"Warm Fill" or Even "Hot Fill" via petrol (gas or oil) water heaters is quite possible, at least on this side of the pond. However much will depend upon several factors including the setting of the boiler/water heater.
Boiler for our building delivers tap hot water at around 125F during warmer months, and it reaches the washer (first a Malber, then now Miele) which is located not a few feet away at nearly the same temp. After a long wash cycle in either, water drains at about ten or twenty degrees less. Much depended upon the ambient temerature of the washer, wash temperature of wash/rinse loads before and so forth.
For the record commercial laundromats in the United States do not have washers with heaters, but rely upon constantly circulating hot water and short cycles. The first does away with having to "purge" lines before a machine fills, so instant hot water is delivered. The next gives less time for water temperature to cool. Again, much will depend upon the boiler setting for making hot water.
Cold water for laundry purposes is usually defined as 85F, anything lower and most powdered detergents will not disperse, and or ingredients will not work. Liquid detergents probably can go a bit lower and not suffer affects in dispersion, some chemicals may not work properly, such as enzymes.
Cold Water Laundry:
In of itself isn't such a horrible thing. We've been through this again and again. Proper laundry technique revolves around four basic parameter; wash time, water temperature, chemicals, and mechanical action. If you alter any one, the others must be adjusted to compensate.
You can wash laundry in "cold" or "warm" water today because many detergents rely upon enzymes to break down soils and stains, rather than force, mechanical action and or high water temperatures. Indeed have soaked the most badly stained linens almost totally clean in warm or cold water. Yes, the things sat for several hours, but they were clean!
Bleaches, especially activated oxygen bleaches have been improved upon to give excellent results in water temperatures as low as "cold" (85F) with proper contact time. This innovation was behind Tide "Coldwater" powder, which though was not mentioned on the box, contained an activated oxygen bleaching system tweaked to work in cold water. Indeed P&G holds most if not all the patents in the United States for activated oxygen bleaching systems, and it is behind Tide with Bleach, Gain with Bleach and the rest of P&G's detergents that have the stuff.
Of course Americans by and large use chlorine bleach, and it works quite well in cold water. Higher temperatures merely speed up the reaction time. Regardless the work is done in about five minutes. Longer does not give better results, and can lead to textile damage. This is one reason many commercial laundries have a short "bleach" cycle after the wash, or use the first rinse.
Liquid Detergents - Cold Water Washing and "Mold"
Most if not all liquid detergents are in whole or part soap based and or contain surfactants almost similar to soap. Well soap, fat, and not enough not water leads to a gunky, cruddy mess. Just look at any drain drap of a kitchen sink, even when detergent washing up liquid is used and not pure soap.
While many liquid detergents do contain enzymes, they do not contain bleaches. Or rather they cannot contain bleaches and enzymes and the two aren't stable when mixed together. Liquid oxygen bleaches contain surfactants and OBA's but not enzymes.
Without some sort of oxygen or chlorine bleach to act as a sanitiser, doing the wash only in cold water can cause mold/gunk build up. Problem is many liquid laundry detergents will create high levels of froth if the wash temperature is above warm, and certianly at hot or boiling wash temps. Many washer help repair forums from the UK/EU recommend doing a boil wash with either a powdered detergent containing bleach or a washer cleaning cycle using soda crystals (washing soda), to break down the grease and shift biofilm.
Biofilm is what "germs" live off, and if it is not totally removed, the buggers will simply grow back.
It isn't any accident that both P&G and Henkel have introduced various bleaches and sanitisers as laundry additives. In Europe people are finding stains that used to shift with their powdered (bleach containing) detergents, are still there with most liquid or gel versions. In theory enzymes and high amounts of surfactants, along with polymers are supposed to reduce or remove the need for bleaches, but that isn't always true.
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