Dehumidifier Use

[Heron]

Hello all, looking for up date thinking about how to get best results from a dehumidifier.

I have a dessicant unit that I operate on a timer, how long do members run their dehumidifiers for? Is it best to  run for 3 or more hours once a day, or  decide how many hours  over several sessions. What time of day is best to have the unit running.

I assume it is best to close all windows and vents.

Any current thinking would be appreciated.

Thank you.

[Ray]

If you're away from your boat any length of time it's best not to close the vents, ventilation is the best dehumidifier.

I leave our dehumidifier on 24/7 but at a low level/tolerance (I don't know the correct terms lol) The outlet tube goes into the galley sink and all is well

[ExSurveyor]

A dehumidifier works best in a sealed environment with some heat.

I run mine between 10am and 3pm when the boat will be warmed by any limited external warmth. I leave curtains slightly open on the sunny side to add to the heat gain.

don't forget to leave cupboards and drawers slightly open.

Windows shut but I don't seal any vents. They are most efficient when they are set to normal or 65% relative humidity.

 I have a tubular heater in the main cabin set to come on at 5°c.

Drainage down the sink waste.

Never had an issue with mould and condensation yet.

Hope that helps.

 

[Lulu]

3 minutes ago, ExSurveyor said:

A dehumidifier works best in a sealed environment with some heat.

I run mine between 10am and 3pm when the boat will be warmed by any limited external warmth. I leave curtains slightly open on the sunny side to add to the heat gain.

don't forget to leave cupboards and drawers slightly open.

Windows shut but I don't seal any vents. They are most efficient when they are set to normal or 65% relative humidity.

 I have a tubular heater in the main cabin set to come on at 5°c.

Drainage down the sink waste.

Never had an issue with mould and condensation yet.

Hope that helps.

 

Exactly what we do too 

[Mouldy]

Ours is on 24/7, like Ray.  The instructions for ours require it to go through a cool down sequence when it’s turned off, so we just leave it on with the waste down the sink in the galley.  We don’t close any vents, nor do we leave windows open.  Our dehumidifier is a Meaco dessicant type.

[ExSurveyor]

If it is running 24/7 70% rh or economy will make it effective and more economic.

[Mouldy]

1 hour ago, ExSurveyor said:

If it is running 24/7 70% rh or economy will make it effective and more economic.

The controls don’t give specific levels, but we run it on a medium setting.  Last winter, due to lockdown, we were unable to visit the boat from mid December, when we set it going, until late in March.  There was no mould or dampness anywhere.  It certainly does what it says on the box and worth whatever it costs to run.

[Bikertov]

Do you just have one humidifier unit running in the boat, or a number spread around the cabins, heads, saloon etc.

[ExSurveyor]

3 minutes ago, Bikertov said:

Do you just have one humidifier unit running in the boat, or a number spread around the cabins, heads, saloon etc.

Just the one, a centre cockpit might mean having one in each area as a canvas canopy would allow too much outside air in.

[AndyTBoater]

If you put a humidifier and a dehumidifier in the same boat, which would win?

[ExSurveyor]

18 minutes ago, AndyTBoater said:

If you put a humidifier and a dehumidifier in the same boat, which would win?

The electricity company

[kpnut]

Ha, ha.

am I wasting money having mine set on 45%. It does have an auto cut off but now presume from what you are all saying that it won't be switching off at all

[ExSurveyor]

It would probably never achieve anywhere near 45% rh sitting in a river, 65 or 70% is a good level.

[floydraser]

A very interesting and worthwhile thread.

I too have a dessicant unit as recommended by a neighbour at the marina, as they operate at low temperatures. I also control it via the wifi and a Sonoff unit with temp/humidity sensor. Using an app I can switch it on and off as required or set programs to do it automatically. Cor, reading that back it sounds really posh! 

I thought the damp got worse during the night so I've had mine running at night. I used to run it for 4 hours from 02.00 but I'm experimenting with 21.00 to 23.00 and 05.00 to 08.00 Still learning though and open to suggestions. Importantly though, no damp issues since using it.

[kpnut]

Thanks, I'll notch it up to 65% when I go next and save some money with a bit of luck. It does always feel nice and dry when I first go onboard.

Because of the initial outlay I did think twice about getting one ( I think it's a seago dessicant), but would certainly recommend using one to anyone with access to electric. I lie the fact it blows out some warm air (costing me more money I expect!) so slightly fewer worries about things going pearshaped in winter too.

[Smoggy]

Don't have a dehumidifier,  have a small solar panel inside the hatch glass connected to a PC case fan in a roof vent, during daylight always have active ventilation, the planet is warm enough without pointless power use.

Oh yeah,  don't have damp either, 6 years now on this boat and not an issue.

[ExSurveyor]

51 minutes ago, floydraser said:

A very interesting and worthwhile thread.

I too have a dessicant unit as recommended by a neighbour at the marina, as they operate at low temperatures. I also control it via the wifi and a Sonoff unit with temp/humidity sensor. Using an app I can switch it on and off as required or set programs to do it automatically. Cor, reading that back it sounds really posh! 

I thought the damp got worse during the night so I've had mine running at night. I used to run it for 4 hours from 02.00 but I'm experimenting with 21.00 to 23.00 and 05.00 to 08.00 Still learning though and open to suggestions. Importantly though, no damp issues since using it.

When the temperature drops the air loses it’s ability to hold the moisture so it is better to take the rh down during the day whilst it is warmer, any limited condensation that forms overnight is dried the next day when the unit comes back on. The unit will generate heat as a byproduct so it saves some cost on heaters.

The other option is a humidity activated extractor, ideally with a remote sensor, the draw back is the removal of heat as well as moisture.

[Bytheriver]

You need 70% or below to dry clothes successfully outdoors so suspect that is a good marker to aim for - any improvement on that would be a bonus but costly.

I recently brought a small unit for a damp cupboard in the house but realised it ran 24/7 ( presumably no sensor)with the instruction not to control from the mains switch ruling out a timer - worth noting though it seems to have improved things in the cupboard but at 22w seems a bit expensive to run for a small space

[annv]

Or you could have solar powered fans in the roof they then work 365 days a year even in just daylight they  fit in the chrome pancake ventilator cowls 'and cost nothing to run and are silent. John

[stumpy]

3 hours ago, annv said:

Or you could have solar powered fans in the roof they then work 365 days a year even in just daylight they  fit in the chrome pancake ventilator cowls 'and cost nothing to run and are silent. John

One of our first improvements for No Worries was a pancake vent with a solar fan in it. It lives in the forecabin hatch and has chuntered away happily for 10 years. We have a 60w tube heater in the saloon and another under the cockpit floor, both on thermostat plugs at +5°C. Some mould but a quick flit round with a bleachy cloth sorts it come Spring.