Drying clothes with dehumidifier (2023 Update)

[R D S]

We d this and have the machine pointing towards the clothes blowing the dry air at them. I'm wondering whether it would be better the other way around?

[Andrew]

If you are hanging the clothes in fairly small room and keep the door closed then it doesn't really matter.

[PeterC]

Just a note: keep the evaporator clean; all the fluff and dust seems to accumulate on the wet fins and the effectiveness drops right off.

[Harry Bloomfield Esq]

It might make a slight difference, either way, but I would suggest adding some sort of extra fan. A fan will move the air around the room, giving the dehumidifier a better 'share' of the moist air, as well as aiding greatly the evaporation of the moisture from the clothes.

[Andrew]

The ebac Powerdry that I bought recently clogs up its fins with frost after about 15 minutes. This blocks the air throughput but it chugs on until an hour has elapsed and then the compressor switches off for 10 minutes and the frost+ice melts and dribbles into the container.

There doesn't seem to be any way for it to detect this icing up by measuring the airflow?. My old ebac homedry circa 1986 had no fins in its aluminium cold coils so the build up of ice did not impede air flow through them.

The most it seems to collect over 24 hours is about 750ml yet it claims to extract over 15 litres a day. This might be true in a hot humid location but not during typical winter weather in the UK.

[Andrew]

Or even a fan heater plus the dehumidier effectively giving you a heat-pump/condenser dryer. :-)

[Chris Hogg]

Forcibly circulating dry air through the rack of wet clothes must surely be the best way of drying them. Allowing room-dampness air to diffuse slowly through the rack is bound to be slower.

[Paul]

If the room humidity is high, even forcing that air through the rack does not work quickly. It could take the whole day (60%-70%).

Numbers at my place:

January hot air heating: ~25% RH (Dry a snow-shoveling coat in three hours) Between seasons: 60% RH (Hard to dry clothes with a fan) June air conditioning: 40% RH (Easily dry rinsed biking clothes)

Current humidity is 31%.

Thick items need to be turned inside-out, to finish the drying process. You can't expect miracles :-)

Paul

[PeterC]

Seems to be over-gassed for a cool room.

[Andrew Gabriel]

The draft from the fan will probably help. I have one in the airing cupboard. I can hang a load of washing in there, switch the dehumidifier on, and shut the door. Dries the clothes quite quickly.

I bought 3 ebac-lookalikes about 20 years ago. They all suffered from icing up the evaporator when running below around 14C. There was a temperature probe on the evaporators connected back to the control boards, and a defrost indicator light, but it never worked on any of them.

When the controller died in one of them, I built a raspberry pi to control it instead. My logic for icing up was, when the evaporator drops below zero, kick off a 10 minute timer. When that expires, switch off the compressor (and switch on the defrost indicator lamp), but keep the fan running. This 10 minutes was found by experimentation to not be long enough to block the fins with ice. You then see the ice melt quite quickly helped by the air still being fanned through. When the evaporator goes back above zero, a 5 minute timer is kicked off, which allows the melted water to drain out of the evaporator, and then the compressor comes back on.

The 10 min run-on of the compressor when the evaporator drops below zero before initiating a defrost cycle allowed the dehumidifier to work effectively at a lower ambient temperature than the units could originally handle.

If the unit had a variable speed fan, that also could have been utilised to delay or prevent icing up, but these units don't.

It will depend on the humidity.

Andrew

[Andrew Gabriel]

The dehumidifier does heat via the condenser. If operated in a small room (or airing cupboard in my case), it gets warmer in there as you'd expect. You get the 250W of heat from the power consumption, but you also get the latent heat of evaporation back from condensing out the water on top of that. Using it in a larger room will also do this, but the effect is going to be much less noticeable, and probably less effective at further enhancing the drying.

Andrew

[Andrew]

My elderly ebac Homedry has a small circuit board with a 555 timer. Once an hour it activates a valve that sends warm refridgerant backwards through the cooling coils, whereupon the ice crackles, and drops off into the water tray beneath. After 5 minutes the valve closes and the cooling coils go cold again. Both the 1 hour and 5 minute timers must be set by rotary pots on the circuit board but I haven't tried fiddling with them.

Odd that their latest models don't seem to have this quick defrost ability.

[Animal]

R D S

dry air at them.

blowing the dry air at the clothes is the fastest way to dry them. The fan has more effect than the dehumidifier, in most cases you can just use a fan.

Andrew

There do seem to be a lot of questionably designed control cycles out there. It seems someone somewhere doesn't give a whatsit how well they work.

true of all dehumidifiers really. 20C 60% air holds a lot less water than 30C 100%, and the machine can only remove some of it.

Andrew

sure, but a waste of energy

depends what you consider best. If best is zero work, zero energy consumption, zero costs then just hang them up in the wardrobe, job done (if your house is dry).

Andrew Gabriel:

It's working by letting you know it needs deicing :)

I think the future is variable speed fan & compressor. The machine can then run at the most energy efficient all the time. And die in 1.1 years.

Andrew

it's cheaper & more energy efficient to turn the compressor off.

[Rob Morley]

All the electrical energy you put into the dehumidifier ends up heating the room, you don't really need to add any more.