Comment by e12e | Hacker News Reader

Comment by e12e | Hacker News Reader

> My sister Christy has an older top loader (not HE). She washed this laundry on hot and added the 1/2 cup chlorine bleach directly to the wash water and it was very, very clean. She measured the temperature of her wash water when the tank filled up using her meat thermometer and it was 130 degrees F. She used Sam's club detergent. Her laundry was perfectly clean (to the limits of my detection abilities).

So, 130F is just under 60C - what's usually the minimum considered to kill bacteria. While I haven't measured the actual temperature, my aging, second hand washer have three "white" programs: "hot" is 90 C, and there are two rated 60C. I'd never assume any of the other programs had a sterilising effect.

If "hot" is just 60C, and often not that - I can see a need to use bleach for some loads (or other means of killing off bacteria) if the norm is to use warm (not hot) water for washing.

Would be interesting to see similar test with just water (no soap, bleach) and a 90C degree program.

I'd guess the results would be "dotted middleground" like many of the test here.

Also would be nice to see how hanging in the sun would effect otherwise clean clothes (airborne bacteria vs uv death ray stand-off - might be meaningless without checking for type of bacteria).

An interesting side effect here is that the house water heater has its own temperature control. For years people have been turning down the temperature setting on their water heaters to save energy, as a result the typical house water heater might be set to 60C (130F) and the washing machine was doing the best it could.

Washing machines use cold water and heat it up themselves, so I don't see the connection?

Clearly not all of them do :-) But curious as to the relative ratio I discover that best buy has a separate listing for machines that include an internal water heater. According to their web site, of the models that Best buy sells the population is about 40% (54 models with internal water heaters over a population of 138 models)

Only very specific models of washers in the US actually heat up the water. Most just use water from the water heater.

Good to know! I'm pretty sure I've only encountered self-heating cold-water-in machines here in Europe.

Most machines in Europe are heating the cold water and are not able to use hot water directly.

That must be why they're so incredibly slow.

Not sure if you're joking, but no, that's not the reason. At some point I hooked up an electricity consumption meter, and it was a surprisingly short timespan that the machine used for heating. The draw was around 1-1.5 kW during the heating phase.

Your machine has longer and shorter programs, my 60C wash takes about 3 hours by default while a quick was is obviously considerably faster.

"Industrial" washing machines are typically faster (for reasons) than domestic ones, and the difference is pretty much that they simply use more water.

Nope, not joking. I just know that euro machines are way slower than what we have in NA.

I just find this broad statement incorrect - sure, my washing machine has a default cotton program that takes 3 hours, but it has a variety of other settings which are much quicker and just as good - I always use "mixed colours" setting which takes 1:20h, or if I'm in a hurry there's a "quick" setting which takes 60 minutes - surely that's not long by any standard?

60 minutes is reasonable. IIRC my mixed colors setting (what I use except for bedding or towels) takes 45 min. I don't have an eco mode. Since we don't have a water heater in the washing machine itself, the only thing that would really save any electricity would be to turn off the spin cycle, but I like dry clothes so that's not gonna happen ;)

My "fast" cycle takes 40 minutes. How is that slow? Sure, if you set it to ultra power saving mode (in my case this is the default) it'll take hours, but that is just the environmentally conscious thing to do. Not to mention it's better for your wallet.

my washing machine has 2 hookups. https://www.youtube.com/watch?v=pCy-N_qAZ8I

They do? Where do you live? I've never seen such a machine in the US. At most they give a bit of a boost to already hot water.

Dishwashers typically do this, but generally not clothes washing machines.

Do they? My dishwasher pulls from both the hot and cold water lines. This is evidenced by the fact that although usually one has to run either tap for 2-3 min to get non-tepid water, when the dishwasher is running both taps dispense water of extreme temperature instantly.

Most dishwashers have a heating element in the bottom that is used to both dry the dishes but also heat the water/keep it hot during the wash cycle.

If you pull hot water from the heater and circulate it around for 30 min, it's not going to be that hot at the end of the cycle.

I guess it depends on whether you're more concerned about water efficiency or energy efficiency. If you're OK with not reusing the water, the building's water heater (especially in a multi-unit dwelling) is going to be larger and thus more energy efficient (also possibly slower, providing large quantities by dint of its tank) than the smaller heating element in a dishwasher. And you can just trickle a little bit in throughout the cycle to keep it hot.

Definitely. Heating water with an electric element isn't all that efficient at all compared to say a gas water heater.

I think you got the terms mixed up here - electric heating is far more efficient(for every 1kWh of energy used, almost all of it goes into heating water) than using gas, but electricity is also more expensive so even taking account lower efficiency of gas heating it's usually cheaper anyway.

While vaguely modern European ones generally do, American ones often don’t. I suspect this is down to the 120V power; with normal wiring you can only get about 2kW if not less, vs about 3 on a European system.

Don't most washing machines plug into a 240V circuit?

No. Electric dryers do, but not washers.

But that said, it would not be hard to run 240V to washer, so that can't be the reason.

Do Europeans typically heat water with electricity? That might be the reason - if you are anyway using electricity, you might as well let the washer do it.

In the US natural gas water heaters are very common (it's more efficient). And natural gas dryers too.

No, it is typically done with natural gas still (at least, that is the kind I see almost everywhere). A lot of new housing developments use electricity though (occasionally combined with solar heating tanks).

No, most water heating in most places in Europe is gas.

Modern front-loading washing machines, especially those managing an A or better on the EC's energy rating system, tend to use very little water, though. Depending on the plumbing system, by the time the potential cold water in the hot water pipes had run through, you might not get very much hot water at all before you were done, so you'd have to heat electrically anyway.

> might be set to 60C (130F)

Don't do that. You risk legionnaires disease. Set the temperature to at least 140F.

140F = 60C. 130F = 54.4C.

Huh...I moved into a house about 2 1/2 years ago and the water heater I believe is set to only 122 (Maybe 126? I know it's in the 120s) and I never changed it because it seemed hot enough.

I have a tankless water heater, though. The water won't be at 140F for very long, so I can't imagine it actually killing very much bacteria.

"Don't do that. You risk legionnaires disease. Set the temperature to at least 140F."

How does water heater temperature below 140F increase the risk of getting legionnaires disease?

Also, I always wash my clothes on warm, never on hot, because I don't want my clothes to shrink.

Many clothes manufacturers also label the clothes they make with directions saying to only wash on warm or cold. Otherwise, presumably, the clothes might get damaged.

> How does water heater temperature below 140F increase the risk of getting legionnaires disease?

At 140F or above it's killed. Around 100F it thrives. It's one of the rare bacteria that do well in hot water, and is naturally found in our water supply (as opposed to exotic locales).

Don't do that. You risk scalding burns. Far more people get scalded by tap/shower water that is too hot than contract legionnaires by several orders of magnitude.

120F is the max recommended hot water temperature in the International Plumbing Code.

120F is the temperature at the tap. Your hot water tank should be hotter, and you should have a tempering/mixing valve at the tap.

And not at the dishwasher or washing machine.

> Far more people get scalded by tap/shower water that is too hot than contract legionnaires by several orders of magnitude.

First of all virtually no one actually sets their tank at 120F.

Second:

"It is estimated that Legionnaires' disease is the cause of between two and nine percent of pneumonia cases that are acquired outside of hospital." [1]

"There are an estimated 8,000 to 18,000 cases a year in the United States that require hospitalization for legionnaires" [1]

"11,028 scald burns in children younger than 3 years old annually." [2]

"8,620 visits per year among Adults Aged ≥65 Years" [3]

I don't have numbers for the full population, but your "several orders of magnitude" is clearly quite off. At best it's a single order of magnitude - and that's only because almost no one actually sets the temperature so low.

If they did the number would swing.

And don't forget the pneumonia rates. This is not some rare unheard of disease.

[1] doi:10.1016/s0140-6736(15)60078-2.

[2] https://www.researchgate.net/publication/276065254_Scald_bur...

[3] https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5836a1.htm

Isn't legionnaires disease only developing in standing water? Surely not an issue when the boiler is only flow-through, without a storage tank?

Serious question - people connect their washing machines to the hot water line? I have lived in about 8 different houses in UK so far and I have never ever seen this - it's just the cold water line that connects to appliances like washing machines and dishwashers.

Yes. Some washing machines have both hot and cold inputs, though it seems less common nowadays. My gas combi-boiler heats water more cheaply than my washing machine, so it makes sense to use it. However, washing machines use much less water these days so perhaps the savings are marginal now.

Interestingly this is the 'more common' set up in the US. Hot water line, cold water line, and 110V power. I would not be surprised if the speculation in this thread about the lack of power available to do a local heater is a common issue. With a 220V mains you have a lot more power available at every plug, in the US the "220V" plugs are special and are usually dedicated to something like an oven or a dryer or other high power device.

> Also would be nice to see how hanging in the sun would effect otherwise clean clothes

http://www.stopthestomachflu.com/does-sunlight-kill-germs

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