h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Call all science types!

Over in the parent and child section, we were lamenting what central heating does to dry baby skin - not a good thing.

You know how you can get little pots to hang on radiators, evaporate water and humidify rooms - would they really work in practice? How much water would you have to evaporate to make a difference? Is it the best answer - is there a better answer?

Any help appreciated!

Turn the heating off or down I get bad throat if the heating is on too much, and when I have to have it on, I.E., when its damm freezing outside, I always keep a window in the room, I'm not sure if that would help, but it seems to do so a little bit... Depending on where you live, increasing the water content of the air in the house may have undesirible effects; Back at my Fathers we have a dehumidifyer, as we have walls that get covered in mould; Living near the fens, and up the road from a marsh...

Y-e-s. Just the sort of problem I've come across. My house is draughty 18th C stone, and the baby in question currently has a bit of a cold, so there's a limit to how far I can turm things down, butI have a horror of damp - and spores aren''t going to help either of us!

Anna-the-Italic was asking the question in the first place, and I bet she lives in in a more salubrious dwelling...

...so is there no use in those radiator humidity things?

I must say I've never come across them before I guess, theoretically it sounds like it would make sense; putting them on the radiator so the heat of th eradiator evaporates the water Not sure what it would be like in practise though : Are they expensive? You could always try a couple in one room, see how they went.... Or wait for someone who has some knowledge (I.E., definatly not me ) to post here

My nanna use to have a big (trifle sized) bowl of water in front of the vent for the heating...mainly because it was a stupid house type thing built in the 60s and so the heating was so bad that without it or with the windows open the house just froze.

She raised 9 children in a 3 bedroom terrace so she must have had some idea what she was doing

Personally, I think it's a bit of an old wives' tale. A simple radiator will alter the temperature of the air around it; it won't add or take away moisture. Warm air is likely to be moister, as any damp in the surroundings is more likely to evaporate into it.

My mother always keeps a trifle-mould full of water by her radiators, and a towel on the windowsill to catch all the water running off the windows because of this. Frankly, I'd have "cut out the middle man" and just left a damp towel on the windowsill... But, she just complains about the bad condensation and how the council should do something about it, and appears incapable of understanding the connection between the water on the windows and the bowl of water on the radiator, no matter how often it is explained to her.

I'll go with that, radiators alone won't actually reduce humidity levels... however, if you've the type of central heating they put into some houses in the 60s with air vents or a reversible air conditioning system it might have an effect.

Nope, we had the central heating put in, and a right b*llsup they made of it too My lovely wooden floors As we don't have a tumble dryer, there is plenty of damp washing in the house at this time of year, so I'd have thought the atmosphere was pretty humid...

I don't know if they are available in UK, but I've seen room humidifiers before. Basically, they're a tank of water with an opening at the top and something inside that causes the water to vaporize. My parents used to whip it out every time someone had a cold, so they could increase the humidity in the room and allievate dry, sore throats and such.

I don't remember the exact formulas for how much water one can evaporate into air, but I remember it was a very small number. Basically, when increasing the humidity in the room, relatively little water goes a long way. Probably if you were to evaporate a tea kettle full of water into a largish room, it would dramatically increase the relative humidity. Unfortunately, that usually leads to condensation on any cold surface, which includes windows, walls, drinking glasses, etc. If you put a tea kettle on a radiator, it would probably evaporate the water in the kettle, but at a slow rate. And you would have to put the kettle right on the radiator, not just hang it above.

And radiator room humidifiers needent cost a fortune, all they are are clay pots with a hook to hang them over the radiator.

Indeed, and I have plenty of clay pots!

Will hanging wet washing on the radiators have the same effect then?

It'll certainly increase the humidity levels in the room. But are you sure it's humidity that's the real problem?

No I'm not certain. I do have my doubts. But I'm trying as many things as poss, providing they don't contra-indicate and they're easy to do, just to see if I can get anywhere. It was Anna who suggested it - I think she may be trying it with Dom, but I don't know if he's got 'just' dry skin or worse. We're definitely at the 'worse' stage, but without going throught the 'dry' stage.

Doc has given us a cream for one area, but now slightly different things breaking out elsewhere. Hubby has eczema but Doc says the two are not necessarily related - it can be something that babies go through at this stage.

Thing is we *always* have damp washing around, so I imagine the air isn't that dry...

Not expecting to cure it, just looking for things that might help.

Me - I've got skin like tarpaulin

Hmm, I'll pop over to the other thread and read the backlog I think before suggesting anything over here

You won't find that much!

You're not wrong

Skin like a tarpulin?

Does that mean you're waterproof and make for good shade at picnics?

Ouch!

*puts on crash helmet and hides under the table*

Hmm, interesting problem. Actually, you are asking two questions, if I read you right. (1) How much water would you have to add to your home (i.e. how many humidifiers) in order to maintain a high humidity, and (2) would that, in fact, actually help keep your child's skin from drying out. Right off the bat, I don't have a clue about (2).

The first question is an interesting engineering question (interesting to me anyway, being of chemical engineering persuation ). What you're really after is the amount of moisture (or % relative humidity) you're likely to lose per hour - and from that, what amount of moisture should you be trying to put back into the air to maintain a high % rel. humidity (say, 80%). In order to solve that problem rigorously, I'd need information about the size of your home (volume, not just floor area), the size of your heater (specifically energy output/rating), and also the current realtive humidity (or absolute humidity or percent humidity). That last bit can be found, if I knew the temperature of your house (just with a thermometer, an average is ok) but I'd need also the wet bulb temperature, which is a bit trickier. It's usually much easier to just go out and buy a relative humidity gauge at the local hardwares or housewares store. Even with all that info, I'd probably wind up making some assumptions that may turn out to be wrong.

After saying all that, know what the easiest thing to do is (and, incidentally, what I do living in the desert Southwest USA with guitars and a throat that all like it more humid than %5) ... just go buy a humidity gauge and a humidifier, and try to crank that sucker up until you get it around 80%. Calculating it all would be fine, but in reality it's gets pretty complicated in a hurry. I have a 1400 square foot house, with vaulted (12' high) ceilings. For one small room (12'x14'), I maintain a % rel. humidity of 50%-60% with an air temperature of about 65F by adding about 3-4 gallons (US) of water every other day. Of course, this is very dry, high-altitude air out here in New Mexico (where a "humid" day is anything 20% and above), and I keep my house pretty cool by most people's standards. YMMV.

- JD

Don't forget, the more people and pets in your house, the higher the humidity, as exhaled air is always more humid than inhaled air.