Continued questions indirectly related to buying a new washing machine
Should I buy a cold fill washing machine or hot and cold fill?
The short answer is that you don't have much choice these days. Most washing machine manufacturers are only making cold fill washing machines. I've always suspected that the main reason hot water valves in washing machines have disappeared is because it suits the manufacturers. It clearly saves a reasonable amount on production costs which have been under constant pressure for many years. Removing the hot valve should reduce manufacturing costs by saving money on the following -
- Hot fill hose
- Hot valve
- Wiring to the hot valve
- Hose from hot valve to dispenser
Here's the long answer, and an analysis of the reasons why the valve has been removed, and the implications -
Washing machine manufacturers say that a cold fill washing machine increases washing efficiency when using biological detergents and washing at 40 degrees. This is because the enzymes in the detergent work best at low temperatures and die off at high temperatures. They also say it is more economical to heat the small amount of water up inside the washing machine than to use the inefficient hot water systems in many UK homes.
However, many people don't use biological detergents because at least one member of the family may be allergic to them and suffers irritation or simply because they prefer a non biological detergent. These consumers would therefore miss out on the biological powder-boost benefit from cold fill washing machines. ( Related Whitegoodshelp Blog article - Biological detergents do not cause skin irritation )
But do washing machines with a hot valve actually use much of our hot water anyway?
Ah, well in most cases apparently not, and this is the crux of the argument for cold fill washing machines. 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 truth is that hardly any hot water ever gets into the average washing machine on most washes and your washing machine has probably always heated up the water a lot more than you may have assumed.
Washing machines with a hot water valve almost always fill with hot and cold water on most washes (non-fast coloureds, woollens etc.) So, because hot water cools rapidly in the hoses and the household pipe work, and it usually has much lower water pressure than the cold water supply, by the time the hot water starts to get through into the washing machine, the washing machine has just about finished filling anyway. This is particularly true these days because washing machines are using a lot less water than ever before.
Still not sure? Most modern washing machines (5.5Kg drum capacity) only use about a washing-up-bowlful of water to wash in or something like 6 litres. The water usage figures may be 40 odd litres or more but most of that water is used on the rinses. Try this experiment -
- Use an empty washing up bowl in the sink, and turn on the cold water tap (fairly high) to start filling it up
- Then count "one thousand and one, one thousand and two" to simulate the initial period of filling where ONLY the cold water valve is energised in a modern washing machine (to make sure no detergent gets flushed into the sump hose and therefore wasted)
- Then turn on the hot water tap fully as well, and let them both fill the bowl
- When almost full, turn off both taps.
- You should see that the water is 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.
UPDATE: April 2010
Since writing this article the drum capacity on modern washing machines has increased. 7Kg and even larger drums are now pretty common and they use more water. Because they also wash more laundry they are actually more economical to use but if they use more water on wash then this weakens the argument that very little hot water will get into the washing machine because it doesn't have time to run hot.
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 is unlikely the washing machine would get any 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 tap or in the washing machine case to the water valve. This water quickly cools in the pipes so when the washing machine calls for hot water it has to take all the cooled water in first. Because they only use a couple of litres of water and they take in cold water at the same time by the time the heated water from the boiler reached the washer it's too late - the washer has finished filling for wash and has started to wash.
All the hot water that's just been heated up now lies wasted in the plumbing 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 ).
Arguments against cold fill only washing machines:
Although I can think of several arguments against cold fill only washing machines, many need caveats which can minimise the effectiveness of the argument somewhat for many people.
- A hot valve is very useful for boil washes to give a proper head start. Although manufacturers say that most people rarely (if ever) use the boil wash these days washing machine manufacturers now recommend a maintenance wash once a month so this means everyone should be doing at least one boil wash a month which will cost more and take longer without a hot valve
- There are scenarios where having a hot water valve on a washing machine would be very desirable such as for those with solar powered, and other environmentally friendly or cheap hot water supplies, or for people never using biological detergent or using high temperature washes. However, these people are going to be a minority, and unless the hot water is supplied at a high flow rate and runs hot quite quickly then very little of the economically heated water would be used anyway (as explained above in - But do washing machines with a hot valve actually use much of our hot water anyway?)
- Increased wash times. If you used a lot of high temperature washes such as boil wash, I would expect an adverse effect on wash times and extra wear and tear on the washing machine. However, the general increased wash times in modern washing machines is not solely due to losing the hot water valve. It's as much a result of using a lot less water overall, which necessitates longer rinsing, and forces longer wash times to help achieve "A" wash ratings. Increased wash times directly attributable to the missing hot water valve are likely to be relatively inconsequential on the average 40 degree wash (as mentioned above in but do washing machines with a hot valve actually use much hot water anyway?)
Arguments in favour of cold fill only washing machines:
- Modern washing machines hardly use any water on wash, and a hot water valve would hardly fetch much hot water from the customer's hot water supply in cases where the water is supplied from a hot water tank or with a long run from the boiler. This also makes the economic difference between gas and electric water heating systems less relevant in most scenarios
- Manufacturers claim that in "most cases" it will be more economical energy-wise to let the modern washing machine heat the water up. Any hot water drained from the hot water cylinder is replaced by cold water from the tank in the loft. This cools the hot water in the cylinder and causes the boiler to have to reheat it. Drawing off hot water from such a system also draws more hot water into the plumbing pipe work between the hot water tank and the washing machine than is used by the washer. Unless drawn off quickly for other purposes this water cools down in the pipes and is wasted. The amount of water involved could easily be a full bowlful of water. In effect this means twice as much water is heated than is used by the washing machine and manufacturers argue that it's more economical to just draw in cold water and heat only the amount you need to use. This is a solid argument to me but again only relevant for people with a hot water cylinder or with long runs of pipe work from the boiler. People with a combination boiler near to the washing machine shouldn't have this problem
- A cold fill is better for biological detergent users and starting with cold water gives better wash results when using biological detergents. Flushing biological detergent into the drum with 60 degrees (and higher) hot water can kill off many of the enzymes that remove dirt and stains. However, you don't need to remove the hot valve to not use hot water on 40 degree washes you just need to design the washer to fill only with cold
- There is also a saving in manufacturing costs on the hot water valve, hot water hose and electrical wiring and internal hose connections
Rough and ready (summary) guide
- If you use biological detergents, and do mostly 30 degrees or 40 degrees washes then you are the type of customer the washing machine manufacturers say will benefit from a cold fill washing machine. [ Related: Causes of grease, slime and black mould inside washing machine ]
- If you don't use biological detergents, you may only see a marginal difference in wash results as a direct result of having no hot valve
- If you regularly use boil wash, a cold fill washing machine will be subject to more wear and tear through longer wash cycles
- If you heat your water using solar energy or other environmentally or economical ways then a hot water valve could be useful, but as mentioned above, you really don't get much actual hot water into a modern washing machine any way if your hot water is stored in a gravity fed cylinder or you have a long run of pipe work from your boiler to the washing machine so it's only relevant if you also use a lot of high temperature washes
- If you decide that you want a washing machine with a hot water valve, but can only find it on one of the cheap washing machines (most decent to quality washing machines are cold fill now) then it could be a false economy. Any savings made on energy could be wiped out by extra repair and maintenance costs or by lack of longevity
- Overall, more energy is saved nationwide with cold fill only washing machines.
The subject is more complex than you'd think but most people shouldn't unduly worry about not having a hot water valve in their washing machine and many people may indeed be better off without one. Although the majority of people may (according to manufacturers) not lose out with the absence of a hot valve I can see many examples where washing machines would probably be better with a hot valve. Using an already hot supply of water can be cheaper but it needs a sophisticated washing machine to utilise it properly in all the different circumstances at people's homes and at this time manufacturers aren't concerned about doing this.
Washing machines are currently designed for an average user with an assumed type of hot water system, washing with biological detergents on low temperature washes and they fail to accommodate any users not falling into this category.
Currently there are so few washing machines with hot valves that it isn't worth picking one simply for a hot valve unless you do a lot of very hot washes. Even then it could easily be a case of swings and roundabouts in that the savings you make with the hot valve may be wiped out by having a lesser quality washing machine or through other missing features or economies due to severe lack of choice.
Why not let the user choose?
It would be nice if washing machines went back to having hot and cold valves and had an option button where a user can inform the machine that they want to use the hot valve under the following circumstances -
- When they are not using biological detergents
- They are doing a maintenance boil wash
- They are doing a normal hot wash at 60 - 90 degrees
- They have a very cheap or environmentally friendly source of hot water and want to run the hot tap to draw hot water into the pipes before washing so that a reasonable amount goes in (for hot washes)
- They use a combination boiler which supplies instant hot water at a pressure equal to the cold supply and they do hot washes
- Their combination boiler is close to the washing machine and hardly suffers any loss of hot water through lack of pressure and cooling in the pipe work
Remember, if you wash with biological detergents and wash mostly at 40 degrees and your hot water is stored in a hot water cylinder in the airing cupboard you most probably don't need a hot valve anyway. ( Related advice: Washing machine smells - causes of grease, slime and black mould inside washing machines )
Do you want to add your thoughts and comments on this topic?
My blog article pointing to this page accepts comments. Please feel free to add yours - What's happened to the hot water valve in washing machines? (some washing machine manufacturers read Washerhelp and my blog)
I still want a washing machine with a hot valve
I still get people asking if I know of any washing machines with a hot water valve. My blog entry on the subject may be of help - I want a washing machine with a hot water valve
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