Solar Heated Water for Washing Machines with a Cold Feed only.

[knighty]

the numbers here might be a bit rough.....

but the specific heat capacity of water means it takes 4200j to heat 1kg of water 1'C  (1kg = 1litre)

0.4kw is 1440000j

which means you can heat 1litre of water by 342'C

or 10 litres to 34'C

so if the water comes in at approx. 10'C and is heated to 40'C, you'll be using just over 10litres of water each time ?


also... (for a later date)

what about running a new feed line right from the CH tank to the washing machine using microbore tubing ?   ok it could take a while to fill... but that doesen't really matter ?


also... as for using mixer valves etc... what you really need is to tap into the washing machines thermostat - so you can fill with pure hot untill you hit the desired temp and then mix ?

[David]

Now we've got copious amounts of hot water in the cylinder most of the time, I'm going to try the washing machine filled entirely from the hot fill, and see what happens.

I have filled my dishwasher with hot water for years. These have more hot stages than a washing machine and so the savings are probably greater than for clothes washing. Electricity costs will be down and the dishes come out cleaner.

[David]

what about running a new feed line right from the CH tank to the washing machine using microbore tubing ?   ok it could take a while to fill... but that doesen't really matter ?

I reduced the size of the hot pipe to my kitchen tap, from the junction where it splits to go to the kitchen and other places, from 22mm to 15mm. It means that hot water comes through far faster. It makes no noticeable difference to flow rates, but the cold water storage tank is high up.

Microbore tubing from a cylinder to a washing machine, or better still from a suitable place in the already insulated hot pipework, will be fine provided there is enough pressure to push the water through the tube in a reasonable time.

[Ivan]

Knighty, Your calculation is the amount of water being heated....but there's also the water used for rinses - which tends to be a lot more. I think washing machines generally use 50-60litres of water altogether - so I'd be wasting 40-50litres of heated water each time. If that was heated with gas rather than electricity, assuming a 4:1 energy equivalence, it just about breaks even. I'd hoped it was rather less than 50-60litres. Looks like a mixer valve is a good idea - if my tank is at 60C, then it can mix in cold water, so I'm not throwing as much hot water through the rinse cycles.

Anyone have the figures for a dishwasher? I used to run my dishwasher on hot water, but decided I was probably throwing away too much (it was before solar). I think the old dishwashers use a lot more water than the new ones. (Mine's old!).

[Amy]

Just as a matter of interest, i changed 4 x 50watt lamps for CFLs and went over to cold water washes in the machine!!!

The next quarters electric bill was down by 50%. I dont think much can be attributed to the lamps so the cold fill does make a huge difference, .....in the machine !!! 

[rob26440]

... and went over to cold water washes

  You must be made of sterner stuff than me.  Are you of Russian extract?

Anyway, my machine is cold fill only and uses about 60 litres total for a wash cycle and & 3 rinses.  I pre-fill the drum with water at the correct temperature - between 30 & 40C using the lo-tech "fill a bowl from tap" method.  It's worked fine for the last 15 years on 3 different machines (the latest one being new & "free" 2 years ago so long as I took out a 5yr maint agreement for £200).  No need for fancy pipe work, timers, valves, relays or TMVs.  It only takes 2 minutes to put in the water and once the drum is filled, the machine is switched on and left to sort itself out without further use of hot water.  No clothing shrinkage disasters either.

Electricity used during 2008 for the washing machine was around 140KWH costing about £13.60 for 7 to 8 loads/week.  No heating of water by electricity so it's all the drum motor & pump plus a little bit for its brain to function.

[Amy]

Edited to make more sense.

In the machine !!

[billi]

I guess i have to be the first one here to get a ready made advice    , boring me   

will report

billi

[Ivan]

Rob - now that's an interesting idea. Might try that one when my wife isn't looking. I guess you have to put the powder in the water your transferring with the bowls. How do you know how much to put in. I know my machine comes up with pressure sensor faults very readily - so I guess if it was over-filled it would have a fit.

[rob26440]

Ivan,

My machine doesn't complain about the water level.  Usually start off with about 8 litres at the required temperature poured directly into the drum and add more via the soap tray if necessary when the machine has started.  However, if I don't put enough in, it tops itself up.  But I tend to put in more than the machine normally takes.  As for the powder - I use liquid.  Poured into one of those little plastic things.  Sometimes I just throw it into the drum with the water; sometimes I pour it in the soap dispenser and then run in some water.  (This is usually when I have forgotten the washing liquid and the door is locked!)  Don't use powder at all these days.  Haven't done for years because it sometimes didn't dissolve fully and left marks on the items - even for the hotter, towel washes.

Rob.

[knighty]

if filling it like that is ok with you... then a very easy and pretty low tek idea would be to add a small switch to the colonoid valve.... so you can fill using the hot water from the mains via the solonoid valve on the back of the washing machine before you turn it on ?

stick the washing in
press the switch till it looks about right
turn the machine on and set it going ?

[rob26440]

knighty,

Agreed but.... how do you know how hot the water is in the drum and, my machine has a maintenance contract which would be voided if mods had been fitted.

Rob.

[Billy]

Mmmmmmmh,

Depends on the powder.  I used powder tablets in the draw and there just was not enough water to dissolve them.  In the drum they just went mushy and stayed there forming rather hard rocks on the fast spin.  Ended up having to pre melt them in some water.  Ecover powder powder is fine in the draw.

Tragically my machine sees whether there is any water left over and runs the pump, so any pre fill with hot would get pumped out instantly.  At least that's what I think it's doing but maybe it is just making sure the pump isn't seized of something.  Might need to check that 'cause after the faff of dissolving those tablets, chucking a bit o hot in would be a breeze.

 

[Amy]

So maybe its time for a geek to re write the software and make it do whats needed

[PhatBob]

Time for an aftermarket control system that allows you to define the cycles that are right for the wash and the available power.