Changing temp at which hot water is used

[hgibson]

We have an AEG Lavamat 610 (The E.Nr is 605 637 104 and F.Nr 024 984 327). It has hot and cold feeds.

We’re having solar hot water installed and I wanted to change the temperature at which the machine opens up the hot water solenoid. At the moment it’s about 70 degrees on the dial.

I wondered if it was possible to make it around 55 degrees. The hot water from the cylinder can be mixed down to that temperature using a thermostatic mixer so the wash temperature won’t be exceeded. The machine will be within a couple of metres of the cylinder. We quite often do 60 degree washes and it would make sense to use the free energy when at that temperature.

I’m an ex-electronics engineer so understand circuits (and particularly what must be a simple circuit in this machine). Is it a switch on the temperature dial? Or some resistor ladder driving a relay?

Hugh

[kwatt]

Re: Changing temp at which hot water is used

Hi Hugh,

A quick read of this article should explain why what you are asking is not possible to do as well as, why it isn’t really practical.

HTH

K.

[iadom]

Re: Changing temp at which hot water is used

Second one in a week. Solar panels 😉

[Penguin45]

Re: Changing temp at which hot water is used

Hot water valve is turned on by a cam operated switch on the front of the vari-stat.

Penguin45.

[hgibson]

Re: Changing temp at which hot water is used

Thanks (I think!) for the comments guys…

Regarding the article: as I say, the washing machine will be very close to the hot water cylinder – and we’ve already bought it, 14 years or more ago. It’s got a stainless steel drum (rare these days) and new brushes and still works fine, so we have no plans to replace it.

I’m aware that it only uses hot for the main wash cycle, and even then it doesn’t use much. We used to wash nappies in it and when you turn the temp up too high it would switch to hot fill, with no cold intake. As I don’t have the hot water connected I had to do this by letting it fill on 60 degrees and then turn the temp up.

As we have asthma sufferers in the house we wash all sheets at 60 degrees and we have twins on the way so may wash nappies again at 90 degrees. In that case being able to preheat will help, as the hot water is free.

Thanks for the information, Penguin45. I’ll take a look at the switch. Maybe a bit of filing will do the job! And if I mess it up we can just connect cold to both hot and cold intakes.

Hugh

[kwatt]

Re: Changing temp at which hot water is used

Hi Hugh,

It doesn’t get round the fact that the detergent (any one) is designed to be used on a temperature curve, not instant immersion in hot water, so you may well end up with poor results simply due to that alone.

I’m not familiar with that particular AEG but, assuming it’s the usual Zanussi in a dress, it will only fill with hot on the first fill after pre-wash on the main white 90ËšC wash. At no other time will they usually fill with hot water.

Most machines were designed never to use a hot fill and, to be honest, every one that says it’s a hot and cold fill is a bit of a con as they’re not really. And, they certainly aren’t intelligent enough to get round the problems of doing it.

The only way you could make it work is to build an external mixer valve from scratch then somehow tell it when to use or not use that and what temperature to use for each wash. Good luck with that for anyone that wants to give it a go as I know what my better half would say if I told her I was thinking about that sort of thing. 😉

K.

[hgibson]

Re: Changing temp at which hot water is used

Thanks K. I forgot to say that we use non-biological detergent. Also, it seems to me that with the large thermal mass of the inner and outer drum (as well as the clothes) that even the initial fill will end up quite cool.

This machine has a continuously variable temperature dial plus rotary electromechanical timer with a couple of different programs plus switch selectable options. You can choose any temperature for the main wash, so I know at what point it switches over to hot, which is about 70 degrees (you can adjust the temp while it’s filling). That’s obviously set for the normal temperature of hot water in the UK, ignoring any losses in the pipework.

I’m not planning to have an adjustable external mixer. Just one to bring the temperature down to 55 degrees, and then change the cam so that hot fill is used for anything over 60 degrees.

I might also consider making the cold intake 20 degrees using another mixer so that colder washes have less heating to do. Rinses will be hotter but we will have lots of hot water available.

Hugh

[kwatt]

Re: Changing temp at which hot water is used

Hi Hugh,

Non-bio is a farce for the most part IMO, unless of course we Brits have different skin to the rest of the planet but, that aside, it still is designed to operate on a temperature curve, not instant immersion in hot water.

The thermal mass won’t take that much away given that it will already sit at room temperature, it won’t soak up that much really. Of course that is entirely dependent on the water temperature as it hits the tub and drum, how hot it was to start with and what’s in it. Too many variables for my liking, most unpredictable at best.

I did have a quick look at the schematics for that machine though and I don’t see it switching over to a hot fill at a preset temperature, it appears only to operate on certain programs, like most all washing machines operate.

There is no “normal” hot water temperature in the UK or anywhere else. It can vary wildly between 20ËšC and 70ËšC or more, it is far too unpredictable to engineer for. Then add to that the problem of how fast the delivery is through varying pressures and it’s just a lost cause.

However, looking at that machine in a little more detail, I wouldn’t bother going too far with it as it’s a good age and parts are starting to go NLA so it will probably need replacing soon. Then the whole game changes again where hot fill is concerned.

Most people will ask about hot fill in order to try to save money heating water, we get asked about it all the time, but really, it’s honestly not worth the effort pursuing based on the amount of energy used to heat up a modern washing machine. The general advice is, it costs more to boil a kettle than heat a washer for a normal 40ËšC or 60ËšC wash which will usually account for well in excess of 70{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of most people’s washing in the UK. So, you won’t save much at all by doing this.

Largely, this is why you’ll struggle to find a washing machine these days that has hot fill at all as, all in all, it’s not practical.

K.

[hgibson]

Re: Changing temp at which hot water is used

Fair comments, K. I’ll look into the detergent – we use Surcare… Hmmm, lots of reports online saying how good it is for reducing eczema, nothing about wash temperature gradients. I might call them tomorrow.

Regarding the machine – it seems to use hot fill on the main wash filling cycle only (code 2 or 7 from memory) and then only if the temperature dial is up around 70 degrees or higher. Any chance of getting a copy of the circuit?

When I had to replace the brushes (6 months or so ago) I had a good look around inside the machine. Everything looked fine, and the most encouraging thing was that the drum ran extremely smoothly with the belt off. Hopefully it will last a bit longer, even with the tinkering I’m planning. What’s liable to fail next? What should I get in stock here?

We were thinking about a new machine, higher capacity and washer dryer as we were planning on putting the machine under the stairs and only had room for one appliance. However I read all the scare stories about modern machines, OOB detectors vs. higher capacity, plastic drums etc and concluded that the machine we had was actually quite good – and maybe we could live with the occasional use of the dryer if it was in the garage.

Since then we’ve added a laundry to our building work so have room for two appliances. So we’ll continue with this old machine.

I’ll run an experiment with a plug-in power meter and see how much energy is used by a very cold wash versus a 60 degree wash. That will show the relative amount of electricity consumed by heating the water vs turning the drum etc. I know that a hot fill won’t replace all the heating as there will be considerable loss from the uninsulated drum, but it will give an indication of possible savings.

Hugh

[kwatt]

Re: Changing temp at which hot water is used

Hi Hugh,

Don’t get me wrong, that’s one of the good AEG machines as it’s a real one. 😉

The new one’s aren’t a patch in that one you have.

There’s no way to anticipate failure, there’s no components that are more liable to failure.

K.

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