My wife bought a new steam iron today, a T-fal, and the instructions said not to use several kinds of water that would have contaminants but also to not use distillewater or rain water. It said to use tap water only but if it is extremely hard it can be mixed 50-50 with demineralized water. WTF? Why should I not use purified water? It has a removable scale cleaning valve that has to be removed once a month and soaked in vinegar but I’d prefer to avoid that hassle altogether. How can I hurt it by using purified water?
Perhaps a certain amount of mineral content is necessary for electrolytic reasons?
Electrolytic? I don’t think an iron uses electrolyis to produce steam. I’m pretty sure they use good old fashion heat to make steam.
Yeah, I bought a Rowenta recently, and the instructions specifically said “No distilled water.” Go figure.
When I was a wee lad, my mom had a big jug of distilled water that they used just for filling up the iron and nothing else.
I think some irons are designed to adjust for tap water and if you put distilled water in, it won’t steam correctly.
That makes no sense. I’ve used dehumidifier water for steam irons, car batteries, and such for many years.
This is what Rowetna says on its website:
Well, using water with calcium in it should increase the sale of new irons.
This is just a theory.
Distilled water is made by boiling off regular water then condensing it. Perhaps the fact that it has been once boiled already affects it’s performance in the iron.
I don’t know how this applies to rain-water.
Rain water has been evaporated and condensed at least once and probably thousands and thousands of times.
I’ll try a WAG - distilled water has a tendency to superheat rather than nucleating around dissolved impurities and producing steam bubbles at the normal boiling point.
I think this is the answer. The steam from distilled water will be hotter than the steam from normal water, because the impurity-free water must get hotter before you can get a good roiling boil going. Perhaps you’re risking burning your clothes if you use purified water.
Yes. This is the same reason I had to put a little salt in my humidifier the first time I used it.
What abou corrosion? I know this pchem guy I worked for a few years back said he couldn’t cool his lasers with ultra dionized water because it would corrode the innards of the cooling system. I didn’t ask for any further explanation, but I’m assuming it was because of the following:
A system containing water and a solid will have an equilibrium between dissolved and undissolved solid. Deionized water has been shifted in one direction completely away from equilibrium. Shifting back to equilibrium involves dissolving some of the cooling system (or in this case, the inside of the iron.)
Does this sound at all plausible?
(I’m thinking it’s probably the super-heating issue)
The steam from distilled water will be hotter than the steam from normal water, because the impurity-free water must get hotter before you can get a good roiling boil going.
Not according to the science fair project I did when I was 12. There’s a property of solutions called Freezing Point Depression/Boiling Point Elevation. When you add solute to a solution (something like salt or other minerals to water, for example) the boiling point goes up and the freezing point goes down. This is chem 101 stuff. You can find the math here.
Water with some solute in it will boil more evenly, but that is due to the nucleation effect previously mentioned.
Does anyone have any numbers as to how much this purported superheating amounts to? All of the sources I’ve found show that boiling point of pure water at 1 atmosphere pressure is 100 C and that adding minerals raises the temperature at which the solution boils.
Is the boiling point really raised to the point that cloth might be scorched if distilled water is used but not if tap water?
I can’t imagine that non-pressurized steam, even if “superheated”, is going to be to scorch or “burn” a regular clothing textile material just by contact.
BTW, when I WAG’ed about superheating, burning anything wasn’t what I had in mind - I was just thinking about it as an explanation for why the thing might not operate correctly with distilled water.
Just a personal experience here. My husband has sleep apnea and has to sleep with humidified air pumped at 13 lbs pressure directly into his nose. The humidified air is made by heating water on a special heater in a special container with an aluminum bottom. We used to use distilled water we bought at the grocery store, and he would have holes in the container in about 2 months. When we asked the respiratory therapist about it, he said that distilled water STILL HAS SOME SALT IN IT! We got a reverse osmosis system and we haven’t lost any containers in two YEARS.
Yes, I think this is the answer.
We have many chambers at work that require water for maintaining precise levels of RH. Most of the manuals say to not use ordinary tap water (for obvious reasons), but they also say to not use distilled water. (They recommend deionized water.) In fact, they say the warranty is void if distilled water is used. IIRC, it has something to do with corrosion; because distilled water is completely void of ions and minerals, the water will leach ions and minerals from metal.