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Old 11-09-2012
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Re: Winter Moisture Control

Guys,

The difference between an oil bath electric heater and a fan assisted "ceramic disc" type heater is like the difference between hydronic heat and forced hot air or "scorched air", as we affectionately refereed to it when I was a manufacturers rep in the HVAC business selling boilers, furnaces, radiant heating systems, radiators, baseboard etc. etc...

The oil bath heater acts more like baseboard heat or a hydronic radiator. It moves air, warms it, but does not do much to "dry" it because the surface temp is far to low to dry the air as it moves across the surface.

A fan assisted ceramic disc etc. type heater moves air across a very hot element and in the process the air has some moisture dried out of it. Eventually a good chunk of the moisture in the cabin will be dried using a scorched air type heater whether it be diesel fired or electric.. This is the same with a Webasto, or Espar type FHA diesel furnace as they do a great job at drying the air by moving the moist cabin air across a very hot heat exchanger..

Here in the North East most houses are hydronic heat because it is more comfortable and dries the air out less. Most FHA installations also need duct mounted humidifiers (Maid-O-Mist etc.) so inhabitants of the home don't suffer nose bleeds and dry cracked skin all winter long.

On a boat, that is already a moist environment, you'd actually welcome the dry air that results from moving moist air across a hot element or heat exchanger.

I work on boats all winter long and the ceramic disc "Pelonis" type heaters do a far better job at keeping moisture levels down. When I get to a boat it is often 5F - 30F inside. I can warm the air in the boat, with ceramic disc heaters, without causing much condensation to occur. Of course when I am working on these boats I always try to completely drain the bilge first so the boat is not trying to create its own eco system on top of my own breathing.

I own an number of these ceramic type heaters and they all offer tip over protection and automatic shut down features if the fan becomes blocked and the element gets too hot. The fans in them, like computer fans, draw mA's... I like them because they are small and can be placed out of the way of knock overs etc. because they take up so little floor or shelf space. I have one customer who heats his entire 42' power boat with them and it is very comfortable. His electric bill on the other hand, not so comfortable.....

Be aware that with any 1500W electric heater they draw 12.5A + on the high setting. Just two of them, plus a water heater, EXCEEDS what a single 30A shore power system can handle by over 7.5A.. If you are planning on going electric a second shore power system should ideally be added to handle the massive current used by electric heaters..
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