Do you use electric clothes dryers?

grumbler

Bendy_House said:

grumbler said:

Bendy_House said:

grumbler said:

  Yes, beer from the fridge is colder, but not the windscreen that has the same temperature as the surrounding air (unless you switch on the aircon inside).

Interesting.

I'm going to guess that the screen on the inside has condensation on it because the screen IS colder than the surrounding air. 

If it's only inside, that's because of higher humidity resulting from breathing - right now or yesterday (or if you leave something wet to dry inside).

The outside surface of the screen will be cooled by evaporation - a bit like if you blow on wet hands, the effect is cooling. The colder window will encourage condensation to form on the inside, even if the RH inside is very low.

Well, inside it's either (a) condensation or (b) evaporation or (c) balance.
(a) - the glass is getting warmer as a result of condensation (opposite to evaporation in your post)
(c) - the glass has the same temperature
(b) - the only reason for evaporation is that the air inside or the glass is getting warmer, e.g. from the sun rising. That's not the condition when condensation outside normally happens.

It doesn't mean, tho', that a misting inside screen indicates 100% humidity inside the car?

It does - if the air inside is well mixed, that is the case if the temperature changes slowly. Otherwise it means that it's 100% near the screen, where the air is cooler than in other places. Any condensation means 100% in the surrounding volume.

Also, condensation is more visible on glass. It may happen on other surfaces, less gloss and more porous, but is less visible there. A mirror in bathroom is a good example.

Going back to the beer glass, if the inside air is at, say, 60% RH, and feeling 'dry', then the presence of the cold glass doesn't change that RH figure, but cond still forms on the glass?

The layer of air around the bottle gets colder and its relative humidity reaches 100% as a result.

Bendy_House

Ah! Semantics!

So, the ambient air doesn't have to be at 100% or anywhere close, but it becomes an effective 100% in close contact with the cold surface?

YBE, warm air is able to hold far more water dissolved in it than cold air. That's why, after a warm evening of hot bodies and bathing, when the air seems quite 'dry' and the windows clear, it all changes overnight. The temperature drops, the air simply cannot contain all that water, and it condenses out on the coldest surfaces it can find first.

With the cold screen or beer glass, this is making the immediately-surrounding air cooler, so it cannot hold on to the moisture, so it condenses out. The rest of the room will remain pretty constant.

Wouldn't it be fun if a cold surface affected the whole room's air? Walk in with your beer, and it starts to rain

Eldi_Dos

Bendy_House said:

Ah! Semantics!

So, the ambient air doesn't have to be at 100% or anywhere close, but it becomes an effective 100% in close contact with the cold surface?

Spare a thought for the engineers responsible for fueling space rockets, there will be some who have been following thread (myself included) who thought it's not rocket science.

getmore4less

YoungBlueEyes said:

I can’t work out to phrase this without sounding deliberately argumentative; I’m trying to understand the science behind it 🙂

Surely water is 100% humid, so washing after a good spin must be lower. I said 50% but that was just a figure for illustration, I don’t know if it’s accurate. 

Maybe I’m thinking of it acting in the same way as heat and cold. Heat always rushes to cold, so does moisture not settle in/onto something that’s drier than it? So 80% moist air will dampen 50% moist clothes..? 

A washer with efficient spin will get residual moisture down to around 40% 
(You need to look at the white goods delegated regulations to see what defines 100%)

As has been said residual moisture is not the same a relative humidity.

BooJewels

I've been dipping in and out of this thread and my takeaway is . . . to drink the cold beer and then you'll care much less if your pants are damp.  Or in my case, you'll get very warm from the alcohol and they'll dry that bit faster.

I have one of the pulley operated drying racks up near the ceiling in my utility room - it appears to be about 7' 6" at its lowest point.  It used to be at a level with our old pre-combi boiler that got quite warm, but everything still dries well enough. I don't do enough laundry for it ever to be time sensitive.   I'm not sure how, but that room is not at all damp - little condensation in there, no mold.  I do spin my loads several times - modern washing machines aren't as fast as they used to be - at least the ones I can afford aren't.

If I ever move house, it will be an absolute deal breaker not to have a place for one.  You could offer to swap me for a top of the range energy efficient tumble dryer and I wouldn't take it.  I've had one all of my married life and my Mum and Grandma had them too.

YoungBlueEyes

I think that’s part of where I was going wrong getmore4less. I wasn’t differentiating between moisture and humidity. Grumbler explained it gently and plainly enough for my brain to take in. 

getmore4less

BooJewels said:

I've been dipping in and out of this thread and my takeaway is . . . to drink the cold beer and then you'll care much less if your pants are damp.  Or in my case, you'll get very warm from the alcohol and they'll dry that bit faster.

I have one of the pulley operated drying racks up near the ceiling in my utility room - it appears to be about 7' 6" at its lowest point.  It used to be at a level with our old pre-combi boiler that got quite warm, but everything still dries well enough. I don't do enough laundry for it ever to be time sensitive.   I'm not sure how, but that room is not at all damp - little condensation in there, no mold.  I do spin my loads several times - modern washing machines aren't as fast as they used to be - at least the ones I can afford aren't.

If I ever move house, it will be an absolute deal breaker not to have a place for one.  You could offer to swap me for a top of the range energy efficient tumble dryer and I wouldn't take it.  I've had one all of my married life and my Mum and Grandma had them too.

You need to look at spin efficiency some lower speed are just as good as some high speed.

Can still get stand alone spin dryers that can have lower residual moisture.

BooJewels

Thanks @getmore4less - I'm not in the market for a new washing machine at the moment, but I'll bear it in mind when I am.  I had an old standalone spin drier when I first married and that was a cracker.

YoungBlueEyes

They have a spin dryer at my local laundrette, I think it's more efficient than the max spin cycle on my 3 week old washing machine!

getmore4less

BooJewels said:

Thanks @getmore4less - I'm not in the market for a new washing machine at the moment, but I'll bear it in mind when I am.  I had an old standalone spin drier when I first married and that was a cracker.

We still have one hidden in the rubbish in the garage, thinking of resurrecting it,  check it over as not been used for over 20years, then see if it can reduce the moisture content of the stuff that will still go in the HP dryer, can measure if it saves any electric.