Could hot fill appliances make a come back?

waqasahmed

Ebac have always had hot fill 
Miele are pushing hot fill in their most expensive appliances, for washing machines / dishwashers

I've never had a hot fill before, and apparently they weren't amazing on the efficiency side of things, and now Miele has both the "solarsave" dishwashers that take hot fill as well as just...one hot fill washing machine which is also their most expensive washing machine

Given that they're now in the highest spec appliances, and also with the expressed aim of increasing efficiency with ever stringent EPC guidelines (and another overhaul in the future), could those things come back en masse?

Section62

waqasahmed said:

...could those things come back en masse?

Hot fill enables the use of stored hot water heated by solar or off-peak electricity, but in overall efficiency terms it may be better to store the electricity to operate a cold-fill WM at a convenient time.

Perhaps replace the heavy lumps of concrete used as part of the damper system with some heavy batteries and we could have a winner.

grumbler

Section62 said:

waqasahmed said:

...could those things come back en masse?

Hot fill enables the use of stored hot water heated by solar or off-peak electricity, 

Why only solar or electric, not gas that is now much cheaper to heat water than electricity?

GDB2222

grumbler said:

Section62 said:

waqasahmed said:

...could those things come back en masse?

Hot fill enables the use of stored hot water heated by solar or off-peak electricity, 

Why only solar or electric, not gas that is now much cheaper to heat water than electricity?

These machines use so little water, that the hot water from the tank just sits in the pipework and the machine just gets the cold water that was in the pipes. Hot fill only makes sense if there’s a very short distance between the tank and the machine. 

Section62

grumbler said:

Section62 said:

waqasahmed said:

...could those things come back en masse?

Hot fill enables the use of stored hot water heated by solar or off-peak electricity, 

Why only solar or electric, not gas that is now much cheaper to heat water than electricity?

Are there any off-peak gas tariffs yet?  If not, there isn't an obvious advantage to storing gas-heated water for use later.  The inefficiency of using hot+cold fill appliances (whether using stored or combi-heated water) is well documented.  The opportunity hot+cold fill provides is to be able to use the water which is heated at low cost at a more convenient time. Although using a cold fill WM during off-peak hours (or when generating solar) would be better.

I'm currently paying 11p (+VAT) for an off-peak kWh of electricity, compared to 10p (+VAT) per kWh for gas.

I don't know the exact efficiency of my boiler and hot water heating system, but I doubt it is anything like high enough to make it cheaper to heat water by gas than off-peak electricity, let alone "much cheaper".

EssexExile

As GDB says above, in the vast majority of homes the machine will have finished taking in water long before any hot water reaches it. Machines used to use use an awful lot more water than they do now, so the cost of heating the small amount used now is not as significant as it was.

grumbler

1L of water is about 6m of 15mm pipe.
Full cycle takes about 50L. Washing with hot water takes less, but much more than 1L.

Section62 said:

grumbler said:

Section62 said:

waqasahmed said:

...could those things come back en masse?

Hot fill enables the use of stored hot water heated by solar or off-peak electricity, 

Why only solar or electric, not gas that is now much cheaper to heat water than electricity?

 The inefficiency of using hot+cold fill appliances (whether using stored or combi-heated water) is well documented.  

Well documented that heating with electricity is more efficient? I don't think so. The boiler or the HW cylinder can be just few meters away.

I'm currently paying 11p (+VAT) for an off-peak kWh of electricity, compared to 10p (+VAT) per kWh for gas.

Well, switching to a two-rate tariff only for washing and dishwashing makes little sense for many people as you pay more during the day.

Jonboy_1984

Still wouldn’t want to pay to heat water to 55-65 degrees in the hot water tank only for the washing machine to mix with cold water back down to 30, so I wouldn’t buy one (unless I had a dedicated solar hot water array when I would need to think carefully).

Eldi_Dos

I know the technology has moved on but in the old days some machines could not tell if incoming water from the tank was too hot for the programme set, this could lead to shrinkage of woolens, not very money saving at all .

FFHillbilly

I think they could make a return, if you have a hot water cylinder and can heat water cheaper than on peak electric (ie gas or off peak elec, solar, biomass etc) then it makes sense to use that instead.
I'm sure a new generation of hot fill machines could work but they would need more sensors and control than the old ones

Jonboy_1984 said:

Still wouldn’t want to pay to heat water to 55-65 degrees in the hot water tank only for the washing machine to mix with cold water back down to 30, so I wouldn’t buy one (unless I had a dedicated solar hot water array when I would need to think carefully).

I'm sure the machine wouldn't actually cool the water and waste energy, it would just draw say 10L of hot water at 55degrees and mix it with 5 l of cold

waqasahmed

FFHillbilly said:

I think they could make a return, if you have a hot water cylinder and can heat water cheaper than on peak electric (ie gas or off peak elec, solar, biomass etc) then it makes sense to use that instead.
I'm sure a new generation of hot fill machines could work but they would need more sensors and control than the old ones

Jonboy_1984 said:

Still wouldn’t want to pay to heat water to 55-65 degrees in the hot water tank only for the washing machine to mix with cold water back down to 30, so I wouldn’t buy one (unless I had a dedicated solar hot water array when I would need to think carefully).

I'm sure the machine wouldn't actually cool the water and waste energy, it would just draw say 10L of hot water at 55degrees and mix it with 5 l of cold

I think that's likely the case given the Miele machines that do that tend to cost less to run