In most cases apparently not, and this is the crux of the argument for cold fill washing machines. Even if you have a hot and cold fill washing machine the chances are your washing machine won’t even call for any hot water on most wash cycles including the most commonly used 40 degrees cotton wash. This is because the temperature of hot water in a hot supply (when it eventually starts to run hot) is at least 60 degrees, and far too hot for most wash cycles. Therefore even the old hot and cold fill machines used to always take in hot and cold water at the same time to ensure the temperature wasn’t too hot.
Because modern washing machines now use so little water the washer would commonly have already stopped filling by the time most people’s hot water came through. In the UK, most washing machines traditionally get their hot water supply through a gravity fed hot water cylinder which usually has low pressure. In this scenario the majority of water taken in will be from the much higher water pressure in the cold tap. The truth is that hardly any hot water ever gets into the average washing machine on most washes these days, and your hot and cold fill washing machine has probably always heated up the water a lot more than you may have assumed.
Still not sure? Most modern washing machines (6Kg drum capacity) only use about a washing-up-bowlful of water to wash in, or something like 6 litres. The total water usage figures may be 40 odd litres or more but most of that water is used on the rinses. Try this experiment –
- Have an empty washing up bowl in the sink, and turn on the hot & cold water taps to start filling it up
- When almost full, turn off both taps.
- You should see that the water is not particularly warm or may even be virtually cold. If you have a combination boiler you may get more hot water in, but even repeating the experiment by running the hot water tap for a minute or more first (so the hot tap produces instant hot water) the resulting "starting" temperature is still only tepid. The washing machine will need to heat the water up from virtually cold and shows that your already heated hot water supply is hardly making any real difference.
The plumbing in my house is a good example of this problem. Downstairs in the kitchen I need to run the hot water tap for at least 1 minute before proper hot water starts to run through. So if I had a washing machine with a hot valve virtually no hot water would enter my washer at all.
What about instant hot water from a combination boiler, can’t that be used?
Even if a washing machine is supplied with hot water from a combination boiler that heats water almost straight away it’s unlikely the washing machine would get much hot water in most cases. This is because previous hot water drawn off fills the long pipe run from the boiler to the end of the fill hose at the washing machine. This water quickly cools in the pipes so when the washer calls for hot water it has to take all the cooled water in first. Because they don’t use that much water, and they are also taking in cold water at mains pressure, by the time the heated water from the boiler reached the washer it’s just about finished filling for wash and has started to wash.
Not only that, but now all the hot water that’s just been heated up lies wasted in the fill hose and the plumbing’s pipes and will quickly cool down. If the hot water supply is not a combination boiler and is a hot water cylinder then all the water drawn into the pipe work is replaced in the cylinder from the header tank with stone cold water which cools down the rest of the stored water and may cause the boiler to kick in to start reheating it. Manufacturers say this is all very wasteful and inefficient. They say it’s more efficient to just draw in cold and heat up what’s required in the washing machine.
But what about the whites boil wash?
On a whites boil wash, most washing machines with a hot water valve usually fill up with hot water only, so they would get off to a head start on this cycle and benefit from having a hot valve. A cold fill washing machine is going to take a fair bit longer to reach 90 degrees when starting from stone cold water. It must be remembered though that the argument about the washer not taking much hot water in due to the small amounts drawn and the cooling in the pipes is still relevant although slightly less so because hot washes can fill with hot water only so some hot water should eventually get in but in many case it may still not be significant because of the small amount of water needed.
The main counter argument here though, is that people these days rarely use the boil wash and this is mostly true – except that manufacturers now advise people to do a boil maintenance wash once a month! (Washing machine manufacturers now recommend a maintenance wash once a month to prevent smells).
You can now buy a British made washing machine with a hot water valve. Ebac’s hot & cold fill washing machine uses, “Intelligent hot fill technology”. Ebac said my articles on hot and cold fill washing machines were excellent, and it appears they have now made one that isn’t just a dumb hot fill machine. It’s especially for people this article is aimed at who want to use their hot water. Check it out here Ebac – Intelligent Hot Fill Technology