrap of any kind, right up to the point it just stops working altogether.
Hi redneckrob, thanks for that info. According to noaa, the water temps in Portsmouth are 48 to 51 at their coldest. In light of that, do you think we'll be good? It's a webasco 12000 btu. Boat is 30 foot loa, 25 lwl Thanks!
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Old 29-03-2020, 17:50   #21
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Re: Air con for heat in winter?

Our boat came with 3 heat pump air con units. To mitigate heating ineficiencies due to cold raw water temperatures, I changed the coolant raw water circuits to instead recirculate through one of our 110 gallon potable water tanks. [One of our refrigerators was already rigged this way, and that spawned the idea...]

It works great since our potable tanks stay 10-20F warmer than the water we are floating in [in winter anyway...]

Our A/C units also have resistance heat coils as an option [not nearly as efficient as the heat pump...] for use if heat pump efficiency is compromized.

If you are interested, there are many more details about this arrangement, and the trade-offs, in my post on this topic.

I hope your system meets your needs.

Cheers! Bill
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Old 29-03-2020, 17:59   #22
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Re: Air con for heat in winter?

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Originally Posted by wrwakefield View Post
Our boat came with 3 heat pump air con units. To mitigate heating ineficiencies due to cold raw water temperatures, I changed the coolant raw water circuits to instead recirculate through one of our 110 gallon potable water tanks. [One of our refrigerators was already rigged this way, and that spawned the idea...]

It works great since our potable tanks stay 10-20F warmer than the water we are floating in [in winter anyway...]

Our A/C units also have resistance heat coils as an option [not nearly as efficient as the heat pump...] for use if heat pump efficiency is compromized.

If you are interested, there are many more details about this arrangement, and the trade-offs, in my post on this topic.

I hope your system meets your needs.

Cheers! Bill
That's a crazy good idea, thank you!
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Old 29-03-2020, 18:24   #23
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Re: Air con for heat in winter?

Quick question on that idea- if you have 3 air cons running off of 110 gallons, do you think I could get away with one running off of a 40 gallon tank? I'm thinking if there's too little water to cycle, the water will get too hot in summer and too cold in winter to have an adequate heat differential.
That would save me a ton of time and a haul out! And would allow our heat to run more smoothly.
Thanks!
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Old 29-03-2020, 18:35   #24
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Re: Air con for heat in winter?

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Originally Posted by CamWrenRoo View Post
Hi redneckrob, thanks for that info. According to noaa, the water temps in Portsmouth are 48 to 51 at their coldest. In light of that, do you think we'll be good? It's a webasco 12000 btu. Boat is 30 foot loa, 25 lwl Thanks!
I lived in Chesapeake before I had this boat. The water froze behind our house, just past the highrise bridge on the ICW pretty much every winter for at least a few days, so definitely was way below 48. I'd check where that NOAA instrument is physically located compared to where you're at, Portsmouth is a big area with a pretty wide range of frontages. If you're at Hospital Point, you're probably fine, but if you're further up the ICW or in one of the many bays, that temp and salinity might not be close to yours.
I've got two Mabru Power System units. They're fine, one did die a few months after install but they literally flew someone up to Annapolis from Fort Lauderdale a week later to replace it for free, so they do stand by the product. Don't know anything specific about the Webasco units and my experience is with a cat so probably pretty different heating curve.
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Old 29-03-2020, 18:59   #25
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Re: Air con for heat in winter?

Awesome, thank you for the info! I'm pretty sure the data is from hospital point. We'll be pretty close to there.
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Old 30-03-2020, 04:38   #26
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Re: Air con for heat in winter?

CamWrenRoo, the first year I let a contractor install everything. The following 4 years I made the supporting structure myself, saving significant dollars. I used the grey conduit found at Lowe’s or HomeDepot. 1” tubing...has a female end on one side...so tube simply fits into other tube to increase lenght...easy peasy! Bends very easy and cuts easy as well. I used zip ties to see use to the stanchions. Make it high enough to walk under to facilitate pump outs, water tank fills, etc. given u need industrial type “torches”/heat guns to shrink the wrap, as well as wide and long lengths of wrap, I used a contractor for that part. My boat is 44’...cost about $850 for the contractor. Trust me, given the MD climate/winters it was well worth it! Also, someone suggested using a water tank to simply recirculate for a heat pump. This won’t work if sea water temps go below or near 40...law of thermodynamics. Eventually it freezes/sludges up...yeah, don’t ask how I know. Aaarggh.
The wrap...which I referred to as our “boat condom” also kept snow and ice off. Our dog could chill on the weather decks virtually the entire winter...and my wife and I could sit in the cockpit and be comfortable in a light jacket due to the green house effect. I know folks that didn’t wrap...we tried it one winter to save dollars...and wrapped the next two winters as we realized the savings wasn’t worth the trade off/lack of comfort.
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Old 30-03-2020, 04:47   #27
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Re: Air con for heat in winter?

Thanks SailorRob! I think one can rent those heat torches. The PVC frame is a great idea. Affordable and familiar to me (that's how farmers set up hoop houses! ).
Regarding the fresh water tank cycling through a tank, if the tank is below decks (we have space under a berth that could accommodate a 50 gallon tank) it seems like the water temp would be warmer than the sea water. Worst case scenario, I have a fish tank heater that would definitely keep it warmer. They pull very little power and work well in a 50 gallon aquarium. Just a thought. What do you think? I really like the idea of not adding more thru-hulls...
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Old 30-03-2020, 05:03   #28
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Re: Air con for heat in winter?

Quote:
Originally Posted by wrwakefield View Post
Our boat came with 3 heat pump air con units. To mitigate heating ineficiencies due to cold raw water temperatures, I changed the coolant raw water circuits to instead recirculate through one of our 110 gallon potable water tanks. [One of our refrigerators was already rigged this way, and that spawned the idea...]

It works great since our potable tanks stay 10-20F warmer than the water we are floating in [in winter anyway...]

Our A/C units also have resistance heat coils as an option [not nearly as efficient as the heat pump...] for use if heat pump efficiency is compromized.

If you are interested, there are many more details about this arrangement, and the trade-offs, in my post on this topic.

I hope your system meets your needs.

Cheers! Bill
Hi Bill, any thoughts on how much water volume we would need to circulate? I'm thinking I could install a 50 gallon tank under my aft berth. If you have 3 aircons (2 15000 btu, 1 9000 btu) and a fridge running on 110 gallons in Alaska, I'm thinking 50 gallons ought to do it. What do you think? I highly doubt the water would go below 50 or above 90 if it's under a berth with insulation between the tank and the hull. Thanks!
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Old 30-03-2020, 05:09   #29
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Re: Air con for heat in winter?

Lived aboard for almost 23 years in NYC. Electric heat is fine if the marina has power after a storm.I used a Dickinson oil furnace, no electric needed.

Since the water there freezes reverse cycle does not work

However the air sourced Mini Splits (Mitsubishi) would be fine.

One neighbor was Irish and used coal. His technique was to get a ton delivered , and put in a small paper bag. When all the bags were filled , he used a second bag for a cleaner outer surface. It was all stored in a large garbage can with a lid.

Coming home from work, he would shake the grates and stick in a bag, this was enough heat for all night. In the AM before heading out tossing another bag in was all that is required.

Coal is not EZ to find anymore , but charcoal works as well tho its lighter so more is consumed.
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Old 30-03-2020, 06:15   #30
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Re: Air con for heat in winter?

I'm on the Pamlico in NC with two (5Kbtu & 16Kbtu) reverse cycle units on my 35' S2. Indispensable in the heat but troublesome in the cold. The raw water circulation lines freeze up about 5AM on cold nights. Anybody else have this problem?
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