Which is more economical - hot and cold fill or cold fill?
I've written extensively about hot and cold fill verses cold fill only washing machines. I've been wanting to do a simple experiment to test one of the arguments for cold fill only and finally I've done it - is a hot and cold fill washing machine more economical than a cold fill?
Solution Summary
AI-generated from this discussion
This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.
Hot and cold fill versus cold fill washing machine economy depends on hot water source
- The problem
- The discussion asked whether a hot and cold fill washing machine is more economical to run than a cold-fill-only model.
- Likely cause
- No fault was discussed. The accepted answer says running cost depends mainly on how household hot water is produced, with pipe heat loss and appliance design also affecting the result.
- What fixed it
- The accepted answer concludes there is no universal winner. A hot and cold fill machine may be cheaper if the home's hot water is heated by gas. If hot water is produced by immersion or another direct electric method, savings are often small or absent and it may cost more overall. Heat losses from stored hot water and long pipe runs can reduce or remove any advantage. Modern lower-temperature washing also reduces the benefit of hot fill. No specific experiment results or measured repair-style outcome were provided.
- Checks to try
- Consider how the household hot water is heated
- Consider heat loss from stored hot water
- Consider the distance between the washing machine and hot water source
- Consider typical wash temperatures used
Safety: Disconnect the appliance from the electricity supply before any inspection. Work involving mains electrics, gas or sealed refrigeration systems should only be carried out by a suitably qualified appliance engineer.
1 Answer
In simple terms, a hot and cold fill washer is not automatically cheaper to run than a cold-fill-only one. It depends mainly on how your household hot water is produced.
1. If your hot water comes from a gas boiler A hot and cold fill machine can be more economical, because gas-heated water is usually cheaper than heating water inside the washing machine with electricity.
2. If your hot water comes from an immersion heater or direct electric cylinder There is often little or no saving, and it can even cost more. In that case the machine is effectively using electrically heated hot water anyway, just from a different source.
3. Heat losses matter Stored hot water in a cylinder loses heat over time, and hot water sitting in pipework cools between washes. A cold-fill machine only heats exactly what it needs, when it needs it.
4. Modern washing habits changed things Most washes now are 30°C or 40°C, and modern detergents are designed to work well at lower temperatures. A hot fill can sometimes bring in water that is hotter than ideal, so the machine has to dilute it or control the fill carefully.
5. Distance from the boiler/tank is important If the washing machine is a long way from the hot water source, quite a lot of hot water may never actually reach the machine during the fill. You pay to heat it, but it stays in the pipe.
So the old assumption that hot and cold fill is always more economical is no longer reliably true. It can be cheaper in some homes, but not all. The appliance design and your hot water system make the real difference.
If you want, I can also help compare the two using a real example with gas, immersion, or combi boiler costs.
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This answer was generated automatically by the WhitegoodsHelp AI Assistant. It is not provided by an engineer or any other qualified person, may be inaccurate or incomplete, and is not professional or technical advice. Do not rely on it. Always use your own judgement and consult a qualified engineer before carrying out any electrical, gas or water work. Use is entirely at your own risk. See our full Terms of Use.
SAFETY FIRST: READ BEFORE ACTING ON THIS GUIDANCE
Never work on a live appliance
Always unplug it at the mains before going near it with any tools.
Never attempt gas work
By law, gas appliances must only be worked on by a Gas Safe registered engineer. If your fault involves gas, stop and call a professional. Do not attempt it yourself.
Watch for sharp edges
Outer panels are smooth, but internal parts have sharp machined edges. Wear protective gloves and arm sleeves.
Water appliances can leak
Turn off the water supply before disconnecting any hoses.
Know your limits
If you are not confident testing or working inside the appliance, stop and call a professional.
AI guidance, not guaranteed
This response is generated automatically by the WhitegoodsHelp AI Assistant. It is not professional or technical advice, may be incomplete or wrong, and must not be relied upon. Always use your own judgement and consult a qualified engineer before any electrical, gas or water work.
This is general information only and is not professional advice. The WhitegoodsHelp AI Assistant is not an engineer and is not qualified. See our full Terms of Use.
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