Dehumidifier Worries.

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jakeroyd

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I have an XM dehumidifier running on my boat.
It's a refrigerant type with auto hot gas defrost.
It also can auto start after an interruption to the supply.
In the current conditions I assume it will not be running at all.
It must have a thermostat as well as a humidistat.

I guess it must defrost by heating the refrigerant up ?

I image it's trying to defrost all the time (when powered up, I have it on a timer with 3 periods of 'on' per 24hrs) ?

Or will it just remain dormant untill it gets well above freezing.

I suppose it could also start up when the drain is still frozen or the sink drain out of the boat is also still frozen up.

I'm trying to decide if I should check it out or leave it alone , I live 3 hrs drive away , so it's not a small job to make a visit.

Can anyone advise ?

TIA
 
Dehumidifier

Hi Jakeroyd,
Does your insurance company know you are running a dehumidifier whilst the boat is unattended ?
There have been a few instances of dehumidifiers catching alight on boats. It's not something I would recommend. I assume you have it draining into the sink, this weather the unit can fail to defrost or as you mention, the drain can freeze.
For piece of mind I would be on the motorway by now with an oil filled radiator to plug in on low setting.
No doubt there will be someone along soon to say dehumidifiers don't catch fire but they do.
 
BoyBlue49 said:
Hi Jakeroyd,
Does your insurance company know you are running a dehumidifier whilst the boat is unattended ?
There have been a few instances of dehumidifiers catching alight on boats. It's not something I would recommend. I assume you have it draining into the sink, this weather the unit can fail to defrost or as you mention, the drain can freeze.
For piece of mind I would be on the motorway by now with an oil filled radiator to plug in on low setting.
No doubt there will be someone along soon to say dehumidifiers don't catch fire but they do.
Click to expand...

Bet that's cheered him up!
 
Were is the boat?

If you are in the water... and it hasnt frozen up... then it will probably not go much below freezing if at all onboard....

I use a dimplex heater set on the frost setting in conjunction with the dehumidifier... and I leave the boat in the water... I havnt had a problem..(Knock on wood) so far..
 
BoyBlue49 said:
Hi Jakeroyd,
Does your insurance company know you are running a dehumidifier whilst the boat is unattended ?
There have been a few instances of dehumidifiers catching alight on boats. It's not something I would recommend. I assume you have it draining into the sink, this weather the unit can fail to defrost or as you mention, the drain can freeze.
For piece of mind I would be on the motorway by now with an oil filled radiator to plug in on low setting.
No doubt there will be someone along soon to say dehumidifiers don't catch fire but they do.
Click to expand...

Are you saying de-humidifiers are inherently unsafe? Are they banned from houses too? Does having them in a house invalidate the insurance too? How did they get the CE mark? Is it a forgery?

Interestingly, my oil filled radiator says it is not to be left turned on unattended. So if you're already on the motorway yourself, best check yours is safe & if necessary turn around immediately.

That said, I've found leaving a de-humidifier running in cold weather is an inefficient way of keeping damp at bay.

My approach now is to pick one part of the boat at a time, heat it up for 30-60 mins with a 2KW fan heater then run the de-humidifier flat out for a few hours. If they can be run together that is better. Of course it's also necessary to seal off the part of the boat that's being warmed & dried, which means closing the relevant cabin doors and avoiding nipping into that cabin every 20 mins.
 
BoyBlue49 said:
pvb,
All in the service, no extra charge.



photodog,
Glad you touched wood, should keep you safe.



maybe
Click to expand...

Its not the dehumidifier he should be worried about...

Its the rats that have chewed there way aboard... and the polyestermites slowly destroying his gelcoat... the Fray Bentos that have frozen and exploded.... the stray electric currents from his poorly earthed neighbors boat which has worked its way through his anodes and is right now feasting on his P Bracket and heat exchanger... the slight damp in the foresail that is mouldering away and destroying the stitching... the mooring lines which are chaffing through and will fail in the next gale... the keel bolts slowly rusting away.. the hatch left partially open by accident in the heads, which are now slowly filling with rain water... the diesel bug throwing a party in his fuel tank.. the fresh water tank that has frozen and will burst.... the batteries set to explode due to being overcharged... the scrote currently rooting through his lockers and making off with his outboard... the marina managment scheming up new ways to screw him out of his hard earned cash... The steel dutch barge which parks opposite which will make a ill judged approach next weekend and then punch a nice hole in his transom... the Bavaria full of students which will bounce off his toerail and bend his stanchions... The Stalocks on his rigging which have had some moisture trapped and is slowly rusting through his stays...

I could go on.


Dont sweat it.
 
l'escargot said:
Never seen that as a question on an insurance proposal. Is it something new?
Click to expand...

Well, many of us run our battery charger, our oil radiator and our dehumidifier in the winter precisely because the boat is left unattended. Don't want her freezing up, or suffering from damp, or the batteries going flat. Any sensible insurance underwriter wants precautions taken against the real risk of frost damage rather than the remote risk that your dehumidifier is dangerous.

Unless you dehumidifier is in a parlous electrical state, don't worry about it - very sensible to run it.
 
BoyBlue49 said:
Hi Jakeroyd,
Does your insurance company know you are running a dehumidifier whilst the boat is unattended ?
There have been a few instances of dehumidifiers catching alight on boats. It's not something I would recommend. I assume you have it draining into the sink, this weather the unit can fail to defrost or as you mention, the drain can freeze.
For piece of mind I would be on the motorway by now with an oil filled radiator to plug in on low setting.
No doubt there will be someone along soon to say dehumidifiers don't catch fire but they do.
Click to expand...

The large percentage of the 180 plus unattended boats in my marina have dehumidifiers running, as they did last year :rolleyes:
 
jbweston said:
Well, many of us run our battery charger, our oil radiator and our dehumidifier in the winter precisely because the boat is left unattended. Don't want her freezing up, or suffering from damp, or the batteries going flat. Any sensible insurance underwriter wants precautions taken against the real risk of frost damage rather than the remote risk that your dehumidifier is dangerous.

Unless you dehumidifier is in a parlous electrical state, don't worry about it - very sensible to run it.
Click to expand...

but with the charger on a timer ;)
 
BoyBlue49 said:
Hi Jakeroyd,
Does your insurance company know you are running a dehumidifier whilst the boat is unattended ?
There have been a few instances of dehumidifiers catching alight on boats. It's not something I would recommend. I assume you have it draining into the sink, this weather the unit can fail to defrost or as you mention, the drain can freeze.
For piece of mind I would be on the motorway by now with an oil filled radiator to plug in on low setting.
No doubt there will be someone along soon to say dehumidifiers don't catch fire but they do.
Click to expand...

Cobblers, substantiate your claims or be quiet.
 
interesting range of responses !
Yes , my insurance company are aware and have noted it.
I was trying to find out technically what's going on with the dehumidifier.
The boat is out of the water so it will be pretty cold.
 
If your not living on board,the hull is perfecly dry in the bilges,your engine room vents are sealed with tape,why would you need a dehumidifier? When I go on mine its perfectly dry inside,with no dehumidifier.Also with the frosts we,ve had I wouldnt want to run a dehumidifier.
 
jbweston said:
Well, many of us run our battery charger, our oil radiator and our dehumidifier in the winter precisely because the boat is left unattended. Don't want her freezing up, or suffering from damp, or the batteries going flat. Any sensible insurance underwriter wants precautions taken against the real risk of frost damage rather than the remote risk that your dehumidifier is dangerous.

Unless you dehumidifier is in a parlous electrical state, don't worry about it - very sensible to run it.
Click to expand...
Sorry, missed off my sarcasm smiley - I don't use a dehumidifier on my current boat, although I have in the past, but I do run 2 heaters and a battery charger. :cool:
 
Thanks for the links Sarabande.
I'm not really that worried about a fire , these are rare.
What I do worry about is how the unit is perfroming and what it is doing in this very cold weather.
A fridge works by the compressed refrigerant being allowed to expand , giving up energy(heat) to atmosphere via the heat exchanger at the back of the fridge.
As I understand it a dehumidifier uses pumped refrigerant to cool the condenser, a fan then blows air over the matrix , where water condenses out on the matrix and drips out.
So with it's hot gas auto defrost it must be heating the condenser somehow , probably using the same refrigerant.
I wanted to know how this works and if it will be trying to do this all the time or perhaps detecting the low temps will mean it shuts off till say 10 degrees C , till it has a chance of running normally.

In a sense , whilst frozen , there is little need for dehumidifieing , it's when moisture laden air then meets cold surfaces that you need to reduce the air moisture content to avoid condensation.
It's avoiding mould inside that is my goal on the 'carpeted' inside surfaces of the hull at the ends where the air does not move much.

All soft furnishings etc. were removed when I winterised the boat.
 
Exploding dehumidifiers

Well done sarabande, I new someone would come along with some decent information.

The dehumidifier mechanism uses a reverse heating programme to defrost the build up of frozen water on the matrix accumulated from the atmosphere to drain into a receptacle.
When the ambient temperature is below zero this defrost does not take place and a subsequent build up of ice on the matrix can stop the mechanism, usually an electric fan which then over heats --- need I go on ?

Why don't you doubters including sledge hammer Google -- Exploding Dehumidifiers.

Happy winterising.
 
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