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Old 29-11-2017, 14:57   #1
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Trying to decide between ac w/ reverse cycle heat or dedicated systems

I will be liveaboard in Annapolis area shortly and am looking at cold winters and hot summers. Defender has the webasto fcf aircon w/reverse cycle heat on sale for a very low price - I am wondering if I can get away with this versus a dedicated diese heat system. The min avg water temp for Annapolis in cold months is around 44f.

I have read prior threads and know that dedicated systems would be best but hard to beat 1200 for a system that could do both well. Right now I have ceramic heaters and itís not great.

Related question - I have two seacocks both or one can feed the single Lehman and gen - can I just feed this system off the second seacock and not put another thru hull in for the webasto unit?

Thanks for any thoughts.
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Old 29-11-2017, 16:12   #2
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

I donít know the specs of the unit youíre looking at but mine wonít heat under 46f and even so heating would be abmismally low at that water temp. The heating temperature is going to be proportional to the water temperature since it does extract the heat from the water. Reverse heating is usually considered just good enough for late spring and fall, but never for winter in your latitude. Get yourself a good dedicated diesel heater to be crispy warm. Best to have a high capacity one so it can continuously suck in and heat up fresh outside air instead of recycling your inside air.
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Old 29-11-2017, 16:16   #3
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

+1, youíre going to want a diesel fired heater for winter. The reverse cycle unit will work well spring, summer and fall though.
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Old 01-12-2017, 21:55   #4
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

I live across the Bay from Annapolis and as others have said... beat pumps just can work once water temps get into mid-40s and lower. Airtonic diesel heaters, while they put out plenty of heat for Winter (if sized properly) are not recommended for the heavy running of full-time liveaboard use, but work well for weekends/ occasional week out in late Fall and Winter. Helped brother install a hydrotonic system fir his 53í liveaboard ketch up here.
NICE steady white heat. His spent last 35 yrs in Caribbean and every time I visited him here during the Winter, it must have been 80 degrees inside!
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Old 08-12-2017, 11:35   #5
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

If you go with the reverse cycle AC//heateróbe sure you pay the extra for the electric heat strips that augment the air output. Reverse cycle only is good on my boat down to 10c, and is not very hot air at all.
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Old 08-12-2017, 11:46   #6
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

The minimum sustaied water temperature in any marina around Annapolis is closer to 32F. They get ice, sometimes thick. We get ice 20 miles south in Deale.

Additionally, think of how much stuff you will burst if the electricity fails... and it will.

You need fired heat.

This water aint' 44F. That's ice.
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Old 08-12-2017, 12:35   #7
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

Quote:
Originally Posted by parobellum View Post
I will be liveaboard in Annapolis area shortly and am looking at cold winters and hot summers. Defender has the webasto fcf aircon w/reverse cycle heat on sale for a very low price - I am wondering if I can get away with this versus a dedicated diese heat system. The min avg water temp for Annapolis in cold months is around 44f.

Our marina near Annapolis occasionally freezes over, hard. Average doesn't much matter, at that point.

There's a middle ground to consider. Some boat neighbors began to live aboard, and when they did, they replaced their old and well worn (out) AC with reverse cycle AC AND they installed a resistance heat unit in it at the same time... all using the same vents and blower system... so when outside water temps go too cold for the heat pump to work, they just closed the seacock and used the resistance unit.

They said it worked pretty well, only needed augmenting with a portable electric oil heater very occasionally. Helps to run a de-icer outside, so thick ice doesn't actually form up too close to the hull.

I have the model numbers of whatever it was they installed (somewhere), but the short version is that it was Dometic stuff, Vector Turbo based I think, all sold and installed by the Annapolis Cruiseair guys.

I have had some contact with Annapolis Cruiseair about my own system; was having a fault they helped me diagnose and fix over the phone... so my impression of them is pretty good.

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Old 09-12-2017, 12:21   #8
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Trying to decide between ac w/ reverse cycle heat or dedicated systems

If your going to use electric resistance heating and have a 30amp Boat, you may look into heat being on a separate circuit or changing the boat to 50 amp service.
I think I would run a separate cord and panel for the heat myself, I looked briefly into changing my boat to 50 amp and there was more to it than I wanted to tackle.
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Old 09-12-2017, 13:01   #9
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

I've never heard anyone even consider a heat pump for real "winter" use, versus one of the dedicated diesel heaters. In the 50F-60F temp range, sure, maybe. But once you're talking "winter" ? Heat pumps usually disappoint, even if performance is the only criteria and you ignore everything else.

Esper, Esbacher, Webasto...whatever...just be sure to read AND FOLLOW the instructions, for installation (intake and exhaust) and proper use (i.e. proper shutdown) and perhaps get the most common spares to have on hand. they make such nice toasty dry heat, you quickly fall in love with them.
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Old 10-12-2017, 06:12   #10
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

I lived aboard in Annapolis for a few years. Primary heat was two oil-filled radiators which was fine for 95% of the winter. During cold snaps the diesel heater would kick in. I donít agree that these are good for only ďoccasionalĒ use...Iíve used mine extensively cruising in colder climes as primary heat and itís great although some occasional maintenance is required.

Youíll want to have your boat wrapped, if possible. Keeps snow and ice off it and condensation down. The greenhouse effect helps too.

Summer. Itís HOT. Be prepared to run your AC right up to the boat show some years.
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Old 10-12-2017, 09:13   #11
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

The oil-filled electric heaters (and for many years, DeLonghi was the only brand name that sold them in the US) ARE NOT HEAT PUMPS. They are direct electric heaters.

But for decades they have been praised for being many times safer than the cheaper common "hot wire" and later "ceramic" or "radiant" types, simply because the heating element is completely enclosed, and it never gets hot enough to set things on fire. Instead, it just warms the oil in the sealed radiator and produces a much more tightly controlled heat.

They're very effective, but folks still say "Eeeyyyoooo, bulky old fashioned radiator...." and you must admit, they do take up floor space. A great way to add SAFE portable heat though. Heat pumps are generally not portable, they are fixed installations. Just like the Espar and other diesel heaters, which are not to be confused with things like the diesel "fireplaces" and other plain heaters.

And for that matter, there are very nice twelve volt electric mattress warmers. Like an electric blanket but placed under the sheet or mattress so they warm up the bed without having to heat the whole cabin. Long haul truckers are probably the main users of those. For occasional use, or for minimal installation footprint, that's not such a bad idea. (Save the bigger heater for when you wake up.)
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Old 10-12-2017, 09:26   #12
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Re: Trying to decide between ac w/ reverse cycle heat or dedicated systems

As a live aboard in Annapolis, you're not likely leaving the dock until it warms up in the spring. The oil-filled heaters are a good solution because they are cheap, relatively safe, and use energy that you're already paying for as most marinas charge a flat electric/liveaboard fee.

I had mine plugged directly into the dock electric pylon, with adequately sized cords, to relieve the load on the boat's AC wiring. That said, it's prudent to check the plugs every now and then for good connections.

And as someone mentioned, the water temperature in Annapolis can drop to near freezing, or even below. Back Creek froze over a few times while I was there.

I suppose if you're installing AC you might as well go with a unit with a heat pump function. But it's a lot of money (probably >$2500 after the smoke clears) when a couple of radiators and a used $250 Cruiseair hatch-top AC unit from Bacon Marine will get you through the year just as well.
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