Solar heated washing machine

[Greenbeast]

Here is my solution to the question:
“How do I use my excess solar hot water in my cold fill washing machine?”

I now have my cold fill machine working with hot and cold water.
This is the layout of the plumbing inside the machine (Hotpoint WF545 ‘Aquarius’):



Luckily ,as you can see, I had a blanked off inlet to the drawer that goes straight to the main wash section,
there was also a nice little space on the back of the machine marked ‘H’, next to the ‘C’ (cold solenoid).
So obviously it’s all pretty identical to a H&C fill machine they must produce too.
Also luckily, my machine is modern (3 years old) but very simple, there's no digital display or anything and as such,
it doesn't complain about the water temp going in.

What happens when the machine runs as standard is that the prewash side of the solenoid runs for about 10 seconds,
just rinsing the pre-wash drawer out. It then stops and the main wash side of the valve opens up, on and off, for about 4-5 minutes.
When it needs to use the softener, both valves open and the combined water from both jets hitting each other
forces it down the middle channel and into the softener section.
So with advice and assistance from a member on the navitron forum (daftlad) I have added a DPDT relay (http://www.maplin.co.uk/module.aspx?moduleno=37518), a switch (http://www.maplin.co.uk/module.aspx?moduleno=2504) and a 7 minute timer (MK Sentry Time Delay switch – ebay £6).

A scavenged washing machine solenoid valve:



Also a new momentary push-to-make button and some neons for information:



Here’s the circuit diagram:


Basically I fill the machine and add detergent/softener as normal and then I run the kitchen hot tap to prime
the pipework with hot water (I’m lucky in that my machine is close to my kitchen sink and they’re both close to the hot water cylinder,
so I can prime the pipework with hot water easily and quickly), when it’s hot I turn the machine on, press my new button
and then the programme start button.

While the timer is activated the relay switches power off of the pre-wash valve (to stop any cold water from entering the drum)
and switches the power between the main wash valve and the new hot valve.

So for 7 minutes the machine only has access to hot water. After that it switches back to normal and will rinse in cold water.
Doing this has cost me about £21. The machine is meant to consume 1.14kWh per wash ( I don’t know which programme/temperature though), using our solar water it consumes 0.12kWh on a 50C colour wash ( I assume it’d be the same for any temp wash as long as the incoming water is far enough above the dial temp to counter the cooling due to the machine).

At 9p per kWh and doing 4 washes a week it should pay itself back within 2 years (taking into account winter,
where we may not have the excess hot water).

If electricity goes up, it’ll payback sooner, and if the solar performs well during winter it’ll also payback sooner.

[Clara]

Way over my head, my machine is directly filled from the solar tank and there is a button on the front which disables the heating element so our clothes are just washed at whatever temp the water comes out of the tank (usually mixed down to 40 - 50 degrees). This button seems standard on spanish machines but can't recall ever seeing it on machines i had in the uk.

[Greenbeast]

i like the simplicity, in my case i wanted to be able to use the machine as normal.
Our boiler is very inefficient so i wouldn't want to use tank hot water if that meant the boiler coming on.

This modification is for excess solar only
Perhaps when i replace my boiler i'll change it to default to hot.

what do you do about rinsing?
does it rinse in cold or everything from your solar tank?

[Clara]

Until you mentioned it I never considered that rinsing was done at a different temperature!! No everything comes from our hot water source which is solar by default. We have a small boiler (a slightly larger one than you used to get in small lavvies in offices etc, but the same type), we use it a few times a year, e.g. in winter if we've been in a cloud for a few days, so we only light the pilot light if we're using it. If I want to wash something cold, I simply turn a couple of keys and the water comes via the boiler instead (the two are distinct systems) which if it isn't lit means that the machine washes with cold.

[Greenbeast]

so does the machine have hot and cold input, i take it, in stead of the usual (nowadays) cold only?

[Clara]

No just a cold input, but because it's very basic and the heating element is cut out it takes what it gets!!

[Greenbeast]

oh ok (my machine is similarly simple, luckily)
that means that you're wasting hot water on your rinses?
which is a shame.

i solution like mine would sort that but you've got to be willing to take the top off and start modifying!

[Clara]

oh ok (my machine is similarly simple, luckily)
that means that you're wasting hot water on your rinses?
which is a shame.

i solution like mine would sort that but you've got to be willing to take the top off and start modifying!

I can see what you mean, but I'm not a tinkerer I'm afraid. In our case we have plenty of solar hot water (south of spain) so I don't worry about the waste because we never use fossil fuels to heat it, I suppose I could just flip the taps as it goes into rinse cycle so that it fills via the non-lit boiler instead, but I have two kids who distract me

[Greenbeast]

lol fair enough!