eberspach / webasto, do they dehumidify ?

[simonfraser]

i intend to use one of the above units during the day. when i go home it will be switched off. now the trouble starts, no other heating available, and i'll get condensation.

how can i minimize this, run the blower without heat ? if so, which one comes with a suitable timer, i don't seem to be able to find this on the relevant web sites.

many thanks for your input

 

[Sinbad2222]

Here we go !! The summer is over - stand by for 10000 Eberspacher questions!! No offence Simon!

 

[sailorman]

hot air heaters produce dry air
combustion gases exhaust via "balanced flue" from heat exchanger

 

[hlb]

i intend to use one of the above units during the day. when i go home it will be switched off.

It will do F-all when switched off.!! /forums/images/graemlins/tongue.gif

 

[simonfraser]

sinbad, i just thought i'd get in first !

p.s. i thought hot air held more moisture ???

 

[duncan]

[ QUOTE ]
hot air heaters produce dry air

[/ QUOTE ] so where does any water in the input air magically go then?

with both these units surely the hot air is simply heated air and not the actual product of combustion so, if your air intake is from within the boat then there will be no net change to the volume of water in the air in the boat and the combusion air cycle is also likely to be similarily neutral if the air intake is from outside and I presume the exhaust is outside!
Even if the air intake for the combustion is internal too the air used will have to be replaced by air drawn from outside.

So - I would suggest that thte use of these heaters will make no difference to the water content of the air in the boat.

This is not of course to say that they will not affect condensation etc through thier use and the creation of heat.

 

[[2574]]

Simon,

The obvious answer is to use a dehumidifier - but perhaps I've missed the point?

rob

 

[simonfraser]

Hi Rob,

afraid so, i'm on a swinging mooring, i'd need a 500m chord and no shore power !

Simon

 

[cookjwm]

Warmed air is able to hold more moisture than the same air at a lower temperature. So when you heat air ,all other things equal, the relative humidity of that air will reduce and it will be able to absorb more moisture. Conversely of course when that air cools, its ability to hold moisture reduces and ther you go -condensation ,the result of the air cooling and giving up moisture, usually to the coldest surface.
Get a dehumidifier!

 

[StugeronSteve]

Sounds like a job for a passive dehumidification system, like the bowls of silica crystals that you take home and dry out every so often.

 

[simonfraser]

Steve,

that would work better than a small fan running at times ?

with the crystals, i guess no ventilation ?

Simon

 

[savageseadog]

Yes the heater will warm the air, that air will carry more moisture but as long as there is some ventilation the moisture will eventually be dispersed to the atmosphere. The boat will dry I can assure you.

 

[Gordonmc]

Forget the Eber. The counter to condensation is ventilation, especially as a dehumidifier is out of the question without shore power.
I am on a swinging mooring and maintaina constant stream of air through the boat. Forward portholes are left open with flower pots insterted... they keep the critters out while the drainage holes let air in. The cockpit has a full cover with an eave at the back.
The only time I get condensation is when there is a severe frost, which is rare.
I only use the Eber when I am on the boat... I wouldn't trust it to work remotely as I am uncomfortable about high DC draw.
BTW, I found the crystals are only of real value in a confined space such as a locker.

 

[pheran]

I don't go much on this 'keep it ventilated' solution, not for the interior of the boat anyway. Unless there is something on-board to circulate the air, all that happens is that more fresh, moist air is allowed in, that condenses out and the cycle continues ad finitum. What has worked for us is several large bowls of ordinary cooking salt placed strategically throughout the boat. Will probably need replacing every 6-8 weeks depending on conditions - we have found anything up to an inch of water on top of the old salt. Cheap as chips and in over 30 years we have never suffered from dampness, mould or any of the other effects of condensation over the winter.

 

[alb40]

Keep it vented is the easiest solution. Just Leave a couple of windows slightly open, and it will stay pretty dry.

As an example, In the winter, to avoid the car steaming up on cold mornings, I leave the sunroof tilted up instead of shutting it all up each night. The windows are perfectly clear everytime I get in in the morning that way. No fans or other gizmos required!

 

[geem]

Why does everybody go for blown air heating on boats? Its the wrong solution. They use lots of power and they are full of electronics so they go wrong. Whats wrong with the old fashioned drip feed diesel heater? I stripped out 2 air blown heater from my boat and put in one 5 kw drip feed heater. It boils a kettle on top if I want to. It provides a convective heat output but more importantly a radiant heat output. This means that you can leave the hatch open for ventilation without feeling cold as the radiant component keeps you warm (like sitting in front of the fire at home). When I am not on-board the 3 large dorades blow air through the boat. The inside of the boat will not be any less damp than outside unless you raise the temperature(and thereby lower the relative humidity below dew point) or install a dehumidifier with a power supply. I dont get mold ever cos it doesnt like ventilation