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Old 26-12-2013, 09:26   #16
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Re: Air Versus Hydronic Heater

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Originally Posted by typhoon View Post
The biggest drawback was with moisture buildup in the boat ...heater cores just recycle the air in the boat, if you don't know what I mean switch to recycle heat in your car and see how much moisture builds up , then go to fresh, bam! it's all gone.
One of the better examples and explanations I've seen on this subject. Thanks.
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Old 26-12-2013, 11:06   #17
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Re: Air Versus Hydronic Heater

DeepF,

I appreciate your concern, but I am pretty sure of my abilities in this case. I was a Machinist's Mate in the U. S. Navy for 15 years and I have a pretty good handle on the hows and whys of the installation. I will admit, though, that I can't crawl through bilges or hang up side down as well as I used to so, if all other things were equal, two "simple" installations would have been preferable to one "complex" one. However, given the relative disparagement of the air heater units, I have to conclude that all things are not equal

As for doing this "on the cheap," far from it. The only piece of equipment that I have not ordered from Sure Marine was the actual DBW 2010 and, at the risk of creating thread drift in my own thread, that was a horrible mistake caused by my futile attempts to make eBay work for me.

Apparently, for some people, eBay is wonderful and those people always seem to be seated next to me at cruiser gatherings. I am regaled with stories about how they were able to get a $50,000 piece of gear for $10 because the widget handle had gone missing and all they had to do was whittle a new one from an old piece of whale's tusk they had also gotten off of eBay. When I say that I never seem to get what I want, they always look at me with a pitying glance and tell me that I just need to try again, but do more checking before I buy (or sell - I have had bad experiences on both sides). This was another one of those attempts. When all is said and done, I will undoubtedly end up spending more than I would have if I had gone to Sure in the first place, but...

By the way, does anyone have any experience with the Proheat PH0405 X-45 Heater?
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Old 26-12-2013, 19:27   #18
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Re: Air Versus Hydronic Heater

LOL...
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Old 26-12-2013, 19:49   #19
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Re: Air Versus Hydronic Heater

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Originally Posted by Stu Jackson View Post
One of the better examples and explanations I've seen on this subject. Thanks.

Thanks,

I remember a couple of years ago on my last boat , I was living aboard, it was an aluminum cutter, fully insulated with spray foam during construction. Every were there was a stringer touching the headliner , there would be condensation, it literately rained inside my boat! LOL . I think using reciculated air was not a good idea, it just builds up inside the boat. I will do something different this time.


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Old 26-12-2013, 20:01   #20
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Re: Air Versus Hydronic Heater

Hydronic or Air you need to ventilate the boat. The best way for hydronic I think is to draw some of the combustion air from inside the boat and replace that through a mushroom or cowl vent with an air duct down to a heat exchanger.
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Old 27-12-2013, 06:25   #21
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Re: Air Versus Hydronic Heater

I agree. The most central of my

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Old 27-12-2013, 06:27   #22
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Re: Air Versus Hydronic Heater

Sorry - fat thumbs, small keyboard. The most central of my coils will take a suction from outside. Air flow is everything!

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Old 27-12-2013, 07:51   #23
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Re: Air Versus Hydronic Heater

Usually condensation is a result of not getting the moisture (humidity) out of the air and the moisture attaches to the cold surfaces that are not conditioned. In the winter, moisture is low and humidity is added by cooking, people breathing in the small space being closed up and trapped in the space, like in the car in the recirculation mode. Your reverse cycle units (heat pump) will not heat up enough to evaporate the moisture and it degenerates the efficiency of the unit; the colder the condenser water or air gets. Thus you need a backup heat source like an electric or hydronic heating coil to assist the temperature rise you are looking to get for comfort. The trouble with the heat pump in humid cold conditions is the saturated air cannot be condensed by the coil because it is trying to maintain the desired temperature by reversing cycles from heat to cool. The cooling cycle will condense the moisture on the evaporator coil and run it to the condensate pan and drain. But the heat cycle expands the moisture in the air but can't dry it out causing warm moist air to condense on cold surfaces.

I recommend the air source heat system for your boat. Check out this Espar link: Espar - Marine Heaters, Boat Heaters - Eberspächer

I have this system in my boat with 6 outlets off of a 3" flexible duct system. It uses negligible fuel to operate, it's quiet, it has a 1.25" chimney, and recirculate the cabin air. My unit is under the master berth and I don't find it to be and annoyance. It will drive you outside if run in the high setting.

Running hydronic lines requires a supply and return line to each coil, a pump to keep it moving, a heat exchanger, an expansion tank, control and isolation valves for each coil, freeze protection etc. The lines should also be insulated separately to be efficient.

Just a note on efficiency: A big mistake often made is oversizing the cooling and heating units. To evaporate moisture the unit has to run. Most units are controlled by temperature and not humidity. You can get a cool temperature quickly with an oversized unit, but it may create a cave like environment and grow mold. We all want to save fuel and operating costs but a saturated space can cost a lot more in damage to joinery and soft goods inside the boat.
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Old 27-12-2013, 08:25   #24
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Re: Air Versus Hydronic Heater

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Usually condensation is a result of not getting the moisture (humidity) out of the air and the moisture attaches to the cold surfaces that are not conditioned. In the winter, moisture is low and humidity is added by cooking, people breathing in the small space being closed up and trapped in the space, like in the car in the recirculation mode. Your reverse cycle units (heat pump) will not heat up enough to evaporate the moisture and it degenerates the efficiency of the unit; the colder the condenser water or air gets. Thus you need a backup heat source like an electric or hydronic heating coil to assist the temperature rise you are looking to get for comfort. The trouble with the heat pump in humid cold conditions is the saturated air cannot be condensed by the coil because it is trying to maintain the desired temperature by reversing cycles from heat to cool. The cooling cycle will condense the moisture on the evaporator coil and run it to the condensate pan and drain. But the heat cycle expands the moisture in the air but can't dry it out causing warm moist air to condense on cold surfaces.

I recommend the air source heat system for your boat. Check out this Espar link: Espar - Marine Heaters, Boat Heaters - Eberspächer

I have this system in my boat with 6 outlets off of a 3" flexible duct system. It uses negligible fuel to operate, it's quiet, it has a 1.25" chimney, and recirculate the cabin air. My unit is under the master berth and I don't find it to be and annoyance. It will drive you outside if run in the high setting.

Running hydronic lines requires a supply and return line to each coil, a pump to keep it moving, a heat exchanger, an expansion tank, control and isolation valves for each coil, freeze protection etc. The lines should also be insulated separately to be efficient.

Just a note on efficiency: A big mistake often made is oversizing the cooling and heating units. To evaporate moisture the unit has to run. Most units are controlled by temperature and not humidity. You can get a cool temperature quickly with an oversized unit, but it may create a cave like environment and grow mold. We all want to save fuel and operating costs but a saturated space can cost a lot more in damage to joinery and soft goods inside the boat.

I agree, In heating a boat you need to bring in as much outside air as you can . It takes more to heat cold air but you will drive out the moisture inside the boat and be ahead in the spring. So get a high BTU unit and try to use outside air, not recirculated damp boat air.

This is hard to do with a hydronic system unless you use something like this

New Hot Water Heater Kit Military Army 6x6 Truck M35 M35A2 M275 M109 M54 5 Ton | eBay

This is what I am installing this spring with a Webasto 2010. I have installed the heater cores all around the boat before and I don't foresee this install to be anymore work then that .

Regards
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Old 27-12-2013, 11:37   #25
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Re: Air Versus Hydronic Heater

Apparently, I was not clear when I said I have lived aboard, over the winter, since 2008. I know what living aboard in the winter feels like. I know how much humidity we generate and I know how much outside air is needed to compensate for that.

For those of you unfamiliar with the southern Chesapeake Bay area, the water temperature in the winter rarely falls to freezing and the air temperature rarely falls below 10 degrees F. Most days, the temperature is much warmer than that.

For those of you unfamilar with the layout of a 1978 Morgan 452, most of the hull area under water is below or just above the level of the cabin sole. Therefore, most condensation caused by warm moist air coming into contact with cold hull surface is below the deck and captured in the bilge. To offset this, we use throw rugs with thermal pads on the bottom surface. They are sold for use in bathrooms, but we find they work very well throughout the boat.

The other place where we have seen condensation is on the interior of the main salon portlights and hatches, but since there is at least a two inch deep lip between the interior bulkhead and the portlight, we use some clear poly film to create a dead air space between the interior cabin bulkheads and overheads. The dead air space works as a near perfect insulation, somewhat like a double pane window on a house.

It is true that cooking - particularly boiling water - will add condensation to the boat. However, since the companionway is right next to the stove, if we leave the companionway hood cracked open, the steam rises and passes out of the boat. As for showering, the small hatch in the head takes care of most of that.

In short, my problem was not dealing with the effects of the heating system. As I indicated initially, all I wanted was an appreciation of the relative merits of the air heating systems. I already have an understanding of the Webasto DBW 2010 hydronic heater - since that is what I had originally decided upon.

FlightPlan - while I appreciate your input, I think you are the first person I have talked to with a boat bigger than about 32 feet that has recommended an air heater. When I was considering going with the air units, I was actually considering two of them - one forward and one aft. However, an Espar Airtronic D5 - which is the size the website you referenced indicated would be appropriate for a 45 foot sailboat - only has a heating output of less than 20,000 BTUs. If I were to run two of those, I still would not getting the heating capacity of one DBW 2010, and I would be spending about 2/3rds of what I would be spending for the Webasto system complete.

I assume your comments regarding sizing units is related to air conditioning rather than heating, but I think the underlying concept is the same. Your point is valid - for you. Perhaps I like having my boat cold enough to be "a cave" - or warm enough to be "a sauna." I apologize if that comes across as "snarky" but...

By the way, DeepFrz, Typhoon's link is EXACTLY what I was talking about earlier
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Old 27-12-2013, 12:04   #26
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Capt Frank where did you get the poly film? Is it the stick on kind? I need to do the same thing for my hatches. Right now I'm using three of the radiator type heaters and they keep the boat at about 70 degrees and have so far this winter. Low tech and low cost solution for now. I see the webasto in my future as well.
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Old 27-12-2013, 13:47   #27
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Re: Air Versus Hydronic Heater

I got the poly film from CostCo. Basically, it's an industrial size roll of Saran wrap. It sticks to the bulkheads OK, but I have to use blue masking tape and to get it to stick to the wooden frames on overhead hatches. By the way, putting this stuff up has always been a two person job for us. Otherwise, I end up throwing hundreds of feet of film away, wadded up in big balls. Life is too short to try to untangle it!

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Old 27-12-2013, 13:49   #28
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Re: Air Versus Hydronic Heater

By the way, the poly film/Saran wrap thing works for me on my boat in my weather conditions. It is JUST MY OPINION of how to do this. Your mileage may vary
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Old 30-12-2013, 10:05   #29
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Re: Air Versus Hydronic Heater

On my present liveaboard I have an Espar D5 L. She is a 47 foot boat.

Even in the relatively warm Puget sound it is not enough.

Though it throws out plenty of heat the blower has difficulty reaching the bow.
Thankfully it is mostly only me. She is well insulated and it rarely gets below freezing.

The unit was well suited for the bay area where it was installed and was used to keep the boat dry in winter.

I have a huricane ii in my future - after the weather warms up.

Mub

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Old 30-12-2013, 11:42   #30
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Re: Air Versus Hydronic Heater

Having spent a year in Bremerton, I can appreciate the "relative" part of that statement .

I also was going to say that you were braver than me if you were already planning to take on a hurricane until I realized you meant an ITR heater!

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