Best Dehumidifier to work from a 100W Solar Panel?

[Fithawk]

Hi all.

Is there a Dehumidifier that will run from my 100W Solar Panel over the Autumn/Winter months whilst in storage? If not, what are my options please? Thanks in advance.

 

[Jcloughie]

As caravans are ventilated, using a dehumidifier, whether powered or passive is, imho, useless.

Just ensure all vents are clear and that there is full circulation.

I also just used the sun blind on the roof lights, so that some heat might be generated if there was sun, but not too much, which would increase circulation.


John

 

[Fithawk]

As caravans are ventilated, using a dehumidifier, whether powered or passive is, imho, useless.

Just ensure all vents are clear and that there is full circulation.

I also just used the sun blind on the roof lights, so that some heat might be generated if there was sun, but not too much, which would increase circulation.


John

Thanks for the reply John however, I’m a little confused on ”all vents are clear”. Which vents do you mean? Cheers.

 

[Jcloughie]

Normally there are vents beneath the benches, these feed into the van via gaps at floor level. Also known as gas drops or something like that.

Also, roof lights are not totally sealed even when closed, and allow a trickle ventilation. There may well be more,

Without some sort of passive ventilation, the air would soon be unbreathable and dangerous.

John

 

[otherclive]

I opened all cupboards, wardrobes, lockers etc plus opened door to bedroom and bathroom. Lifted the mattress and seats. The aim being to ensure good air circulation throughout caravan. Don’t clean surfaces with Pledge or similar as it encourages mould. Just wipe down with a detergent cleaner

In effect our van when not being used in winter looked a bit like an explosion in a furniture factory. But all our vans went through winter without any problems.

 

[Fithawk]

Normally there are vents beneath the benches, these feed into the van via gaps at floor level. Also known as gas drops or something like that.

Also, roof lights are not totally sealed even when closed, and allow a trickle ventilation. There may well be more,

Without some sort of passive ventilation, the air would soon be unbreathable and dangerous.

John

Makes sense now. Thank you.

 

[Fithawk]

I opened all cupboards, wardrobes, lockers etc plus opened door to bedroom and bathroom. Lifted the mattress and seats. The aim being to ensure good air circulation throughout caravan. Don’t clean surfaces with Pledge or similar as it encourages mould. Just wipe down with a detergent cleaner

In effect our van when not being used in winter looked a bit like an explosion in a furniture factory. But all our vans went through winter without any problems.

Thanks for that. On a mission now to do the same😀

 

[trevormonty]

Worth running heater for few hours every month or so when you visit. Then vent van totally before leaving to flush out warm air carrying any moisture.

Anything that runs off solar and house battery will need a controller so equipment only operates when battery has good charge. Eg turn on if charge 90% and turn off when 50%.

As it happens just designed and built something like this for charging my ebike batteries when off grid. I've electronics background. For those with electronics back ground its simple hystersis circuit. Worth running separate battery voltage monitoring +&- wires directly to battery terminals. Means you don't need to worry about voltage drop over wires feeding controller.

 

[otherclive]

Worth running heater for few hours every month or so when you visit. Then vent van totally before leaving to flush out warm air carrying any moisture.

Anything that runs off solar and house battery will need a controller so equipment only operates when battery has good charge. Eg turn on if charge 90% and turn off when 50%.

As it happens just designed and built something like this for charging my ebike batteries when off grid. I've electronics background. For those with electronics back ground its simple hystersis circuit. Worth running separate battery voltage monitoring +&- wires directly to battery terminals. Means you don't need to worry about voltage drop over wires feeding controller.

I have never put heat onto a caravan during winter apart from if we were away in it., and I never suffered any mould/mildew problems. I really do not see that heating it for a few hours then opening it to cold/humid air would give any benefit as very quickly the caravan would have atmospheric air entering again, and would come back down to ambient temperatures. Its inner air would then cycle as the outside air varies, and with the amount of ventilation in a caravan it would then exchange with external air.

 

[Buckman]

Worth running heater for few hours every month or so when you visit. Then vent van totally before leaving to flush out warm air carrying any moisture.

Not sure if running a heater every now and then is a good idea. As the van cools down after using the heater, you may have a condensation issue.
Make sure caravan is well ventilated and none of the vent holes are closed up preventing circulation of air.

 

[trevormonty]

Heating van will cause moisture in furnishings to evaporate. Unless you flush air out before turning heating off it will just condensate back in van.

 

[ProfJohnL]

Heating van will cause moisture in furnishings to evaporate. Unless you flush air out before turning heating off it will just condensate back in van.

It's not quite that simple. Assuming you don't have a water ingress problem which is artificially raising water content inside the caravan, when in storage the entire caravan will assimilate to the level of humidity in the ambient air over a few days. That is as low you can realistically hope to get a caravans moisture level, and that should not be a problem long term.

If you periodically introduce heat into the air, that may initially cause the air to absorb some moisture from the furnishings and fittings, but the warm air will also raises the temperature of the same fixtures and furnishings, which just like the air actually increases its own ability to absorb moisture, which it will do from the ambient air that ventilates the caravan. theis cyclic heating won't do harm to the caravan, but neither does it have any long term benefit.

Ultimately such warming for a few hours makes no overall difference to caravan nominal moisture content and it just uses energy and money.

 

[Fithawk]

It's not quite that simple. Assuming you don't have a water ingress problem which is artificially raising water content inside the caravan, when in storage the entire caravan will assimilate to the level of humidity in the ambient air over a few days. That is as low you can realistically hope to get a caravans moisture level, and that should not be a problem long term.

If you periodically introduce heat into the air, that may initially cause the air to absorb some moisture from the furnishings and fittings, but the warm air will also raises the temperature of the same fixtures and furnishings, which just like the air actually increases its own ability to absorb moisture, which it will do from the ambient air that ventilates the caravan. theis cyclic heating won't do harm to the caravan, but neither does it have any long term benefit.

Ultimately such warming for a few hours makes no overall difference to caravan nominal moisture content and it just uses energy and money.

Many thanks for that. Great advice.

 

[Fithawk]

Not sure if running a heater every now and then is a good idea. As the van cools down after using the heater, you may have a condensation issue.
Make sure caravan is well ventilated and none of the vent holes are closed up preventing circulation of air.

I turned the caravan upside down earlier and could only find one Vent adjacent the Water Heater. Have now asked the dealership for advice on any other Vents. If there are, I’ll post on this thread. Thanks.

 

[Jcloughie]

I turned the caravan upside down earlier and could only find one Vent adjacent the Water Heater. Have now asked the dealership for advice on any other Vents. If there are, I’ll post on this thread. Thanks.

What van is it, and what year? Vans legally have to have minimum ventilation. Some have too much and can be draughty.

John

 

[ProfJohnL]

As Jcloughie has stated, UK specification caravans must have a certain area of fixed (non adjustable) ventilation at both low and high level to allow for the inhabitants to survive.

 

[Fithawk]

What van is it, and what year? Vans legally have to have minimum ventilation. Some have too much and can be draughty.

John

It’s a Bailey Phoenix 640+. 2022.

 

[Mr Plodd]

I have had a fair few motorhomes and caravans over the years.
I have never bothered with any form of moisture control or heating. But what I have always done is to ensure plenty of adequate ventilation.

 

[Jaydug]

I turned the caravan upside down earlier and could only find one Vent adjacent the Water Heater.

I would be very much surprised if there wasn't a drop hole (covered with mesh) below the fridge and the cooker.

 

[otherclive]

We also had one in the cupboard adjacent to the fridge, and one at front under seats by water heater.

 

[ProfJohnL]

A symptom that is also often misunderstood, is how if you look into a caravan that in storage, you can often see some condensation on windows. That is most often caused by differential heating resulting from sunshine on one side of a caravan whilst the other sides are in cooler air. Some owners see this and mistakenly install some type of dehumidification.

They are gratified to find the dehumidifier is collecting water, and they assume its actually working. Unfortunately they're wrong, all its shows is the fixed ventilation is doing its job, and all the water they collect is just from the free air moving through the caravan, and the actual moisture content of the caravans internals is exactly the same as previously.

 

[trevormonty]

I would be very much surprised if there wasn't a drop hole (covered with mesh) below the fridge and the cooker.

My little bailey has one under cooker, left and right seats. Maybe others I've not found. Don't forget fridge vents on side and also gas heaters flue. They are far from airtight.

 

[ProfJohnL]

The principle of "room sealing" in the context of gas appliances is not defined as "air tight" because air tightness is impossible to achieve, so there is a formula that involves pressure differences, burner power, and other factors that defines the maximum permitted levels of flue product transmission/ leakage to a habitation volume.

The fridge vents on the outside of the caravan are not part of the statutory habitation ventilation. If the fridge were fitted in accordance with its installation instructions, there would be no air exchange between the fridge vents and the habitation space. However most of us know that the caravan manufacturers have got away with poor room sealing of the fridges for many years, principally because the the fridges flue is directed outside and any blow back into the fridges vents would be diluted even further, enough to render a very low risk to occupants. I'm not defending the caravan manufacturers practice, as they have had more than enough experience and time to comply with the fridge installation instructions.

Space heaters are on different scale of burner size and therefore risks are greater should the room sealing fail to meet the required standard.

Due to the design of space heaters, the room sealing to the required standard is much easier to achieve, and is usually managed successfully and safely.

 

[Mandarin]

Never used a dehumidifier in a caravan as you're basically trying to dry out the county unless you seal every vent, which you shouldn't.

We did find them useful on a boat, which has very limited ventilation (and is naturally in a rather damp environment) and we sealed it as much as possible since demundifiers work best in a sealed room.

 

[Fithawk]

I would be very much surprised if there wasn't a drop hole (covered with mesh) below the fridge and the cooker.

Ahh the hidden ones. I take it they’re only visible from under the caravan?