Cold fill verses Hot fill washing machines

Hot or cold fill washing machine? This is a summary of the argument about cold fill verses hot & cold fill washing machines. For many decades all washing machines were hot and cold fill. Now they are mostly cold fill only. Because of this many people are confused about why it has changed..

..The information in this article used to be part of my main article on why washing machines are now only cold fill but in order to reduce the size of it I’ve now placed this information on its own. For a full understanding of the issue make sure you read the previous article too.

Cold fill verses hot fill summary

If you use biological detergents, and do mostly 30 or 40 degrees washes then you are the type of customer the washing machine manufacturers say will benefit from a cold fill washing machine. Biological detergents don’t like water too hot, and work best when cold water is slowly warmed up

But 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 so a hot valve might be useful depending on your plumbing (see link in next item)

If you heat your water using solar energy or another environmentally friendly or economical way then a hot water valve could be useful if you can get a reasonable amount of hot water into the machine. However, as this article explains, that’s not easy these days – Do washing machines with a hot valve use much hot water?

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 and you know you can get hot water into the machine quickly (for example – a combination boiler with a very short pipework run to the washer). 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 your severe lack of choice.

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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

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 as only the water needed by the washing machine is heated up

SUMMARY The subject is more complex than you’d think but most people shouldn’t worry about not having a hot water valve in their washing machine and most people may indeed be better off without one.

Although the majority of people may (according to manufacturers) be better off with a cold fill only machine I can see many examples where washing machines would probably be better with a hot valve. Utilising an already hot supply of water can be cheaper and speed up some wash cycles.

However, because modern washing machines use very little water and it takes so long for most people’s hot water to actually run hot it needs a sophisticated washing machine to utilise it properly in all the different circumstances at people’s homes. At this present 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 of the many thousands of users not falling into this category.

Related: My original in depth article about why cold fill washing machines: Should I buy a cold fill washing machine or hot and cold fill?

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 as explained here – is a hot & cold fill washing machine more economical?

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