Best heater for use during winter?

[Sandero]

Perhaps noisey was the wrong word. The system has a blower and you are aware of it and the moving air when it is in the high fan mode. When it reverts to low fan you cannot hear anything unless you are next to the unit... which I am not as it is "hidden" in a bilge compartment under the aft cabin berth.

Jef
sv Shiva
Contest 36s

[GordMay]

...”When it reverts to low fan you cannot hear anything...” because you have reduced the air velocity (fpm), and are no longer moving too much air volume (cfm) through the duct.
cfm = fpm x f/a
where:
cfm = air volume (cubic feet / min.)
fpm = air velocity (feet / min)
f/a = free area of duct or grille (smallest, in square feet)

The important factor is to keep the speed of the air (its velocity) as low as possible. This is usually achieved by having a large size fan, moving the same volume of air, through a larger aperture or duct, thus keeping the velocity low.
HVAC duct sections are typically sized so that air velocities don't exceed 400-800 fpm, but premium designs (quiet) limit velocities to around 225fpm.

There are other factors involved in fan / duct design, but duct size & geometry (smoothe bore, round duct is quietest) are the two over which the consumer has most control.

[coot]

The feature I like most about the Espar is that it can safely run unattended. The computer will shut down the system if it detects any of various faults. For example, it shuts down if it overheats. It also shuts down if it fails to detect a flame in the combustion chamber.

The behaviour of the fuel pump suggests to me that it depends on the computer to function. That is, I think the individual ticks of the fuel pump are caused by the computer and therefore it can not continue pumping if the computer fails.

There are things I would do differently if I were designing the unit, but the safety systems do not concern me.


The ticking of the fuel pump does not bother me, even though it is right under the bed. After a while, I got used to hearing it and it just sounds like part of the boat. It helps to put some foam between the pump and whatever it is mounted on. (My pump is just held in place with cable ties.)


It seems to me that the Espar keeps down condensation better than electric heaters. I suspect air movement from the fan is responsible, so any forced air heater might do well compared to any convection heater. The warm air ducts also heat the areas they pass through, which would normally be closed up and therefore not heated well by convection.


I "solved" the condensation problem in some lockers by installing insulation along the back walls of the lockers. I used a pink foam that is about 2 - 3 mm thick and maybe 10-15 cm wide. It looks like a solid sheet of plastic with bubbles in it. It is intended for use along the edge of attics or something like that.

I taped vertical strips of this insulation along the back of a hanging locker to cover the entire back wall. This doesn't totally prevent condensation, but it usually forms inside the wall and outside the insulation, where it can't get on the clothes. (Well, first the condensation runs down between the wall and insulation, then pools on the floor, where THEN it gets on stuff.) Sometimes, when it is cold enough, I still get condensation on the inside of the insulation.

To date, I have not detected anything growing behind the insulation, but I haven't looked very hard. It is a bit of work to tape all this stuff in there, so I am reluctant to pull any significant amount of it out just to look under it. Interesting smells would change my mind, but there aren't any yet after over a year.

[SkiprJohn]

Aloha All,
I plan to sail to Alaska and bought a Dickinson Newport Diesel Heater to install. I want to do a gravity diesel feed. I haven't read from any of the previous posts anything about this. Can anyone comment?
Regards, --John--

[KevinE]

Quijote
Can you elaborate on your dehumidifer a little bit? I have been looking into getting one for winter storage on my boat - my thinking being that if I can dry the interior out more (I am on the west coast, vancouver island) I can maybe cut down on the storage temperature I keep my boat when not in use, as in the coldest portion of the year, I am looking at $60-80 month just to keep my boat of 5-8 deg. C.

Do you leave your dehumifier on when your boat is in storage and how do you balance the boat temp versus the effectiveness of the dehumidifier (it is my understanding that they don't work too well at cooler temperatures - ie. below 60 deg.F)

I have spoken with a few people around my marina and nobody seems to be using dehumidiers even though boat condensation and mould is a big problem on the wet west coast. West marine is selling a small unit for $100 but I have read some reviews somewhere that they don't work very well (and you can buy them elsewhere for half the price).

I am looking at something like a 30 quart maytag that I can just empty into my bilge, they are running around $200 Can.

Cheers,
Kevin

[lilly]

Skiper,
We had a gravity feed system for our heater on our last boat. The 5 gal tank was hidden in the deck box just in front of the mast. Our propane tank for the stove/oven was in the same box. It was handy to have both there because we could turn off both valves when we left the boat. I also plumbed the shore water line (when we were tied dockside) through the box so we could turn off three valves.
The gravity fuel tank was trouble free but I should have installed a hand pump from the main tank to fill the gravity tank on deck. Instead I had to carry an extra 5 gal plastic container. It took up space and it was a hassle getting refilled sometimes. So I would recommend having some type of hand pump to draw from your main tank.

[Craig Harlamoff]

Just a quick comment. Some boats by design are cold. For example, a Hunter sailboat that sits next to our Bayliner runs his heater all the time. It seems the Hunter takes on the temperature of the surrounding water. The Bay is quite a bit higher on the water and has tanks under the deck, insulating us from the water. We have a flybridge above, so our main cabin has more insulation between the ceiling and flybridge. We haven't run the heater this year.

In summary, some boats are warmer by design.

[SkiprJohn]

Thanks Lilly. All good suggestions about the gravity feed. A really good idea about the hand pump to the gravity feed tank.
Regards, --John--

[Quijote]

Kevin and Skipper John,
Sorry about being slow to get back. We were gone for the weekend.

Let's start with the gravity tank. I don't use one, but I considered it when I installed the Dickenson. I use a low pressure fuel pump that uses almost no current and so far has shown no problems. If I were going gravity feed, I would just find a 1 or 2 gallon container mounted higher than the burner. It could be filled with the same fuel pump that you might use to bleed the engine, polish fuel, etc. Either way works fine.

Now the dehumidifier. This thing has revolutionized the comfort factor while living aboard. We used to have green stuff growing on our extra shoes, soggy locker bottoms, you know the way it gets... And we shower aboard, cook pasta, etc. all of which raised the moisture level. Since we got the dehumidifier, the boat is as dry as a house!
When we were researching the topic, we looked at information for tiny dehumidifiers that listed their output in pints per day. That didn't seem nearly enough. So we finally found a serious dehumidifier with the smallest possible size. It is a Soleus Air Portable Dehumidifier. (You can google it) Now it isn't all that small, but the ones we used to use in our basement at home were like small refrigerators. This thing is about the size of a carry-on suitcase - the kind with wheels and an extending handle. It removes a few gallons a day in humid weather. We just leave it running anytime the boat is closed up. If we go away and the tank fills up, it turns itself off.

It's nice to get into bed between dry sheets!!! Highly recommended.
Best regards,
Richard Black
S/V Saeta
Sceptre 41

[GordMay]

Low Ambient Dehumidifiers:

Anything under 15 deg C (59 deg F) is low temperature for a Condensate Type Dehumidifier, and there is a risk of the machine icing up, because the air is cooled inside the dehumidifier until the water vapour condenses. Since a condensate dehumidifier works by reducing the temperature internally, it can easily reduce down to freezing even if the ambient temperature is 10 - 15 deg C.
For lower temperature use (down to “freezing”), you need a machine with a “Hot Gas Defrost” function*. Hot gas defrost works by reversing the coils and using the heat from the hot side of the coils to melt the ice to water. When this is done the heat is returned to the front of the machine to warm the air before it is blown back out.

Adsorption Dehumidifiers use a completely different principle to extract the moisture from the air. Air is passed through a high surface area, that is impregnated with silica-gel desiccant. As the air passes through the rotor the moisture is adsorbed onto its surface. Part of the rotor is separated off from the main airflow. Through this part a small amount of air is ducted in from outside, heated and passed through the rotor. The moisture on the rotor is given up to the hot air which is then exhausted back outside as hot wet air. The newly-dried section of the rotor then re-emerges to the main airflow ready to adsorb more moisture. The rotor turns slowly making the operation continuous.
The adsorption principle has important advantages. Firstly, its action is independent of temperature. An adsorption dehumidifier will operate as efficiently at -20C as +30C. Secondly the adsorption principle makes it possible to reduce the humidity levels to lower levels than condensate types.

[Quijote]

Hi all,
As Gord points out, the kind of dehumidifier that I am so enthused about only works well when we are living aboard and keeping the boat warm. While it is capable of working continuously by plumbing the condensed water to the bilge and thence overboard, it probably won't do very well in cold conditions.
Richard Black

[KevinE]

Gord,
Do you have any sources for absorption dehumidifiers in North America? It googled them and seems quite popular in the UK but can't seem to find anything here. Seems like the cats meow though for me, given that they work down to 5 degrees and also give off some heat, I might be able to use one of these units by itself with additional heater.

Kevin

[GordMay]

Sorry, I don’t have a source for smaller sized adsorption dehumidifiers.

[GordMay]

Here’s a good overview of “Boat Heat”, from ”Pacific Fishing” (Nov. 2002) ~ by Terry Johnson (University of Alaska Sea Grant)
http://seagrant.uaf.edu/bookstore/bo.../boat-heat.pdf

[islandplanet]

We're quite sold on hydronic heating.