Which dehumidifier to use without electrics?

Discussion in 'Motorhome Chat' started by etap, Dec 21, 2015.

  1. etap

    etap

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    When electrics are not available and the MH is kept outside which is the best dehumidifier to buy, any ideas would be grateful.
    Etap
     
  2. Clickem

    Clickem Funster

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    We use the tubs from Poundland. Last year they were 2 for £1 and lasted about 4 weeks, for us. This years stock contain more granules, but are £1 each
     
  3. Lenny HB

    Lenny HB Funster

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    Not much point as Motorhomes have permanent venterlation, moist air will constantly be replaced from the atmospher.
     
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  4. Poohbear

    Poohbear Funster

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    So do houses but people use them there successfully.
     
  5. matamoros

    matamoros Funster

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    So there is no point in heating, air conditioning either as the heated air, cooled air will constantly be replaced?

    Surely any form of de humidification will reduce the humidity to some extent. That has certainly been my experience of using de humidifying crystals in our static van unused over winter in a very damp area of France without any damp issues or musty smells.
     
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  6. Lenny HB

    Lenny HB Funster

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    If the van has good permanent ventilation shouldn't be necessary, if the ventilation is poor or non existent it will help, most touring vans have good ventilation.
     
  7. DABurleigh

    DABurleigh Funster

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    I'm struggling to think of a situation whether motorhome or home, where a dehumidifier is other than a a temporary solution to a problem that needs to be fixed.

    Dave
     
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  8. pyro

    pyro Funster

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    I beg to differ. The situation where mould growth proliferates is dependent upon three principle factors, relative humidity above around 55%, a dew point below around 18 degrees C (68F) and the length of time that these conditions are allowed to prevail. Condensation is one primary cause that is practically unavoidable (cab glazing), water dripping through an open roof vent (which is often the only means of ventilating without compromising security) is an avoidable cause.

    The silica crystal dehumidifiers are good, but need frequent replacement. As a long term boater, the conditions are perfect for mould growth. We used a cheap sub £100 B&Q ("Airforce") humidifier on a timeswitch that came on for 30 minute intervals three times a day from mid October to mid April. The condensate was chucked into the bilge, which was automatically pumped dry. Many others who didn't have access to shore power used small (PC type) vent fans (running off solar panel assisted batteries) to keep a good throughput of air. In the end I programmed up an Arduino and coupled that to a cheap B&Q dehumidifier and humidity/temperature sensor. Cost around 5p a day to run, and has kept the boat dry in some of the worst conditions possible for years.

    For my own M/H I plan to programme up another Arduino/humidity/temperature setup and simply stick a cheap 12v PC fan in to keep the van gently vented via the fridge vent outlet, as there is no other way of leaving anything open safely. Total cost? £35 and a couple of hours work

    If you get a dehumidifier, do make sure that it has provision to discharge externally. Usually leaving it beside the sink will work

    I suppose those with SOG toilets could always leave their fans running on a timer :giggle:
     
    Last edited: May 28, 2016
  9. Lenny HB

    Lenny HB Funster

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    All you will achieve is an attempt to dry out the atmosphere, the fridge vent area is completely sealed from the inside of the van.

    Motorhomes have plenty of permanent ventilation no need for any more, I've never had and problems just leave the van as it with the beds made up.
     
  10. pyro

    pyro Funster

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    Correct. The plan is to dry out the atmosphere, that is how humidity is best controlled.

    The fan outlet will either be breaking into the sealed area of the fridge upper exhaust vent or venting through the floor (hence the tongue in cheek SOG analogy). My only hesitation is to be 100% certain that no CO from the AES fridge gas burner can leak back into the van, which would be courting disaster, therefore I may well integrate this into an extractor for cooking fumes. I have a workshop and I have a bit of time on my hands, so why not?

    The ventilation of our M/H is largely determined by the van cab, not very much (if any) airflow as best as I can tell, and as the van is left unattended for quite long periods I do not plan to compromise security. I have seen plenty of condensation on the cab windows of other Ducato vehicles left just overnight. Perhaps I am unlucky in having an (almost hermetically) sealed coachbuilt? 35 quid and a couple of hours work doesn't seem too high a price to pay for insurance against mould in a country (Portugal) whose weather alternates between monsoon and arid meteorological conditions, often in a single day. And an exhaust extractor to eliminate cooking smells would serve a very useful additional function.

    The OP sought a non electric solution, which means silica crystals are fine if you have regular access to change them. If it is a problem for them (presumably that is why they posted in the first place) then they can either use a silica crystal based solution or a self contained solar powered marine grade vent, which are available everywhere.

    Certainly the well known M/H dealer we bought our van from thought condensation control was necessary, as they had packs of crystals in all their show vans, and threw in a couple for us as a freebie. Perhaps Oxfordshire, like Portugal, is more humid than Sussex?
     
    Last edited: May 28, 2016
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