Dishwasher on cold water!

[jerrod6]

In the USA we could kinda do solar but there are limitations.  Parts of the country are warm/hot year round so there is abundant sun.  But the rest of the country does not receive enough sun during the long winter months, so we will go days/or an entire week without sun.  This is even true during the mild  spring season.  Then there is the fact that if our water system receives water from streams or rivers during the winter this water temp is close to freezing.  Freezing water trying to be heated by cloudy no sun skies is a tough sell for solar water heating in many parts of the USA.

 

[spinspeed]

Washer111 I agree that layout costs for solar are high. It was already installed in our house when we brought it. It does have an elecric booster for cloudy winter days which works on a timer to take advantage of cheaper electricity at night. Today it is chucking it down with rain but from yesterday's wall to wall sunshine we have heaps of very hot water but pretty sure I will need to switch the booster on as have done 4 loads of laundry but did use the same hot water for all 4 loads using suds transfer from one TL to other TL. Hate to think of the cost of running the Maytag dryer but has to be done on a day like this.

Our solar system was set up in the mid 80s and we might replace as we have some issues with poor hot water pressure and some green metallic residue in the hot water system. Old copper pipes I think but it will certainly do for now. Apparentley Harvey Norman does a really good deal on solar hot water.

I know nothing about heat pumps or how they work. Unfortunately we have no gas supply in our street. We had to have an induction cooktop which I have to say is bloody brilliant, as quick and controllable as gas. I have never liked conventional electric cook tops and always preferred gas. Our Fisher and Paykel electric oven and cook top were really great purchases and highly recommend them. Pyrolitic cleaning is just the best invention. Sory I have rambled off the subject a bit here.

Off to see Prometheus this evening, very excited!

Simon

 

[washer111]

Solar in the US

I think solar in the US may only be practical on what, the west coast? They don't get snow there, do they?

But after just taking a shower, yesterday's good solar gain certainly kept the water nice for when the rain came today - thank goodness for a warmer night! We're lucky to have some decent light now, patchy light amounts of cloud.

If you want a booster in this house, boil the kettle

P.S. Spin-speed
We have a Westinghouse Catylic clean oven, induction cooktop and range hood. Induction cooking is GREAT. Next time we have cold hot water, I'll have to see if it can boil around 3L of water quicker than the kettle does 1.8L of water (probably will!)

 

[mikeklondon]

Hot fill DW

HI
I always fined it interesting that US machines use hot fill but still seen to do a good job, i have been given many explanations over years as to why you cant do it in the UK ranging from it set on the food if the wash starts in hot water to it would be very Unhygienic as in the UK our hot water is fed to the tap by a gravity system and not pure so must be heated to a minimum temp of 65C to combat the risk of bacteria and this is not cost effective due to the small displacement of water a DW uses IE the water at the point of the DW would be cold and still need heating in the machine + the displaced water in the system would also need to re reheated. Are hot water Systems in the US fed by mains pressure? Moreover, are the storage tanks usually located near the Kitchen? In our current house the tank is a very long way from the kitchen so I would have to draw off about 5 LT of water if the DW was hot fill. with 2/3 load a day the cost would be much higher here to use hot fill I think.

 

[mikeklondon]

One More Question

In the UK DW have a built in Water softener is this the case in the US? most of the UK has very hard water and I'm told you cant put hot water in the Softener.

 

[launderess]

Water Heaters/Boilers

Are usually located in the basement or ground floor ultility area. The latter can be anywhere from off the kitchen to outdoors on a patio, etc. Much depends upon where in the USA one lives and how one heats the water.

Pressure is very much determined by location as well. Here in NYC the water system was designed to use gravity and can push water up to the height of a six story (or is it seven?) building. Higher than that requires the use of rooftop water tanks you see in all those picutures of the NYC skyline. Other locations use pumps or similar means to create proper pressue to serve local community. Of course if one is on a well or other source of water that is different.

Bacteria in hot water tanks is not urban myth. A serious disease is spread by the bacteria Legionellosis which can breed in hot water tanks if they aren't kept to a certain temperature.

Before the energy crisis of the 1970's it was common to find USA domestic hot water supplies at temps of 140F to 180F. Out of concerns for scald burns and to save energy the government and people on their own began to reduce that temp. However some went too far and the result was an outbreak of disease.

Much of the reasons you gave against hot water tanks as opposed to a tankless system are vaild and often used here to get persons to install the latter. However so many Americans think the opposite of those on the otherside of the pond. They cannot see why an appliance should heat water when they've got a big old tank to do the same. The only real time they will consider such a thing is for dishwashers, though have been warming to the idea for front loading washing machines as well.

http://en.wikipedia.org/wiki/Legionellosis

 

[mikeklondon]

Legionellosis

My Dear Launderess
Again I have to say a thank you to you for information, your post above has stopped my partner moaning about the size of our energy bill and reminded me to have the water tanks in the loft cleaned. I think your post makes it a little more clear why its not safe to connect a DW to the hot line in the UK, like most of the homes here the System gives a good pressure but not a constant temperature IE our boiler comes on a 4AM and heats the 150 L water tank to 86C that’s plenty of water for 2/3 baths/ showers and house cleaning ect. Boiler go’s off at 7AM leaving a tank of water around 50C until 4PM when its reheated to 86C again for the evening baths dinner ECT, ECT. Now if I put the DW on when I go out about 9 AM and it filled from hot line in theory this water may not be free from water born bacteria., if said DW only washes at 50-55c cups glasses plates ect sit all day and I come home remove glass and drink from it if may not be as clean as I think. At the end of the day I think I’ll stick to a cold fill DW.

 

[foraloysius]

IIRC Legionellosis is spread by inhaling misty water, like in a shower. I don't think using dishes etc from a dishwasher, that has used water contaminated with Legionellosis, is a huge risk.

In 1999 200 people got infected with Legionellosis from a jacuzzi that was on display on a flower show. The jacuzzi was running every day with the same water at 30*C or so. The air around the jacuzzi was full of the bacteria. It was a huge disaster, 32 people died.

The advice overhere in the Netherlands is to keep water heaters over 60*C/140*F so the bacteries get no chance. I've often wondered why people in the USA keep their water heaters at a lower temperature. Might it be that the risk of Legionellosis is lower because there is more chlorine bleach in the water?

 

[launderess]

120F Hot Water In The USA

Think this explains things better than I.

http://www.hgexperts.com/article.asp?id=5135

 

[foraloysius]

Interesting article. It looks like the advice is still to keep the temperature of the water heater at 140*F, but use a mixing valve that makes the temperature of the outgoing water at 120*F. All kind of valves or adjustments are available too. I would prefer regulating at the valve, with a mixing valve just after the water heater leaves the possibility of the Legionella bacteria to grow in the water pipes.

 

[launderess]

@MikeLondon

Have to second the above posts in that Legionellosis or probably anything else "growing" in one's hot water heater would affect the household directly. The dw like the washing machine are closed units so the chances of inhaling bacteria laden mist/droplets is low.

Built In Water Softeners:

No, best as one knows no domestic American made dw has or had internal water softeners like those from the otherside of the pond. This of course excludes offerings from European brands such as Bosch or Miele.

Homes with hard water here usually either make do or install whole home water softener systems. Some of the posts of dishwashers and washing machines found by members on this side of the pond show various "damage" from hard water deposits. Everything from nearly rock solid formations to green tinged interiors.

 

[launderess]

Here's Another View

Pipe:

http://books.google.com/books?id=96...0CFAQ6AEwAQ#v=onepage&q=Hot Water 120&f=false

 

[launderess]

To Many Heating Water To 140F or Higher

Is simply a waste of energy with a storage tank system. It means unless some sort of control is rigged the thing is heating all that water every day and night to that high temperture regardless of need.

There was a thread here in the group awhile ago about vintag Rudd and other water heaters that promised water as hot as 180F (circa 1940). Supposedly this provided enough hot water for all the household's needs. Near boiling hot water for washing machines and dishwashers, while being able to supply for His Nibbs's bath. A member explained that it was likely some sort of tempering valve of valves provided water at the taps and bath much lower than 180F, while sending that very hot water directly where needed.

 

[dj-gabriele]

Legionellosis

You guys take this legionellosis thing too seriously.
Over here most boilers have an anti-legionella cycle that activates ONCE A MONTH: the heater turns on to bring the water temperature over 60°C for at least three hours, that effectively removes every risk of bacterial growth as the bacteria is inactivated at temperatures over 55°C.
This way one can effectively use low temperature-high volume storage (energy efficient heat pumps as an example) and still spare any kind of risk of disease.

One more note about dishwashers and legionellosis risk:

every European style dishwasher rinses (even if run from hot water) the last rinse at least at 65°C (more often at 70-72°C) even if delicate or china cycles are selected, this to both aid in drying and to sanitize the load so the risk is nil.

 

[foraloysius]

Gabriele

Not every European dishwasher does every last rinse at 65*C, especially not on the delicate cycle! But then again the risk lies not in the dishwasher. You can't get legionellosis from that. Showering etc. is the risky thing here, when the water is sprayed around, you inhale the bacteria and the lungs are infected.

The problem is that with heating a water heater up to 60*C once a month, the bacteria that might have grown in the water heater are killed, but most likely they have spread through the pipes. Those pipes will never reach 60*C for three hours and the bacteria will not be killed because of the cycle of the water heater.

Overhere in the Netherlands we see cases of hot water systems infected with the Legionella bacterie on a somewhat regular basis. The systems in swimming pools, sport schools and retirement homes seem to be the most sensitive to it.

 

[rolls_rapide]

Washer111

Your solar heating set-up doesn't sound as though you have a modern photovoltaic system. This would supply electricity to the house and back to the grid.

You made mention of "topping-up", so this must mean that you have an older, much less efficient system, based on water flowing through arrays of matt-black painted pipes (radiators in reverse).

 

[toggleswitch]

Watts = Volts x Amperes. (Amps)

Apologies if this was responded to, I did not see it.

"How does voltage affect the water heating capability? Is there less "oomph" available to drive the heating element.

A 20 ammp circuit on 230v = 4,600 watts is what the wire can carry.
A 20 amp circuit on 115v = 2,300 watts is what the sire can carry.

A 15 amp circuit in 230v = 3,450 wattts is what the wire can carry.
A 15 amp circuit on 115v = 1,725 watts is what the wire can carry.

So on our voltage we can't get in a heater powerful enough (on an ordinary circuit of 15a or 20a) to start with cold water in a dishwasher. The time contsraints (to heat the water adequately) would be ridiuculously long.

Logic also dictates that showering cold water on hot dishes and glasses can only stress them. Not appealing to us. LOL

 

[foraloysius]

"Logic also dictates that showering cold water on hot dishes and glasses can only stress them. Not appealing to us. LOL"

I guess for us it's the other way around, showering hot water on cold dishes isn't appealing to us. LOL
Not because the dishes and glasses can't handle it, but because some food, for instance with proteins, might get burned on to the plates.

 

[rolls_rapide]

Logic also dictates that showering cold water on hot dishes

Which is where Bosch's heat exchanger comes in: a stepped reduction in temperature per fill.

 

[dj-gabriele]

a heater powerful enough (on an ordinary circuit of 15a or

Don't worry, 1 kWh is plenty of heating power for a dishwasher! Indeed Miele, SMEG, and even Ariston models for export can complete nicely a cycle starting on cold water in reasonable time while doing a wonderful job.

A theoretical example:
heating 4 litres of water plus 10 kg of dishes, considering the heat capacity for dishes at 2 J/(K*g)
Water enters at 15°C and we need to wash at 55°C and rinse at 70°C.

For the wash we'll need a dT of 40°C: around 0,41 kWh of energy.
A 1 kW heater will supply that in less than 25 minutes, a more than reasonable time frame.