Is it cheaper to heat washing machine water by the machine or boiler?

narabanekeater

I guess the title says it all really. Our new machine can either heat the water itself or get our boiler to (hope that makes sence as we have gas central heating instant hot water) I do do a lot of washing due to 2 of my children being quite poorly. I do as much washing as possible on 40c

HappyMJ

Cheaper to heat via a gas boiler if your machine will take it.

Ken68

Depends on the length of pipe from the b oiler to your machine.
Can have lost heat on the way and as with a tap the drawn water won't be immediately hot.

50Twuncle

HappyMJ wrote: »

Cheaper to heat via a gas boiler if your machine will take it.

I agree - especially if your gas boiler is a modern condensing type - costs approx 5p per kwh - and with (up to 95% efficiency) - compared to electric heating (99% efficiency) of around 20p per kwh - it is much MUCH cheaper to heat water via Gas boiler.....

flusk

If you Google around (uk whitegoods hot fill) you can see that this is quite a contentious issue. As mentioned above I think a lot depends on how close your boiler is to the washing machine and whether or not you do a lot of hot washes (sounds like you don't).

Norman_Castle

Mine is only hot fill for washes over 40 degrees. Unless I have recently used the hot tap near the washing machine, the first 15 litres will be cold and therefore fully heated by the machine. This will also leave 15 litres of hot water unused in the hot pipe.

Nilrem

flusk wrote: »

If you Google around (uk whitegoods hot fill) you can see that this is quite a contentious issue. As mentioned above I think a lot depends on how close your boiler is to the washing machine and whether or not you do a lot of hot washes (sounds like you don't).

Also if you only do the washing at the time the boiler is on.

If the boiler is heating water in a tank, you're heating a lot of water up that may be sat there (gradually cooling and raising the temperature of your house*), for hours before it's needed.

I suspect it's swings and roundabouts, and will vary massively depending on your system and how often you have the water on, and how often you do the washing.
IE if you do one wash a day it's probably no cheaper to do it with water heated from the boiler than with it heated at the washer (especially with modern washing machines that don't use much water, or if you do 40/30c washes), but if you're doing a lot of washes (especially hot - 60c+) washes it's probably cheaper with preheated water.


*Not a problem in the winter when you might have the heating on, but in the summer...;)

jbainbridge

- modern washing machines use relatively little water
- the pipe from your tank or boiler will contain cold water
- combi boilers can take a little time to start heating the water (this is compounded by the fact that the machine doesn't generally take the intake of water all in one go)

... given the above it probably makes little differnce using a cold only fill.

HappyMJ

Norman_Castle wrote: »

Mine is only hot fill for washes over 40 degrees. Unless I have recently used the hot tap near the washing machine, the first 15 litres will be cold and therefore fully heated by the machine. This will also leave 15 litres of hot water unused in the hot pipe.

15 litres....that's a huge amount.....how big are your pipes?

That's about 80 metres from your hot water cylinder/boiler to the washing machine....assuming 15mm pipes.

narabanekeater

wow thnks for all your response. The machines approx 3m from my condensing boiler

cyclonebri1

Given near zero heat loss for heating within the washer, the small amount of water actually heated, against the dead leg of the system at both ends, and the heat loss when in the delivery pipe, I'd be very surprised if gas was cheaper. Didn't even factor in efficiency loss of less than new boiler.

Aren't condensing boilers only efficient when condensing?;);) that doesn't happen in 2 mins of water heating does it?